1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef _EXPRESSION_H
18#define _EXPRESSION_H
19
20#include <unistd.h>
21
22#include "yydefs.h"
23
24#ifdef __cplusplus
25extern "C" {
26#endif
27
28#define MAX_STRING_LEN 1024
29
30typedef struct Expr Expr;
31
32typedef struct {
33    // Optional pointer to app-specific data; the core of edify never
34    // uses this value.
35    void* cookie;
36
37    // The source of the original script.  Must be NULL-terminated,
38    // and in writable memory (Evaluate may make temporary changes to
39    // it but will restore it when done).
40    char* script;
41
42    // The error message (if any) returned if the evaluation aborts.
43    // Should be NULL initially, will be either NULL or a malloc'd
44    // pointer after Evaluate() returns.
45    char* errmsg;
46} State;
47
48#define VAL_STRING  1  // data will be NULL-terminated; size doesn't count null
49#define VAL_BLOB    2
50
51typedef struct {
52    int type;
53    ssize_t size;
54    char* data;
55} Value;
56
57typedef Value* (*Function)(const char* name, State* state,
58                           int argc, Expr* argv[]);
59
60struct Expr {
61    Function fn;
62    char* name;
63    int argc;
64    Expr** argv;
65    int start, end;
66};
67
68// Take one of the Expr*s passed to the function as an argument,
69// evaluate it, return the resulting Value.  The caller takes
70// ownership of the returned Value.
71Value* EvaluateValue(State* state, Expr* expr);
72
73// Take one of the Expr*s passed to the function as an argument,
74// evaluate it, assert that it is a string, and return the resulting
75// char*.  The caller takes ownership of the returned char*.  This is
76// a convenience function for older functions that want to deal only
77// with strings.
78char* Evaluate(State* state, Expr* expr);
79
80// Glue to make an Expr out of a literal.
81Value* Literal(const char* name, State* state, int argc, Expr* argv[]);
82
83// Functions corresponding to various syntactic sugar operators.
84// ("concat" is also available as a builtin function, to concatenate
85// more than two strings.)
86Value* ConcatFn(const char* name, State* state, int argc, Expr* argv[]);
87Value* LogicalAndFn(const char* name, State* state, int argc, Expr* argv[]);
88Value* LogicalOrFn(const char* name, State* state, int argc, Expr* argv[]);
89Value* LogicalNotFn(const char* name, State* state, int argc, Expr* argv[]);
90Value* SubstringFn(const char* name, State* state, int argc, Expr* argv[]);
91Value* EqualityFn(const char* name, State* state, int argc, Expr* argv[]);
92Value* InequalityFn(const char* name, State* state, int argc, Expr* argv[]);
93Value* SequenceFn(const char* name, State* state, int argc, Expr* argv[]);
94
95// Convenience function for building expressions with a fixed number
96// of arguments.
97Expr* Build(Function fn, YYLTYPE loc, int count, ...);
98
99// Global builtins, registered by RegisterBuiltins().
100Value* IfElseFn(const char* name, State* state, int argc, Expr* argv[]);
101Value* AssertFn(const char* name, State* state, int argc, Expr* argv[]);
102Value* AbortFn(const char* name, State* state, int argc, Expr* argv[]);
103
104
105// For setting and getting the global error string (when returning
106// NULL from a function).
107void SetError(const char* message);  // makes a copy
108const char* GetError();              // retains ownership
109void ClearError();
110
111
112typedef struct {
113  const char* name;
114  Function fn;
115} NamedFunction;
116
117// Register a new function.  The same Function may be registered under
118// multiple names, but a given name should only be used once.
119void RegisterFunction(const char* name, Function fn);
120
121// Register all the builtins.
122void RegisterBuiltins();
123
124// Call this after all calls to RegisterFunction() but before parsing
125// any scripts to finish building the function table.
126void FinishRegistration();
127
128// Find the Function for a given name; return NULL if no such function
129// exists.
130Function FindFunction(const char* name);
131
132
133// --- convenience functions for use in functions ---
134
135// Evaluate the expressions in argv, giving 'count' char* (the ... is
136// zero or more char** to put them in).  If any expression evaluates
137// to NULL, free the rest and return -1.  Return 0 on success.
138int ReadArgs(State* state, Expr* argv[], int count, ...);
139
140// Evaluate the expressions in argv, giving 'count' Value* (the ... is
141// zero or more Value** to put them in).  If any expression evaluates
142// to NULL, free the rest and return -1.  Return 0 on success.
143int ReadValueArgs(State* state, Expr* argv[], int count, ...);
144
145// Evaluate the expressions in argv, returning an array of char*
146// results.  If any evaluate to NULL, free the rest and return NULL.
147// The caller is responsible for freeing the returned array and the
148// strings it contains.
149char** ReadVarArgs(State* state, int argc, Expr* argv[]);
150
151// Evaluate the expressions in argv, returning an array of Value*
152// results.  If any evaluate to NULL, free the rest and return NULL.
153// The caller is responsible for freeing the returned array and the
154// Values it contains.
155Value** ReadValueVarArgs(State* state, int argc, Expr* argv[]);
156
157// Use printf-style arguments to compose an error message to put into
158// *state.  Returns NULL.
159Value* ErrorAbort(State* state, const char* format, ...) __attribute__((format(printf, 2, 3)));
160
161// Wrap a string into a Value, taking ownership of the string.
162Value* StringValue(char* str);
163
164// Free a Value object.
165void FreeValue(Value* v);
166
167int parse_string(const char* str, Expr** root, int* error_count);
168
169#ifdef __cplusplus
170}  // extern "C"
171#endif
172
173#endif  // _EXPRESSION_H
174