1 /* 2 * Copyright 2017 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SKSL_REGEXPARSER 9 #define SKSL_REGEXPARSER 10 11 #include "RegexNode.h" 12 13 #include <stack> 14 #include <string> 15 16 /** 17 * Turns a simple regular expression into a parse tree. The regular expression syntax supports only 18 * the basic quantifiers ('*', '+', and '?'), alternation ('|'), character sets ('[a-z]'), and 19 * groups ('()'). 20 */ 21 class RegexParser { 22 public: 23 RegexNode parse(std::string source); 24 25 private: 26 static constexpr char END = '\0'; 27 28 char peek(); 29 30 void expect(char c); 31 32 RegexNode pop(); 33 34 /** 35 * Matches a char literal, parenthesized group, character set, or dot ('.'). 36 */ 37 void term(); 38 39 /** 40 * Matches a term followed by an optional quantifier ('*', '+', or '?'). 41 */ 42 void quantifiedTerm(); 43 44 /** 45 * Matches a sequence of quantifiedTerms. 46 */ 47 void sequence(); 48 49 /** 50 * Returns a node representing the given escape character (e.g. escapeSequence('n') returns a 51 * node which matches a newline character). 52 */ 53 RegexNode escapeSequence(char c); 54 55 /** 56 * Matches a literal character or escape sequence. 57 */ 58 void literal(); 59 60 /** 61 * Matches a dot ('.'). 62 */ 63 void dot(); 64 65 /** 66 * Matches a parenthesized group. 67 */ 68 void group(); 69 70 /** 71 * Matches a literal character, escape sequence, or character range from a character set. 72 */ 73 void setItem(); 74 75 /** 76 * Matches a character set. 77 */ 78 void set(); 79 80 void regex(); 81 82 std::string fSource; 83 84 size_t fIndex; 85 86 std::stack<RegexNode> fStack; 87 }; 88 89 #endif 90
