parsermodule.c revision af68c874a6803b4e90b616077a602c0593719a1d
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) (int length);
59typedef int (*SeqInserter) (PyObject* sequence,
60                            int 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, const 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 const 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 const 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 const 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 const 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 const 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, const 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 const 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 const 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    int len = PyObject_Size(tuple);
636    int i, err;
637
638    for (i = 1; i < len; ++i) {
639        /* elem must always be a sequence, however simple */
640        PyObject* elem = PySequence_GetItem(tuple, i);
641        int ok = elem != NULL;
642        long  type = 0;
643        char *strn = 0;
644
645        if (ok)
646            ok = PySequence_Check(elem);
647        if (ok) {
648            PyObject *temp = PySequence_GetItem(elem, 0);
649            if (temp == NULL)
650                ok = 0;
651            else {
652                ok = PyInt_Check(temp);
653                if (ok)
654                    type = PyInt_AS_LONG(temp);
655                Py_DECREF(temp);
656            }
657        }
658        if (!ok) {
659            PyErr_SetObject(parser_error,
660                            Py_BuildValue("os", elem,
661                                          "Illegal node construct."));
662            Py_XDECREF(elem);
663            return (0);
664        }
665        if (ISTERMINAL(type)) {
666            int len = PyObject_Size(elem);
667            PyObject *temp;
668
669            if ((len != 2) && (len != 3)) {
670                err_string("terminal nodes must have 2 or 3 entries");
671                return 0;
672            }
673            temp = PySequence_GetItem(elem, 1);
674            if (temp == NULL)
675                return 0;
676            if (!PyString_Check(temp)) {
677                PyErr_Format(parser_error,
678                             "second item in terminal node must be a string,"
679                             " found %s",
680                             temp->ob_type->tp_name);
681                Py_DECREF(temp);
682                return 0;
683            }
684            if (len == 3) {
685                PyObject *o = PySequence_GetItem(elem, 2);
686                if (o != NULL) {
687                    if (PyInt_Check(o))
688                        *line_num = PyInt_AS_LONG(o);
689                    else {
690                        PyErr_Format(parser_error,
691                                     "third item in terminal node must be an"
692                                     " integer, found %s",
693				     temp->ob_type->tp_name);
694                        Py_DECREF(o);
695                        Py_DECREF(temp);
696                        return 0;
697                    }
698                    Py_DECREF(o);
699                }
700            }
701            len = PyString_GET_SIZE(temp) + 1;
702            strn = (char *)PyMem_MALLOC(len);
703            if (strn != NULL)
704                (void) memcpy(strn, PyString_AS_STRING(temp), len);
705            Py_DECREF(temp);
706        }
707        else if (!ISNONTERMINAL(type)) {
708            /*
709             *  It has to be one or the other; this is an error.
710             *  Throw an exception.
711             */
712            PyErr_SetObject(parser_error,
713                            Py_BuildValue("os", elem, "unknown node type."));
714            Py_XDECREF(elem);
715            return (0);
716        }
717        err = PyNode_AddChild(root, type, strn, *line_num);
718        if (err == E_NOMEM) {
719            PyMem_DEL(strn);
720            return (node *) PyErr_NoMemory();
721        }
722        if (err == E_OVERFLOW) {
723            PyMem_DEL(strn);
724            PyErr_SetString(PyExc_ValueError,
725                            "unsupported number of child nodes");
726            return NULL;
727        }
728
729        if (ISNONTERMINAL(type)) {
730            node* new_child = CHILD(root, i - 1);
731
732            if (new_child != build_node_children(elem, new_child, line_num)) {
733                Py_XDECREF(elem);
734                return (0);
735            }
736        }
737        else if (type == NEWLINE) {     /* It's true:  we increment the     */
738            ++(*line_num);              /* line number *after* the newline! */
739        }
740        Py_XDECREF(elem);
741    }
742    return (root);
743}
744
745
746static node*
747build_node_tree(PyObject *tuple)
748{
749    node* res = 0;
750    PyObject *temp = PySequence_GetItem(tuple, 0);
751    long num = -1;
752
753    if (temp != NULL)
754        num = PyInt_AsLong(temp);
755    Py_XDECREF(temp);
756    if (ISTERMINAL(num)) {
757        /*
758         *  The tuple is simple, but it doesn't start with a start symbol.
759         *  Throw an exception now and be done with it.
760         */
761        tuple = Py_BuildValue("os", tuple,
762                    "Illegal syntax-tree; cannot start with terminal symbol.");
763        PyErr_SetObject(parser_error, tuple);
764    }
765    else if (ISNONTERMINAL(num)) {
766        /*
767         *  Not efficient, but that can be handled later.
768         */
769        int line_num = 0;
770        PyObject *encoding = NULL;
771
772        if (num == encoding_decl) {
773            encoding = PySequence_GetItem(tuple, 2);
774            /* tuple isn't borrowed anymore here, need to DECREF */
775            tuple = PySequence_GetSlice(tuple, 0, 2);
776        }
777        res = PyNode_New(num);
778        if (res != NULL) {
779            if (res != build_node_children(tuple, res, &line_num)) {
780                PyNode_Free(res);
781                res = NULL;
782            }
783            if (res && encoding) {
784                int len;
785                len = PyString_GET_SIZE(encoding) + 1;
786                res->n_str = (char *)PyMem_MALLOC(len);
787                if (res->n_str != NULL)
788                    (void) memcpy(res->n_str, PyString_AS_STRING(encoding), len);
789                Py_DECREF(encoding);
790                Py_DECREF(tuple);
791            }
792        }
793    }
794    else
795        /*  The tuple is illegal -- if the number is neither TERMINAL nor
796         *  NONTERMINAL, we can't use it.  Not sure the implementation
797         *  allows this condition, but the API doesn't preclude it.
798         */
799        PyErr_SetObject(parser_error,
800                        Py_BuildValue("os", tuple,
801                                      "Illegal component tuple."));
802
803    return (res);
804}
805
806
807/*
808 *  Validation routines used within the validation section:
809 */
810static int validate_terminal(node *terminal, int type, char *string);
811
812#define validate_ampersand(ch)  validate_terminal(ch,      AMPER, "&")
813#define validate_circumflex(ch) validate_terminal(ch, CIRCUMFLEX, "^")
814#define validate_colon(ch)      validate_terminal(ch,      COLON, ":")
815#define validate_comma(ch)      validate_terminal(ch,      COMMA, ",")
816#define validate_dedent(ch)     validate_terminal(ch,     DEDENT, "")
817#define validate_equal(ch)      validate_terminal(ch,      EQUAL, "=")
818#define validate_indent(ch)     validate_terminal(ch,     INDENT, (char*)NULL)
819#define validate_lparen(ch)     validate_terminal(ch,       LPAR, "(")
820#define validate_newline(ch)    validate_terminal(ch,    NEWLINE, (char*)NULL)
821#define validate_rparen(ch)     validate_terminal(ch,       RPAR, ")")
822#define validate_semi(ch)       validate_terminal(ch,       SEMI, ";")
823#define validate_star(ch)       validate_terminal(ch,       STAR, "*")
824#define validate_vbar(ch)       validate_terminal(ch,       VBAR, "|")
825#define validate_doublestar(ch) validate_terminal(ch, DOUBLESTAR, "**")
826#define validate_dot(ch)        validate_terminal(ch,        DOT, ".")
827#define validate_at(ch)         validate_terminal(ch,         AT, "@")
828#define validate_name(ch, str)  validate_terminal(ch,       NAME, str)
829
830#define VALIDATER(n)    static int validate_##n(node *tree)
831
832VALIDATER(node);                VALIDATER(small_stmt);
833VALIDATER(class);               VALIDATER(node);
834VALIDATER(parameters);          VALIDATER(suite);
835VALIDATER(testlist);            VALIDATER(varargslist);
836VALIDATER(fpdef);               VALIDATER(fplist);
837VALIDATER(stmt);                VALIDATER(simple_stmt);
838VALIDATER(expr_stmt);           VALIDATER(power);
839VALIDATER(print_stmt);          VALIDATER(del_stmt);
840VALIDATER(return_stmt);         VALIDATER(list_iter);
841VALIDATER(raise_stmt);          VALIDATER(import_stmt);
842VALIDATER(import_name);         VALIDATER(import_from);
843VALIDATER(global_stmt);         VALIDATER(list_if);
844VALIDATER(assert_stmt);         VALIDATER(list_for);
845VALIDATER(exec_stmt);           VALIDATER(compound_stmt);
846VALIDATER(while);               VALIDATER(for);
847VALIDATER(try);                 VALIDATER(except_clause);
848VALIDATER(test);                VALIDATER(and_test);
849VALIDATER(not_test);            VALIDATER(comparison);
850VALIDATER(comp_op);             VALIDATER(expr);
851VALIDATER(xor_expr);            VALIDATER(and_expr);
852VALIDATER(shift_expr);          VALIDATER(arith_expr);
853VALIDATER(term);                VALIDATER(factor);
854VALIDATER(atom);                VALIDATER(lambdef);
855VALIDATER(trailer);             VALIDATER(subscript);
856VALIDATER(subscriptlist);       VALIDATER(sliceop);
857VALIDATER(exprlist);            VALIDATER(dictmaker);
858VALIDATER(arglist);             VALIDATER(argument);
859VALIDATER(listmaker);           VALIDATER(yield_stmt);
860VALIDATER(testlist1);           VALIDATER(gen_for);
861VALIDATER(gen_iter);            VALIDATER(gen_if);
862VALIDATER(testlist_gexp);	VALIDATER(yield_expr);
863VALIDATER(yield_or_testlist);
864
865#undef VALIDATER
866
867#define is_even(n)      (((n) & 1) == 0)
868#define is_odd(n)       (((n) & 1) == 1)
869
870
871static int
872validate_ntype(node *n, int t)
873{
874    if (TYPE(n) != t) {
875        PyErr_Format(parser_error, "Expected node type %d, got %d.",
876                     t, TYPE(n));
877        return 0;
878    }
879    return 1;
880}
881
882
883/*  Verifies that the number of child nodes is exactly 'num', raising
884 *  an exception if it isn't.  The exception message does not indicate
885 *  the exact number of nodes, allowing this to be used to raise the
886 *  "right" exception when the wrong number of nodes is present in a
887 *  specific variant of a statement's syntax.  This is commonly used
888 *  in that fashion.
889 */
890static int
891validate_numnodes(node *n, int num, const char *const name)
892{
893    if (NCH(n) != num) {
894        PyErr_Format(parser_error,
895                     "Illegal number of children for %s node.", name);
896        return 0;
897    }
898    return 1;
899}
900
901
902static int
903validate_terminal(node *terminal, int type, char *string)
904{
905    int res = (validate_ntype(terminal, type)
906               && ((string == 0) || (strcmp(string, STR(terminal)) == 0)));
907
908    if (!res && !PyErr_Occurred()) {
909        PyErr_Format(parser_error,
910                     "Illegal terminal: expected \"%s\"", string);
911    }
912    return (res);
913}
914
915
916/*  X (',' X) [',']
917 */
918static int
919validate_repeating_list(node *tree, int ntype, int (*vfunc)(node *),
920                        const char *const name)
921{
922    int nch = NCH(tree);
923    int res = (nch && validate_ntype(tree, ntype)
924               && vfunc(CHILD(tree, 0)));
925
926    if (!res && !PyErr_Occurred())
927        (void) validate_numnodes(tree, 1, name);
928    else {
929        if (is_even(nch))
930            res = validate_comma(CHILD(tree, --nch));
931        if (res && nch > 1) {
932            int pos = 1;
933            for ( ; res && pos < nch; pos += 2)
934                res = (validate_comma(CHILD(tree, pos))
935                       && vfunc(CHILD(tree, pos + 1)));
936        }
937    }
938    return (res);
939}
940
941
942/*  validate_class()
943 *
944 *  classdef:
945 *      'class' NAME ['(' testlist ')'] ':' suite
946 */
947static int
948validate_class(node *tree)
949{
950    int nch = NCH(tree);
951    int res = (validate_ntype(tree, classdef) &&
952	       	((nch == 4) || (nch == 6) || (nch == 7)));
953
954    if (res) {
955        res = (validate_name(CHILD(tree, 0), "class")
956               && validate_ntype(CHILD(tree, 1), NAME)
957               && validate_colon(CHILD(tree, nch - 2))
958               && validate_suite(CHILD(tree, nch - 1)));
959    }
960    else {
961        (void) validate_numnodes(tree, 4, "class");
962    }
963
964    if (res) {
965	if (nch == 7) {
966		res = ((validate_lparen(CHILD(tree, 2)) &&
967			validate_testlist(CHILD(tree, 3)) &&
968			validate_rparen(CHILD(tree, 4))));
969	}
970	else if (nch == 6) {
971		res = (validate_lparen(CHILD(tree,2)) &&
972			validate_rparen(CHILD(tree,3)));
973	}
974    }
975    return (res);
976}
977
978
979/*  if_stmt:
980 *      'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
981 */
982static int
983validate_if(node *tree)
984{
985    int nch = NCH(tree);
986    int res = (validate_ntype(tree, if_stmt)
987               && (nch >= 4)
988               && validate_name(CHILD(tree, 0), "if")
989               && validate_test(CHILD(tree, 1))
990               && validate_colon(CHILD(tree, 2))
991               && validate_suite(CHILD(tree, 3)));
992
993    if (res && ((nch % 4) == 3)) {
994        /*  ... 'else' ':' suite  */
995        res = (validate_name(CHILD(tree, nch - 3), "else")
996               && validate_colon(CHILD(tree, nch - 2))
997               && validate_suite(CHILD(tree, nch - 1)));
998        nch -= 3;
999    }
1000    else if (!res && !PyErr_Occurred())
1001        (void) validate_numnodes(tree, 4, "if");
1002    if ((nch % 4) != 0)
1003        /* Will catch the case for nch < 4 */
1004        res = validate_numnodes(tree, 0, "if");
1005    else if (res && (nch > 4)) {
1006        /*  ... ('elif' test ':' suite)+ ...  */
1007        int j = 4;
1008        while ((j < nch) && res) {
1009            res = (validate_name(CHILD(tree, j), "elif")
1010                   && validate_colon(CHILD(tree, j + 2))
1011                   && validate_test(CHILD(tree, j + 1))
1012                   && validate_suite(CHILD(tree, j + 3)));
1013            j += 4;
1014        }
1015    }
1016    return (res);
1017}
1018
1019
1020/*  parameters:
1021 *      '(' [varargslist] ')'
1022 *
1023 */
1024static int
1025validate_parameters(node *tree)
1026{
1027    int nch = NCH(tree);
1028    int res = validate_ntype(tree, parameters) && ((nch == 2) || (nch == 3));
1029
1030    if (res) {
1031        res = (validate_lparen(CHILD(tree, 0))
1032               && validate_rparen(CHILD(tree, nch - 1)));
1033        if (res && (nch == 3))
1034            res = validate_varargslist(CHILD(tree, 1));
1035    }
1036    else {
1037        (void) validate_numnodes(tree, 2, "parameters");
1038    }
1039    return (res);
1040}
1041
1042
1043/*  validate_suite()
1044 *
1045 *  suite:
1046 *      simple_stmt
1047 *    | NEWLINE INDENT stmt+ DEDENT
1048 */
1049static int
1050validate_suite(node *tree)
1051{
1052    int nch = NCH(tree);
1053    int res = (validate_ntype(tree, suite) && ((nch == 1) || (nch >= 4)));
1054
1055    if (res && (nch == 1))
1056        res = validate_simple_stmt(CHILD(tree, 0));
1057    else if (res) {
1058        /*  NEWLINE INDENT stmt+ DEDENT  */
1059        res = (validate_newline(CHILD(tree, 0))
1060               && validate_indent(CHILD(tree, 1))
1061               && validate_stmt(CHILD(tree, 2))
1062               && validate_dedent(CHILD(tree, nch - 1)));
1063
1064        if (res && (nch > 4)) {
1065            int i = 3;
1066            --nch;                      /* forget the DEDENT     */
1067            for ( ; res && (i < nch); ++i)
1068                res = validate_stmt(CHILD(tree, i));
1069        }
1070        else if (nch < 4)
1071            res = validate_numnodes(tree, 4, "suite");
1072    }
1073    return (res);
1074}
1075
1076
1077static int
1078validate_testlist(node *tree)
1079{
1080    return (validate_repeating_list(tree, testlist,
1081                                    validate_test, "testlist"));
1082}
1083
1084
1085static int
1086validate_testlist1(node *tree)
1087{
1088    return (validate_repeating_list(tree, testlist1,
1089                                    validate_test, "testlist1"));
1090}
1091
1092
1093static int
1094validate_testlist_safe(node *tree)
1095{
1096    return (validate_repeating_list(tree, testlist_safe,
1097                                    validate_test, "testlist_safe"));
1098}
1099
1100
1101/* '*' NAME [',' '**' NAME] | '**' NAME
1102 */
1103static int
1104validate_varargslist_trailer(node *tree, int start)
1105{
1106    int nch = NCH(tree);
1107    int res = 0;
1108    int sym;
1109
1110    if (nch <= start) {
1111        err_string("expected variable argument trailer for varargslist");
1112        return 0;
1113    }
1114    sym = TYPE(CHILD(tree, start));
1115    if (sym == STAR) {
1116        /*
1117         *  ('*' NAME [',' '**' NAME]
1118         */
1119        if (nch-start == 2)
1120            res = validate_name(CHILD(tree, start+1), NULL);
1121        else if (nch-start == 5)
1122            res = (validate_name(CHILD(tree, start+1), NULL)
1123                   && validate_comma(CHILD(tree, start+2))
1124                   && validate_doublestar(CHILD(tree, start+3))
1125                   && validate_name(CHILD(tree, start+4), NULL));
1126    }
1127    else if (sym == DOUBLESTAR) {
1128        /*
1129         *  '**' NAME
1130         */
1131        if (nch-start == 2)
1132            res = validate_name(CHILD(tree, start+1), NULL);
1133    }
1134    if (!res)
1135        err_string("illegal variable argument trailer for varargslist");
1136    return res;
1137}
1138
1139
1140/*  validate_varargslist()
1141 *
1142 *  varargslist:
1143 *      (fpdef ['=' test] ',')*
1144 *           ('*' NAME [',' '**' NAME]
1145 *         | '**' NAME)
1146 *    | fpdef ['=' test] (',' fpdef ['=' test])* [',']
1147 *
1148 */
1149static int
1150validate_varargslist(node *tree)
1151{
1152    int nch = NCH(tree);
1153    int res = validate_ntype(tree, varargslist) && (nch != 0);
1154    int sym;
1155
1156    if (!res)
1157        return 0;
1158    if (nch < 1) {
1159        err_string("varargslist missing child nodes");
1160        return 0;
1161    }
1162    sym = TYPE(CHILD(tree, 0));
1163    if (sym == STAR || sym == DOUBLESTAR)
1164        /* whole thing matches:
1165         *      '*' NAME [',' '**' NAME] | '**' NAME
1166         */
1167        res = validate_varargslist_trailer(tree, 0);
1168    else if (sym == fpdef) {
1169        int i = 0;
1170
1171        sym = TYPE(CHILD(tree, nch-1));
1172        if (sym == NAME) {
1173            /*
1174             *   (fpdef ['=' test] ',')+
1175             *       ('*' NAME [',' '**' NAME]
1176             *     | '**' NAME)
1177             */
1178            /* skip over (fpdef ['=' test] ',')+ */
1179            while (res && (i+2 <= nch)) {
1180                res = validate_fpdef(CHILD(tree, i));
1181                ++i;
1182                if (res && TYPE(CHILD(tree, i)) == EQUAL && (i+2 <= nch)) {
1183                    res = (validate_equal(CHILD(tree, i))
1184                           && validate_test(CHILD(tree, i+1)));
1185                    if (res)
1186                        i += 2;
1187                }
1188                if (res && i < nch) {
1189                    res = validate_comma(CHILD(tree, i));
1190                    ++i;
1191                    if (res && i < nch
1192                        && (TYPE(CHILD(tree, i)) == DOUBLESTAR
1193                            || TYPE(CHILD(tree, i)) == STAR))
1194                        break;
1195                }
1196            }
1197            /* ... '*' NAME [',' '**' NAME] | '**' NAME
1198             * i --^^^
1199             */
1200            if (res)
1201                res = validate_varargslist_trailer(tree, i);
1202        }
1203        else {
1204            /*
1205             *  fpdef ['=' test] (',' fpdef ['=' test])* [',']
1206             */
1207            /* strip trailing comma node */
1208            if (sym == COMMA) {
1209                res = validate_comma(CHILD(tree, nch-1));
1210                if (!res)
1211                    return 0;
1212                --nch;
1213            }
1214            /*
1215             *  fpdef ['=' test] (',' fpdef ['=' test])*
1216             */
1217            res = validate_fpdef(CHILD(tree, 0));
1218            ++i;
1219            if (res && (i+2 <= nch) && TYPE(CHILD(tree, i)) == EQUAL) {
1220                res = (validate_equal(CHILD(tree, i))
1221                       && validate_test(CHILD(tree, i+1)));
1222                i += 2;
1223            }
1224            /*
1225             *  ... (',' fpdef ['=' test])*
1226             *  i ---^^^
1227             */
1228            while (res && (nch - i) >= 2) {
1229                res = (validate_comma(CHILD(tree, i))
1230                       && validate_fpdef(CHILD(tree, i+1)));
1231                i += 2;
1232                if (res && (nch - i) >= 2 && TYPE(CHILD(tree, i)) == EQUAL) {
1233                    res = (validate_equal(CHILD(tree, i))
1234                           && validate_test(CHILD(tree, i+1)));
1235                    i += 2;
1236                }
1237            }
1238            if (res && nch - i != 0) {
1239                res = 0;
1240                err_string("illegal formation for varargslist");
1241            }
1242        }
1243    }
1244    return res;
1245}
1246
1247
1248/*  list_iter:  list_for | list_if
1249 */
1250static int
1251validate_list_iter(node *tree)
1252{
1253    int res = (validate_ntype(tree, list_iter)
1254               && validate_numnodes(tree, 1, "list_iter"));
1255    if (res && TYPE(CHILD(tree, 0)) == list_for)
1256        res = validate_list_for(CHILD(tree, 0));
1257    else
1258        res = validate_list_if(CHILD(tree, 0));
1259
1260    return res;
1261}
1262
1263/*  gen_iter:  gen_for | gen_if
1264 */
1265static int
1266validate_gen_iter(node *tree)
1267{
1268    int res = (validate_ntype(tree, gen_iter)
1269               && validate_numnodes(tree, 1, "gen_iter"));
1270    if (res && TYPE(CHILD(tree, 0)) == gen_for)
1271        res = validate_gen_for(CHILD(tree, 0));
1272    else
1273        res = validate_gen_if(CHILD(tree, 0));
1274
1275    return res;
1276}
1277
1278/*  list_for:  'for' exprlist 'in' testlist [list_iter]
1279 */
1280static int
1281validate_list_for(node *tree)
1282{
1283    int nch = NCH(tree);
1284    int res;
1285
1286    if (nch == 5)
1287        res = validate_list_iter(CHILD(tree, 4));
1288    else
1289        res = validate_numnodes(tree, 4, "list_for");
1290
1291    if (res)
1292        res = (validate_name(CHILD(tree, 0), "for")
1293               && validate_exprlist(CHILD(tree, 1))
1294               && validate_name(CHILD(tree, 2), "in")
1295               && validate_testlist_safe(CHILD(tree, 3)));
1296
1297    return res;
1298}
1299
1300/*  gen_for:  'for' exprlist 'in' test [gen_iter]
1301 */
1302static int
1303validate_gen_for(node *tree)
1304{
1305    int nch = NCH(tree);
1306    int res;
1307
1308    if (nch == 5)
1309        res = validate_gen_iter(CHILD(tree, 4));
1310    else
1311        res = validate_numnodes(tree, 4, "gen_for");
1312
1313    if (res)
1314        res = (validate_name(CHILD(tree, 0), "for")
1315               && validate_exprlist(CHILD(tree, 1))
1316               && validate_name(CHILD(tree, 2), "in")
1317               && validate_test(CHILD(tree, 3)));
1318
1319    return res;
1320}
1321
1322/*  list_if:  'if' test [list_iter]
1323 */
1324static int
1325validate_list_if(node *tree)
1326{
1327    int nch = NCH(tree);
1328    int res;
1329
1330    if (nch == 3)
1331        res = validate_list_iter(CHILD(tree, 2));
1332    else
1333        res = validate_numnodes(tree, 2, "list_if");
1334
1335    if (res)
1336        res = (validate_name(CHILD(tree, 0), "if")
1337               && validate_test(CHILD(tree, 1)));
1338
1339    return res;
1340}
1341
1342/*  gen_if:  'if' test [gen_iter]
1343 */
1344static int
1345validate_gen_if(node *tree)
1346{
1347    int nch = NCH(tree);
1348    int res;
1349
1350    if (nch == 3)
1351        res = validate_gen_iter(CHILD(tree, 2));
1352    else
1353        res = validate_numnodes(tree, 2, "gen_if");
1354
1355    if (res)
1356        res = (validate_name(CHILD(tree, 0), "if")
1357               && validate_test(CHILD(tree, 1)));
1358
1359    return res;
1360}
1361
1362/*  validate_fpdef()
1363 *
1364 *  fpdef:
1365 *      NAME
1366 *    | '(' fplist ')'
1367 */
1368static int
1369validate_fpdef(node *tree)
1370{
1371    int nch = NCH(tree);
1372    int res = validate_ntype(tree, fpdef);
1373
1374    if (res) {
1375        if (nch == 1)
1376            res = validate_ntype(CHILD(tree, 0), NAME);
1377        else if (nch == 3)
1378            res = (validate_lparen(CHILD(tree, 0))
1379                   && validate_fplist(CHILD(tree, 1))
1380                   && validate_rparen(CHILD(tree, 2)));
1381        else
1382            res = validate_numnodes(tree, 1, "fpdef");
1383    }
1384    return (res);
1385}
1386
1387
1388static int
1389validate_fplist(node *tree)
1390{
1391    return (validate_repeating_list(tree, fplist,
1392                                    validate_fpdef, "fplist"));
1393}
1394
1395
1396/*  simple_stmt | compound_stmt
1397 *
1398 */
1399static int
1400validate_stmt(node *tree)
1401{
1402    int res = (validate_ntype(tree, stmt)
1403               && validate_numnodes(tree, 1, "stmt"));
1404
1405    if (res) {
1406        tree = CHILD(tree, 0);
1407
1408        if (TYPE(tree) == simple_stmt)
1409            res = validate_simple_stmt(tree);
1410        else
1411            res = validate_compound_stmt(tree);
1412    }
1413    return (res);
1414}
1415
1416
1417/*  small_stmt (';' small_stmt)* [';'] NEWLINE
1418 *
1419 */
1420static int
1421validate_simple_stmt(node *tree)
1422{
1423    int nch = NCH(tree);
1424    int res = (validate_ntype(tree, simple_stmt)
1425               && (nch >= 2)
1426               && validate_small_stmt(CHILD(tree, 0))
1427               && validate_newline(CHILD(tree, nch - 1)));
1428
1429    if (nch < 2)
1430        res = validate_numnodes(tree, 2, "simple_stmt");
1431    --nch;                              /* forget the NEWLINE    */
1432    if (res && is_even(nch))
1433        res = validate_semi(CHILD(tree, --nch));
1434    if (res && (nch > 2)) {
1435        int i;
1436
1437        for (i = 1; res && (i < nch); i += 2)
1438            res = (validate_semi(CHILD(tree, i))
1439                   && validate_small_stmt(CHILD(tree, i + 1)));
1440    }
1441    return (res);
1442}
1443
1444
1445static int
1446validate_small_stmt(node *tree)
1447{
1448    int nch = NCH(tree);
1449    int res = validate_numnodes(tree, 1, "small_stmt");
1450
1451    if (res) {
1452        int ntype = TYPE(CHILD(tree, 0));
1453
1454        if (  (ntype == expr_stmt)
1455              || (ntype == print_stmt)
1456              || (ntype == del_stmt)
1457              || (ntype == pass_stmt)
1458              || (ntype == flow_stmt)
1459              || (ntype == import_stmt)
1460              || (ntype == global_stmt)
1461              || (ntype == assert_stmt)
1462              || (ntype == exec_stmt))
1463            res = validate_node(CHILD(tree, 0));
1464        else {
1465            res = 0;
1466            err_string("illegal small_stmt child type");
1467        }
1468    }
1469    else if (nch == 1) {
1470        res = 0;
1471        PyErr_Format(parser_error,
1472                     "Unrecognized child node of small_stmt: %d.",
1473                     TYPE(CHILD(tree, 0)));
1474    }
1475    return (res);
1476}
1477
1478
1479/*  compound_stmt:
1480 *      if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef
1481 */
1482static int
1483validate_compound_stmt(node *tree)
1484{
1485    int res = (validate_ntype(tree, compound_stmt)
1486               && validate_numnodes(tree, 1, "compound_stmt"));
1487    int ntype;
1488
1489    if (!res)
1490        return (0);
1491
1492    tree = CHILD(tree, 0);
1493    ntype = TYPE(tree);
1494    if (  (ntype == if_stmt)
1495          || (ntype == while_stmt)
1496          || (ntype == for_stmt)
1497          || (ntype == try_stmt)
1498          || (ntype == funcdef)
1499          || (ntype == classdef))
1500        res = validate_node(tree);
1501    else {
1502        res = 0;
1503        PyErr_Format(parser_error,
1504                     "Illegal compound statement type: %d.", TYPE(tree));
1505    }
1506    return (res);
1507}
1508
1509
1510static int
1511validate_yield_or_testlist(node *tree)
1512{
1513	if (TYPE(tree) == yield_expr)
1514		return validate_yield_expr(tree);
1515	else
1516		return validate_testlist(tree);
1517}
1518
1519static int
1520validate_expr_stmt(node *tree)
1521{
1522    int j;
1523    int nch = NCH(tree);
1524    int res = (validate_ntype(tree, expr_stmt)
1525               && is_odd(nch)
1526               && validate_testlist(CHILD(tree, 0)));
1527
1528    if (res && nch == 3
1529        && TYPE(CHILD(tree, 1)) == augassign) {
1530        res = validate_numnodes(CHILD(tree, 1), 1, "augassign")
1531		&& validate_yield_or_testlist(CHILD(tree, 2));
1532
1533        if (res) {
1534            char *s = STR(CHILD(CHILD(tree, 1), 0));
1535
1536            res = (strcmp(s, "+=") == 0
1537                   || strcmp(s, "-=") == 0
1538                   || strcmp(s, "*=") == 0
1539                   || strcmp(s, "/=") == 0
1540                   || strcmp(s, "//=") == 0
1541                   || strcmp(s, "%=") == 0
1542                   || strcmp(s, "&=") == 0
1543                   || strcmp(s, "|=") == 0
1544                   || strcmp(s, "^=") == 0
1545                   || strcmp(s, "<<=") == 0
1546                   || strcmp(s, ">>=") == 0
1547                   || strcmp(s, "**=") == 0);
1548            if (!res)
1549                err_string("illegal augmmented assignment operator");
1550        }
1551    }
1552    else {
1553        for (j = 1; res && (j < nch); j += 2)
1554            res = validate_equal(CHILD(tree, j))
1555                   && validate_yield_or_testlist(CHILD(tree, j + 1));
1556    }
1557    return (res);
1558}
1559
1560
1561/*  print_stmt:
1562 *
1563 *      'print' ( [ test (',' test)* [','] ]
1564 *              | '>>' test [ (',' test)+ [','] ] )
1565 */
1566static int
1567validate_print_stmt(node *tree)
1568{
1569    int nch = NCH(tree);
1570    int res = (validate_ntype(tree, print_stmt)
1571               && (nch > 0)
1572               && validate_name(CHILD(tree, 0), "print"));
1573
1574    if (res && nch > 1) {
1575        int sym = TYPE(CHILD(tree, 1));
1576        int i = 1;
1577        int allow_trailing_comma = 1;
1578
1579        if (sym == test)
1580            res = validate_test(CHILD(tree, i++));
1581        else {
1582            if (nch < 3)
1583                res = validate_numnodes(tree, 3, "print_stmt");
1584            else {
1585                res = (validate_ntype(CHILD(tree, i), RIGHTSHIFT)
1586                       && validate_test(CHILD(tree, i+1)));
1587                i += 2;
1588                allow_trailing_comma = 0;
1589            }
1590        }
1591        if (res) {
1592            /*  ... (',' test)* [',']  */
1593            while (res && i+2 <= nch) {
1594                res = (validate_comma(CHILD(tree, i))
1595                       && validate_test(CHILD(tree, i+1)));
1596                allow_trailing_comma = 1;
1597                i += 2;
1598            }
1599            if (res && !allow_trailing_comma)
1600                res = validate_numnodes(tree, i, "print_stmt");
1601            else if (res && i < nch)
1602                res = validate_comma(CHILD(tree, i));
1603        }
1604    }
1605    return (res);
1606}
1607
1608
1609static int
1610validate_del_stmt(node *tree)
1611{
1612    return (validate_numnodes(tree, 2, "del_stmt")
1613            && validate_name(CHILD(tree, 0), "del")
1614            && validate_exprlist(CHILD(tree, 1)));
1615}
1616
1617
1618static int
1619validate_return_stmt(node *tree)
1620{
1621    int nch = NCH(tree);
1622    int res = (validate_ntype(tree, return_stmt)
1623               && ((nch == 1) || (nch == 2))
1624               && validate_name(CHILD(tree, 0), "return"));
1625
1626    if (res && (nch == 2))
1627        res = validate_testlist(CHILD(tree, 1));
1628
1629    return (res);
1630}
1631
1632
1633static int
1634validate_raise_stmt(node *tree)
1635{
1636    int nch = NCH(tree);
1637    int res = (validate_ntype(tree, raise_stmt)
1638               && ((nch == 1) || (nch == 2) || (nch == 4) || (nch == 6)));
1639
1640    if (res) {
1641        res = validate_name(CHILD(tree, 0), "raise");
1642        if (res && (nch >= 2))
1643            res = validate_test(CHILD(tree, 1));
1644        if (res && nch > 2) {
1645            res = (validate_comma(CHILD(tree, 2))
1646                   && validate_test(CHILD(tree, 3)));
1647            if (res && (nch > 4))
1648                res = (validate_comma(CHILD(tree, 4))
1649                       && validate_test(CHILD(tree, 5)));
1650        }
1651    }
1652    else
1653        (void) validate_numnodes(tree, 2, "raise");
1654    if (res && (nch == 4))
1655        res = (validate_comma(CHILD(tree, 2))
1656               && validate_test(CHILD(tree, 3)));
1657
1658    return (res);
1659}
1660
1661
1662/* yield_expr: 'yield' [testlist]
1663 */
1664static int
1665validate_yield_expr(node *tree)
1666{
1667    int nch = NCH(tree);
1668    int res = (validate_ntype(tree, yield_expr)
1669               && ((nch == 1) || (nch == 2))
1670               && validate_name(CHILD(tree, 0), "yield"));
1671
1672    if (res && (nch == 2))
1673        res = validate_testlist(CHILD(tree, 1));
1674
1675    return (res);
1676}
1677
1678
1679/* yield_stmt: yield_expr
1680 */
1681static int
1682validate_yield_stmt(node *tree)
1683{
1684    return (validate_ntype(tree, yield_stmt)
1685            && validate_numnodes(tree, 1, "yield_stmt")
1686            && validate_yield_expr(CHILD(tree, 0)));
1687}
1688
1689
1690static int
1691validate_import_as_name(node *tree)
1692{
1693    int nch = NCH(tree);
1694    int ok = validate_ntype(tree, import_as_name);
1695
1696    if (ok) {
1697        if (nch == 1)
1698            ok = validate_name(CHILD(tree, 0), NULL);
1699        else if (nch == 3)
1700            ok = (validate_name(CHILD(tree, 0), NULL)
1701                  && validate_name(CHILD(tree, 1), "as")
1702                  && validate_name(CHILD(tree, 2), NULL));
1703        else
1704            ok = validate_numnodes(tree, 3, "import_as_name");
1705    }
1706    return ok;
1707}
1708
1709
1710/* dotted_name:  NAME ("." NAME)*
1711 */
1712static int
1713validate_dotted_name(node *tree)
1714{
1715    int nch = NCH(tree);
1716    int res = (validate_ntype(tree, dotted_name)
1717               && is_odd(nch)
1718               && validate_name(CHILD(tree, 0), NULL));
1719    int i;
1720
1721    for (i = 1; res && (i < nch); i += 2) {
1722        res = (validate_dot(CHILD(tree, i))
1723               && validate_name(CHILD(tree, i+1), NULL));
1724    }
1725    return res;
1726}
1727
1728
1729/* dotted_as_name:  dotted_name [NAME NAME]
1730 */
1731static int
1732validate_dotted_as_name(node *tree)
1733{
1734    int nch = NCH(tree);
1735    int res = validate_ntype(tree, dotted_as_name);
1736
1737    if (res) {
1738        if (nch == 1)
1739            res = validate_dotted_name(CHILD(tree, 0));
1740        else if (nch == 3)
1741            res = (validate_dotted_name(CHILD(tree, 0))
1742                   && validate_name(CHILD(tree, 1), "as")
1743                   && validate_name(CHILD(tree, 2), NULL));
1744        else {
1745            res = 0;
1746            err_string("illegal number of children for dotted_as_name");
1747        }
1748    }
1749    return res;
1750}
1751
1752
1753/* dotted_as_name (',' dotted_as_name)* */
1754static int
1755validate_dotted_as_names(node *tree)
1756{
1757	int nch = NCH(tree);
1758	int res = is_odd(nch) && validate_dotted_as_name(CHILD(tree, 0));
1759	int i;
1760
1761	for (i = 1; res && (i < nch); i += 2)
1762	    res = (validate_comma(CHILD(tree, i))
1763		   && validate_dotted_as_name(CHILD(tree, i + 1)));
1764	return (res);
1765}
1766
1767
1768/* import_as_name (',' import_as_name)* [','] */
1769static int
1770validate_import_as_names(node *tree)
1771{
1772    int nch = NCH(tree);
1773    int res = validate_import_as_name(CHILD(tree, 0));
1774    int i;
1775
1776    for (i = 1; res && (i + 1 < nch); i += 2)
1777	res = (validate_comma(CHILD(tree, i))
1778	       && validate_import_as_name(CHILD(tree, i + 1)));
1779    return (res);
1780}
1781
1782
1783/* 'import' dotted_as_names */
1784static int
1785validate_import_name(node *tree)
1786{
1787	return (validate_ntype(tree, import_name)
1788		&& validate_numnodes(tree, 2, "import_name")
1789		&& validate_name(CHILD(tree, 0), "import")
1790		&& validate_dotted_as_names(CHILD(tree, 1)));
1791}
1792
1793
1794/* 'from' dotted_name 'import' ('*' | '(' import_as_names ')' |
1795 *     import_as_names
1796 */
1797static int
1798validate_import_from(node *tree)
1799{
1800	int nch = NCH(tree);
1801	int res = validate_ntype(tree, import_from)
1802		  && (nch >= 4)
1803		  && validate_name(CHILD(tree, 0), "from")
1804		  && validate_dotted_name(CHILD(tree, 1))
1805		  && validate_name(CHILD(tree, 2), "import");
1806
1807	if (res && TYPE(CHILD(tree, 3)) == LPAR)
1808	    res = ((nch == 6)
1809		   && validate_lparen(CHILD(tree, 3))
1810		   && validate_import_as_names(CHILD(tree, 4))
1811		   && validate_rparen(CHILD(tree, 5)));
1812	else if (res && TYPE(CHILD(tree, 3)) != STAR)
1813	    res = validate_import_as_names(CHILD(tree, 3));
1814	return (res);
1815}
1816
1817
1818/* import_stmt: import_name | import_from */
1819static int
1820validate_import_stmt(node *tree)
1821{
1822    int nch = NCH(tree);
1823    int res = validate_numnodes(tree, 1, "import_stmt");
1824
1825    if (res) {
1826	int ntype = TYPE(CHILD(tree, 0));
1827
1828	if (ntype == import_name || ntype == import_from)
1829            res = validate_node(CHILD(tree, 0));
1830        else {
1831            res = 0;
1832            err_string("illegal import_stmt child type");
1833        }
1834    }
1835    else if (nch == 1) {
1836        res = 0;
1837        PyErr_Format(parser_error,
1838                     "Unrecognized child node of import_stmt: %d.",
1839                     TYPE(CHILD(tree, 0)));
1840    }
1841    return (res);
1842}
1843
1844
1845
1846
1847static int
1848validate_global_stmt(node *tree)
1849{
1850    int j;
1851    int nch = NCH(tree);
1852    int res = (validate_ntype(tree, global_stmt)
1853               && is_even(nch) && (nch >= 2));
1854
1855    if (!res && !PyErr_Occurred())
1856        err_string("illegal global statement");
1857
1858    if (res)
1859        res = (validate_name(CHILD(tree, 0), "global")
1860               && validate_ntype(CHILD(tree, 1), NAME));
1861    for (j = 2; res && (j < nch); j += 2)
1862        res = (validate_comma(CHILD(tree, j))
1863               && validate_ntype(CHILD(tree, j + 1), NAME));
1864
1865    return (res);
1866}
1867
1868
1869/*  exec_stmt:
1870 *
1871 *  'exec' expr ['in' test [',' test]]
1872 */
1873static int
1874validate_exec_stmt(node *tree)
1875{
1876    int nch = NCH(tree);
1877    int res = (validate_ntype(tree, exec_stmt)
1878               && ((nch == 2) || (nch == 4) || (nch == 6))
1879               && validate_name(CHILD(tree, 0), "exec")
1880               && validate_expr(CHILD(tree, 1)));
1881
1882    if (!res && !PyErr_Occurred())
1883        err_string("illegal exec statement");
1884    if (res && (nch > 2))
1885        res = (validate_name(CHILD(tree, 2), "in")
1886               && validate_test(CHILD(tree, 3)));
1887    if (res && (nch == 6))
1888        res = (validate_comma(CHILD(tree, 4))
1889               && validate_test(CHILD(tree, 5)));
1890
1891    return (res);
1892}
1893
1894
1895/*  assert_stmt:
1896 *
1897 *  'assert' test [',' test]
1898 */
1899static int
1900validate_assert_stmt(node *tree)
1901{
1902    int nch = NCH(tree);
1903    int res = (validate_ntype(tree, assert_stmt)
1904               && ((nch == 2) || (nch == 4))
1905               && (validate_name(CHILD(tree, 0), "assert"))
1906               && validate_test(CHILD(tree, 1)));
1907
1908    if (!res && !PyErr_Occurred())
1909        err_string("illegal assert statement");
1910    if (res && (nch > 2))
1911        res = (validate_comma(CHILD(tree, 2))
1912               && validate_test(CHILD(tree, 3)));
1913
1914    return (res);
1915}
1916
1917
1918static int
1919validate_while(node *tree)
1920{
1921    int nch = NCH(tree);
1922    int res = (validate_ntype(tree, while_stmt)
1923               && ((nch == 4) || (nch == 7))
1924               && validate_name(CHILD(tree, 0), "while")
1925               && validate_test(CHILD(tree, 1))
1926               && validate_colon(CHILD(tree, 2))
1927               && validate_suite(CHILD(tree, 3)));
1928
1929    if (res && (nch == 7))
1930        res = (validate_name(CHILD(tree, 4), "else")
1931               && validate_colon(CHILD(tree, 5))
1932               && validate_suite(CHILD(tree, 6)));
1933
1934    return (res);
1935}
1936
1937
1938static int
1939validate_for(node *tree)
1940{
1941    int nch = NCH(tree);
1942    int res = (validate_ntype(tree, for_stmt)
1943               && ((nch == 6) || (nch == 9))
1944               && validate_name(CHILD(tree, 0), "for")
1945               && validate_exprlist(CHILD(tree, 1))
1946               && validate_name(CHILD(tree, 2), "in")
1947               && validate_testlist(CHILD(tree, 3))
1948               && validate_colon(CHILD(tree, 4))
1949               && validate_suite(CHILD(tree, 5)));
1950
1951    if (res && (nch == 9))
1952        res = (validate_name(CHILD(tree, 6), "else")
1953               && validate_colon(CHILD(tree, 7))
1954               && validate_suite(CHILD(tree, 8)));
1955
1956    return (res);
1957}
1958
1959
1960/*  try_stmt:
1961 *      'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
1962 *    | 'try' ':' suite 'finally' ':' suite
1963 *
1964 */
1965static int
1966validate_try(node *tree)
1967{
1968    int nch = NCH(tree);
1969    int pos = 3;
1970    int res = (validate_ntype(tree, try_stmt)
1971               && (nch >= 6) && ((nch % 3) == 0));
1972
1973    if (res)
1974        res = (validate_name(CHILD(tree, 0), "try")
1975               && validate_colon(CHILD(tree, 1))
1976               && validate_suite(CHILD(tree, 2))
1977               && validate_colon(CHILD(tree, nch - 2))
1978               && validate_suite(CHILD(tree, nch - 1)));
1979    else if (!PyErr_Occurred()) {
1980        const char* name = "except";
1981        if (TYPE(CHILD(tree, nch - 3)) != except_clause)
1982            name = STR(CHILD(tree, nch - 3));
1983
1984        PyErr_Format(parser_error,
1985                     "Illegal number of children for try/%s node.", name);
1986    }
1987    /*  Skip past except_clause sections:  */
1988    while (res && (TYPE(CHILD(tree, pos)) == except_clause)) {
1989        res = (validate_except_clause(CHILD(tree, pos))
1990               && validate_colon(CHILD(tree, pos + 1))
1991               && validate_suite(CHILD(tree, pos + 2)));
1992        pos += 3;
1993    }
1994    if (res && (pos < nch)) {
1995        res = validate_ntype(CHILD(tree, pos), NAME);
1996        if (res && (strcmp(STR(CHILD(tree, pos)), "finally") == 0))
1997            res = (validate_numnodes(tree, 6, "try/finally")
1998                   && validate_colon(CHILD(tree, 4))
1999                   && validate_suite(CHILD(tree, 5)));
2000        else if (res) {
2001            if (nch == (pos + 3)) {
2002                res = ((strcmp(STR(CHILD(tree, pos)), "except") == 0)
2003                       || (strcmp(STR(CHILD(tree, pos)), "else") == 0));
2004                if (!res)
2005                    err_string("illegal trailing triple in try statement");
2006            }
2007            else if (nch == (pos + 6)) {
2008                res = (validate_name(CHILD(tree, pos), "except")
2009                       && validate_colon(CHILD(tree, pos + 1))
2010                       && validate_suite(CHILD(tree, pos + 2))
2011                       && validate_name(CHILD(tree, pos + 3), "else"));
2012            }
2013            else
2014                res = validate_numnodes(tree, pos + 3, "try/except");
2015        }
2016    }
2017    return (res);
2018}
2019
2020
2021static int
2022validate_except_clause(node *tree)
2023{
2024    int nch = NCH(tree);
2025    int res = (validate_ntype(tree, except_clause)
2026               && ((nch == 1) || (nch == 2) || (nch == 4))
2027               && validate_name(CHILD(tree, 0), "except"));
2028
2029    if (res && (nch > 1))
2030        res = validate_test(CHILD(tree, 1));
2031    if (res && (nch == 4))
2032        res = (validate_comma(CHILD(tree, 2))
2033               && validate_test(CHILD(tree, 3)));
2034
2035    return (res);
2036}
2037
2038
2039static int
2040validate_test(node *tree)
2041{
2042    int nch = NCH(tree);
2043    int res = validate_ntype(tree, test) && is_odd(nch);
2044
2045    if (res && (TYPE(CHILD(tree, 0)) == lambdef))
2046        res = ((nch == 1)
2047               && validate_lambdef(CHILD(tree, 0)));
2048    else if (res) {
2049        int pos;
2050        res = validate_and_test(CHILD(tree, 0));
2051        for (pos = 1; res && (pos < nch); pos += 2)
2052            res = (validate_name(CHILD(tree, pos), "or")
2053                   && validate_and_test(CHILD(tree, pos + 1)));
2054    }
2055    return (res);
2056}
2057
2058
2059static int
2060validate_and_test(node *tree)
2061{
2062    int pos;
2063    int nch = NCH(tree);
2064    int res = (validate_ntype(tree, and_test)
2065               && is_odd(nch)
2066               && validate_not_test(CHILD(tree, 0)));
2067
2068    for (pos = 1; res && (pos < nch); pos += 2)
2069        res = (validate_name(CHILD(tree, pos), "and")
2070               && validate_not_test(CHILD(tree, 0)));
2071
2072    return (res);
2073}
2074
2075
2076static int
2077validate_not_test(node *tree)
2078{
2079    int nch = NCH(tree);
2080    int res = validate_ntype(tree, not_test) && ((nch == 1) || (nch == 2));
2081
2082    if (res) {
2083        if (nch == 2)
2084            res = (validate_name(CHILD(tree, 0), "not")
2085                   && validate_not_test(CHILD(tree, 1)));
2086        else if (nch == 1)
2087            res = validate_comparison(CHILD(tree, 0));
2088    }
2089    return (res);
2090}
2091
2092
2093static int
2094validate_comparison(node *tree)
2095{
2096    int pos;
2097    int nch = NCH(tree);
2098    int res = (validate_ntype(tree, comparison)
2099               && is_odd(nch)
2100               && validate_expr(CHILD(tree, 0)));
2101
2102    for (pos = 1; res && (pos < nch); pos += 2)
2103        res = (validate_comp_op(CHILD(tree, pos))
2104               && validate_expr(CHILD(tree, pos + 1)));
2105
2106    return (res);
2107}
2108
2109
2110static int
2111validate_comp_op(node *tree)
2112{
2113    int res = 0;
2114    int nch = NCH(tree);
2115
2116    if (!validate_ntype(tree, comp_op))
2117        return (0);
2118    if (nch == 1) {
2119        /*
2120         *  Only child will be a terminal with a well-defined symbolic name
2121         *  or a NAME with a string of either 'is' or 'in'
2122         */
2123        tree = CHILD(tree, 0);
2124        switch (TYPE(tree)) {
2125            case LESS:
2126            case GREATER:
2127            case EQEQUAL:
2128            case EQUAL:
2129            case LESSEQUAL:
2130            case GREATEREQUAL:
2131            case NOTEQUAL:
2132              res = 1;
2133              break;
2134            case NAME:
2135              res = ((strcmp(STR(tree), "in") == 0)
2136                     || (strcmp(STR(tree), "is") == 0));
2137              if (!res) {
2138                  PyErr_Format(parser_error,
2139                               "illegal operator '%s'", STR(tree));
2140              }
2141              break;
2142          default:
2143              err_string("illegal comparison operator type");
2144              break;
2145        }
2146    }
2147    else if ((res = validate_numnodes(tree, 2, "comp_op")) != 0) {
2148        res = (validate_ntype(CHILD(tree, 0), NAME)
2149               && validate_ntype(CHILD(tree, 1), NAME)
2150               && (((strcmp(STR(CHILD(tree, 0)), "is") == 0)
2151                    && (strcmp(STR(CHILD(tree, 1)), "not") == 0))
2152                   || ((strcmp(STR(CHILD(tree, 0)), "not") == 0)
2153                       && (strcmp(STR(CHILD(tree, 1)), "in") == 0))));
2154        if (!res && !PyErr_Occurred())
2155            err_string("unknown comparison operator");
2156    }
2157    return (res);
2158}
2159
2160
2161static int
2162validate_expr(node *tree)
2163{
2164    int j;
2165    int nch = NCH(tree);
2166    int res = (validate_ntype(tree, expr)
2167               && is_odd(nch)
2168               && validate_xor_expr(CHILD(tree, 0)));
2169
2170    for (j = 2; res && (j < nch); j += 2)
2171        res = (validate_xor_expr(CHILD(tree, j))
2172               && validate_vbar(CHILD(tree, j - 1)));
2173
2174    return (res);
2175}
2176
2177
2178static int
2179validate_xor_expr(node *tree)
2180{
2181    int j;
2182    int nch = NCH(tree);
2183    int res = (validate_ntype(tree, xor_expr)
2184               && is_odd(nch)
2185               && validate_and_expr(CHILD(tree, 0)));
2186
2187    for (j = 2; res && (j < nch); j += 2)
2188        res = (validate_circumflex(CHILD(tree, j - 1))
2189               && validate_and_expr(CHILD(tree, j)));
2190
2191    return (res);
2192}
2193
2194
2195static int
2196validate_and_expr(node *tree)
2197{
2198    int pos;
2199    int nch = NCH(tree);
2200    int res = (validate_ntype(tree, and_expr)
2201               && is_odd(nch)
2202               && validate_shift_expr(CHILD(tree, 0)));
2203
2204    for (pos = 1; res && (pos < nch); pos += 2)
2205        res = (validate_ampersand(CHILD(tree, pos))
2206               && validate_shift_expr(CHILD(tree, pos + 1)));
2207
2208    return (res);
2209}
2210
2211
2212static int
2213validate_chain_two_ops(node *tree, int (*termvalid)(node *), int op1, int op2)
2214 {
2215    int pos = 1;
2216    int nch = NCH(tree);
2217    int res = (is_odd(nch)
2218               && (*termvalid)(CHILD(tree, 0)));
2219
2220    for ( ; res && (pos < nch); pos += 2) {
2221        if (TYPE(CHILD(tree, pos)) != op1)
2222            res = validate_ntype(CHILD(tree, pos), op2);
2223        if (res)
2224            res = (*termvalid)(CHILD(tree, pos + 1));
2225    }
2226    return (res);
2227}
2228
2229
2230static int
2231validate_shift_expr(node *tree)
2232{
2233    return (validate_ntype(tree, shift_expr)
2234            && validate_chain_two_ops(tree, validate_arith_expr,
2235                                      LEFTSHIFT, RIGHTSHIFT));
2236}
2237
2238
2239static int
2240validate_arith_expr(node *tree)
2241{
2242    return (validate_ntype(tree, arith_expr)
2243            && validate_chain_two_ops(tree, validate_term, PLUS, MINUS));
2244}
2245
2246
2247static int
2248validate_term(node *tree)
2249{
2250    int pos = 1;
2251    int nch = NCH(tree);
2252    int res = (validate_ntype(tree, term)
2253               && is_odd(nch)
2254               && validate_factor(CHILD(tree, 0)));
2255
2256    for ( ; res && (pos < nch); pos += 2)
2257        res = (((TYPE(CHILD(tree, pos)) == STAR)
2258               || (TYPE(CHILD(tree, pos)) == SLASH)
2259               || (TYPE(CHILD(tree, pos)) == DOUBLESLASH)
2260               || (TYPE(CHILD(tree, pos)) == PERCENT))
2261               && validate_factor(CHILD(tree, pos + 1)));
2262
2263    return (res);
2264}
2265
2266
2267/*  factor:
2268 *
2269 *  factor: ('+'|'-'|'~') factor | power
2270 */
2271static int
2272validate_factor(node *tree)
2273{
2274    int nch = NCH(tree);
2275    int res = (validate_ntype(tree, factor)
2276               && (((nch == 2)
2277                    && ((TYPE(CHILD(tree, 0)) == PLUS)
2278                        || (TYPE(CHILD(tree, 0)) == MINUS)
2279                        || (TYPE(CHILD(tree, 0)) == TILDE))
2280                    && validate_factor(CHILD(tree, 1)))
2281                   || ((nch == 1)
2282                       && validate_power(CHILD(tree, 0)))));
2283    return (res);
2284}
2285
2286
2287/*  power:
2288 *
2289 *  power: atom trailer* ('**' factor)*
2290 */
2291static int
2292validate_power(node *tree)
2293{
2294    int pos = 1;
2295    int nch = NCH(tree);
2296    int res = (validate_ntype(tree, power) && (nch >= 1)
2297               && validate_atom(CHILD(tree, 0)));
2298
2299    while (res && (pos < nch) && (TYPE(CHILD(tree, pos)) == trailer))
2300        res = validate_trailer(CHILD(tree, pos++));
2301    if (res && (pos < nch)) {
2302        if (!is_even(nch - pos)) {
2303            err_string("illegal number of nodes for 'power'");
2304            return (0);
2305        }
2306        for ( ; res && (pos < (nch - 1)); pos += 2)
2307            res = (validate_doublestar(CHILD(tree, pos))
2308                   && validate_factor(CHILD(tree, pos + 1)));
2309    }
2310    return (res);
2311}
2312
2313
2314static int
2315validate_atom(node *tree)
2316{
2317    int pos;
2318    int nch = NCH(tree);
2319    int res = validate_ntype(tree, atom);
2320
2321    if (res && nch < 1)
2322        res = validate_numnodes(tree, nch+1, "atom");
2323    if (res) {
2324        switch (TYPE(CHILD(tree, 0))) {
2325          case LPAR:
2326            res = ((nch <= 3)
2327                   && (validate_rparen(CHILD(tree, nch - 1))));
2328
2329            if (res && (nch == 3)) {
2330		if (TYPE(CHILD(tree, 1))==yield_expr)
2331			res = validate_yield_expr(CHILD(tree, 1));
2332		else
2333                	res = validate_testlist_gexp(CHILD(tree, 1));
2334	    }
2335            break;
2336          case LSQB:
2337            if (nch == 2)
2338                res = validate_ntype(CHILD(tree, 1), RSQB);
2339            else if (nch == 3)
2340                res = (validate_listmaker(CHILD(tree, 1))
2341                       && validate_ntype(CHILD(tree, 2), RSQB));
2342            else {
2343                res = 0;
2344                err_string("illegal list display atom");
2345            }
2346            break;
2347          case LBRACE:
2348            res = ((nch <= 3)
2349                   && validate_ntype(CHILD(tree, nch - 1), RBRACE));
2350
2351            if (res && (nch == 3))
2352                res = validate_dictmaker(CHILD(tree, 1));
2353            break;
2354          case BACKQUOTE:
2355            res = ((nch == 3)
2356                   && validate_testlist1(CHILD(tree, 1))
2357                   && validate_ntype(CHILD(tree, 2), BACKQUOTE));
2358            break;
2359          case NAME:
2360          case NUMBER:
2361            res = (nch == 1);
2362            break;
2363          case STRING:
2364            for (pos = 1; res && (pos < nch); ++pos)
2365                res = validate_ntype(CHILD(tree, pos), STRING);
2366            break;
2367          default:
2368            res = 0;
2369            break;
2370        }
2371    }
2372    return (res);
2373}
2374
2375
2376/*  listmaker:
2377 *    test ( list_for | (',' test)* [','] )
2378 */
2379static int
2380validate_listmaker(node *tree)
2381{
2382    int nch = NCH(tree);
2383    int ok = nch;
2384
2385    if (nch == 0)
2386        err_string("missing child nodes of listmaker");
2387    else
2388        ok = validate_test(CHILD(tree, 0));
2389
2390    /*
2391     *  list_for | (',' test)* [',']
2392     */
2393    if (nch == 2 && TYPE(CHILD(tree, 1)) == list_for)
2394        ok = validate_list_for(CHILD(tree, 1));
2395    else {
2396        /*  (',' test)* [',']  */
2397        int i = 1;
2398        while (ok && nch - i >= 2) {
2399            ok = (validate_comma(CHILD(tree, i))
2400                  && validate_test(CHILD(tree, i+1)));
2401            i += 2;
2402        }
2403        if (ok && i == nch-1)
2404            ok = validate_comma(CHILD(tree, i));
2405        else if (i != nch) {
2406            ok = 0;
2407            err_string("illegal trailing nodes for listmaker");
2408        }
2409    }
2410    return ok;
2411}
2412
2413/*  testlist_gexp:
2414 *    test ( gen_for | (',' test)* [','] )
2415 */
2416static int
2417validate_testlist_gexp(node *tree)
2418{
2419    int nch = NCH(tree);
2420    int ok = nch;
2421
2422    if (nch == 0)
2423        err_string("missing child nodes of testlist_gexp");
2424    else {
2425        ok = validate_test(CHILD(tree, 0));
2426    }
2427
2428    /*
2429     *  gen_for | (',' test)* [',']
2430     */
2431    if (nch == 2 && TYPE(CHILD(tree, 1)) == gen_for)
2432        ok = validate_gen_for(CHILD(tree, 1));
2433    else {
2434        /*  (',' test)* [',']  */
2435        int i = 1;
2436        while (ok && nch - i >= 2) {
2437            ok = (validate_comma(CHILD(tree, i))
2438                  && validate_test(CHILD(tree, i+1)));
2439            i += 2;
2440        }
2441        if (ok && i == nch-1)
2442            ok = validate_comma(CHILD(tree, i));
2443        else if (i != nch) {
2444            ok = 0;
2445            err_string("illegal trailing nodes for testlist_gexp");
2446        }
2447    }
2448    return ok;
2449}
2450
2451/*  decorator:
2452 *    '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
2453 */
2454static int
2455validate_decorator(node *tree)
2456{
2457    int ok;
2458    int nch = NCH(tree);
2459    ok = (validate_ntype(tree, decorator) &&
2460	  (nch == 3 || nch == 5 || nch == 6) &&
2461	  validate_at(CHILD(tree, 0)) &&
2462	  validate_dotted_name(CHILD(tree, 1)) &&
2463	  validate_newline(RCHILD(tree, -1)));
2464
2465    if (ok && nch != 3) {
2466	ok = (validate_lparen(CHILD(tree, 2)) &&
2467	      validate_rparen(RCHILD(tree, -2)));
2468
2469	if (ok && nch == 6)
2470	    ok = validate_arglist(CHILD(tree, 3));
2471    }
2472
2473    return ok;
2474}
2475
2476/*  decorators:
2477 *    decorator+
2478 */
2479static int
2480validate_decorators(node *tree)
2481{
2482    int i, nch, ok;
2483    nch = NCH(tree);
2484    ok = validate_ntype(tree, decorators) && nch >= 1;
2485
2486    for (i = 0; ok && i < nch; ++i)
2487	ok = validate_decorator(CHILD(tree, i));
2488
2489    return ok;
2490}
2491
2492/*  funcdef:
2493 *
2494 *            -6   -5    -4         -3  -2 -1
2495 *  [decorators] 'def' NAME parameters ':' suite
2496 */
2497static int
2498validate_funcdef(node *tree)
2499{
2500    int nch = NCH(tree);
2501    int ok = (validate_ntype(tree, funcdef)
2502	       && ((nch == 5) || (nch == 6))
2503	       && validate_name(RCHILD(tree, -5), "def")
2504	       && validate_ntype(RCHILD(tree, -4), NAME)
2505	       && validate_colon(RCHILD(tree, -2))
2506	       && validate_parameters(RCHILD(tree, -3))
2507	       && validate_suite(RCHILD(tree, -1)));
2508
2509    if (ok && (nch == 6))
2510	ok = validate_decorators(CHILD(tree, 0));
2511
2512    return ok;
2513}
2514
2515
2516static int
2517validate_lambdef(node *tree)
2518{
2519    int nch = NCH(tree);
2520    int res = (validate_ntype(tree, lambdef)
2521               && ((nch == 3) || (nch == 4))
2522               && validate_name(CHILD(tree, 0), "lambda")
2523               && validate_colon(CHILD(tree, nch - 2))
2524               && validate_test(CHILD(tree, nch - 1)));
2525
2526    if (res && (nch == 4))
2527        res = validate_varargslist(CHILD(tree, 1));
2528    else if (!res && !PyErr_Occurred())
2529        (void) validate_numnodes(tree, 3, "lambdef");
2530
2531    return (res);
2532}
2533
2534
2535/*  arglist:
2536 *
2537 *  (argument ',')* (argument [','] | '*' test [',' '**' test] | '**' test)
2538 */
2539static int
2540validate_arglist(node *tree)
2541{
2542    int nch = NCH(tree);
2543    int i = 0;
2544    int ok = 1;
2545
2546    if (nch <= 0)
2547        /* raise the right error from having an invalid number of children */
2548        return validate_numnodes(tree, nch + 1, "arglist");
2549
2550    if (nch > 1) {
2551        for (i=0; i<nch; i++) {
2552            if (TYPE(CHILD(tree, i)) == argument) {
2553                node *ch = CHILD(tree, i);
2554                if (NCH(ch) == 2 && TYPE(CHILD(ch, 1)) == gen_for) {
2555                    err_string("need '(', ')' for generator expression");
2556                    return 0;
2557                }
2558            }
2559        }
2560    }
2561
2562    while (ok && nch-i >= 2) {
2563        /* skip leading (argument ',') */
2564        ok = (validate_argument(CHILD(tree, i))
2565              && validate_comma(CHILD(tree, i+1)));
2566        if (ok)
2567            i += 2;
2568        else
2569            PyErr_Clear();
2570    }
2571    ok = 1;
2572    if (nch-i > 0) {
2573        /*
2574         * argument | '*' test [',' '**' test] | '**' test
2575         */
2576        int sym = TYPE(CHILD(tree, i));
2577
2578        if (sym == argument) {
2579            ok = validate_argument(CHILD(tree, i));
2580            if (ok && i+1 != nch) {
2581                err_string("illegal arglist specification"
2582                           " (extra stuff on end)");
2583                ok = 0;
2584            }
2585        }
2586        else if (sym == STAR) {
2587            ok = validate_star(CHILD(tree, i));
2588            if (ok && (nch-i == 2))
2589                ok = validate_test(CHILD(tree, i+1));
2590            else if (ok && (nch-i == 5))
2591                ok = (validate_test(CHILD(tree, i+1))
2592                      && validate_comma(CHILD(tree, i+2))
2593                      && validate_doublestar(CHILD(tree, i+3))
2594                      && validate_test(CHILD(tree, i+4)));
2595            else {
2596                err_string("illegal use of '*' in arglist");
2597                ok = 0;
2598            }
2599        }
2600        else if (sym == DOUBLESTAR) {
2601            if (nch-i == 2)
2602                ok = (validate_doublestar(CHILD(tree, i))
2603                      && validate_test(CHILD(tree, i+1)));
2604            else {
2605                err_string("illegal use of '**' in arglist");
2606                ok = 0;
2607            }
2608        }
2609        else {
2610            err_string("illegal arglist specification");
2611            ok = 0;
2612        }
2613    }
2614    return (ok);
2615}
2616
2617
2618
2619/*  argument:
2620 *
2621 *  [test '='] test [gen_for]
2622 */
2623static int
2624validate_argument(node *tree)
2625{
2626    int nch = NCH(tree);
2627    int res = (validate_ntype(tree, argument)
2628               && ((nch == 1) || (nch == 2) || (nch == 3))
2629               && validate_test(CHILD(tree, 0)));
2630
2631    if (res && (nch == 2))
2632        res = validate_gen_for(CHILD(tree, 1));
2633    else if (res && (nch == 3))
2634        res = (validate_equal(CHILD(tree, 1))
2635               && validate_test(CHILD(tree, 2)));
2636
2637    return (res);
2638}
2639
2640
2641
2642/*  trailer:
2643 *
2644 *  '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
2645 */
2646static int
2647validate_trailer(node *tree)
2648{
2649    int nch = NCH(tree);
2650    int res = validate_ntype(tree, trailer) && ((nch == 2) || (nch == 3));
2651
2652    if (res) {
2653        switch (TYPE(CHILD(tree, 0))) {
2654          case LPAR:
2655            res = validate_rparen(CHILD(tree, nch - 1));
2656            if (res && (nch == 3))
2657                res = validate_arglist(CHILD(tree, 1));
2658            break;
2659          case LSQB:
2660            res = (validate_numnodes(tree, 3, "trailer")
2661                   && validate_subscriptlist(CHILD(tree, 1))
2662                   && validate_ntype(CHILD(tree, 2), RSQB));
2663            break;
2664          case DOT:
2665            res = (validate_numnodes(tree, 2, "trailer")
2666                   && validate_ntype(CHILD(tree, 1), NAME));
2667            break;
2668          default:
2669            res = 0;
2670            break;
2671        }
2672    }
2673    else {
2674        (void) validate_numnodes(tree, 2, "trailer");
2675    }
2676    return (res);
2677}
2678
2679
2680/*  subscriptlist:
2681 *
2682 *  subscript (',' subscript)* [',']
2683 */
2684static int
2685validate_subscriptlist(node *tree)
2686{
2687    return (validate_repeating_list(tree, subscriptlist,
2688                                    validate_subscript, "subscriptlist"));
2689}
2690
2691
2692/*  subscript:
2693 *
2694 *  '.' '.' '.' | test | [test] ':' [test] [sliceop]
2695 */
2696static int
2697validate_subscript(node *tree)
2698{
2699    int offset = 0;
2700    int nch = NCH(tree);
2701    int res = validate_ntype(tree, subscript) && (nch >= 1) && (nch <= 4);
2702
2703    if (!res) {
2704        if (!PyErr_Occurred())
2705            err_string("invalid number of arguments for subscript node");
2706        return (0);
2707    }
2708    if (TYPE(CHILD(tree, 0)) == DOT)
2709        /* take care of ('.' '.' '.') possibility */
2710        return (validate_numnodes(tree, 3, "subscript")
2711                && validate_dot(CHILD(tree, 0))
2712                && validate_dot(CHILD(tree, 1))
2713                && validate_dot(CHILD(tree, 2)));
2714    if (nch == 1) {
2715        if (TYPE(CHILD(tree, 0)) == test)
2716            res = validate_test(CHILD(tree, 0));
2717        else
2718            res = validate_colon(CHILD(tree, 0));
2719        return (res);
2720    }
2721    /*  Must be [test] ':' [test] [sliceop],
2722     *  but at least one of the optional components will
2723     *  be present, but we don't know which yet.
2724     */
2725    if ((TYPE(CHILD(tree, 0)) != COLON) || (nch == 4)) {
2726        res = validate_test(CHILD(tree, 0));
2727        offset = 1;
2728    }
2729    if (res)
2730        res = validate_colon(CHILD(tree, offset));
2731    if (res) {
2732        int rem = nch - ++offset;
2733        if (rem) {
2734            if (TYPE(CHILD(tree, offset)) == test) {
2735                res = validate_test(CHILD(tree, offset));
2736                ++offset;
2737                --rem;
2738            }
2739            if (res && rem)
2740                res = validate_sliceop(CHILD(tree, offset));
2741        }
2742    }
2743    return (res);
2744}
2745
2746
2747static int
2748validate_sliceop(node *tree)
2749{
2750    int nch = NCH(tree);
2751    int res = ((nch == 1) || validate_numnodes(tree, 2, "sliceop"))
2752              && validate_ntype(tree, sliceop);
2753    if (!res && !PyErr_Occurred()) {
2754        res = validate_numnodes(tree, 1, "sliceop");
2755    }
2756    if (res)
2757        res = validate_colon(CHILD(tree, 0));
2758    if (res && (nch == 2))
2759        res = validate_test(CHILD(tree, 1));
2760
2761    return (res);
2762}
2763
2764
2765static int
2766validate_exprlist(node *tree)
2767{
2768    return (validate_repeating_list(tree, exprlist,
2769                                    validate_expr, "exprlist"));
2770}
2771
2772
2773static int
2774validate_dictmaker(node *tree)
2775{
2776    int nch = NCH(tree);
2777    int res = (validate_ntype(tree, dictmaker)
2778               && (nch >= 3)
2779               && validate_test(CHILD(tree, 0))
2780               && validate_colon(CHILD(tree, 1))
2781               && validate_test(CHILD(tree, 2)));
2782
2783    if (res && ((nch % 4) == 0))
2784        res = validate_comma(CHILD(tree, --nch));
2785    else if (res)
2786        res = ((nch % 4) == 3);
2787
2788    if (res && (nch > 3)) {
2789        int pos = 3;
2790        /*  ( ',' test ':' test )*  */
2791        while (res && (pos < nch)) {
2792            res = (validate_comma(CHILD(tree, pos))
2793                   && validate_test(CHILD(tree, pos + 1))
2794                   && validate_colon(CHILD(tree, pos + 2))
2795                   && validate_test(CHILD(tree, pos + 3)));
2796            pos += 4;
2797        }
2798    }
2799    return (res);
2800}
2801
2802
2803static int
2804validate_eval_input(node *tree)
2805{
2806    int pos;
2807    int nch = NCH(tree);
2808    int res = (validate_ntype(tree, eval_input)
2809               && (nch >= 2)
2810               && validate_testlist(CHILD(tree, 0))
2811               && validate_ntype(CHILD(tree, nch - 1), ENDMARKER));
2812
2813    for (pos = 1; res && (pos < (nch - 1)); ++pos)
2814        res = validate_ntype(CHILD(tree, pos), NEWLINE);
2815
2816    return (res);
2817}
2818
2819
2820static int
2821validate_node(node *tree)
2822{
2823    int   nch  = 0;                     /* num. children on current node  */
2824    int   res  = 1;                     /* result value                   */
2825    node* next = 0;                     /* node to process after this one */
2826
2827    while (res && (tree != 0)) {
2828        nch  = NCH(tree);
2829        next = 0;
2830        switch (TYPE(tree)) {
2831            /*
2832             *  Definition nodes.
2833             */
2834          case funcdef:
2835            res = validate_funcdef(tree);
2836            break;
2837          case classdef:
2838            res = validate_class(tree);
2839            break;
2840            /*
2841             *  "Trivial" parse tree nodes.
2842             *  (Why did I call these trivial?)
2843             */
2844          case stmt:
2845            res = validate_stmt(tree);
2846            break;
2847          case small_stmt:
2848            /*
2849             *  expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt
2850             *  | import_stmt | global_stmt | exec_stmt | assert_stmt
2851             */
2852            res = validate_small_stmt(tree);
2853            break;
2854          case flow_stmt:
2855            res  = (validate_numnodes(tree, 1, "flow_stmt")
2856                    && ((TYPE(CHILD(tree, 0)) == break_stmt)
2857                        || (TYPE(CHILD(tree, 0)) == continue_stmt)
2858                        || (TYPE(CHILD(tree, 0)) == yield_stmt)
2859                        || (TYPE(CHILD(tree, 0)) == return_stmt)
2860                        || (TYPE(CHILD(tree, 0)) == raise_stmt)));
2861            if (res)
2862                next = CHILD(tree, 0);
2863            else if (nch == 1)
2864                err_string("illegal flow_stmt type");
2865            break;
2866          case yield_stmt:
2867            res = validate_yield_stmt(tree);
2868            break;
2869            /*
2870             *  Compound statements.
2871             */
2872          case simple_stmt:
2873            res = validate_simple_stmt(tree);
2874            break;
2875          case compound_stmt:
2876            res = validate_compound_stmt(tree);
2877            break;
2878            /*
2879             *  Fundamental statements.
2880             */
2881          case expr_stmt:
2882            res = validate_expr_stmt(tree);
2883            break;
2884          case print_stmt:
2885            res = validate_print_stmt(tree);
2886            break;
2887          case del_stmt:
2888            res = validate_del_stmt(tree);
2889            break;
2890          case pass_stmt:
2891            res = (validate_numnodes(tree, 1, "pass")
2892                   && validate_name(CHILD(tree, 0), "pass"));
2893            break;
2894          case break_stmt:
2895            res = (validate_numnodes(tree, 1, "break")
2896                   && validate_name(CHILD(tree, 0), "break"));
2897            break;
2898          case continue_stmt:
2899            res = (validate_numnodes(tree, 1, "continue")
2900                   && validate_name(CHILD(tree, 0), "continue"));
2901            break;
2902          case return_stmt:
2903            res = validate_return_stmt(tree);
2904            break;
2905          case raise_stmt:
2906            res = validate_raise_stmt(tree);
2907            break;
2908          case import_stmt:
2909            res = validate_import_stmt(tree);
2910            break;
2911	  case import_name:
2912	    res = validate_import_name(tree);
2913	    break;
2914	  case import_from:
2915	    res = validate_import_from(tree);
2916	    break;
2917          case global_stmt:
2918            res = validate_global_stmt(tree);
2919            break;
2920          case exec_stmt:
2921            res = validate_exec_stmt(tree);
2922            break;
2923          case assert_stmt:
2924            res = validate_assert_stmt(tree);
2925            break;
2926          case if_stmt:
2927            res = validate_if(tree);
2928            break;
2929          case while_stmt:
2930            res = validate_while(tree);
2931            break;
2932          case for_stmt:
2933            res = validate_for(tree);
2934            break;
2935          case try_stmt:
2936            res = validate_try(tree);
2937            break;
2938          case suite:
2939            res = validate_suite(tree);
2940            break;
2941            /*
2942             *  Expression nodes.
2943             */
2944          case testlist:
2945            res = validate_testlist(tree);
2946            break;
2947          case yield_expr:
2948            res = validate_yield_expr(tree);
2949            break;
2950          case testlist1:
2951            res = validate_testlist1(tree);
2952            break;
2953          case test:
2954            res = validate_test(tree);
2955            break;
2956          case and_test:
2957            res = validate_and_test(tree);
2958            break;
2959          case not_test:
2960            res = validate_not_test(tree);
2961            break;
2962          case comparison:
2963            res = validate_comparison(tree);
2964            break;
2965          case exprlist:
2966            res = validate_exprlist(tree);
2967            break;
2968          case comp_op:
2969            res = validate_comp_op(tree);
2970            break;
2971          case expr:
2972            res = validate_expr(tree);
2973            break;
2974          case xor_expr:
2975            res = validate_xor_expr(tree);
2976            break;
2977          case and_expr:
2978            res = validate_and_expr(tree);
2979            break;
2980          case shift_expr:
2981            res = validate_shift_expr(tree);
2982            break;
2983          case arith_expr:
2984            res = validate_arith_expr(tree);
2985            break;
2986          case term:
2987            res = validate_term(tree);
2988            break;
2989          case factor:
2990            res = validate_factor(tree);
2991            break;
2992          case power:
2993            res = validate_power(tree);
2994            break;
2995          case atom:
2996            res = validate_atom(tree);
2997            break;
2998
2999          default:
3000            /* Hopefully never reached! */
3001            err_string("unrecognized node type");
3002            res = 0;
3003            break;
3004        }
3005        tree = next;
3006    }
3007    return (res);
3008}
3009
3010
3011static int
3012validate_expr_tree(node *tree)
3013{
3014    int res = validate_eval_input(tree);
3015
3016    if (!res && !PyErr_Occurred())
3017        err_string("could not validate expression tuple");
3018
3019    return (res);
3020}
3021
3022
3023/*  file_input:
3024 *      (NEWLINE | stmt)* ENDMARKER
3025 */
3026static int
3027validate_file_input(node *tree)
3028{
3029    int j;
3030    int nch = NCH(tree) - 1;
3031    int res = ((nch >= 0)
3032               && validate_ntype(CHILD(tree, nch), ENDMARKER));
3033
3034    for (j = 0; res && (j < nch); ++j) {
3035        if (TYPE(CHILD(tree, j)) == stmt)
3036            res = validate_stmt(CHILD(tree, j));
3037        else
3038            res = validate_newline(CHILD(tree, j));
3039    }
3040    /*  This stays in to prevent any internal failures from getting to the
3041     *  user.  Hopefully, this won't be needed.  If a user reports getting
3042     *  this, we have some debugging to do.
3043     */
3044    if (!res && !PyErr_Occurred())
3045        err_string("VALIDATION FAILURE: report this to the maintainer!");
3046
3047    return (res);
3048}
3049
3050static int
3051validate_encoding_decl(node *tree)
3052{
3053    int nch = NCH(tree);
3054    int res = ((nch == 1)
3055        && validate_file_input(CHILD(tree, 0)));
3056
3057    if (!res && !PyErr_Occurred())
3058        err_string("Error Parsing encoding_decl");
3059
3060    return res;
3061}
3062
3063static PyObject*
3064pickle_constructor = NULL;
3065
3066
3067static PyObject*
3068parser__pickler(PyObject *self, PyObject *args)
3069{
3070    NOTE(ARGUNUSED(self))
3071    PyObject *result = NULL;
3072    PyObject *st = NULL;
3073    PyObject *empty_dict = NULL;
3074
3075    if (PyArg_ParseTuple(args, "O!:_pickler", &PyST_Type, &st)) {
3076        PyObject *newargs;
3077        PyObject *tuple;
3078
3079        if ((empty_dict = PyDict_New()) == NULL)
3080            goto finally;
3081        if ((newargs = Py_BuildValue("Oi", st, 1)) == NULL)
3082            goto finally;
3083        tuple = parser_st2tuple((PyST_Object*)NULL, newargs, empty_dict);
3084        if (tuple != NULL) {
3085            result = Py_BuildValue("O(O)", pickle_constructor, tuple);
3086            Py_DECREF(tuple);
3087        }
3088        Py_DECREF(empty_dict);
3089        Py_DECREF(newargs);
3090    }
3091  finally:
3092    Py_XDECREF(empty_dict);
3093
3094    return (result);
3095}
3096
3097
3098/*  Functions exported by this module.  Most of this should probably
3099 *  be converted into an ST object with methods, but that is better
3100 *  done directly in Python, allowing subclasses to be created directly.
3101 *  We'd really have to write a wrapper around it all anyway to allow
3102 *  inheritance.
3103 */
3104static PyMethodDef parser_functions[] =  {
3105    {"ast2tuple",       (PyCFunction)parser_st2tuple,  PUBLIC_METHOD_TYPE,
3106        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3107    {"ast2list",        (PyCFunction)parser_st2list,   PUBLIC_METHOD_TYPE,
3108        PyDoc_STR("Creates a list-tree representation of an ST.")},
3109    {"compileast",      (PyCFunction)parser_compilest, PUBLIC_METHOD_TYPE,
3110        PyDoc_STR("Compiles an ST object into a code object.")},
3111    {"compilest",      (PyCFunction)parser_compilest,  PUBLIC_METHOD_TYPE,
3112        PyDoc_STR("Compiles an ST object into a code object.")},
3113    {"expr",            (PyCFunction)parser_expr,      PUBLIC_METHOD_TYPE,
3114        PyDoc_STR("Creates an ST object from an expression.")},
3115    {"isexpr",          (PyCFunction)parser_isexpr,    PUBLIC_METHOD_TYPE,
3116        PyDoc_STR("Determines if an ST object was created from an expression.")},
3117    {"issuite",         (PyCFunction)parser_issuite,   PUBLIC_METHOD_TYPE,
3118        PyDoc_STR("Determines if an ST object was created from a suite.")},
3119    {"suite",           (PyCFunction)parser_suite,     PUBLIC_METHOD_TYPE,
3120        PyDoc_STR("Creates an ST object from a suite.")},
3121    {"sequence2ast",    (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3122        PyDoc_STR("Creates an ST object from a tree representation.")},
3123    {"sequence2st",     (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3124        PyDoc_STR("Creates an ST object from a tree representation.")},
3125    {"st2tuple",        (PyCFunction)parser_st2tuple,  PUBLIC_METHOD_TYPE,
3126        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3127    {"st2list",         (PyCFunction)parser_st2list,   PUBLIC_METHOD_TYPE,
3128        PyDoc_STR("Creates a list-tree representation of an ST.")},
3129    {"tuple2ast",       (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3130        PyDoc_STR("Creates an ST object from a tree representation.")},
3131    {"tuple2st",        (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3132        PyDoc_STR("Creates an ST object from a tree representation.")},
3133
3134    /* private stuff: support pickle module */
3135    {"_pickler",        (PyCFunction)parser__pickler,  METH_VARARGS,
3136        PyDoc_STR("Returns the pickle magic to allow ST objects to be pickled.")},
3137
3138    {NULL, NULL, 0, NULL}
3139    };
3140
3141
3142PyMODINIT_FUNC initparser(void);  /* supply a prototype */
3143
3144PyMODINIT_FUNC
3145initparser(void)
3146{
3147    PyObject *module, *copyreg;
3148
3149    PyST_Type.ob_type = &PyType_Type;
3150    module = Py_InitModule("parser", parser_functions);
3151
3152    if (parser_error == 0)
3153        parser_error = PyErr_NewException("parser.ParserError", NULL, NULL);
3154
3155    if (parser_error == 0)
3156        /* caller will check PyErr_Occurred() */
3157        return;
3158    /* CAUTION:  The code next used to skip bumping the refcount on
3159     * parser_error.  That's a disaster if initparser() gets called more
3160     * than once.  By incref'ing, we ensure that each module dict that
3161     * gets created owns its reference to the shared parser_error object,
3162     * and the file static parser_error vrbl owns a reference too.
3163     */
3164    Py_INCREF(parser_error);
3165    if (PyModule_AddObject(module, "ParserError", parser_error) != 0)
3166        return;
3167
3168    Py_INCREF(&PyST_Type);
3169    PyModule_AddObject(module, "ASTType", (PyObject*)&PyST_Type);
3170    Py_INCREF(&PyST_Type);
3171    PyModule_AddObject(module, "STType", (PyObject*)&PyST_Type);
3172
3173    PyModule_AddStringConstant(module, "__copyright__",
3174                               parser_copyright_string);
3175    PyModule_AddStringConstant(module, "__doc__",
3176                               parser_doc_string);
3177    PyModule_AddStringConstant(module, "__version__",
3178                               parser_version_string);
3179
3180    /* Register to support pickling.
3181     * If this fails, the import of this module will fail because an
3182     * exception will be raised here; should we clear the exception?
3183     */
3184    copyreg = PyImport_ImportModule("copy_reg");
3185    if (copyreg != NULL) {
3186        PyObject *func, *pickler;
3187
3188        func = PyObject_GetAttrString(copyreg, "pickle");
3189        pickle_constructor = PyObject_GetAttrString(module, "sequence2st");
3190        pickler = PyObject_GetAttrString(module, "_pickler");
3191        Py_XINCREF(pickle_constructor);
3192        if ((func != NULL) && (pickle_constructor != NULL)
3193            && (pickler != NULL)) {
3194            PyObject *res;
3195
3196            res = PyObject_CallFunction(func, "OOO", &PyST_Type, pickler,
3197                                        pickle_constructor);
3198            Py_XDECREF(res);
3199        }
3200        Py_XDECREF(func);
3201        Py_XDECREF(pickle_constructor);
3202        Py_XDECREF(pickler);
3203        Py_DECREF(copyreg);
3204    }
3205}
3206