parsermodule.c revision 52318d6215f9f9626d38a9b81b52d411dbbdb36a
1/*  parsermodule.c
2 *
3 *  Copyright 1995-1996 by Fred L. Drake, Jr. and Virginia Polytechnic
4 *  Institute and State University, Blacksburg, Virginia, USA.
5 *  Portions copyright 1991-1995 by Stichting Mathematisch Centrum,
6 *  Amsterdam, The Netherlands.  Copying is permitted under the terms
7 *  associated with the main Python distribution, with the additional
8 *  restriction that this additional notice be included and maintained
9 *  on all distributed copies.
10 *
11 *  This module serves to replace the original parser module written
12 *  by Guido.  The functionality is not matched precisely, but the
13 *  original may be implemented on top of this.  This is desirable
14 *  since the source of the text to be parsed is now divorced from
15 *  this interface.
16 *
17 *  Unlike the prior interface, the ability to give a parse tree
18 *  produced by Python code as a tuple to the compiler is enabled by
19 *  this module.  See the documentation for more details.
20 *
21 *  I've added some annotations that help with the lint code-checking
22 *  program, but they're not complete by a long shot.  The real errors
23 *  that lint detects are gone, but there are still warnings with
24 *  Py_[X]DECREF() and Py_[X]INCREF() macros.  The lint annotations
25 *  look like "NOTE(...)".
26 */
27
28#include "Python.h"                     /* general Python API             */
29#include "graminit.h"                   /* symbols defined in the grammar */
30#include "node.h"                       /* internal parser structure      */
31#include "errcode.h"                    /* error codes for PyNode_*()     */
32#include "token.h"                      /* token definitions              */
33                                        /* ISTERMINAL() / ISNONTERMINAL() */
34#include "compile.h"                    /* PyNode_Compile()               */
35
36#ifdef lint
37#include <note.h>
38#else
39#define NOTE(x)
40#endif
41
42/*  String constants used to initialize module attributes.
43 *
44 */
45static char parser_copyright_string[] =
46"Copyright 1995-1996 by Virginia Polytechnic Institute & State\n\
47University, Blacksburg, Virginia, USA, and Fred L. Drake, Jr., Reston,\n\
48Virginia, USA.  Portions copyright 1991-1995 by Stichting Mathematisch\n\
49Centrum, Amsterdam, The Netherlands.";
50
51
52PyDoc_STRVAR(parser_doc_string,
53"This is an interface to Python's internal parser.");
54
55static char parser_version_string[] = "0.5";
56
57
58typedef PyObject* (*SeqMaker) (Py_ssize_t length);
59typedef int (*SeqInserter) (PyObject* sequence,
60                            Py_ssize_t index,
61                            PyObject* element);
62
63/*  The function below is copyrighted by Stichting Mathematisch Centrum.  The
64 *  original copyright statement is included below, and continues to apply
65 *  in full to the function immediately following.  All other material is
66 *  original, copyrighted by Fred L. Drake, Jr. and Virginia Polytechnic
67 *  Institute and State University.  Changes were made to comply with the
68 *  new naming conventions.  Added arguments to provide support for creating
69 *  lists as well as tuples, and optionally including the line numbers.
70 */
71
72
73static PyObject*
74node2tuple(node *n,                     /* node to convert               */
75           SeqMaker mkseq,              /* create sequence               */
76           SeqInserter addelem,         /* func. to add elem. in seq.    */
77           int lineno)                  /* include line numbers?         */
78{
79    if (n == NULL) {
80        Py_INCREF(Py_None);
81        return (Py_None);
82    }
83    if (ISNONTERMINAL(TYPE(n))) {
84        int i;
85        PyObject *v;
86        PyObject *w;
87
88        v = mkseq(1 + NCH(n) + (TYPE(n) == encoding_decl));
89        if (v == NULL)
90            return (v);
91        w = PyInt_FromLong(TYPE(n));
92        if (w == NULL) {
93            Py_DECREF(v);
94            return ((PyObject*) NULL);
95        }
96        (void) addelem(v, 0, w);
97        for (i = 0; i < NCH(n); i++) {
98            w = node2tuple(CHILD(n, i), mkseq, addelem, lineno);
99            if (w == NULL) {
100                Py_DECREF(v);
101                return ((PyObject*) NULL);
102            }
103            (void) addelem(v, i+1, w);
104        }
105
106        if (TYPE(n) == encoding_decl)
107            (void) addelem(v, i+1, PyString_FromString(STR(n)));
108        return (v);
109    }
110    else if (ISTERMINAL(TYPE(n))) {
111        PyObject *result = mkseq(2 + lineno);
112        if (result != NULL) {
113            (void) addelem(result, 0, PyInt_FromLong(TYPE(n)));
114            (void) addelem(result, 1, PyString_FromString(STR(n)));
115            if (lineno == 1)
116                (void) addelem(result, 2, PyInt_FromLong(n->n_lineno));
117        }
118        return (result);
119    }
120    else {
121        PyErr_SetString(PyExc_SystemError,
122                        "unrecognized parse tree node type");
123        return ((PyObject*) NULL);
124    }
125}
126/*
127 *  End of material copyrighted by Stichting Mathematisch Centrum.
128 */
129
130
131
132/*  There are two types of intermediate objects we're interested in:
133 *  'eval' and 'exec' types.  These constants can be used in the st_type
134 *  field of the object type to identify which any given object represents.
135 *  These should probably go in an external header to allow other extensions
136 *  to use them, but then, we really should be using C++ too.  ;-)
137 */
138
139#define PyST_EXPR  1
140#define PyST_SUITE 2
141
142
143/*  These are the internal objects and definitions required to implement the
144 *  ST type.  Most of the internal names are more reminiscent of the 'old'
145 *  naming style, but the code uses the new naming convention.
146 */
147
148static PyObject*
149parser_error = 0;
150
151
152typedef struct {
153    PyObject_HEAD                       /* standard object header           */
154    node* st_node;                      /* the node* returned by the parser */
155    int   st_type;                      /* EXPR or SUITE ?                  */
156} PyST_Object;
157
158
159static void parser_free(PyST_Object *st);
160static int parser_compare(PyST_Object *left, PyST_Object *right);
161static PyObject *parser_getattr(PyObject *self, char *name);
162
163
164static
165PyTypeObject PyST_Type = {
166    PyObject_HEAD_INIT(NULL)
167    0,
168    "parser.st",                        /* tp_name              */
169    (int) sizeof(PyST_Object),          /* tp_basicsize         */
170    0,                                  /* tp_itemsize          */
171    (destructor)parser_free,            /* tp_dealloc           */
172    0,                                  /* tp_print             */
173    parser_getattr,                     /* tp_getattr           */
174    0,                                  /* tp_setattr           */
175    (cmpfunc)parser_compare,            /* tp_compare           */
176    0,                                  /* tp_repr              */
177    0,                                  /* tp_as_number         */
178    0,                                  /* tp_as_sequence       */
179    0,                                  /* tp_as_mapping        */
180    0,                                  /* tp_hash              */
181    0,                                  /* tp_call              */
182    0,                                  /* tp_str               */
183    0,                                  /* tp_getattro          */
184    0,                                  /* tp_setattro          */
185
186    /* Functions to access object as input/output buffer */
187    0,                                  /* tp_as_buffer         */
188
189    Py_TPFLAGS_DEFAULT,                 /* tp_flags             */
190
191    /* __doc__ */
192    "Intermediate representation of a Python parse tree."
193};  /* PyST_Type */
194
195
196static int
197parser_compare_nodes(node *left, node *right)
198{
199    int j;
200
201    if (TYPE(left) < TYPE(right))
202        return (-1);
203
204    if (TYPE(right) < TYPE(left))
205        return (1);
206
207    if (ISTERMINAL(TYPE(left)))
208        return (strcmp(STR(left), STR(right)));
209
210    if (NCH(left) < NCH(right))
211        return (-1);
212
213    if (NCH(right) < NCH(left))
214        return (1);
215
216    for (j = 0; j < NCH(left); ++j) {
217        int v = parser_compare_nodes(CHILD(left, j), CHILD(right, j));
218
219        if (v != 0)
220            return (v);
221    }
222    return (0);
223}
224
225
226/*  int parser_compare(PyST_Object* left, PyST_Object* right)
227 *
228 *  Comparison function used by the Python operators ==, !=, <, >, <=, >=
229 *  This really just wraps a call to parser_compare_nodes() with some easy
230 *  checks and protection code.
231 *
232 */
233static int
234parser_compare(PyST_Object *left, PyST_Object *right)
235{
236    if (left == right)
237        return (0);
238
239    if ((left == 0) || (right == 0))
240        return (-1);
241
242    return (parser_compare_nodes(left->st_node, right->st_node));
243}
244
245
246/*  parser_newstobject(node* st)
247 *
248 *  Allocates a new Python object representing an ST.  This is simply the
249 *  'wrapper' object that holds a node* and allows it to be passed around in
250 *  Python code.
251 *
252 */
253static PyObject*
254parser_newstobject(node *st, int type)
255{
256    PyST_Object* o = PyObject_New(PyST_Object, &PyST_Type);
257
258    if (o != 0) {
259        o->st_node = st;
260        o->st_type = type;
261    }
262    else {
263        PyNode_Free(st);
264    }
265    return ((PyObject*)o);
266}
267
268
269/*  void parser_free(PyST_Object* st)
270 *
271 *  This is called by a del statement that reduces the reference count to 0.
272 *
273 */
274static void
275parser_free(PyST_Object *st)
276{
277    PyNode_Free(st->st_node);
278    PyObject_Del(st);
279}
280
281
282/*  parser_st2tuple(PyObject* self, PyObject* args, PyObject* kw)
283 *
284 *  This provides conversion from a node* to a tuple object that can be
285 *  returned to the Python-level caller.  The ST object is not modified.
286 *
287 */
288static PyObject*
289parser_st2tuple(PyST_Object *self, PyObject *args, PyObject *kw)
290{
291    PyObject *line_option = 0;
292    PyObject *res = 0;
293    int ok;
294
295    static char *keywords[] = {"ast", "line_info", NULL};
296
297    if (self == NULL) {
298        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|O:st2tuple", keywords,
299                                         &PyST_Type, &self, &line_option);
300    }
301    else
302        ok = PyArg_ParseTupleAndKeywords(args, kw, "|O:totuple", &keywords[1],
303                                         &line_option);
304    if (ok != 0) {
305        int lineno = 0;
306        if (line_option != NULL) {
307            lineno = (PyObject_IsTrue(line_option) != 0) ? 1 : 0;
308        }
309        /*
310         *  Convert ST into a tuple representation.  Use Guido's function,
311         *  since it's known to work already.
312         */
313        res = node2tuple(((PyST_Object*)self)->st_node,
314                         PyTuple_New, PyTuple_SetItem, lineno);
315    }
316    return (res);
317}
318
319
320/*  parser_st2list(PyObject* self, PyObject* args, PyObject* kw)
321 *
322 *  This provides conversion from a node* to a list object that can be
323 *  returned to the Python-level caller.  The ST object is not modified.
324 *
325 */
326static PyObject*
327parser_st2list(PyST_Object *self, PyObject *args, PyObject *kw)
328{
329    PyObject *line_option = 0;
330    PyObject *res = 0;
331    int ok;
332
333    static char *keywords[] = {"ast", "line_info", NULL};
334
335    if (self == NULL)
336        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|O:st2list", keywords,
337                                         &PyST_Type, &self, &line_option);
338    else
339        ok = PyArg_ParseTupleAndKeywords(args, kw, "|O:tolist", &keywords[1],
340                                         &line_option);
341    if (ok) {
342        int lineno = 0;
343        if (line_option != 0) {
344            lineno = PyObject_IsTrue(line_option) ? 1 : 0;
345        }
346        /*
347         *  Convert ST into a tuple representation.  Use Guido's function,
348         *  since it's known to work already.
349         */
350        res = node2tuple(self->st_node,
351                         PyList_New, PyList_SetItem, lineno);
352    }
353    return (res);
354}
355
356
357/*  parser_compilest(PyObject* self, PyObject* args)
358 *
359 *  This function creates code objects from the parse tree represented by
360 *  the passed-in data object.  An optional file name is passed in as well.
361 *
362 */
363static PyObject*
364parser_compilest(PyST_Object *self, PyObject *args, PyObject *kw)
365{
366    PyObject*     res = 0;
367    char*         str = "<syntax-tree>";
368    int ok;
369
370    static char *keywords[] = {"ast", "filename", NULL};
371
372    if (self == NULL)
373        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|s:compilest", keywords,
374                                         &PyST_Type, &self, &str);
375    else
376        ok = PyArg_ParseTupleAndKeywords(args, kw, "|s:compile", &keywords[1],
377                                         &str);
378
379    if (ok)
380        res = (PyObject *)PyNode_Compile(self->st_node, str);
381
382    return (res);
383}
384
385
386/*  PyObject* parser_isexpr(PyObject* self, PyObject* args)
387 *  PyObject* parser_issuite(PyObject* self, PyObject* args)
388 *
389 *  Checks the passed-in ST object to determine if it is an expression or
390 *  a statement suite, respectively.  The return is a Python truth value.
391 *
392 */
393static PyObject*
394parser_isexpr(PyST_Object *self, PyObject *args, PyObject *kw)
395{
396    PyObject* res = 0;
397    int ok;
398
399    static char *keywords[] = {"ast", NULL};
400
401    if (self == NULL)
402        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!:isexpr", keywords,
403                                         &PyST_Type, &self);
404    else
405        ok = PyArg_ParseTupleAndKeywords(args, kw, ":isexpr", &keywords[1]);
406
407    if (ok) {
408        /* Check to see if the ST represents an expression or not. */
409        res = (self->st_type == PyST_EXPR) ? Py_True : Py_False;
410        Py_INCREF(res);
411    }
412    return (res);
413}
414
415
416static PyObject*
417parser_issuite(PyST_Object *self, PyObject *args, PyObject *kw)
418{
419    PyObject* res = 0;
420    int ok;
421
422    static char *keywords[] = {"ast", NULL};
423
424    if (self == NULL)
425        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!:issuite", keywords,
426                                         &PyST_Type, &self);
427    else
428        ok = PyArg_ParseTupleAndKeywords(args, kw, ":issuite", &keywords[1]);
429
430    if (ok) {
431        /* Check to see if the ST represents an expression or not. */
432        res = (self->st_type == PyST_EXPR) ? Py_False : Py_True;
433        Py_INCREF(res);
434    }
435    return (res);
436}
437
438
439#define PUBLIC_METHOD_TYPE (METH_VARARGS|METH_KEYWORDS)
440
441static PyMethodDef
442parser_methods[] = {
443    {"compile",         (PyCFunction)parser_compilest,  PUBLIC_METHOD_TYPE,
444        PyDoc_STR("Compile this ST object into a code object.")},
445    {"isexpr",          (PyCFunction)parser_isexpr,     PUBLIC_METHOD_TYPE,
446        PyDoc_STR("Determines if this ST object was created from an expression.")},
447    {"issuite",         (PyCFunction)parser_issuite,    PUBLIC_METHOD_TYPE,
448        PyDoc_STR("Determines if this ST object was created from a suite.")},
449    {"tolist",          (PyCFunction)parser_st2list,    PUBLIC_METHOD_TYPE,
450        PyDoc_STR("Creates a list-tree representation of this ST.")},
451    {"totuple",         (PyCFunction)parser_st2tuple,   PUBLIC_METHOD_TYPE,
452        PyDoc_STR("Creates a tuple-tree representation of this ST.")},
453
454    {NULL, NULL, 0, NULL}
455};
456
457
458static PyObject*
459parser_getattr(PyObject *self, char *name)
460{
461    return (Py_FindMethod(parser_methods, self, name));
462}
463
464
465/*  err_string(char* message)
466 *
467 *  Sets the error string for an exception of type ParserError.
468 *
469 */
470static void
471err_string(char *message)
472{
473    PyErr_SetString(parser_error, message);
474}
475
476
477/*  PyObject* parser_do_parse(PyObject* args, int type)
478 *
479 *  Internal function to actually execute the parse and return the result if
480 *  successful or set an exception if not.
481 *
482 */
483static PyObject*
484parser_do_parse(PyObject *args, PyObject *kw, char *argspec, int type)
485{
486    char*     string = 0;
487    PyObject* res    = 0;
488
489    static char *keywords[] = {"source", NULL};
490
491    if (PyArg_ParseTupleAndKeywords(args, kw, argspec, keywords, &string)) {
492        node* n = PyParser_SimpleParseString(string,
493                                             (type == PyST_EXPR)
494                                             ? eval_input : file_input);
495
496	if (n)
497	    res = parser_newstobject(n, type);
498    }
499    return (res);
500}
501
502
503/*  PyObject* parser_expr(PyObject* self, PyObject* args)
504 *  PyObject* parser_suite(PyObject* self, PyObject* args)
505 *
506 *  External interfaces to the parser itself.  Which is called determines if
507 *  the parser attempts to recognize an expression ('eval' form) or statement
508 *  suite ('exec' form).  The real work is done by parser_do_parse() above.
509 *
510 */
511static PyObject*
512parser_expr(PyST_Object *self, PyObject *args, PyObject *kw)
513{
514    NOTE(ARGUNUSED(self))
515    return (parser_do_parse(args, kw, "s:expr", PyST_EXPR));
516}
517
518
519static PyObject*
520parser_suite(PyST_Object *self, PyObject *args, PyObject *kw)
521{
522    NOTE(ARGUNUSED(self))
523    return (parser_do_parse(args, kw, "s:suite", PyST_SUITE));
524}
525
526
527
528/*  This is the messy part of the code.  Conversion from a tuple to an ST
529 *  object requires that the input tuple be valid without having to rely on
530 *  catching an exception from the compiler.  This is done to allow the
531 *  compiler itself to remain fast, since most of its input will come from
532 *  the parser directly, and therefore be known to be syntactically correct.
533 *  This validation is done to ensure that we don't core dump the compile
534 *  phase, returning an exception instead.
535 *
536 *  Two aspects can be broken out in this code:  creating a node tree from
537 *  the tuple passed in, and verifying that it is indeed valid.  It may be
538 *  advantageous to expand the number of ST types to include funcdefs and
539 *  lambdadefs to take advantage of the optimizer, recognizing those STs
540 *  here.  They are not necessary, and not quite as useful in a raw form.
541 *  For now, let's get expressions and suites working reliably.
542 */
543
544
545static node* build_node_tree(PyObject *tuple);
546static int   validate_expr_tree(node *tree);
547static int   validate_file_input(node *tree);
548static int   validate_encoding_decl(node *tree);
549
550/*  PyObject* parser_tuple2st(PyObject* self, PyObject* args)
551 *
552 *  This is the public function, called from the Python code.  It receives a
553 *  single tuple object from the caller, and creates an ST object if the
554 *  tuple can be validated.  It does this by checking the first code of the
555 *  tuple, and, if acceptable, builds the internal representation.  If this
556 *  step succeeds, the internal representation is validated as fully as
557 *  possible with the various validate_*() routines defined below.
558 *
559 *  This function must be changed if support is to be added for PyST_FRAGMENT
560 *  ST objects.
561 *
562 */
563static PyObject*
564parser_tuple2st(PyST_Object *self, PyObject *args, PyObject *kw)
565{
566    NOTE(ARGUNUSED(self))
567    PyObject *st = 0;
568    PyObject *tuple;
569    node *tree;
570
571    static char *keywords[] = {"sequence", NULL};
572
573    if (!PyArg_ParseTupleAndKeywords(args, kw, "O:sequence2st", keywords,
574                                     &tuple))
575        return (0);
576    if (!PySequence_Check(tuple)) {
577        PyErr_SetString(PyExc_ValueError,
578                        "sequence2st() requires a single sequence argument");
579        return (0);
580    }
581    /*
582     *  Convert the tree to the internal form before checking it.
583     */
584    tree = build_node_tree(tuple);
585    if (tree != 0) {
586        int start_sym = TYPE(tree);
587        if (start_sym == eval_input) {
588            /*  Might be an eval form.  */
589            if (validate_expr_tree(tree))
590                st = parser_newstobject(tree, PyST_EXPR);
591            else
592                PyNode_Free(tree);
593        }
594        else if (start_sym == file_input) {
595            /*  This looks like an exec form so far.  */
596            if (validate_file_input(tree))
597                st = parser_newstobject(tree, PyST_SUITE);
598            else
599                PyNode_Free(tree);
600        }
601        else if (start_sym == encoding_decl) {
602            /* This looks like an encoding_decl so far. */
603            if (validate_encoding_decl(tree))
604                st = parser_newstobject(tree, PyST_SUITE);
605            else
606                PyNode_Free(tree);
607        }
608        else {
609            /*  This is a fragment, at best. */
610            PyNode_Free(tree);
611            err_string("parse tree does not use a valid start symbol");
612        }
613    }
614    /*  Make sure we throw an exception on all errors.  We should never
615     *  get this, but we'd do well to be sure something is done.
616     */
617    if (st == NULL && !PyErr_Occurred())
618        err_string("unspecified ST error occurred");
619
620    return st;
621}
622
623
624/*  node* build_node_children()
625 *
626 *  Iterate across the children of the current non-terminal node and build
627 *  their structures.  If successful, return the root of this portion of
628 *  the tree, otherwise, 0.  Any required exception will be specified already,
629 *  and no memory will have been deallocated.
630 *
631 */
632static node*
633build_node_children(PyObject *tuple, node *root, int *line_num)
634{
635    Py_ssize_t len = PyObject_Size(tuple);
636    Py_ssize_t i;
637    int  err;
638
639    for (i = 1; i < len; ++i) {
640        /* elem must always be a sequence, however simple */
641        PyObject* elem = PySequence_GetItem(tuple, i);
642        int ok = elem != NULL;
643        long  type = 0;
644        char *strn = 0;
645
646        if (ok)
647            ok = PySequence_Check(elem);
648        if (ok) {
649            PyObject *temp = PySequence_GetItem(elem, 0);
650            if (temp == NULL)
651                ok = 0;
652            else {
653                ok = PyInt_Check(temp);
654                if (ok)
655                    type = PyInt_AS_LONG(temp);
656                Py_DECREF(temp);
657            }
658        }
659        if (!ok) {
660            PyObject *err = Py_BuildValue("os", elem,
661                                          "Illegal node construct.");
662            PyErr_SetObject(parser_error, err);
663            Py_XDECREF(err);
664            Py_XDECREF(elem);
665            return (0);
666        }
667        if (ISTERMINAL(type)) {
668            Py_ssize_t len = PyObject_Size(elem);
669            PyObject *temp;
670
671            if ((len != 2) && (len != 3)) {
672                err_string("terminal nodes must have 2 or 3 entries");
673                return 0;
674            }
675            temp = PySequence_GetItem(elem, 1);
676            if (temp == NULL)
677                return 0;
678            if (!PyString_Check(temp)) {
679                PyErr_Format(parser_error,
680                             "second item in terminal node must be a string,"
681                             " found %s",
682                             temp->ob_type->tp_name);
683                Py_DECREF(temp);
684                return 0;
685            }
686            if (len == 3) {
687                PyObject *o = PySequence_GetItem(elem, 2);
688                if (o != NULL) {
689                    if (PyInt_Check(o))
690                        *line_num = PyInt_AS_LONG(o);
691                    else {
692                        PyErr_Format(parser_error,
693                                     "third item in terminal node must be an"
694                                     " integer, found %s",
695				     temp->ob_type->tp_name);
696                        Py_DECREF(o);
697                        Py_DECREF(temp);
698                        return 0;
699                    }
700                    Py_DECREF(o);
701                }
702            }
703            len = PyString_GET_SIZE(temp) + 1;
704            strn = (char *)PyObject_MALLOC(len);
705            if (strn != NULL)
706                (void) memcpy(strn, PyString_AS_STRING(temp), len);
707            Py_DECREF(temp);
708        }
709        else if (!ISNONTERMINAL(type)) {
710            /*
711             *  It has to be one or the other; this is an error.
712             *  Throw an exception.
713             */
714            PyObject *err = Py_BuildValue("os", elem, "unknown node type.");
715            PyErr_SetObject(parser_error, err);
716            Py_XDECREF(err);
717            Py_XDECREF(elem);
718            return (0);
719        }
720        err = PyNode_AddChild(root, type, strn, *line_num, 0);
721        if (err == E_NOMEM) {
722            PyObject_FREE(strn);
723            return (node *) PyErr_NoMemory();
724        }
725        if (err == E_OVERFLOW) {
726            PyObject_FREE(strn);
727            PyErr_SetString(PyExc_ValueError,
728                            "unsupported number of child nodes");
729            return NULL;
730        }
731
732        if (ISNONTERMINAL(type)) {
733            node* new_child = CHILD(root, i - 1);
734
735            if (new_child != build_node_children(elem, new_child, line_num)) {
736                Py_XDECREF(elem);
737                return (0);
738            }
739        }
740        else if (type == NEWLINE) {     /* It's true:  we increment the     */
741            ++(*line_num);              /* line number *after* the newline! */
742        }
743        Py_XDECREF(elem);
744    }
745    return root;
746}
747
748
749static node*
750build_node_tree(PyObject *tuple)
751{
752    node* res = 0;
753    PyObject *temp = PySequence_GetItem(tuple, 0);
754    long num = -1;
755
756    if (temp != NULL)
757        num = PyInt_AsLong(temp);
758    Py_XDECREF(temp);
759    if (ISTERMINAL(num)) {
760        /*
761         *  The tuple is simple, but it doesn't start with a start symbol.
762         *  Throw an exception now and be done with it.
763         */
764        tuple = Py_BuildValue("os", tuple,
765                    "Illegal syntax-tree; cannot start with terminal symbol.");
766        PyErr_SetObject(parser_error, tuple);
767        Py_XDECREF(tuple);
768    }
769    else if (ISNONTERMINAL(num)) {
770        /*
771         *  Not efficient, but that can be handled later.
772         */
773        int line_num = 0;
774        PyObject *encoding = NULL;
775
776        if (num == encoding_decl) {
777            encoding = PySequence_GetItem(tuple, 2);
778            /* tuple isn't borrowed anymore here, need to DECREF */
779            tuple = PySequence_GetSlice(tuple, 0, 2);
780        }
781        res = PyNode_New(num);
782        if (res != NULL) {
783            if (res != build_node_children(tuple, res, &line_num)) {
784                PyNode_Free(res);
785                res = NULL;
786            }
787            if (res && encoding) {
788                Py_ssize_t len;
789                len = PyString_GET_SIZE(encoding) + 1;
790                res->n_str = (char *)PyObject_MALLOC(len);
791                if (res->n_str != NULL)
792                    (void) memcpy(res->n_str, PyString_AS_STRING(encoding), len);
793                Py_DECREF(encoding);
794                Py_DECREF(tuple);
795            }
796        }
797    }
798    else {
799        /*  The tuple is illegal -- if the number is neither TERMINAL nor
800         *  NONTERMINAL, we can't use it.  Not sure the implementation
801         *  allows this condition, but the API doesn't preclude it.
802         */
803        PyObject *err = Py_BuildValue("os", tuple,
804                                      "Illegal component tuple.");
805        PyErr_SetObject(parser_error, err);
806        Py_XDECREF(err);
807    }
808
809    return (res);
810}
811
812
813/*
814 *  Validation routines used within the validation section:
815 */
816static int validate_terminal(node *terminal, int type, char *string);
817
818#define validate_ampersand(ch)  validate_terminal(ch,      AMPER, "&")
819#define validate_circumflex(ch) validate_terminal(ch, CIRCUMFLEX, "^")
820#define validate_colon(ch)      validate_terminal(ch,      COLON, ":")
821#define validate_comma(ch)      validate_terminal(ch,      COMMA, ",")
822#define validate_dedent(ch)     validate_terminal(ch,     DEDENT, "")
823#define validate_equal(ch)      validate_terminal(ch,      EQUAL, "=")
824#define validate_indent(ch)     validate_terminal(ch,     INDENT, (char*)NULL)
825#define validate_lparen(ch)     validate_terminal(ch,       LPAR, "(")
826#define validate_newline(ch)    validate_terminal(ch,    NEWLINE, (char*)NULL)
827#define validate_rparen(ch)     validate_terminal(ch,       RPAR, ")")
828#define validate_semi(ch)       validate_terminal(ch,       SEMI, ";")
829#define validate_star(ch)       validate_terminal(ch,       STAR, "*")
830#define validate_vbar(ch)       validate_terminal(ch,       VBAR, "|")
831#define validate_doublestar(ch) validate_terminal(ch, DOUBLESTAR, "**")
832#define validate_dot(ch)        validate_terminal(ch,        DOT, ".")
833#define validate_at(ch)         validate_terminal(ch,         AT, "@")
834#define validate_name(ch, str)  validate_terminal(ch,       NAME, str)
835
836#define VALIDATER(n)    static int validate_##n(node *tree)
837
838VALIDATER(node);                VALIDATER(small_stmt);
839VALIDATER(class);               VALIDATER(node);
840VALIDATER(parameters);          VALIDATER(suite);
841VALIDATER(testlist);            VALIDATER(varargslist);
842VALIDATER(fpdef);               VALIDATER(fplist);
843VALIDATER(stmt);                VALIDATER(simple_stmt);
844VALIDATER(expr_stmt);           VALIDATER(power);
845VALIDATER(print_stmt);          VALIDATER(del_stmt);
846VALIDATER(return_stmt);         VALIDATER(list_iter);
847VALIDATER(raise_stmt);          VALIDATER(import_stmt);
848VALIDATER(import_name);         VALIDATER(import_from);
849VALIDATER(global_stmt);         VALIDATER(list_if);
850VALIDATER(assert_stmt);         VALIDATER(list_for);
851VALIDATER(compound_stmt);
852VALIDATER(while);               VALIDATER(for);
853VALIDATER(try);                 VALIDATER(except_clause);
854VALIDATER(test);                VALIDATER(and_test);
855VALIDATER(not_test);            VALIDATER(comparison);
856VALIDATER(comp_op);             VALIDATER(expr);
857VALIDATER(xor_expr);            VALIDATER(and_expr);
858VALIDATER(shift_expr);          VALIDATER(arith_expr);
859VALIDATER(term);                VALIDATER(factor);
860VALIDATER(atom);                VALIDATER(lambdef);
861VALIDATER(trailer);             VALIDATER(subscript);
862VALIDATER(subscriptlist);       VALIDATER(sliceop);
863VALIDATER(exprlist);            VALIDATER(dictsetmaker);
864VALIDATER(arglist);             VALIDATER(argument);
865VALIDATER(listmaker);           VALIDATER(yield_stmt);
866VALIDATER(testlist1);           VALIDATER(gen_for);
867VALIDATER(gen_iter);            VALIDATER(gen_if);
868VALIDATER(testlist_gexp);	VALIDATER(yield_expr);
869VALIDATER(yield_or_testlist);	VALIDATER(or_test);
870VALIDATER(old_test); 		VALIDATER(old_lambdef);
871
872#undef VALIDATER
873
874#define is_even(n)      (((n) & 1) == 0)
875#define is_odd(n)       (((n) & 1) == 1)
876
877
878static int
879validate_ntype(node *n, int t)
880{
881    if (TYPE(n) != t) {
882        PyErr_Format(parser_error, "Expected node type %d, got %d.",
883                     t, TYPE(n));
884        return 0;
885    }
886    return 1;
887}
888
889
890/*  Verifies that the number of child nodes is exactly 'num', raising
891 *  an exception if it isn't.  The exception message does not indicate
892 *  the exact number of nodes, allowing this to be used to raise the
893 *  "right" exception when the wrong number of nodes is present in a
894 *  specific variant of a statement's syntax.  This is commonly used
895 *  in that fashion.
896 */
897static int
898validate_numnodes(node *n, int num, const char *const name)
899{
900    if (NCH(n) != num) {
901        PyErr_Format(parser_error,
902                     "Illegal number of children for %s node.", name);
903        return 0;
904    }
905    return 1;
906}
907
908
909static int
910validate_terminal(node *terminal, int type, char *string)
911{
912    int res = (validate_ntype(terminal, type)
913               && ((string == 0) || (strcmp(string, STR(terminal)) == 0)));
914
915    if (!res && !PyErr_Occurred()) {
916        PyErr_Format(parser_error,
917                     "Illegal terminal: expected \"%s\"", string);
918    }
919    return (res);
920}
921
922
923/*  X (',' X) [',']
924 */
925static int
926validate_repeating_list(node *tree, int ntype, int (*vfunc)(node *),
927                        const char *const name)
928{
929    int nch = NCH(tree);
930    int res = (nch && validate_ntype(tree, ntype)
931               && vfunc(CHILD(tree, 0)));
932
933    if (!res && !PyErr_Occurred())
934        (void) validate_numnodes(tree, 1, name);
935    else {
936        if (is_even(nch))
937            res = validate_comma(CHILD(tree, --nch));
938        if (res && nch > 1) {
939            int pos = 1;
940            for ( ; res && pos < nch; pos += 2)
941                res = (validate_comma(CHILD(tree, pos))
942                       && vfunc(CHILD(tree, pos + 1)));
943        }
944    }
945    return (res);
946}
947
948
949/*  validate_class()
950 *
951 *  classdef:
952 *      'class' NAME ['(' testlist ')'] ':' suite
953 */
954static int
955validate_class(node *tree)
956{
957    int nch = NCH(tree);
958    int res = (validate_ntype(tree, classdef) &&
959	       	((nch == 4) || (nch == 6) || (nch == 7)));
960
961    if (res) {
962        res = (validate_name(CHILD(tree, 0), "class")
963               && validate_ntype(CHILD(tree, 1), NAME)
964               && validate_colon(CHILD(tree, nch - 2))
965               && validate_suite(CHILD(tree, nch - 1)));
966    }
967    else {
968        (void) validate_numnodes(tree, 4, "class");
969    }
970
971    if (res) {
972	if (nch == 7) {
973		res = ((validate_lparen(CHILD(tree, 2)) &&
974			validate_testlist(CHILD(tree, 3)) &&
975			validate_rparen(CHILD(tree, 4))));
976	}
977	else if (nch == 6) {
978		res = (validate_lparen(CHILD(tree,2)) &&
979			validate_rparen(CHILD(tree,3)));
980	}
981    }
982    return (res);
983}
984
985
986/*  if_stmt:
987 *      'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
988 */
989static int
990validate_if(node *tree)
991{
992    int nch = NCH(tree);
993    int res = (validate_ntype(tree, if_stmt)
994               && (nch >= 4)
995               && validate_name(CHILD(tree, 0), "if")
996               && validate_test(CHILD(tree, 1))
997               && validate_colon(CHILD(tree, 2))
998               && validate_suite(CHILD(tree, 3)));
999
1000    if (res && ((nch % 4) == 3)) {
1001        /*  ... 'else' ':' suite  */
1002        res = (validate_name(CHILD(tree, nch - 3), "else")
1003               && validate_colon(CHILD(tree, nch - 2))
1004               && validate_suite(CHILD(tree, nch - 1)));
1005        nch -= 3;
1006    }
1007    else if (!res && !PyErr_Occurred())
1008        (void) validate_numnodes(tree, 4, "if");
1009    if ((nch % 4) != 0)
1010        /* Will catch the case for nch < 4 */
1011        res = validate_numnodes(tree, 0, "if");
1012    else if (res && (nch > 4)) {
1013        /*  ... ('elif' test ':' suite)+ ...  */
1014        int j = 4;
1015        while ((j < nch) && res) {
1016            res = (validate_name(CHILD(tree, j), "elif")
1017                   && validate_colon(CHILD(tree, j + 2))
1018                   && validate_test(CHILD(tree, j + 1))
1019                   && validate_suite(CHILD(tree, j + 3)));
1020            j += 4;
1021        }
1022    }
1023    return (res);
1024}
1025
1026
1027/*  parameters:
1028 *      '(' [varargslist] ')'
1029 *
1030 */
1031static int
1032validate_parameters(node *tree)
1033{
1034    int nch = NCH(tree);
1035    int res = validate_ntype(tree, parameters) && ((nch == 2) || (nch == 3));
1036
1037    if (res) {
1038        res = (validate_lparen(CHILD(tree, 0))
1039               && validate_rparen(CHILD(tree, nch - 1)));
1040        if (res && (nch == 3))
1041            res = validate_varargslist(CHILD(tree, 1));
1042    }
1043    else {
1044        (void) validate_numnodes(tree, 2, "parameters");
1045    }
1046    return (res);
1047}
1048
1049
1050/*  validate_suite()
1051 *
1052 *  suite:
1053 *      simple_stmt
1054 *    | NEWLINE INDENT stmt+ DEDENT
1055 */
1056static int
1057validate_suite(node *tree)
1058{
1059    int nch = NCH(tree);
1060    int res = (validate_ntype(tree, suite) && ((nch == 1) || (nch >= 4)));
1061
1062    if (res && (nch == 1))
1063        res = validate_simple_stmt(CHILD(tree, 0));
1064    else if (res) {
1065        /*  NEWLINE INDENT stmt+ DEDENT  */
1066        res = (validate_newline(CHILD(tree, 0))
1067               && validate_indent(CHILD(tree, 1))
1068               && validate_stmt(CHILD(tree, 2))
1069               && validate_dedent(CHILD(tree, nch - 1)));
1070
1071        if (res && (nch > 4)) {
1072            int i = 3;
1073            --nch;                      /* forget the DEDENT     */
1074            for ( ; res && (i < nch); ++i)
1075                res = validate_stmt(CHILD(tree, i));
1076        }
1077        else if (nch < 4)
1078            res = validate_numnodes(tree, 4, "suite");
1079    }
1080    return (res);
1081}
1082
1083
1084static int
1085validate_testlist(node *tree)
1086{
1087    return (validate_repeating_list(tree, testlist,
1088                                    validate_test, "testlist"));
1089}
1090
1091
1092static int
1093validate_testlist1(node *tree)
1094{
1095    return (validate_repeating_list(tree, testlist1,
1096                                    validate_test, "testlist1"));
1097}
1098
1099
1100static int
1101validate_testlist_safe(node *tree)
1102{
1103    return (validate_repeating_list(tree, testlist_safe,
1104                                    validate_old_test, "testlist_safe"));
1105}
1106
1107
1108/* '*' NAME [',' '**' NAME] | '**' NAME
1109 */
1110static int
1111validate_varargslist_trailer(node *tree, int start)
1112{
1113    int nch = NCH(tree);
1114    int res = 0;
1115    int sym;
1116
1117    if (nch <= start) {
1118        err_string("expected variable argument trailer for varargslist");
1119        return 0;
1120    }
1121    sym = TYPE(CHILD(tree, start));
1122    if (sym == STAR) {
1123        /*
1124         *  ('*' NAME [',' '**' NAME]
1125         */
1126        if (nch-start == 2)
1127            res = validate_name(CHILD(tree, start+1), NULL);
1128        else if (nch-start == 5)
1129            res = (validate_name(CHILD(tree, start+1), NULL)
1130                   && validate_comma(CHILD(tree, start+2))
1131                   && validate_doublestar(CHILD(tree, start+3))
1132                   && validate_name(CHILD(tree, start+4), NULL));
1133    }
1134    else if (sym == DOUBLESTAR) {
1135        /*
1136         *  '**' NAME
1137         */
1138        if (nch-start == 2)
1139            res = validate_name(CHILD(tree, start+1), NULL);
1140    }
1141    if (!res)
1142        err_string("illegal variable argument trailer for varargslist");
1143    return res;
1144}
1145
1146
1147/*  validate_varargslist()
1148 *
1149 *  varargslist:
1150 *      (fpdef ['=' test] ',')*
1151 *           ('*' NAME [',' '**' NAME]
1152 *         | '**' NAME)
1153 *    | fpdef ['=' test] (',' fpdef ['=' test])* [',']
1154 *
1155 */
1156static int
1157validate_varargslist(node *tree)
1158{
1159    int nch = NCH(tree);
1160    int res = validate_ntype(tree, varargslist) && (nch != 0);
1161    int sym;
1162
1163    if (!res)
1164        return 0;
1165    if (nch < 1) {
1166        err_string("varargslist missing child nodes");
1167        return 0;
1168    }
1169    sym = TYPE(CHILD(tree, 0));
1170    if (sym == STAR || sym == DOUBLESTAR)
1171        /* whole thing matches:
1172         *      '*' NAME [',' '**' NAME] | '**' NAME
1173         */
1174        res = validate_varargslist_trailer(tree, 0);
1175    else if (sym == fpdef) {
1176        int i = 0;
1177
1178        sym = TYPE(CHILD(tree, nch-1));
1179        if (sym == NAME) {
1180            /*
1181             *   (fpdef ['=' test] ',')+
1182             *       ('*' NAME [',' '**' NAME]
1183             *     | '**' NAME)
1184             */
1185            /* skip over (fpdef ['=' test] ',')+ */
1186            while (res && (i+2 <= nch)) {
1187                res = validate_fpdef(CHILD(tree, i));
1188                ++i;
1189                if (res && TYPE(CHILD(tree, i)) == EQUAL && (i+2 <= nch)) {
1190                    res = (validate_equal(CHILD(tree, i))
1191                           && validate_test(CHILD(tree, i+1)));
1192                    if (res)
1193                        i += 2;
1194                }
1195                if (res && i < nch) {
1196                    res = validate_comma(CHILD(tree, i));
1197                    ++i;
1198                    if (res && i < nch
1199                        && (TYPE(CHILD(tree, i)) == DOUBLESTAR
1200                            || TYPE(CHILD(tree, i)) == STAR))
1201                        break;
1202                }
1203            }
1204            /* ... '*' NAME [',' '**' NAME] | '**' NAME
1205             * i --^^^
1206             */
1207            if (res)
1208                res = validate_varargslist_trailer(tree, i);
1209        }
1210        else {
1211            /*
1212             *  fpdef ['=' test] (',' fpdef ['=' test])* [',']
1213             */
1214            /* strip trailing comma node */
1215            if (sym == COMMA) {
1216                res = validate_comma(CHILD(tree, nch-1));
1217                if (!res)
1218                    return 0;
1219                --nch;
1220            }
1221            /*
1222             *  fpdef ['=' test] (',' fpdef ['=' test])*
1223             */
1224            res = validate_fpdef(CHILD(tree, 0));
1225            ++i;
1226            if (res && (i+2 <= nch) && TYPE(CHILD(tree, i)) == EQUAL) {
1227                res = (validate_equal(CHILD(tree, i))
1228                       && validate_test(CHILD(tree, i+1)));
1229                i += 2;
1230            }
1231            /*
1232             *  ... (',' fpdef ['=' test])*
1233             *  i ---^^^
1234             */
1235            while (res && (nch - i) >= 2) {
1236                res = (validate_comma(CHILD(tree, i))
1237                       && validate_fpdef(CHILD(tree, i+1)));
1238                i += 2;
1239                if (res && (nch - i) >= 2 && TYPE(CHILD(tree, i)) == EQUAL) {
1240                    res = (validate_equal(CHILD(tree, i))
1241                           && validate_test(CHILD(tree, i+1)));
1242                    i += 2;
1243                }
1244            }
1245            if (res && nch - i != 0) {
1246                res = 0;
1247                err_string("illegal formation for varargslist");
1248            }
1249        }
1250    }
1251    return res;
1252}
1253
1254
1255/*  list_iter:  list_for | list_if
1256 */
1257static int
1258validate_list_iter(node *tree)
1259{
1260    int res = (validate_ntype(tree, list_iter)
1261               && validate_numnodes(tree, 1, "list_iter"));
1262    if (res && TYPE(CHILD(tree, 0)) == list_for)
1263        res = validate_list_for(CHILD(tree, 0));
1264    else
1265        res = validate_list_if(CHILD(tree, 0));
1266
1267    return res;
1268}
1269
1270/*  gen_iter:  gen_for | gen_if
1271 */
1272static int
1273validate_gen_iter(node *tree)
1274{
1275    int res = (validate_ntype(tree, gen_iter)
1276               && validate_numnodes(tree, 1, "gen_iter"));
1277    if (res && TYPE(CHILD(tree, 0)) == gen_for)
1278        res = validate_gen_for(CHILD(tree, 0));
1279    else
1280        res = validate_gen_if(CHILD(tree, 0));
1281
1282    return res;
1283}
1284
1285/*  list_for:  'for' exprlist 'in' testlist [list_iter]
1286 */
1287static int
1288validate_list_for(node *tree)
1289{
1290    int nch = NCH(tree);
1291    int res;
1292
1293    if (nch == 5)
1294        res = validate_list_iter(CHILD(tree, 4));
1295    else
1296        res = validate_numnodes(tree, 4, "list_for");
1297
1298    if (res)
1299        res = (validate_name(CHILD(tree, 0), "for")
1300               && validate_exprlist(CHILD(tree, 1))
1301               && validate_name(CHILD(tree, 2), "in")
1302               && validate_testlist_safe(CHILD(tree, 3)));
1303
1304    return res;
1305}
1306
1307/*  gen_for:  'for' exprlist 'in' test [gen_iter]
1308 */
1309static int
1310validate_gen_for(node *tree)
1311{
1312    int nch = NCH(tree);
1313    int res;
1314
1315    if (nch == 5)
1316        res = validate_gen_iter(CHILD(tree, 4));
1317    else
1318        res = validate_numnodes(tree, 4, "gen_for");
1319
1320    if (res)
1321        res = (validate_name(CHILD(tree, 0), "for")
1322               && validate_exprlist(CHILD(tree, 1))
1323               && validate_name(CHILD(tree, 2), "in")
1324               && validate_or_test(CHILD(tree, 3)));
1325
1326    return res;
1327}
1328
1329/*  list_if:  'if' old_test [list_iter]
1330 */
1331static int
1332validate_list_if(node *tree)
1333{
1334    int nch = NCH(tree);
1335    int res;
1336
1337    if (nch == 3)
1338        res = validate_list_iter(CHILD(tree, 2));
1339    else
1340        res = validate_numnodes(tree, 2, "list_if");
1341
1342    if (res)
1343        res = (validate_name(CHILD(tree, 0), "if")
1344               && validate_old_test(CHILD(tree, 1)));
1345
1346    return res;
1347}
1348
1349/*  gen_if:  'if' old_test [gen_iter]
1350 */
1351static int
1352validate_gen_if(node *tree)
1353{
1354    int nch = NCH(tree);
1355    int res;
1356
1357    if (nch == 3)
1358        res = validate_gen_iter(CHILD(tree, 2));
1359    else
1360        res = validate_numnodes(tree, 2, "gen_if");
1361
1362    if (res)
1363        res = (validate_name(CHILD(tree, 0), "if")
1364               && validate_old_test(CHILD(tree, 1)));
1365
1366    return res;
1367}
1368
1369/*  validate_fpdef()
1370 *
1371 *  fpdef:
1372 *      NAME
1373 *    | '(' fplist ')'
1374 */
1375static int
1376validate_fpdef(node *tree)
1377{
1378    int nch = NCH(tree);
1379    int res = validate_ntype(tree, fpdef);
1380
1381    if (res) {
1382        if (nch == 1)
1383            res = validate_ntype(CHILD(tree, 0), NAME);
1384        else if (nch == 3)
1385            res = (validate_lparen(CHILD(tree, 0))
1386                   && validate_fplist(CHILD(tree, 1))
1387                   && validate_rparen(CHILD(tree, 2)));
1388        else
1389            res = validate_numnodes(tree, 1, "fpdef");
1390    }
1391    return (res);
1392}
1393
1394
1395static int
1396validate_fplist(node *tree)
1397{
1398    return (validate_repeating_list(tree, fplist,
1399                                    validate_fpdef, "fplist"));
1400}
1401
1402
1403/*  simple_stmt | compound_stmt
1404 *
1405 */
1406static int
1407validate_stmt(node *tree)
1408{
1409    int res = (validate_ntype(tree, stmt)
1410               && validate_numnodes(tree, 1, "stmt"));
1411
1412    if (res) {
1413        tree = CHILD(tree, 0);
1414
1415        if (TYPE(tree) == simple_stmt)
1416            res = validate_simple_stmt(tree);
1417        else
1418            res = validate_compound_stmt(tree);
1419    }
1420    return (res);
1421}
1422
1423
1424/*  small_stmt (';' small_stmt)* [';'] NEWLINE
1425 *
1426 */
1427static int
1428validate_simple_stmt(node *tree)
1429{
1430    int nch = NCH(tree);
1431    int res = (validate_ntype(tree, simple_stmt)
1432               && (nch >= 2)
1433               && validate_small_stmt(CHILD(tree, 0))
1434               && validate_newline(CHILD(tree, nch - 1)));
1435
1436    if (nch < 2)
1437        res = validate_numnodes(tree, 2, "simple_stmt");
1438    --nch;                              /* forget the NEWLINE    */
1439    if (res && is_even(nch))
1440        res = validate_semi(CHILD(tree, --nch));
1441    if (res && (nch > 2)) {
1442        int i;
1443
1444        for (i = 1; res && (i < nch); i += 2)
1445            res = (validate_semi(CHILD(tree, i))
1446                   && validate_small_stmt(CHILD(tree, i + 1)));
1447    }
1448    return (res);
1449}
1450
1451
1452static int
1453validate_small_stmt(node *tree)
1454{
1455    int nch = NCH(tree);
1456    int res = validate_numnodes(tree, 1, "small_stmt");
1457
1458    if (res) {
1459        int ntype = TYPE(CHILD(tree, 0));
1460
1461        if (  (ntype == expr_stmt)
1462              || (ntype == print_stmt)
1463              || (ntype == del_stmt)
1464              || (ntype == pass_stmt)
1465              || (ntype == flow_stmt)
1466              || (ntype == import_stmt)
1467              || (ntype == global_stmt)
1468              || (ntype == assert_stmt))
1469            res = validate_node(CHILD(tree, 0));
1470        else {
1471            res = 0;
1472            err_string("illegal small_stmt child type");
1473        }
1474    }
1475    else if (nch == 1) {
1476        res = 0;
1477        PyErr_Format(parser_error,
1478                     "Unrecognized child node of small_stmt: %d.",
1479                     TYPE(CHILD(tree, 0)));
1480    }
1481    return (res);
1482}
1483
1484
1485/*  compound_stmt:
1486 *      if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef
1487 */
1488static int
1489validate_compound_stmt(node *tree)
1490{
1491    int res = (validate_ntype(tree, compound_stmt)
1492               && validate_numnodes(tree, 1, "compound_stmt"));
1493    int ntype;
1494
1495    if (!res)
1496        return (0);
1497
1498    tree = CHILD(tree, 0);
1499    ntype = TYPE(tree);
1500    if (  (ntype == if_stmt)
1501          || (ntype == while_stmt)
1502          || (ntype == for_stmt)
1503          || (ntype == try_stmt)
1504          || (ntype == funcdef)
1505          || (ntype == classdef))
1506        res = validate_node(tree);
1507    else {
1508        res = 0;
1509        PyErr_Format(parser_error,
1510                     "Illegal compound statement type: %d.", TYPE(tree));
1511    }
1512    return (res);
1513}
1514
1515
1516static int
1517validate_yield_or_testlist(node *tree)
1518{
1519	if (TYPE(tree) == yield_expr)
1520		return validate_yield_expr(tree);
1521	else
1522		return validate_testlist(tree);
1523}
1524
1525static int
1526validate_expr_stmt(node *tree)
1527{
1528    int j;
1529    int nch = NCH(tree);
1530    int res = (validate_ntype(tree, expr_stmt)
1531               && is_odd(nch)
1532               && validate_testlist(CHILD(tree, 0)));
1533
1534    if (res && nch == 3
1535        && TYPE(CHILD(tree, 1)) == augassign) {
1536        res = validate_numnodes(CHILD(tree, 1), 1, "augassign")
1537		&& validate_yield_or_testlist(CHILD(tree, 2));
1538
1539        if (res) {
1540            char *s = STR(CHILD(CHILD(tree, 1), 0));
1541
1542            res = (strcmp(s, "+=") == 0
1543                   || strcmp(s, "-=") == 0
1544                   || strcmp(s, "*=") == 0
1545                   || strcmp(s, "/=") == 0
1546                   || strcmp(s, "//=") == 0
1547                   || strcmp(s, "%=") == 0
1548                   || strcmp(s, "&=") == 0
1549                   || strcmp(s, "|=") == 0
1550                   || strcmp(s, "^=") == 0
1551                   || strcmp(s, "<<=") == 0
1552                   || strcmp(s, ">>=") == 0
1553                   || strcmp(s, "**=") == 0);
1554            if (!res)
1555                err_string("illegal augmmented assignment operator");
1556        }
1557    }
1558    else {
1559        for (j = 1; res && (j < nch); j += 2)
1560            res = validate_equal(CHILD(tree, j))
1561                   && validate_yield_or_testlist(CHILD(tree, j + 1));
1562    }
1563    return (res);
1564}
1565
1566
1567/*  print_stmt:
1568 *
1569 *      'print' ( [ test (',' test)* [','] ]
1570 *              | '>>' test [ (',' test)+ [','] ] )
1571 */
1572static int
1573validate_print_stmt(node *tree)
1574{
1575    int nch = NCH(tree);
1576    int res = (validate_ntype(tree, print_stmt)
1577               && (nch > 0)
1578               && validate_name(CHILD(tree, 0), "print"));
1579
1580    if (res && nch > 1) {
1581        int sym = TYPE(CHILD(tree, 1));
1582        int i = 1;
1583        int allow_trailing_comma = 1;
1584
1585        if (sym == test)
1586            res = validate_test(CHILD(tree, i++));
1587        else {
1588            if (nch < 3)
1589                res = validate_numnodes(tree, 3, "print_stmt");
1590            else {
1591                res = (validate_ntype(CHILD(tree, i), RIGHTSHIFT)
1592                       && validate_test(CHILD(tree, i+1)));
1593                i += 2;
1594                allow_trailing_comma = 0;
1595            }
1596        }
1597        if (res) {
1598            /*  ... (',' test)* [',']  */
1599            while (res && i+2 <= nch) {
1600                res = (validate_comma(CHILD(tree, i))
1601                       && validate_test(CHILD(tree, i+1)));
1602                allow_trailing_comma = 1;
1603                i += 2;
1604            }
1605            if (res && !allow_trailing_comma)
1606                res = validate_numnodes(tree, i, "print_stmt");
1607            else if (res && i < nch)
1608                res = validate_comma(CHILD(tree, i));
1609        }
1610    }
1611    return (res);
1612}
1613
1614
1615static int
1616validate_del_stmt(node *tree)
1617{
1618    return (validate_numnodes(tree, 2, "del_stmt")
1619            && validate_name(CHILD(tree, 0), "del")
1620            && validate_exprlist(CHILD(tree, 1)));
1621}
1622
1623
1624static int
1625validate_return_stmt(node *tree)
1626{
1627    int nch = NCH(tree);
1628    int res = (validate_ntype(tree, return_stmt)
1629               && ((nch == 1) || (nch == 2))
1630               && validate_name(CHILD(tree, 0), "return"));
1631
1632    if (res && (nch == 2))
1633        res = validate_testlist(CHILD(tree, 1));
1634
1635    return (res);
1636}
1637
1638
1639static int
1640validate_raise_stmt(node *tree)
1641{
1642    int nch = NCH(tree);
1643    int res = (validate_ntype(tree, raise_stmt)
1644               && ((nch == 1) || (nch == 2) || (nch == 4) || (nch == 6)));
1645
1646    if (res) {
1647        res = validate_name(CHILD(tree, 0), "raise");
1648        if (res && (nch >= 2))
1649            res = validate_test(CHILD(tree, 1));
1650        if (res && nch > 2) {
1651            res = (validate_comma(CHILD(tree, 2))
1652                   && validate_test(CHILD(tree, 3)));
1653            if (res && (nch > 4))
1654                res = (validate_comma(CHILD(tree, 4))
1655                       && validate_test(CHILD(tree, 5)));
1656        }
1657    }
1658    else
1659        (void) validate_numnodes(tree, 2, "raise");
1660    if (res && (nch == 4))
1661        res = (validate_comma(CHILD(tree, 2))
1662               && validate_test(CHILD(tree, 3)));
1663
1664    return (res);
1665}
1666
1667
1668/* yield_expr: 'yield' [testlist]
1669 */
1670static int
1671validate_yield_expr(node *tree)
1672{
1673    int nch = NCH(tree);
1674    int res = (validate_ntype(tree, yield_expr)
1675               && ((nch == 1) || (nch == 2))
1676               && validate_name(CHILD(tree, 0), "yield"));
1677
1678    if (res && (nch == 2))
1679        res = validate_testlist(CHILD(tree, 1));
1680
1681    return (res);
1682}
1683
1684
1685/* yield_stmt: yield_expr
1686 */
1687static int
1688validate_yield_stmt(node *tree)
1689{
1690    return (validate_ntype(tree, yield_stmt)
1691            && validate_numnodes(tree, 1, "yield_stmt")
1692            && validate_yield_expr(CHILD(tree, 0)));
1693}
1694
1695
1696static int
1697validate_import_as_name(node *tree)
1698{
1699    int nch = NCH(tree);
1700    int ok = validate_ntype(tree, import_as_name);
1701
1702    if (ok) {
1703        if (nch == 1)
1704            ok = validate_name(CHILD(tree, 0), NULL);
1705        else if (nch == 3)
1706            ok = (validate_name(CHILD(tree, 0), NULL)
1707                  && validate_name(CHILD(tree, 1), "as")
1708                  && validate_name(CHILD(tree, 2), NULL));
1709        else
1710            ok = validate_numnodes(tree, 3, "import_as_name");
1711    }
1712    return ok;
1713}
1714
1715
1716/* dotted_name:  NAME ("." NAME)*
1717 */
1718static int
1719validate_dotted_name(node *tree)
1720{
1721    int nch = NCH(tree);
1722    int res = (validate_ntype(tree, dotted_name)
1723               && is_odd(nch)
1724               && validate_name(CHILD(tree, 0), NULL));
1725    int i;
1726
1727    for (i = 1; res && (i < nch); i += 2) {
1728        res = (validate_dot(CHILD(tree, i))
1729               && validate_name(CHILD(tree, i+1), NULL));
1730    }
1731    return res;
1732}
1733
1734
1735/* dotted_as_name:  dotted_name [NAME NAME]
1736 */
1737static int
1738validate_dotted_as_name(node *tree)
1739{
1740    int nch = NCH(tree);
1741    int res = validate_ntype(tree, dotted_as_name);
1742
1743    if (res) {
1744        if (nch == 1)
1745            res = validate_dotted_name(CHILD(tree, 0));
1746        else if (nch == 3)
1747            res = (validate_dotted_name(CHILD(tree, 0))
1748                   && validate_name(CHILD(tree, 1), "as")
1749                   && validate_name(CHILD(tree, 2), NULL));
1750        else {
1751            res = 0;
1752            err_string("illegal number of children for dotted_as_name");
1753        }
1754    }
1755    return res;
1756}
1757
1758
1759/* dotted_as_name (',' dotted_as_name)* */
1760static int
1761validate_dotted_as_names(node *tree)
1762{
1763	int nch = NCH(tree);
1764	int res = is_odd(nch) && validate_dotted_as_name(CHILD(tree, 0));
1765	int i;
1766
1767	for (i = 1; res && (i < nch); i += 2)
1768	    res = (validate_comma(CHILD(tree, i))
1769		   && validate_dotted_as_name(CHILD(tree, i + 1)));
1770	return (res);
1771}
1772
1773
1774/* import_as_name (',' import_as_name)* [','] */
1775static int
1776validate_import_as_names(node *tree)
1777{
1778    int nch = NCH(tree);
1779    int res = validate_import_as_name(CHILD(tree, 0));
1780    int i;
1781
1782    for (i = 1; res && (i + 1 < nch); i += 2)
1783	res = (validate_comma(CHILD(tree, i))
1784	       && validate_import_as_name(CHILD(tree, i + 1)));
1785    return (res);
1786}
1787
1788
1789/* 'import' dotted_as_names */
1790static int
1791validate_import_name(node *tree)
1792{
1793	return (validate_ntype(tree, import_name)
1794		&& validate_numnodes(tree, 2, "import_name")
1795		&& validate_name(CHILD(tree, 0), "import")
1796		&& validate_dotted_as_names(CHILD(tree, 1)));
1797}
1798
1799/* Helper function to count the number of leading dots in
1800 * 'from ...module import name'
1801 */
1802static int
1803count_from_dots(node *tree)
1804{
1805        int i;
1806        for (i = 0; i < NCH(tree); i++)
1807		if (TYPE(CHILD(tree, i)) != DOT)
1808			break;
1809        return i;
1810}
1811
1812/* 'from' ('.'* dotted_name | '.') 'import' ('*' | '(' import_as_names ')' |
1813 *     import_as_names
1814 */
1815static int
1816validate_import_from(node *tree)
1817{
1818	int nch = NCH(tree);
1819	int ndots = count_from_dots(tree);
1820	int havename = (TYPE(CHILD(tree, ndots + 1)) == dotted_name);
1821	int offset = ndots + havename;
1822	int res = validate_ntype(tree, import_from)
1823		&& (nch >= 4 + ndots)
1824		&& validate_name(CHILD(tree, 0), "from")
1825		&& (!havename || validate_dotted_name(CHILD(tree, ndots + 1)))
1826		&& validate_name(CHILD(tree, offset + 1), "import");
1827
1828	if (res && TYPE(CHILD(tree, offset + 2)) == LPAR)
1829	    res = ((nch == offset + 5)
1830		   && validate_lparen(CHILD(tree, offset + 2))
1831		   && validate_import_as_names(CHILD(tree, offset + 3))
1832		   && validate_rparen(CHILD(tree, offset + 4)));
1833	else if (res && TYPE(CHILD(tree, offset + 2)) != STAR)
1834	    res = validate_import_as_names(CHILD(tree, offset + 2));
1835	return (res);
1836}
1837
1838
1839/* import_stmt: import_name | import_from */
1840static int
1841validate_import_stmt(node *tree)
1842{
1843    int nch = NCH(tree);
1844    int res = validate_numnodes(tree, 1, "import_stmt");
1845
1846    if (res) {
1847	int ntype = TYPE(CHILD(tree, 0));
1848
1849	if (ntype == import_name || ntype == import_from)
1850            res = validate_node(CHILD(tree, 0));
1851        else {
1852            res = 0;
1853            err_string("illegal import_stmt child type");
1854        }
1855    }
1856    else if (nch == 1) {
1857        res = 0;
1858        PyErr_Format(parser_error,
1859                     "Unrecognized child node of import_stmt: %d.",
1860                     TYPE(CHILD(tree, 0)));
1861    }
1862    return (res);
1863}
1864
1865
1866
1867
1868static int
1869validate_global_stmt(node *tree)
1870{
1871    int j;
1872    int nch = NCH(tree);
1873    int res = (validate_ntype(tree, global_stmt)
1874               && is_even(nch) && (nch >= 2));
1875
1876    if (!res && !PyErr_Occurred())
1877        err_string("illegal global statement");
1878
1879    if (res)
1880        res = (validate_name(CHILD(tree, 0), "global")
1881               && validate_ntype(CHILD(tree, 1), NAME));
1882    for (j = 2; res && (j < nch); j += 2)
1883        res = (validate_comma(CHILD(tree, j))
1884               && validate_ntype(CHILD(tree, j + 1), NAME));
1885
1886    return (res);
1887}
1888
1889
1890/*  assert_stmt:
1891 *
1892 *  'assert' test [',' test]
1893 */
1894static int
1895validate_assert_stmt(node *tree)
1896{
1897    int nch = NCH(tree);
1898    int res = (validate_ntype(tree, assert_stmt)
1899               && ((nch == 2) || (nch == 4))
1900               && (validate_name(CHILD(tree, 0), "assert"))
1901               && validate_test(CHILD(tree, 1)));
1902
1903    if (!res && !PyErr_Occurred())
1904        err_string("illegal assert statement");
1905    if (res && (nch > 2))
1906        res = (validate_comma(CHILD(tree, 2))
1907               && validate_test(CHILD(tree, 3)));
1908
1909    return (res);
1910}
1911
1912
1913static int
1914validate_while(node *tree)
1915{
1916    int nch = NCH(tree);
1917    int res = (validate_ntype(tree, while_stmt)
1918               && ((nch == 4) || (nch == 7))
1919               && validate_name(CHILD(tree, 0), "while")
1920               && validate_test(CHILD(tree, 1))
1921               && validate_colon(CHILD(tree, 2))
1922               && validate_suite(CHILD(tree, 3)));
1923
1924    if (res && (nch == 7))
1925        res = (validate_name(CHILD(tree, 4), "else")
1926               && validate_colon(CHILD(tree, 5))
1927               && validate_suite(CHILD(tree, 6)));
1928
1929    return (res);
1930}
1931
1932
1933static int
1934validate_for(node *tree)
1935{
1936    int nch = NCH(tree);
1937    int res = (validate_ntype(tree, for_stmt)
1938               && ((nch == 6) || (nch == 9))
1939               && validate_name(CHILD(tree, 0), "for")
1940               && validate_exprlist(CHILD(tree, 1))
1941               && validate_name(CHILD(tree, 2), "in")
1942               && validate_testlist(CHILD(tree, 3))
1943               && validate_colon(CHILD(tree, 4))
1944               && validate_suite(CHILD(tree, 5)));
1945
1946    if (res && (nch == 9))
1947        res = (validate_name(CHILD(tree, 6), "else")
1948               && validate_colon(CHILD(tree, 7))
1949               && validate_suite(CHILD(tree, 8)));
1950
1951    return (res);
1952}
1953
1954
1955/*  try_stmt:
1956 *      'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
1957 *    | 'try' ':' suite 'finally' ':' suite
1958 *
1959 */
1960static int
1961validate_try(node *tree)
1962{
1963    int nch = NCH(tree);
1964    int pos = 3;
1965    int res = (validate_ntype(tree, try_stmt)
1966               && (nch >= 6) && ((nch % 3) == 0));
1967
1968    if (res)
1969        res = (validate_name(CHILD(tree, 0), "try")
1970               && validate_colon(CHILD(tree, 1))
1971               && validate_suite(CHILD(tree, 2))
1972               && validate_colon(CHILD(tree, nch - 2))
1973               && validate_suite(CHILD(tree, nch - 1)));
1974    else if (!PyErr_Occurred()) {
1975        const char* name = "except";
1976        if (TYPE(CHILD(tree, nch - 3)) != except_clause)
1977            name = STR(CHILD(tree, nch - 3));
1978
1979        PyErr_Format(parser_error,
1980                     "Illegal number of children for try/%s node.", name);
1981    }
1982    /*  Skip past except_clause sections:  */
1983    while (res && (TYPE(CHILD(tree, pos)) == except_clause)) {
1984        res = (validate_except_clause(CHILD(tree, pos))
1985               && validate_colon(CHILD(tree, pos + 1))
1986               && validate_suite(CHILD(tree, pos + 2)));
1987        pos += 3;
1988    }
1989    if (res && (pos < nch)) {
1990        res = validate_ntype(CHILD(tree, pos), NAME);
1991        if (res && (strcmp(STR(CHILD(tree, pos)), "finally") == 0))
1992            res = (validate_numnodes(tree, 6, "try/finally")
1993                   && validate_colon(CHILD(tree, 4))
1994                   && validate_suite(CHILD(tree, 5)));
1995        else if (res) {
1996            if (nch == (pos + 3)) {
1997                res = ((strcmp(STR(CHILD(tree, pos)), "except") == 0)
1998                       || (strcmp(STR(CHILD(tree, pos)), "else") == 0));
1999                if (!res)
2000                    err_string("illegal trailing triple in try statement");
2001            }
2002            else if (nch == (pos + 6)) {
2003                res = (validate_name(CHILD(tree, pos), "except")
2004                       && validate_colon(CHILD(tree, pos + 1))
2005                       && validate_suite(CHILD(tree, pos + 2))
2006                       && validate_name(CHILD(tree, pos + 3), "else"));
2007            }
2008            else
2009                res = validate_numnodes(tree, pos + 3, "try/except");
2010        }
2011    }
2012    return (res);
2013}
2014
2015
2016static int
2017validate_except_clause(node *tree)
2018{
2019    int nch = NCH(tree);
2020    int res = (validate_ntype(tree, except_clause)
2021               && ((nch == 1) || (nch == 2) || (nch == 4))
2022               && validate_name(CHILD(tree, 0), "except"));
2023
2024    if (res && (nch > 1))
2025        res = validate_test(CHILD(tree, 1));
2026    if (res && (nch == 4))
2027        res = (validate_comma(CHILD(tree, 2))
2028               && validate_test(CHILD(tree, 3)));
2029
2030    return (res);
2031}
2032
2033
2034static int
2035validate_test(node *tree)
2036{
2037    int nch = NCH(tree);
2038    int res = validate_ntype(tree, test) && is_odd(nch);
2039
2040    if (res && (TYPE(CHILD(tree, 0)) == lambdef))
2041        res = ((nch == 1)
2042               && validate_lambdef(CHILD(tree, 0)));
2043    else if (res) {
2044        res = validate_or_test(CHILD(tree, 0));
2045        res = (res && (nch == 1 || (nch == 5 &&
2046            validate_name(CHILD(tree, 1), "if") &&
2047            validate_or_test(CHILD(tree, 2)) &&
2048            validate_name(CHILD(tree, 3), "else") &&
2049            validate_test(CHILD(tree, 4)))));
2050    }
2051    return (res);
2052}
2053
2054static int
2055validate_old_test(node *tree)
2056{
2057    int nch = NCH(tree);
2058    int res = validate_ntype(tree, old_test) && (nch == 1);
2059
2060    if (res && (TYPE(CHILD(tree, 0)) == old_lambdef))
2061        res = (validate_old_lambdef(CHILD(tree, 0)));
2062    else if (res) {
2063        res = (validate_or_test(CHILD(tree, 0)));
2064    }
2065    return (res);
2066}
2067
2068static int
2069validate_or_test(node *tree)
2070{
2071    int nch = NCH(tree);
2072    int res = validate_ntype(tree, or_test) && is_odd(nch);
2073
2074    if (res) {
2075        int pos;
2076        res = validate_and_test(CHILD(tree, 0));
2077        for (pos = 1; res && (pos < nch); pos += 2)
2078            res = (validate_name(CHILD(tree, pos), "or")
2079                   && validate_and_test(CHILD(tree, pos + 1)));
2080    }
2081    return (res);
2082}
2083
2084
2085static int
2086validate_and_test(node *tree)
2087{
2088    int pos;
2089    int nch = NCH(tree);
2090    int res = (validate_ntype(tree, and_test)
2091               && is_odd(nch)
2092               && validate_not_test(CHILD(tree, 0)));
2093
2094    for (pos = 1; res && (pos < nch); pos += 2)
2095        res = (validate_name(CHILD(tree, pos), "and")
2096               && validate_not_test(CHILD(tree, 0)));
2097
2098    return (res);
2099}
2100
2101
2102static int
2103validate_not_test(node *tree)
2104{
2105    int nch = NCH(tree);
2106    int res = validate_ntype(tree, not_test) && ((nch == 1) || (nch == 2));
2107
2108    if (res) {
2109        if (nch == 2)
2110            res = (validate_name(CHILD(tree, 0), "not")
2111                   && validate_not_test(CHILD(tree, 1)));
2112        else if (nch == 1)
2113            res = validate_comparison(CHILD(tree, 0));
2114    }
2115    return (res);
2116}
2117
2118
2119static int
2120validate_comparison(node *tree)
2121{
2122    int pos;
2123    int nch = NCH(tree);
2124    int res = (validate_ntype(tree, comparison)
2125               && is_odd(nch)
2126               && validate_expr(CHILD(tree, 0)));
2127
2128    for (pos = 1; res && (pos < nch); pos += 2)
2129        res = (validate_comp_op(CHILD(tree, pos))
2130               && validate_expr(CHILD(tree, pos + 1)));
2131
2132    return (res);
2133}
2134
2135
2136static int
2137validate_comp_op(node *tree)
2138{
2139    int res = 0;
2140    int nch = NCH(tree);
2141
2142    if (!validate_ntype(tree, comp_op))
2143        return (0);
2144    if (nch == 1) {
2145        /*
2146         *  Only child will be a terminal with a well-defined symbolic name
2147         *  or a NAME with a string of either 'is' or 'in'
2148         */
2149        tree = CHILD(tree, 0);
2150        switch (TYPE(tree)) {
2151            case LESS:
2152            case GREATER:
2153            case EQEQUAL:
2154            case EQUAL:
2155            case LESSEQUAL:
2156            case GREATEREQUAL:
2157            case NOTEQUAL:
2158              res = 1;
2159              break;
2160            case NAME:
2161              res = ((strcmp(STR(tree), "in") == 0)
2162                     || (strcmp(STR(tree), "is") == 0));
2163              if (!res) {
2164                  PyErr_Format(parser_error,
2165                               "illegal operator '%s'", STR(tree));
2166              }
2167              break;
2168          default:
2169              err_string("illegal comparison operator type");
2170              break;
2171        }
2172    }
2173    else if ((res = validate_numnodes(tree, 2, "comp_op")) != 0) {
2174        res = (validate_ntype(CHILD(tree, 0), NAME)
2175               && validate_ntype(CHILD(tree, 1), NAME)
2176               && (((strcmp(STR(CHILD(tree, 0)), "is") == 0)
2177                    && (strcmp(STR(CHILD(tree, 1)), "not") == 0))
2178                   || ((strcmp(STR(CHILD(tree, 0)), "not") == 0)
2179                       && (strcmp(STR(CHILD(tree, 1)), "in") == 0))));
2180        if (!res && !PyErr_Occurred())
2181            err_string("unknown comparison operator");
2182    }
2183    return (res);
2184}
2185
2186
2187static int
2188validate_expr(node *tree)
2189{
2190    int j;
2191    int nch = NCH(tree);
2192    int res = (validate_ntype(tree, expr)
2193               && is_odd(nch)
2194               && validate_xor_expr(CHILD(tree, 0)));
2195
2196    for (j = 2; res && (j < nch); j += 2)
2197        res = (validate_xor_expr(CHILD(tree, j))
2198               && validate_vbar(CHILD(tree, j - 1)));
2199
2200    return (res);
2201}
2202
2203
2204static int
2205validate_xor_expr(node *tree)
2206{
2207    int j;
2208    int nch = NCH(tree);
2209    int res = (validate_ntype(tree, xor_expr)
2210               && is_odd(nch)
2211               && validate_and_expr(CHILD(tree, 0)));
2212
2213    for (j = 2; res && (j < nch); j += 2)
2214        res = (validate_circumflex(CHILD(tree, j - 1))
2215               && validate_and_expr(CHILD(tree, j)));
2216
2217    return (res);
2218}
2219
2220
2221static int
2222validate_and_expr(node *tree)
2223{
2224    int pos;
2225    int nch = NCH(tree);
2226    int res = (validate_ntype(tree, and_expr)
2227               && is_odd(nch)
2228               && validate_shift_expr(CHILD(tree, 0)));
2229
2230    for (pos = 1; res && (pos < nch); pos += 2)
2231        res = (validate_ampersand(CHILD(tree, pos))
2232               && validate_shift_expr(CHILD(tree, pos + 1)));
2233
2234    return (res);
2235}
2236
2237
2238static int
2239validate_chain_two_ops(node *tree, int (*termvalid)(node *), int op1, int op2)
2240 {
2241    int pos = 1;
2242    int nch = NCH(tree);
2243    int res = (is_odd(nch)
2244               && (*termvalid)(CHILD(tree, 0)));
2245
2246    for ( ; res && (pos < nch); pos += 2) {
2247        if (TYPE(CHILD(tree, pos)) != op1)
2248            res = validate_ntype(CHILD(tree, pos), op2);
2249        if (res)
2250            res = (*termvalid)(CHILD(tree, pos + 1));
2251    }
2252    return (res);
2253}
2254
2255
2256static int
2257validate_shift_expr(node *tree)
2258{
2259    return (validate_ntype(tree, shift_expr)
2260            && validate_chain_two_ops(tree, validate_arith_expr,
2261                                      LEFTSHIFT, RIGHTSHIFT));
2262}
2263
2264
2265static int
2266validate_arith_expr(node *tree)
2267{
2268    return (validate_ntype(tree, arith_expr)
2269            && validate_chain_two_ops(tree, validate_term, PLUS, MINUS));
2270}
2271
2272
2273static int
2274validate_term(node *tree)
2275{
2276    int pos = 1;
2277    int nch = NCH(tree);
2278    int res = (validate_ntype(tree, term)
2279               && is_odd(nch)
2280               && validate_factor(CHILD(tree, 0)));
2281
2282    for ( ; res && (pos < nch); pos += 2)
2283        res = (((TYPE(CHILD(tree, pos)) == STAR)
2284               || (TYPE(CHILD(tree, pos)) == SLASH)
2285               || (TYPE(CHILD(tree, pos)) == DOUBLESLASH)
2286               || (TYPE(CHILD(tree, pos)) == PERCENT))
2287               && validate_factor(CHILD(tree, pos + 1)));
2288
2289    return (res);
2290}
2291
2292
2293/*  factor:
2294 *
2295 *  factor: ('+'|'-'|'~') factor | power
2296 */
2297static int
2298validate_factor(node *tree)
2299{
2300    int nch = NCH(tree);
2301    int res = (validate_ntype(tree, factor)
2302               && (((nch == 2)
2303                    && ((TYPE(CHILD(tree, 0)) == PLUS)
2304                        || (TYPE(CHILD(tree, 0)) == MINUS)
2305                        || (TYPE(CHILD(tree, 0)) == TILDE))
2306                    && validate_factor(CHILD(tree, 1)))
2307                   || ((nch == 1)
2308                       && validate_power(CHILD(tree, 0)))));
2309    return (res);
2310}
2311
2312
2313/*  power:
2314 *
2315 *  power: atom trailer* ('**' factor)*
2316 */
2317static int
2318validate_power(node *tree)
2319{
2320    int pos = 1;
2321    int nch = NCH(tree);
2322    int res = (validate_ntype(tree, power) && (nch >= 1)
2323               && validate_atom(CHILD(tree, 0)));
2324
2325    while (res && (pos < nch) && (TYPE(CHILD(tree, pos)) == trailer))
2326        res = validate_trailer(CHILD(tree, pos++));
2327    if (res && (pos < nch)) {
2328        if (!is_even(nch - pos)) {
2329            err_string("illegal number of nodes for 'power'");
2330            return (0);
2331        }
2332        for ( ; res && (pos < (nch - 1)); pos += 2)
2333            res = (validate_doublestar(CHILD(tree, pos))
2334                   && validate_factor(CHILD(tree, pos + 1)));
2335    }
2336    return (res);
2337}
2338
2339
2340static int
2341validate_atom(node *tree)
2342{
2343    int pos;
2344    int nch = NCH(tree);
2345    int res = validate_ntype(tree, atom);
2346
2347    if (res && nch < 1)
2348        res = validate_numnodes(tree, nch+1, "atom");
2349    if (res) {
2350        switch (TYPE(CHILD(tree, 0))) {
2351          case LPAR:
2352            res = ((nch <= 3)
2353                   && (validate_rparen(CHILD(tree, nch - 1))));
2354
2355            if (res && (nch == 3)) {
2356		if (TYPE(CHILD(tree, 1))==yield_expr)
2357			res = validate_yield_expr(CHILD(tree, 1));
2358		else
2359                	res = validate_testlist_gexp(CHILD(tree, 1));
2360	    }
2361            break;
2362          case LSQB:
2363            if (nch == 2)
2364                res = validate_ntype(CHILD(tree, 1), RSQB);
2365            else if (nch == 3)
2366                res = (validate_listmaker(CHILD(tree, 1))
2367                       && validate_ntype(CHILD(tree, 2), RSQB));
2368            else {
2369                res = 0;
2370                err_string("illegal list display atom");
2371            }
2372            break;
2373          case LBRACE:
2374            res = ((nch <= 3)
2375                   && validate_ntype(CHILD(tree, nch - 1), RBRACE));
2376
2377            if (res && (nch == 3))
2378                res = validate_dictsetmaker(CHILD(tree, 1));
2379            break;
2380          case NAME:
2381          case NUMBER:
2382            res = (nch == 1);
2383            break;
2384          case STRING:
2385            for (pos = 1; res && (pos < nch); ++pos)
2386                res = validate_ntype(CHILD(tree, pos), STRING);
2387            break;
2388	  case DOT:
2389	    res = (nch == 3 &&
2390	           validate_ntype(CHILD(tree, 1), DOT) &&
2391		   validate_ntype(CHILD(tree, 2), DOT));
2392	    break;
2393          default:
2394            res = 0;
2395            break;
2396        }
2397    }
2398    return (res);
2399}
2400
2401
2402/*  listmaker:
2403 *    test ( list_for | (',' test)* [','] )
2404 */
2405static int
2406validate_listmaker(node *tree)
2407{
2408    int nch = NCH(tree);
2409    int ok = nch;
2410
2411    if (nch == 0)
2412        err_string("missing child nodes of listmaker");
2413    else
2414        ok = validate_test(CHILD(tree, 0));
2415
2416    /*
2417     *  list_for | (',' test)* [',']
2418     */
2419    if (nch == 2 && TYPE(CHILD(tree, 1)) == list_for)
2420        ok = validate_list_for(CHILD(tree, 1));
2421    else {
2422        /*  (',' test)* [',']  */
2423        int i = 1;
2424        while (ok && nch - i >= 2) {
2425            ok = (validate_comma(CHILD(tree, i))
2426                  && validate_test(CHILD(tree, i+1)));
2427            i += 2;
2428        }
2429        if (ok && i == nch-1)
2430            ok = validate_comma(CHILD(tree, i));
2431        else if (i != nch) {
2432            ok = 0;
2433            err_string("illegal trailing nodes for listmaker");
2434        }
2435    }
2436    return ok;
2437}
2438
2439/*  testlist_gexp:
2440 *    test ( gen_for | (',' test)* [','] )
2441 */
2442static int
2443validate_testlist_gexp(node *tree)
2444{
2445    int nch = NCH(tree);
2446    int ok = nch;
2447
2448    if (nch == 0)
2449        err_string("missing child nodes of testlist_gexp");
2450    else {
2451        ok = validate_test(CHILD(tree, 0));
2452    }
2453
2454    /*
2455     *  gen_for | (',' test)* [',']
2456     */
2457    if (nch == 2 && TYPE(CHILD(tree, 1)) == gen_for)
2458        ok = validate_gen_for(CHILD(tree, 1));
2459    else {
2460        /*  (',' test)* [',']  */
2461        int i = 1;
2462        while (ok && nch - i >= 2) {
2463            ok = (validate_comma(CHILD(tree, i))
2464                  && validate_test(CHILD(tree, i+1)));
2465            i += 2;
2466        }
2467        if (ok && i == nch-1)
2468            ok = validate_comma(CHILD(tree, i));
2469        else if (i != nch) {
2470            ok = 0;
2471            err_string("illegal trailing nodes for testlist_gexp");
2472        }
2473    }
2474    return ok;
2475}
2476
2477/*  decorator:
2478 *    '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
2479 */
2480static int
2481validate_decorator(node *tree)
2482{
2483    int ok;
2484    int nch = NCH(tree);
2485    ok = (validate_ntype(tree, decorator) &&
2486	  (nch == 3 || nch == 5 || nch == 6) &&
2487	  validate_at(CHILD(tree, 0)) &&
2488	  validate_dotted_name(CHILD(tree, 1)) &&
2489	  validate_newline(RCHILD(tree, -1)));
2490
2491    if (ok && nch != 3) {
2492	ok = (validate_lparen(CHILD(tree, 2)) &&
2493	      validate_rparen(RCHILD(tree, -2)));
2494
2495	if (ok && nch == 6)
2496	    ok = validate_arglist(CHILD(tree, 3));
2497    }
2498
2499    return ok;
2500}
2501
2502/*  decorators:
2503 *    decorator+
2504 */
2505static int
2506validate_decorators(node *tree)
2507{
2508    int i, nch, ok;
2509    nch = NCH(tree);
2510    ok = validate_ntype(tree, decorators) && nch >= 1;
2511
2512    for (i = 0; ok && i < nch; ++i)
2513	ok = validate_decorator(CHILD(tree, i));
2514
2515    return ok;
2516}
2517
2518/*  funcdef:
2519 *
2520 *            -6   -5    -4         -3  -2 -1
2521 *  [decorators] 'def' NAME parameters ':' suite
2522 */
2523static int
2524validate_funcdef(node *tree)
2525{
2526    int nch = NCH(tree);
2527    int ok = (validate_ntype(tree, funcdef)
2528	       && ((nch == 5) || (nch == 6))
2529	       && validate_name(RCHILD(tree, -5), "def")
2530	       && validate_ntype(RCHILD(tree, -4), NAME)
2531	       && validate_colon(RCHILD(tree, -2))
2532	       && validate_parameters(RCHILD(tree, -3))
2533	       && validate_suite(RCHILD(tree, -1)));
2534
2535    if (ok && (nch == 6))
2536	ok = validate_decorators(CHILD(tree, 0));
2537
2538    return ok;
2539}
2540
2541
2542static int
2543validate_lambdef(node *tree)
2544{
2545    int nch = NCH(tree);
2546    int res = (validate_ntype(tree, lambdef)
2547               && ((nch == 3) || (nch == 4))
2548               && validate_name(CHILD(tree, 0), "lambda")
2549               && validate_colon(CHILD(tree, nch - 2))
2550               && validate_test(CHILD(tree, nch - 1)));
2551
2552    if (res && (nch == 4))
2553        res = validate_varargslist(CHILD(tree, 1));
2554    else if (!res && !PyErr_Occurred())
2555        (void) validate_numnodes(tree, 3, "lambdef");
2556
2557    return (res);
2558}
2559
2560
2561static int
2562validate_old_lambdef(node *tree)
2563{
2564    int nch = NCH(tree);
2565    int res = (validate_ntype(tree, old_lambdef)
2566               && ((nch == 3) || (nch == 4))
2567               && validate_name(CHILD(tree, 0), "lambda")
2568               && validate_colon(CHILD(tree, nch - 2))
2569               && validate_test(CHILD(tree, nch - 1)));
2570
2571    if (res && (nch == 4))
2572        res = validate_varargslist(CHILD(tree, 1));
2573    else if (!res && !PyErr_Occurred())
2574        (void) validate_numnodes(tree, 3, "old_lambdef");
2575
2576    return (res);
2577}
2578
2579
2580/*  arglist:
2581 *
2582 *  (argument ',')* (argument [','] | '*' test [',' '**' test] | '**' test)
2583 */
2584static int
2585validate_arglist(node *tree)
2586{
2587    int nch = NCH(tree);
2588    int i = 0;
2589    int ok = 1;
2590
2591    if (nch <= 0)
2592        /* raise the right error from having an invalid number of children */
2593        return validate_numnodes(tree, nch + 1, "arglist");
2594
2595    if (nch > 1) {
2596        for (i=0; i<nch; i++) {
2597            if (TYPE(CHILD(tree, i)) == argument) {
2598                node *ch = CHILD(tree, i);
2599                if (NCH(ch) == 2 && TYPE(CHILD(ch, 1)) == gen_for) {
2600                    err_string("need '(', ')' for generator expression");
2601                    return 0;
2602                }
2603            }
2604        }
2605    }
2606
2607    while (ok && nch-i >= 2) {
2608        /* skip leading (argument ',') */
2609        ok = (validate_argument(CHILD(tree, i))
2610              && validate_comma(CHILD(tree, i+1)));
2611        if (ok)
2612            i += 2;
2613        else
2614            PyErr_Clear();
2615    }
2616    ok = 1;
2617    if (nch-i > 0) {
2618        /*
2619         * argument | '*' test [',' '**' test] | '**' test
2620         */
2621        int sym = TYPE(CHILD(tree, i));
2622
2623        if (sym == argument) {
2624            ok = validate_argument(CHILD(tree, i));
2625            if (ok && i+1 != nch) {
2626                err_string("illegal arglist specification"
2627                           " (extra stuff on end)");
2628                ok = 0;
2629            }
2630        }
2631        else if (sym == STAR) {
2632            ok = validate_star(CHILD(tree, i));
2633            if (ok && (nch-i == 2))
2634                ok = validate_test(CHILD(tree, i+1));
2635            else if (ok && (nch-i == 5))
2636                ok = (validate_test(CHILD(tree, i+1))
2637                      && validate_comma(CHILD(tree, i+2))
2638                      && validate_doublestar(CHILD(tree, i+3))
2639                      && validate_test(CHILD(tree, i+4)));
2640            else {
2641                err_string("illegal use of '*' in arglist");
2642                ok = 0;
2643            }
2644        }
2645        else if (sym == DOUBLESTAR) {
2646            if (nch-i == 2)
2647                ok = (validate_doublestar(CHILD(tree, i))
2648                      && validate_test(CHILD(tree, i+1)));
2649            else {
2650                err_string("illegal use of '**' in arglist");
2651                ok = 0;
2652            }
2653        }
2654        else {
2655            err_string("illegal arglist specification");
2656            ok = 0;
2657        }
2658    }
2659    return (ok);
2660}
2661
2662
2663
2664/*  argument:
2665 *
2666 *  [test '='] test [gen_for]
2667 */
2668static int
2669validate_argument(node *tree)
2670{
2671    int nch = NCH(tree);
2672    int res = (validate_ntype(tree, argument)
2673               && ((nch == 1) || (nch == 2) || (nch == 3))
2674               && validate_test(CHILD(tree, 0)));
2675
2676    if (res && (nch == 2))
2677        res = validate_gen_for(CHILD(tree, 1));
2678    else if (res && (nch == 3))
2679        res = (validate_equal(CHILD(tree, 1))
2680               && validate_test(CHILD(tree, 2)));
2681
2682    return (res);
2683}
2684
2685
2686
2687/*  trailer:
2688 *
2689 *  '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
2690 */
2691static int
2692validate_trailer(node *tree)
2693{
2694    int nch = NCH(tree);
2695    int res = validate_ntype(tree, trailer) && ((nch == 2) || (nch == 3));
2696
2697    if (res) {
2698        switch (TYPE(CHILD(tree, 0))) {
2699          case LPAR:
2700            res = validate_rparen(CHILD(tree, nch - 1));
2701            if (res && (nch == 3))
2702                res = validate_arglist(CHILD(tree, 1));
2703            break;
2704          case LSQB:
2705            res = (validate_numnodes(tree, 3, "trailer")
2706                   && validate_subscriptlist(CHILD(tree, 1))
2707                   && validate_ntype(CHILD(tree, 2), RSQB));
2708            break;
2709          case DOT:
2710            res = (validate_numnodes(tree, 2, "trailer")
2711                   && validate_ntype(CHILD(tree, 1), NAME));
2712            break;
2713          default:
2714            res = 0;
2715            break;
2716        }
2717    }
2718    else {
2719        (void) validate_numnodes(tree, 2, "trailer");
2720    }
2721    return (res);
2722}
2723
2724
2725/*  subscriptlist:
2726 *
2727 *  subscript (',' subscript)* [',']
2728 */
2729static int
2730validate_subscriptlist(node *tree)
2731{
2732    return (validate_repeating_list(tree, subscriptlist,
2733                                    validate_subscript, "subscriptlist"));
2734}
2735
2736
2737/*  subscript:
2738 *
2739 *  '.' '.' '.' | test | [test] ':' [test] [sliceop]
2740 */
2741static int
2742validate_subscript(node *tree)
2743{
2744    int offset = 0;
2745    int nch = NCH(tree);
2746    int res = validate_ntype(tree, subscript) && (nch >= 1) && (nch <= 4);
2747
2748    if (!res) {
2749        if (!PyErr_Occurred())
2750            err_string("invalid number of arguments for subscript node");
2751        return (0);
2752    }
2753    if (TYPE(CHILD(tree, 0)) == DOT)
2754        /* take care of ('.' '.' '.') possibility */
2755        return (validate_numnodes(tree, 3, "subscript")
2756                && validate_dot(CHILD(tree, 0))
2757                && validate_dot(CHILD(tree, 1))
2758                && validate_dot(CHILD(tree, 2)));
2759    if (nch == 1) {
2760        if (TYPE(CHILD(tree, 0)) == test)
2761            res = validate_test(CHILD(tree, 0));
2762        else
2763            res = validate_colon(CHILD(tree, 0));
2764        return (res);
2765    }
2766    /*  Must be [test] ':' [test] [sliceop],
2767     *  but at least one of the optional components will
2768     *  be present, but we don't know which yet.
2769     */
2770    if ((TYPE(CHILD(tree, 0)) != COLON) || (nch == 4)) {
2771        res = validate_test(CHILD(tree, 0));
2772        offset = 1;
2773    }
2774    if (res)
2775        res = validate_colon(CHILD(tree, offset));
2776    if (res) {
2777        int rem = nch - ++offset;
2778        if (rem) {
2779            if (TYPE(CHILD(tree, offset)) == test) {
2780                res = validate_test(CHILD(tree, offset));
2781                ++offset;
2782                --rem;
2783            }
2784            if (res && rem)
2785                res = validate_sliceop(CHILD(tree, offset));
2786        }
2787    }
2788    return (res);
2789}
2790
2791
2792static int
2793validate_sliceop(node *tree)
2794{
2795    int nch = NCH(tree);
2796    int res = ((nch == 1) || validate_numnodes(tree, 2, "sliceop"))
2797              && validate_ntype(tree, sliceop);
2798    if (!res && !PyErr_Occurred()) {
2799        res = validate_numnodes(tree, 1, "sliceop");
2800    }
2801    if (res)
2802        res = validate_colon(CHILD(tree, 0));
2803    if (res && (nch == 2))
2804        res = validate_test(CHILD(tree, 1));
2805
2806    return (res);
2807}
2808
2809
2810static int
2811validate_exprlist(node *tree)
2812{
2813    return (validate_repeating_list(tree, exprlist,
2814                                    validate_expr, "exprlist"));
2815}
2816
2817
2818static int
2819validate_dictsetmaker(node *tree)
2820{
2821    int nch = NCH(tree);
2822    int res = (validate_ntype(tree, dictsetmaker)
2823               && (nch >= 3)
2824               && validate_test(CHILD(tree, 0))
2825               && validate_colon(CHILD(tree, 1))
2826               && validate_test(CHILD(tree, 2)));
2827
2828    if (res && ((nch % 4) == 0))
2829        res = validate_comma(CHILD(tree, --nch));
2830    else if (res)
2831        res = ((nch % 4) == 3);
2832
2833    if (res && (nch > 3)) {
2834        int pos = 3;
2835        /*  ( ',' test ':' test )*  */
2836        while (res && (pos < nch)) {
2837            res = (validate_comma(CHILD(tree, pos))
2838                   && validate_test(CHILD(tree, pos + 1))
2839                   && validate_colon(CHILD(tree, pos + 2))
2840                   && validate_test(CHILD(tree, pos + 3)));
2841            pos += 4;
2842        }
2843    }
2844    return (res);
2845}
2846
2847
2848static int
2849validate_eval_input(node *tree)
2850{
2851    int pos;
2852    int nch = NCH(tree);
2853    int res = (validate_ntype(tree, eval_input)
2854               && (nch >= 2)
2855               && validate_testlist(CHILD(tree, 0))
2856               && validate_ntype(CHILD(tree, nch - 1), ENDMARKER));
2857
2858    for (pos = 1; res && (pos < (nch - 1)); ++pos)
2859        res = validate_ntype(CHILD(tree, pos), NEWLINE);
2860
2861    return (res);
2862}
2863
2864
2865static int
2866validate_node(node *tree)
2867{
2868    int   nch  = 0;                     /* num. children on current node  */
2869    int   res  = 1;                     /* result value                   */
2870    node* next = 0;                     /* node to process after this one */
2871
2872    while (res && (tree != 0)) {
2873        nch  = NCH(tree);
2874        next = 0;
2875        switch (TYPE(tree)) {
2876            /*
2877             *  Definition nodes.
2878             */
2879          case funcdef:
2880            res = validate_funcdef(tree);
2881            break;
2882          case classdef:
2883            res = validate_class(tree);
2884            break;
2885            /*
2886             *  "Trivial" parse tree nodes.
2887             *  (Why did I call these trivial?)
2888             */
2889          case stmt:
2890            res = validate_stmt(tree);
2891            break;
2892          case small_stmt:
2893            /*
2894             *  expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt
2895             *  | import_stmt | global_stmt | assert_stmt
2896             */
2897            res = validate_small_stmt(tree);
2898            break;
2899          case flow_stmt:
2900            res  = (validate_numnodes(tree, 1, "flow_stmt")
2901                    && ((TYPE(CHILD(tree, 0)) == break_stmt)
2902                        || (TYPE(CHILD(tree, 0)) == continue_stmt)
2903                        || (TYPE(CHILD(tree, 0)) == yield_stmt)
2904                        || (TYPE(CHILD(tree, 0)) == return_stmt)
2905                        || (TYPE(CHILD(tree, 0)) == raise_stmt)));
2906            if (res)
2907                next = CHILD(tree, 0);
2908            else if (nch == 1)
2909                err_string("illegal flow_stmt type");
2910            break;
2911          case yield_stmt:
2912            res = validate_yield_stmt(tree);
2913            break;
2914            /*
2915             *  Compound statements.
2916             */
2917          case simple_stmt:
2918            res = validate_simple_stmt(tree);
2919            break;
2920          case compound_stmt:
2921            res = validate_compound_stmt(tree);
2922            break;
2923            /*
2924             *  Fundamental statements.
2925             */
2926          case expr_stmt:
2927            res = validate_expr_stmt(tree);
2928            break;
2929          case print_stmt:
2930            res = validate_print_stmt(tree);
2931            break;
2932          case del_stmt:
2933            res = validate_del_stmt(tree);
2934            break;
2935          case pass_stmt:
2936            res = (validate_numnodes(tree, 1, "pass")
2937                   && validate_name(CHILD(tree, 0), "pass"));
2938            break;
2939          case break_stmt:
2940            res = (validate_numnodes(tree, 1, "break")
2941                   && validate_name(CHILD(tree, 0), "break"));
2942            break;
2943          case continue_stmt:
2944            res = (validate_numnodes(tree, 1, "continue")
2945                   && validate_name(CHILD(tree, 0), "continue"));
2946            break;
2947          case return_stmt:
2948            res = validate_return_stmt(tree);
2949            break;
2950          case raise_stmt:
2951            res = validate_raise_stmt(tree);
2952            break;
2953          case import_stmt:
2954            res = validate_import_stmt(tree);
2955            break;
2956	  case import_name:
2957	    res = validate_import_name(tree);
2958	    break;
2959	  case import_from:
2960	    res = validate_import_from(tree);
2961	    break;
2962          case global_stmt:
2963            res = validate_global_stmt(tree);
2964            break;
2965          case assert_stmt:
2966            res = validate_assert_stmt(tree);
2967            break;
2968          case if_stmt:
2969            res = validate_if(tree);
2970            break;
2971          case while_stmt:
2972            res = validate_while(tree);
2973            break;
2974          case for_stmt:
2975            res = validate_for(tree);
2976            break;
2977          case try_stmt:
2978            res = validate_try(tree);
2979            break;
2980          case suite:
2981            res = validate_suite(tree);
2982            break;
2983            /*
2984             *  Expression nodes.
2985             */
2986          case testlist:
2987            res = validate_testlist(tree);
2988            break;
2989          case yield_expr:
2990            res = validate_yield_expr(tree);
2991            break;
2992          case testlist1:
2993            res = validate_testlist1(tree);
2994            break;
2995          case test:
2996            res = validate_test(tree);
2997            break;
2998          case and_test:
2999            res = validate_and_test(tree);
3000            break;
3001          case not_test:
3002            res = validate_not_test(tree);
3003            break;
3004          case comparison:
3005            res = validate_comparison(tree);
3006            break;
3007          case exprlist:
3008            res = validate_exprlist(tree);
3009            break;
3010          case comp_op:
3011            res = validate_comp_op(tree);
3012            break;
3013          case expr:
3014            res = validate_expr(tree);
3015            break;
3016          case xor_expr:
3017            res = validate_xor_expr(tree);
3018            break;
3019          case and_expr:
3020            res = validate_and_expr(tree);
3021            break;
3022          case shift_expr:
3023            res = validate_shift_expr(tree);
3024            break;
3025          case arith_expr:
3026            res = validate_arith_expr(tree);
3027            break;
3028          case term:
3029            res = validate_term(tree);
3030            break;
3031          case factor:
3032            res = validate_factor(tree);
3033            break;
3034          case power:
3035            res = validate_power(tree);
3036            break;
3037          case atom:
3038            res = validate_atom(tree);
3039            break;
3040
3041          default:
3042            /* Hopefully never reached! */
3043            err_string("unrecognized node type");
3044            res = 0;
3045            break;
3046        }
3047        tree = next;
3048    }
3049    return (res);
3050}
3051
3052
3053static int
3054validate_expr_tree(node *tree)
3055{
3056    int res = validate_eval_input(tree);
3057
3058    if (!res && !PyErr_Occurred())
3059        err_string("could not validate expression tuple");
3060
3061    return (res);
3062}
3063
3064
3065/*  file_input:
3066 *      (NEWLINE | stmt)* ENDMARKER
3067 */
3068static int
3069validate_file_input(node *tree)
3070{
3071    int j;
3072    int nch = NCH(tree) - 1;
3073    int res = ((nch >= 0)
3074               && validate_ntype(CHILD(tree, nch), ENDMARKER));
3075
3076    for (j = 0; res && (j < nch); ++j) {
3077        if (TYPE(CHILD(tree, j)) == stmt)
3078            res = validate_stmt(CHILD(tree, j));
3079        else
3080            res = validate_newline(CHILD(tree, j));
3081    }
3082    /*  This stays in to prevent any internal failures from getting to the
3083     *  user.  Hopefully, this won't be needed.  If a user reports getting
3084     *  this, we have some debugging to do.
3085     */
3086    if (!res && !PyErr_Occurred())
3087        err_string("VALIDATION FAILURE: report this to the maintainer!");
3088
3089    return (res);
3090}
3091
3092static int
3093validate_encoding_decl(node *tree)
3094{
3095    int nch = NCH(tree);
3096    int res = ((nch == 1)
3097        && validate_file_input(CHILD(tree, 0)));
3098
3099    if (!res && !PyErr_Occurred())
3100        err_string("Error Parsing encoding_decl");
3101
3102    return res;
3103}
3104
3105static PyObject*
3106pickle_constructor = NULL;
3107
3108
3109static PyObject*
3110parser__pickler(PyObject *self, PyObject *args)
3111{
3112    NOTE(ARGUNUSED(self))
3113    PyObject *result = NULL;
3114    PyObject *st = NULL;
3115    PyObject *empty_dict = NULL;
3116
3117    if (PyArg_ParseTuple(args, "O!:_pickler", &PyST_Type, &st)) {
3118        PyObject *newargs;
3119        PyObject *tuple;
3120
3121        if ((empty_dict = PyDict_New()) == NULL)
3122            goto finally;
3123        if ((newargs = Py_BuildValue("Oi", st, 1)) == NULL)
3124            goto finally;
3125        tuple = parser_st2tuple((PyST_Object*)NULL, newargs, empty_dict);
3126        if (tuple != NULL) {
3127            result = Py_BuildValue("O(O)", pickle_constructor, tuple);
3128            Py_DECREF(tuple);
3129        }
3130        Py_DECREF(empty_dict);
3131        Py_DECREF(newargs);
3132    }
3133  finally:
3134    Py_XDECREF(empty_dict);
3135
3136    return (result);
3137}
3138
3139
3140/*  Functions exported by this module.  Most of this should probably
3141 *  be converted into an ST object with methods, but that is better
3142 *  done directly in Python, allowing subclasses to be created directly.
3143 *  We'd really have to write a wrapper around it all anyway to allow
3144 *  inheritance.
3145 */
3146static PyMethodDef parser_functions[] =  {
3147    {"ast2tuple",       (PyCFunction)parser_st2tuple,  PUBLIC_METHOD_TYPE,
3148        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3149    {"ast2list",        (PyCFunction)parser_st2list,   PUBLIC_METHOD_TYPE,
3150        PyDoc_STR("Creates a list-tree representation of an ST.")},
3151    {"compileast",      (PyCFunction)parser_compilest, PUBLIC_METHOD_TYPE,
3152        PyDoc_STR("Compiles an ST object into a code object.")},
3153    {"compilest",      (PyCFunction)parser_compilest,  PUBLIC_METHOD_TYPE,
3154        PyDoc_STR("Compiles an ST object into a code object.")},
3155    {"expr",            (PyCFunction)parser_expr,      PUBLIC_METHOD_TYPE,
3156        PyDoc_STR("Creates an ST object from an expression.")},
3157    {"isexpr",          (PyCFunction)parser_isexpr,    PUBLIC_METHOD_TYPE,
3158        PyDoc_STR("Determines if an ST object was created from an expression.")},
3159    {"issuite",         (PyCFunction)parser_issuite,   PUBLIC_METHOD_TYPE,
3160        PyDoc_STR("Determines if an ST object was created from a suite.")},
3161    {"suite",           (PyCFunction)parser_suite,     PUBLIC_METHOD_TYPE,
3162        PyDoc_STR("Creates an ST object from a suite.")},
3163    {"sequence2ast",    (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3164        PyDoc_STR("Creates an ST object from a tree representation.")},
3165    {"sequence2st",     (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3166        PyDoc_STR("Creates an ST object from a tree representation.")},
3167    {"st2tuple",        (PyCFunction)parser_st2tuple,  PUBLIC_METHOD_TYPE,
3168        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3169    {"st2list",         (PyCFunction)parser_st2list,   PUBLIC_METHOD_TYPE,
3170        PyDoc_STR("Creates a list-tree representation of an ST.")},
3171    {"tuple2ast",       (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3172        PyDoc_STR("Creates an ST object from a tree representation.")},
3173    {"tuple2st",        (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3174        PyDoc_STR("Creates an ST object from a tree representation.")},
3175
3176    /* private stuff: support pickle module */
3177    {"_pickler",        (PyCFunction)parser__pickler,  METH_VARARGS,
3178        PyDoc_STR("Returns the pickle magic to allow ST objects to be pickled.")},
3179
3180    {NULL, NULL, 0, NULL}
3181    };
3182
3183
3184PyMODINIT_FUNC initparser(void);  /* supply a prototype */
3185
3186PyMODINIT_FUNC
3187initparser(void)
3188{
3189    PyObject *module, *copyreg;
3190
3191    PyST_Type.ob_type = &PyType_Type;
3192    module = Py_InitModule("parser", parser_functions);
3193    if (module == NULL)
3194    	return;
3195
3196    if (parser_error == 0)
3197        parser_error = PyErr_NewException("parser.ParserError", NULL, NULL);
3198
3199    if (parser_error == 0)
3200        /* caller will check PyErr_Occurred() */
3201        return;
3202    /* CAUTION:  The code next used to skip bumping the refcount on
3203     * parser_error.  That's a disaster if initparser() gets called more
3204     * than once.  By incref'ing, we ensure that each module dict that
3205     * gets created owns its reference to the shared parser_error object,
3206     * and the file static parser_error vrbl owns a reference too.
3207     */
3208    Py_INCREF(parser_error);
3209    if (PyModule_AddObject(module, "ParserError", parser_error) != 0)
3210        return;
3211
3212    Py_INCREF(&PyST_Type);
3213    PyModule_AddObject(module, "ASTType", (PyObject*)&PyST_Type);
3214    Py_INCREF(&PyST_Type);
3215    PyModule_AddObject(module, "STType", (PyObject*)&PyST_Type);
3216
3217    PyModule_AddStringConstant(module, "__copyright__",
3218                               parser_copyright_string);
3219    PyModule_AddStringConstant(module, "__doc__",
3220                               parser_doc_string);
3221    PyModule_AddStringConstant(module, "__version__",
3222                               parser_version_string);
3223
3224    /* Register to support pickling.
3225     * If this fails, the import of this module will fail because an
3226     * exception will be raised here; should we clear the exception?
3227     */
3228    copyreg = PyImport_ImportModule("copy_reg");
3229    if (copyreg != NULL) {
3230        PyObject *func, *pickler;
3231
3232        func = PyObject_GetAttrString(copyreg, "pickle");
3233        pickle_constructor = PyObject_GetAttrString(module, "sequence2st");
3234        pickler = PyObject_GetAttrString(module, "_pickler");
3235        Py_XINCREF(pickle_constructor);
3236        if ((func != NULL) && (pickle_constructor != NULL)
3237            && (pickler != NULL)) {
3238            PyObject *res;
3239
3240            res = PyObject_CallFunctionObjArgs(func, &PyST_Type, pickler,
3241                                               pickle_constructor, NULL);
3242            Py_XDECREF(res);
3243        }
3244        Py_XDECREF(func);
3245        Py_XDECREF(pickle_constructor);
3246        Py_XDECREF(pickler);
3247        Py_DECREF(copyreg);
3248    }
3249}
3250