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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.
- */
- #include "src/sksl/lex/NFAtoDFA.h"
- #include "src/sksl/lex/RegexParser.h"
- #include <fstream>
- #include <sstream>
- #include <string>
- /**
- * Processes a .lex file and produces .h and .cpp files which implement a lexical analyzer. The .lex
- * file is a text file with one token definition per line. Each line is of the form:
- * <TOKEN_NAME> = <pattern>
- * where <pattern> is either a regular expression (e.g [0-9]) or a double-quoted literal string.
- */
- static constexpr const char* HEADER =
- "/*\n"
- " * Copyright 2017 Google Inc.\n"
- " *\n"
- " * Use of this source code is governed by a BSD-style license that can be\n"
- " * found in the LICENSE file.\n"
- " */\n"
- "/*****************************************************************************************\n"
- " ******************** This file was generated by sksllex. Do not edit. *******************\n"
- " *****************************************************************************************/\n";
- void writeH(const DFA& dfa, const char* lexer, const char* token,
- const std::vector<std::string>& tokens, const char* hPath) {
- std::ofstream out(hPath);
- SkASSERT(out.good());
- out << HEADER;
- out << "#ifndef SKSL_" << lexer << "\n";
- out << "#define SKSL_" << lexer << "\n";
- out << "#include <cstddef>\n";
- out << "#include <cstdint>\n";
- out << "namespace SkSL {\n";
- out << "\n";
- out << "struct " << token << " {\n";
- out << " enum Kind {\n";
- for (const std::string& t : tokens) {
- out << " #undef " << t << "\n";
- out << " " << t << ",\n";
- }
- out << " };\n";
- out << "\n";
- out << " " << token << "()\n";
- out << " : fKind(Kind::INVALID)\n";
- out << " , fOffset(-1)\n";
- out << " , fLength(-1) {}\n";
- out << "\n";
- out << " " << token << "(Kind kind, int32_t offset, int32_t length)\n";
- out << " : fKind(kind)\n";
- out << " , fOffset(offset)\n";
- out << " , fLength(length) {}\n";
- out << "\n";
- out << " Kind fKind;\n";
- out << " int fOffset;\n";
- out << " int fLength;\n";
- out << "};\n";
- out << "\n";
- out << "class " << lexer << " {\n";
- out << "public:\n";
- out << " void start(const char* text, int32_t length) {\n";
- out << " fText = text;\n";
- out << " fLength = length;\n";
- out << " fOffset = 0;\n";
- out << " }\n";
- out << "\n";
- out << " " << token << " next();\n";
- out << "\n";
- out << "private:\n";
- out << " const char* fText;\n";
- out << " int32_t fLength;\n";
- out << " int32_t fOffset;\n";
- out << "};\n";
- out << "\n";
- out << "} // namespace\n";
- out << "#endif\n";
- }
- void writeCPP(const DFA& dfa, const char* lexer, const char* token, const char* include,
- const char* cppPath) {
- std::ofstream out(cppPath);
- SkASSERT(out.good());
- out << HEADER;
- out << "#include \"" << include << "\"\n";
- out << "\n";
- out << "namespace SkSL {\n";
- out << "\n";
- size_t states = 0;
- for (const auto& row : dfa.fTransitions) {
- states = std::max(states, row.size());
- }
- // arbitrarily-chosen character which is greater than START_CHAR and should not appear in actual
- // input
- out << "static const uint8_t INVALID_CHAR = 18;";
- out << "static int8_t mappings[" << dfa.fCharMappings.size() << "] = {\n ";
- const char* separator = "";
- for (int m : dfa.fCharMappings) {
- out << separator << std::to_string(m);
- separator = ", ";
- }
- out << "\n};\n";
- out << "static int16_t transitions[" << dfa.fTransitions.size() << "][" << states << "] = {\n";
- for (size_t c = 0; c < dfa.fTransitions.size(); ++c) {
- out << " {";
- for (size_t j = 0; j < states; ++j) {
- if ((size_t) c < dfa.fTransitions.size() && j < dfa.fTransitions[c].size()) {
- out << " " << dfa.fTransitions[c][j] << ",";
- } else {
- out << " 0,";
- }
- }
- out << " },\n";
- }
- out << "};\n";
- out << "\n";
- out << "static int8_t accepts[" << states << "] = {";
- for (size_t i = 0; i < states; ++i) {
- if (i < dfa.fAccepts.size()) {
- out << " " << dfa.fAccepts[i] << ",";
- } else {
- out << " " << INVALID << ",";
- }
- }
- out << " };\n";
- out << "\n";
- out << token << " " << lexer << "::next() {\n";
- out << " // note that we cheat here: normally a lexer needs to worry about the case\n";
- out << " // where a token has a prefix which is not itself a valid token - for instance, \n";
- out << " // maybe we have a valid token 'while', but 'w', 'wh', etc. are not valid\n";
- out << " // tokens. Our grammar doesn't have this property, so we can simplify the logic\n";
- out << " // a bit.\n";
- out << " int32_t startOffset = fOffset;\n";
- out << " if (startOffset == fLength) {\n";
- out << " return " << token << "(" << token << "::END_OF_FILE, startOffset, 0);\n";
- out << " }\n";
- out << " int16_t state = 1;\n";
- out << " for (;;) {\n";
- out << " if (fOffset >= fLength) {\n";
- out << " if (accepts[state] == -1) {\n";
- out << " return Token(Token::END_OF_FILE, startOffset, 0);\n";
- out << " }\n";
- out << " break;\n";
- out << " }\n";
- out << " uint8_t c = (uint8_t) fText[fOffset];";
- out << " if (c <= 8 || c >= " << dfa.fCharMappings.size() << ") {";
- out << " c = INVALID_CHAR;";
- out << " }";
- out << " int16_t newState = transitions[mappings[c]][state];\n";
- out << " if (!newState) {\n";
- out << " break;\n";
- out << " }\n";
- out << " state = newState;";
- out << " ++fOffset;\n";
- out << " }\n";
- out << " Token::Kind kind = (" << token << "::Kind) accepts[state];\n";
- out << " return " << token << "(kind, startOffset, fOffset - startOffset);\n";
- out << "}\n";
- out << "\n";
- out << "} // namespace\n";
- }
- void process(const char* inPath, const char* lexer, const char* token, const char* hPath,
- const char* cppPath) {
- NFA nfa;
- std::vector<std::string> tokens;
- tokens.push_back("END_OF_FILE");
- std::string line;
- std::ifstream in(inPath);
- while (std::getline(in, line)) {
- std::istringstream split(line);
- std::string name, delimiter, pattern;
- if (split >> name >> delimiter >> pattern) {
- SkASSERT(split.eof());
- SkASSERT(name != "");
- SkASSERT(delimiter == "=");
- SkASSERT(pattern != "");
- tokens.push_back(name);
- if (pattern[0] == '"') {
- SkASSERT(pattern.size() > 2 && pattern[pattern.size() - 1] == '"');
- RegexNode node = RegexNode(RegexNode::kChar_Kind, pattern[1]);
- for (size_t i = 2; i < pattern.size() - 1; ++i) {
- node = RegexNode(RegexNode::kConcat_Kind, node,
- RegexNode(RegexNode::kChar_Kind, pattern[i]));
- }
- nfa.addRegex(node);
- }
- else {
- nfa.addRegex(RegexParser().parse(pattern));
- }
- }
- }
- NFAtoDFA converter(&nfa);
- DFA dfa = converter.convert();
- writeH(dfa, lexer, token, tokens, hPath);
- writeCPP(dfa, lexer, token, (std::string("src/sksl/SkSL") + lexer + ".h").c_str(), cppPath);
- }
- int main(int argc, const char** argv) {
- if (argc != 6) {
- printf("usage: sksllex <input.lex> <lexername> <tokenname> <output.h> <output.cpp>\n");
- exit(1);
- }
- process(argv[1], argv[2], argv[3], argv[4], argv[5]);
- return 0;
- }
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