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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SKSL_REGEXPARSER
#define SKSL_REGEXPARSER
#include "RegexNode.h"
#include <stack>
#include <string>
/**
* Turns a simple regular expression into a parse tree. The regular expression syntax supports only
* the basic quantifiers ('*', '+', and '?'), alternation ('|'), character sets ('[a-z]'), and
* groups ('()').
*/
class RegexParser {
public:
RegexNode parse(std::string source);
private:
static constexpr char END = '\0';
char peek();
void expect(char c);
RegexNode pop();
/**
* Matches a char literal, parenthesized group, character set, or dot ('.').
*/
void term();
/**
* Matches a term followed by an optional quantifier ('*', '+', or '?').
*/
void quantifiedTerm();
/**
* Matches a sequence of quantifiedTerms.
*/
void sequence();
/**
* Returns a node representing the given escape character (e.g. escapeSequence('n') returns a
* node which matches a newline character).
*/
RegexNode escapeSequence(char c);
/**
* Matches a literal character or escape sequence.
*/
void literal();
/**
* Matches a dot ('.').
*/
void dot();
/**
* Matches a parenthesized group.
*/
void group();
/**
* Matches a literal character, escape sequence, or character range from a character set.
*/
void setItem();
/**
* Matches a character set.
*/
void set();
void regex();
std::string fSource;
size_t fIndex;
std::stack<RegexNode> fStack;
};
#endif
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