/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _EXPRESSION_H
#define _EXPRESSION_H
#include "yydefs.h"
#define MAX_STRING_LEN 1024
typedef struct Expr Expr;
typedef struct {
// Optional pointer to app-specific data; the core of edify never
// uses this value.
void* cookie;
// The source of the original script. Must be NULL-terminated,
// and in writable memory (Evaluate may make temporary changes to
// it but will restore it when done).
char* script;
// The error message (if any) returned if the evaluation aborts.
// Should be NULL initially, will be either NULL or a malloc'd
// pointer after Evaluate() returns.
char* errmsg;
} State;
typedef char* (*Function)(const char* name, State* state,
int argc, Expr* argv[]);
struct Expr {
Function fn;
char* name;
int argc;
Expr** argv;
int start, end;
};
char* Evaluate(State* state, Expr* expr);
// Glue to make an Expr out of a literal.
char* Literal(const char* name, State* state, int argc, Expr* argv[]);
// Functions corresponding to various syntactic sugar operators.
// ("concat" is also available as a builtin function, to concatenate
// more than two strings.)
char* ConcatFn(const char* name, State* state, int argc, Expr* argv[]);
char* LogicalAndFn(const char* name, State* state, int argc, Expr* argv[]);
char* LogicalOrFn(const char* name, State* state, int argc, Expr* argv[]);
char* LogicalNotFn(const char* name, State* state, int argc, Expr* argv[]);
char* SubstringFn(const char* name, State* state, int argc, Expr* argv[]);
char* EqualityFn(const char* name, State* state, int argc, Expr* argv[]);
char* InequalityFn(const char* name, State* state, int argc, Expr* argv[]);
char* SequenceFn(const char* name, State* state, int argc, Expr* argv[]);
// Convenience function for building expressions with a fixed number
// of arguments.
Expr* Build(Function fn, YYLTYPE loc, int count, ...);
// Global builtins, registered by RegisterBuiltins().
char* IfElseFn(const char* name, State* state, int argc, Expr* argv[]);
char* AssertFn(const char* name, State* state, int argc, Expr* argv[]);
char* AbortFn(const char* name, State* state, int argc, Expr* argv[]);
// For setting and getting the global error string (when returning
// NULL from a function).
void SetError(const char* message); // makes a copy
const char* GetError(); // retains ownership
void ClearError();
typedef struct {
const char* name;
Function fn;
} NamedFunction;
// Register a new function. The same Function may be registered under
// multiple names, but a given name should only be used once.
void RegisterFunction(const char* name, Function fn);
// Register all the builtins.
void RegisterBuiltins();
// Call this after all calls to RegisterFunction() but before parsing
// any scripts to finish building the function table.
void FinishRegistration();
// Find the Function for a given name; return NULL if no such function
// exists.
Function FindFunction(const char* name);
// --- convenience functions for use in functions ---
// Evaluate the expressions in argv, giving 'count' char* (the ... is
// zero or more char** to put them in). If any expression evaluates
// to NULL, free the rest and return -1. Return 0 on success.
int ReadArgs(State* state, Expr* argv[], int count, ...);
// Evaluate the expressions in argv, returning an array of char*
// results. If any evaluate to NULL, free the rest and return NULL.
// The caller is responsible for freeing the returned array and the
// strings it contains.
char** ReadVarArgs(State* state, int argc, Expr* argv[]);
#endif // _EXPRESSION_H
