parser.cc - platform/build/kati - Gitiles

 // Copyright 2015 Google Inc. All rights reserved
 //
 // 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.

 // +build ignore

 #include "parser.h"

 #include <stack>
 #include <unordered_map>

 #include "ast.h"
 #include "file.h"
 #include "loc.h"
 #include "log.h"
 #include "string_piece.h"
 #include "strutil.h"
 #include "value.h"

 enum struct ParserState {
   NOT_AFTER_RULE = 0,
   AFTER_RULE,
   MAYBE_AFTER_RULE,
 };

 class Parser {
   struct IfState {
     IfAST* ast;
     bool is_in_else;
     int num_nest;
   };

   typedef void (Parser::*DirectiveHandler)(
       StringPiece line, StringPiece directive);
   typedef unordered_map<StringPiece, DirectiveHandler> DirectiveMap;

  public:
   Parser(StringPiece buf, const char* filename, vector<AST*>* asts)
       : buf_(buf),
         state_(ParserState::NOT_AFTER_RULE),
         asts_(asts),
         out_asts_(asts),
         num_if_nest_(0),
         loc_(filename, 0),
         fixed_lineno_(false) {
   }

   Parser(StringPiece buf, const Loc& loc, vector<AST*>* asts)
       : buf_(buf),
         state_(ParserState::NOT_AFTER_RULE),
         asts_(asts),
         out_asts_(asts),
         num_if_nest_(0),
         loc_(loc),
         fixed_lineno_(true) {
   }

   ~Parser() {
   }

   void Parse() {
     l_ = 0;

     for (l_ = 0; l_ < buf_.size();) {
       size_t lf_cnt = 0;
       size_t e = FindEndOfLine(&lf_cnt);
       if (!fixed_lineno_)
         loc_.lineno += lf_cnt;
       StringPiece line(buf_.data() + l_, e - l_);
       ParseLine(line);
       if (e == buf_.size())
         break;

       l_ = e + 1;
     }
   }

   static void Init() {
     make_directives_ = new DirectiveMap;
     (*make_directives_)["include"] = &Parser::ParseInclude;
     (*make_directives_)["-include"] = &Parser::ParseInclude;
     (*make_directives_)["sinclude"] = &Parser::ParseInclude;
     (*make_directives_)["define"] = &Parser::ParseDefine;
     (*make_directives_)["ifdef"] = &Parser::ParseIfdef;
     (*make_directives_)["ifndef"] = &Parser::ParseIfdef;
     (*make_directives_)["ifeq"] = &Parser::ParseIfeq;
     (*make_directives_)["ifneq"] = &Parser::ParseIfeq;
     (*make_directives_)["else"] = &Parser::ParseElse;
     (*make_directives_)["endif"] = &Parser::ParseEndif;

     else_if_directives_ = new DirectiveMap;
     (*else_if_directives_)["ifdef"] = &Parser::ParseIfdef;
     (*else_if_directives_)["ifndef"] = &Parser::ParseIfdef;

     shortest_directive_len_ = 9999;
     longest_directive_len_ = 0;
     for (auto p : *make_directives_) {
       size_t len = p.first.size();
       shortest_directive_len_ = min(len, shortest_directive_len_);
       longest_directive_len_ = max(len, longest_directive_len_);
     }
   }

   static void Quit() {
     delete make_directives_;
   }

  private:
   void Error(const string& msg) {
     ERROR("%s:%d: %s", LOCF(loc_), msg.c_str());
   }

   size_t FindEndOfLine(size_t* lf_cnt) {
     size_t e = l_;
     bool prev_backslash = false;
     for (; e < buf_.size(); e++) {
       char c = buf_[e];
       if (c == '\\') {
         prev_backslash = !prev_backslash;
       } else if (c == '\n') {
         ++*lf_cnt;
         if (!prev_backslash) {
           return e;
         }
       } else if (c != '\r') {
         prev_backslash = false;
       }
     }
     return e;
   }

   void ParseLine(StringPiece line) {
     if (line.empty() || (line.size() == 1 && line[0] == '\r'))
       return;

     if (!define_name_.empty()) {
       ParseInsideDefine(line);
       return;
     }

     if (line[0] == '\t' && state_ != ParserState::NOT_AFTER_RULE) {
       CommandAST* ast = new CommandAST();
       ast->set_loc(loc_);
       ast->expr = ParseExpr(line.substr(1), ParseExprOpt::COMMAND);
       out_asts_->push_back(ast);
       return;
     }

     line = TrimLeftSpace(line);

     if (line[0] == '#')
       return;

     if (HandleDirective(line, make_directives_)) {
       return;
     }

     size_t sep = FindTwoOutsideParen(line, ':', '=');
     if (sep == string::npos) {
       ParseRule(line, sep);
     } else if (line[sep] == '=') {
       ParseAssign(line, sep);
     } else if (line.get(sep+1) == '=') {
       ParseAssign(line, sep+1);
     } else if (line[sep] == ':') {
       ParseRule(line, sep);
     } else {
       CHECK(false);
     }
   }

   void ParseRule(StringPiece line, size_t sep) {
     const bool is_rule = sep != string::npos && line[sep] == ':';
     RuleAST* ast = new RuleAST();
     ast->set_loc(loc_);

     size_t found = FindTwoOutsideParen(line.substr(sep + 1), '=', ';');
     if (found != string::npos) {
       found += sep + 1;
       ast->term = line[found];
       ParseExprOpt opt =
           ast->term == ';' ? ParseExprOpt::COMMAND : ParseExprOpt::NORMAL;
       ast->after_term = ParseExpr(TrimLeftSpace(line.substr(found + 1)), opt);
       ast->expr = ParseExpr(TrimSpace(line.substr(0, found)));
     } else {
       ast->term = 0;
       ast->after_term = NULL;
       ast->expr = ParseExpr(TrimSpace(line));
     }
     out_asts_->push_back(ast);
     state_ = is_rule ? ParserState::AFTER_RULE : ParserState::MAYBE_AFTER_RULE;
   }

   void ParseAssign(StringPiece line, size_t sep) {
     if (sep == 0)
       Error("*** empty variable name ***");
     StringPiece lhs;
     StringPiece rhs;
     AssignOp op;
     ParseAssignStatement(line, sep, &lhs, &rhs, &op);

     AssignAST* ast = new AssignAST();
     ast->set_loc(loc_);
     ast->lhs = ParseExpr(lhs);
     ast->rhs = ParseExpr(rhs);
     ast->orig_rhs = rhs;
     ast->op = op;
     ast->directive = AssignDirective::NONE;
     out_asts_->push_back(ast);
     state_ = ParserState::NOT_AFTER_RULE;
   }

   void ParseInclude(StringPiece line, StringPiece directive) {
     IncludeAST* ast = new IncludeAST();
     ast->set_loc(loc_);
     ast->expr = ParseExpr(line);
     ast->should_exist = directive[0] == 'i';
     out_asts_->push_back(ast);
   }

   void ParseDefine(StringPiece line, StringPiece) {
     if (line.empty()) {
       Error("*** empty variable name.");
     }
     define_name_ = line;
     define_start_ = 0;
     define_start_line_ = loc_.lineno;
   }

   void ParseInsideDefine(StringPiece line) {
     line = TrimLeftSpace(line);
     if (GetDirective(line) != "endef") {
       if (define_start_ == 0)
         define_start_ = l_;
       return;
     }

     StringPiece rest = TrimRightSpace(RemoveComment(TrimLeftSpace(
         line.substr(sizeof("endef")))));
     if (!rest.empty()) {
       WARN("%s:%d: extraneous text after `endef' directive", LOCF(loc_));
     }

     AssignAST* ast = new AssignAST();
     ast->set_loc(Loc(loc_.filename, define_start_line_));
     ast->lhs = ParseExpr(define_name_);
     StringPiece rhs;
     if (define_start_)
       rhs = TrimRightSpace(buf_.substr(define_start_, l_ - define_start_));
     ast->rhs = ParseExpr(rhs, ParseExprOpt::DEFINE);
     ast->orig_rhs = rhs;
     ast->op = AssignOp::EQ;
     ast->directive = AssignDirective::NONE;
     out_asts_->push_back(ast);
     define_name_.clear();
   }

   void EnterIf(IfAST* ast) {
     IfState* st = new IfState();
     st->ast = ast;
     st->is_in_else = false;
     st->num_nest = num_if_nest_;
     if_stack_.push(st);
     out_asts_ = &ast->true_asts;
   }

   void ParseIfdef(StringPiece line, StringPiece directive) {
     IfAST* ast = new IfAST();
     ast->set_loc(loc_);
     ast->op = directive[2] == 'n' ? CondOp::IFNDEF : CondOp::IFDEF;
     ast->lhs = ParseExpr(line);
     ast->rhs = NULL;
     out_asts_->push_back(ast);
     EnterIf(ast);
   }

   bool ParseIfEqCond(StringPiece s, IfAST* ast) {
     if (s.empty()) {
       return false;
     }

     if (s[0] == '(' && s[s.size() - 1] == ')') {
       s = s.substr(1, s.size() - 2);
       char terms[] = {',', '\0'};
       size_t n;
       ast->lhs = ParseExprImpl(s, terms, ParseExprOpt::NORMAL, &n, true);
       if (s[n] != ',')
         return false;
       s = TrimLeftSpace(s.substr(n+1));
       ast->rhs = ParseExprImpl(s, NULL, ParseExprOpt::NORMAL, &n);
       s = TrimLeftSpace(s.substr(n));
     } else {
       for (int i = 0; i < 2; i++) {
         if (s.empty())
           return false;
         char quote = s[0];
         if (quote != '\'' && quote != '"')
           return false;
         size_t end = s.find(quote, 1);
         if (end == string::npos)
           return false;
         Value* v = ParseExpr(s.substr(1, end - 1), ParseExprOpt::NORMAL);
         if (i == 0)
           ast->lhs = v;
         else
           ast->rhs = v;
         s = TrimLeftSpace(s.substr(end+1));
       }
     }
     if (!s.empty()) {
       Error("extraneous text after `ifeq' directive");
     }
     return true;
   }

   void ParseIfeq(StringPiece line, StringPiece directive) {
     IfAST* ast = new IfAST();
     ast->set_loc(loc_);
     ast->op = directive[2] == 'n' ? CondOp::IFNEQ : CondOp::IFEQ;

     if (!ParseIfEqCond(line, ast)) {
       Error("*** invalid syntax in conditional.");
     }

     out_asts_->push_back(ast);
     EnterIf(ast);
   }

   void ParseElse(StringPiece line, StringPiece) {
     CheckIfStack("else");
     IfState* st = if_stack_.top();
     if (st->is_in_else)
       Error("*** only one `else' per conditional.");
     st->is_in_else = true;
     out_asts_ = &st->ast->false_asts;

     StringPiece next_if = TrimLeftSpace(line);
     if (next_if.empty())
       return;

     num_if_nest_ = st->num_nest + 1;
     if (!HandleDirective(next_if, else_if_directives_)) {
       WARN("%s:%d: extraneous text after `else' directive", LOCF(loc_));
     }
     num_if_nest_ = 0;
   }

   void ParseEndif(StringPiece line, StringPiece) {
     CheckIfStack("endif");
     if (!line.empty())
       Error("extraneous text after `endif` directive");
     IfState st = *if_stack_.top();
     for (int t = 0; t <= st.num_nest; t++) {
       delete if_stack_.top();
       if_stack_.pop();
       if (if_stack_.empty()) {
         out_asts_ = asts_;
       } else {
         IfState* st = if_stack_.top();
         if (st->is_in_else)
           out_asts_ = &st->ast->false_asts;
         else
           out_asts_ = &st->ast->true_asts;
       }
     }
   }

   void CheckIfStack(const char* keyword) {
     if (if_stack_.empty()) {
       Error(StringPrintf("*** extraneous `%s'.", keyword));
     }
   }

   StringPiece RemoveComment(StringPiece line) {
     size_t i = FindOutsideParen(line, '#');
     if (i == string::npos)
       return line;
     return line.substr(0, i);
   }

   StringPiece GetDirective(StringPiece line) {
     if (line.size() < shortest_directive_len_)
       return StringPiece();
     StringPiece prefix = line.substr(0, longest_directive_len_ + 1);
     size_t space_index = prefix.find_first_of(" \t#");
     return prefix.substr(0, space_index);
   }

   bool HandleDirective(StringPiece line, const DirectiveMap* directive_map) {
     StringPiece directive = GetDirective(line);
     auto found = directive_map->find(directive);
     if (found == directive_map->end())
       return false;

     StringPiece rest = TrimRightSpace(RemoveComment(TrimLeftSpace(
         line.substr(directive.size()))));
     (this->*found->second)(rest, directive);
     return true;
   }

   StringPiece buf_;
   size_t l_;
   ParserState state_;

   vector<AST*>* asts_;
   vector<AST*>* out_asts_;

   StringPiece define_name_;
   size_t define_start_;
   int define_start_line_;

   int num_if_nest_;
   stack<IfState*> if_stack_;

   Loc loc_;
   bool fixed_lineno_;

   static DirectiveMap* make_directives_;
   static DirectiveMap* else_if_directives_;
   static size_t shortest_directive_len_;
   static size_t longest_directive_len_;
 };

 void Parse(Makefile* mk) {
   Parser parser(StringPiece(mk->buf(), mk->len()),
                 mk->filename().c_str(),
                 mk->mutable_asts());
   parser.Parse();
 }

 void Parse(StringPiece buf, const Loc& loc, vector<AST*>* out_asts) {
   Parser parser(buf, loc, out_asts);
   parser.Parse();
 }

 void InitParser() {
   Parser::Init();
 }

 void QuitParser() {
   Parser::Quit();
 }

 Parser::DirectiveMap* Parser::make_directives_;
 Parser::DirectiveMap* Parser::else_if_directives_;
 size_t Parser::shortest_directive_len_;
 size_t Parser::longest_directive_len_;

 void ParseAssignStatement(StringPiece line, size_t sep,
                           StringPiece* lhs, StringPiece* rhs, AssignOp* op) {
   CHECK(sep != 0);
   *op = AssignOp::EQ;
   size_t lhs_end = sep;
   switch (line[sep-1]) {
     case ':':
       lhs_end--;
       *op = AssignOp::COLON_EQ;
       break;
     case '+':
       lhs_end--;
       *op = AssignOp::PLUS_EQ;
       break;
     case '?':
       lhs_end--;
       *op = AssignOp::QUESTION_EQ;
       break;
   }
   *lhs = TrimSpace(line.substr(0, lhs_end));
   *rhs = TrimSpace(line.substr(sep + 1));
 }
	// Copyright 2015 Google Inc. All rights reserved
	//
	// 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.

	// +build ignore

	#include "parser.h"

	#include <stack>
	#include <unordered_map>

	#include "ast.h"
	#include "file.h"
	#include "loc.h"
	#include "log.h"
	#include "string_piece.h"
	#include "strutil.h"
	#include "value.h"

	enum struct ParserState {
	NOT_AFTER_RULE = 0,
	AFTER_RULE,
	MAYBE_AFTER_RULE,
	};

	class Parser {
	struct IfState {
	IfAST* ast;
	bool is_in_else;
	int num_nest;
	};

	typedef void (Parser::*DirectiveHandler)(
	StringPiece line, StringPiece directive);
	typedef unordered_map<StringPiece, DirectiveHandler> DirectiveMap;

	public:
	Parser(StringPiece buf, const char* filename, vector<AST> asts)
	: buf_(buf),
	state_(ParserState::NOT_AFTER_RULE),
	asts_(asts),
	out_asts_(asts),
	num_if_nest_(0),
	loc_(filename, 0),
	fixed_lineno_(false) {
	}

	Parser(StringPiece buf, const Loc& loc, vector<AST> asts)
	: buf_(buf),
	state_(ParserState::NOT_AFTER_RULE),
	asts_(asts),
	out_asts_(asts),
	num_if_nest_(0),
	loc_(loc),
	fixed_lineno_(true) {
	}

	~Parser() {
	}

	void Parse() {
	l_ = 0;

	for (l_ = 0; l_ < buf_.size();) {
	size_t lf_cnt = 0;
	size_t e = FindEndOfLine(&lf_cnt);
	if (!fixed_lineno_)
	loc_.lineno += lf_cnt;
	StringPiece line(buf_.data() + l_, e - l_);
	ParseLine(line);
	if (e == buf_.size())
	break;

	l_ = e + 1;
	}
	}

	static void Init() {
	make_directives_ = new DirectiveMap;
	(*make_directives_)["include"] = &Parser::ParseInclude;
	(*make_directives_)["-include"] = &Parser::ParseInclude;
	(*make_directives_)["sinclude"] = &Parser::ParseInclude;
	(*make_directives_)["define"] = &Parser::ParseDefine;
	(*make_directives_)["ifdef"] = &Parser::ParseIfdef;
	(*make_directives_)["ifndef"] = &Parser::ParseIfdef;
	(*make_directives_)["ifeq"] = &Parser::ParseIfeq;
	(*make_directives_)["ifneq"] = &Parser::ParseIfeq;
	(*make_directives_)["else"] = &Parser::ParseElse;
	(*make_directives_)["endif"] = &Parser::ParseEndif;

	else_if_directives_ = new DirectiveMap;
	(*else_if_directives_)["ifdef"] = &Parser::ParseIfdef;
	(*else_if_directives_)["ifndef"] = &Parser::ParseIfdef;

	shortest_directive_len_ = 9999;
	longest_directive_len_ = 0;
	for (auto p : *make_directives_) {
	size_t len = p.first.size();
	shortest_directive_len_ = min(len, shortest_directive_len_);
	longest_directive_len_ = max(len, longest_directive_len_);
	}
	}

	static void Quit() {
	delete make_directives_;
	}

	private:
	void Error(const string& msg) {
	ERROR("%s:%d: %s", LOCF(loc_), msg.c_str());
	}

	size_t FindEndOfLine(size_t* lf_cnt) {
	size_t e = l_;
	bool prev_backslash = false;
	for (; e < buf_.size(); e++) {
	char c = buf_[e];
	if (c == '\\') {
	prev_backslash = !prev_backslash;
	} else if (c == '\n') {
	++*lf_cnt;
	if (!prev_backslash) {
	return e;
	}
	} else if (c != '\r') {
	prev_backslash = false;
	}
	}
	return e;
	}

	void ParseLine(StringPiece line) {
	if (line.empty() \|\| (line.size() == 1 && line[0] == '\r'))
	return;

	if (!define_name_.empty()) {
	ParseInsideDefine(line);
	return;
	}

	if (line[0] == '\t' && state_ != ParserState::NOT_AFTER_RULE) {
	CommandAST* ast = new CommandAST();
	ast->set_loc(loc_);
	ast->expr = ParseExpr(line.substr(1), ParseExprOpt::COMMAND);
	out_asts_->push_back(ast);
	return;
	}

	line = TrimLeftSpace(line);

	if (line[0] == '#')
	return;

	if (HandleDirective(line, make_directives_)) {
	return;
	}

	size_t sep = FindTwoOutsideParen(line, ':', '=');
	if (sep == string::npos) {
	ParseRule(line, sep);
	} else if (line[sep] == '=') {
	ParseAssign(line, sep);
	} else if (line.get(sep+1) == '=') {
	ParseAssign(line, sep+1);
	} else if (line[sep] == ':') {
	ParseRule(line, sep);
	} else {
	CHECK(false);
	}
	}

	void ParseRule(StringPiece line, size_t sep) {
	const bool is_rule = sep != string::npos && line[sep] == ':';
	RuleAST* ast = new RuleAST();
	ast->set_loc(loc_);

	size_t found = FindTwoOutsideParen(line.substr(sep + 1), '=', ';');
	if (found != string::npos) {
	found += sep + 1;
	ast->term = line[found];
	ParseExprOpt opt =
	ast->term == ';' ? ParseExprOpt::COMMAND : ParseExprOpt::NORMAL;
	ast->after_term = ParseExpr(TrimLeftSpace(line.substr(found + 1)), opt);
	ast->expr = ParseExpr(TrimSpace(line.substr(0, found)));
	} else {
	ast->term = 0;
	ast->after_term = NULL;
	ast->expr = ParseExpr(TrimSpace(line));
	}
	out_asts_->push_back(ast);
	state_ = is_rule ? ParserState::AFTER_RULE : ParserState::MAYBE_AFTER_RULE;
	}

	void ParseAssign(StringPiece line, size_t sep) {
	if (sep == 0)
	Error("* empty variable name *");
	StringPiece lhs;
	StringPiece rhs;
	AssignOp op;
	ParseAssignStatement(line, sep, &lhs, &rhs, &op);

	AssignAST* ast = new AssignAST();
	ast->set_loc(loc_);
	ast->lhs = ParseExpr(lhs);
	ast->rhs = ParseExpr(rhs);
	ast->orig_rhs = rhs;
	ast->op = op;
	ast->directive = AssignDirective::NONE;
	out_asts_->push_back(ast);
	state_ = ParserState::NOT_AFTER_RULE;
	}

	void ParseInclude(StringPiece line, StringPiece directive) {
	IncludeAST* ast = new IncludeAST();
	ast->set_loc(loc_);
	ast->expr = ParseExpr(line);
	ast->should_exist = directive[0] == 'i';
	out_asts_->push_back(ast);
	}

	void ParseDefine(StringPiece line, StringPiece) {
	if (line.empty()) {
	Error("*** empty variable name.");
	}
	define_name_ = line;
	define_start_ = 0;
	define_start_line_ = loc_.lineno;
	}

	void ParseInsideDefine(StringPiece line) {
	line = TrimLeftSpace(line);
	if (GetDirective(line) != "endef") {
	if (define_start_ == 0)
	define_start_ = l_;
	return;
	}

	StringPiece rest = TrimRightSpace(RemoveComment(TrimLeftSpace(
	line.substr(sizeof("endef")))));
	if (!rest.empty()) {
	WARN("%s:%d: extraneous text after `endef' directive", LOCF(loc_));
	}

	AssignAST* ast = new AssignAST();
	ast->set_loc(Loc(loc_.filename, define_start_line_));
	ast->lhs = ParseExpr(define_name_);
	StringPiece rhs;
	if (define_start_)
	rhs = TrimRightSpace(buf_.substr(define_start_, l_ - define_start_));
	ast->rhs = ParseExpr(rhs, ParseExprOpt::DEFINE);
	ast->orig_rhs = rhs;
	ast->op = AssignOp::EQ;
	ast->directive = AssignDirective::NONE;
	out_asts_->push_back(ast);
	define_name_.clear();
	}

	void EnterIf(IfAST* ast) {
	IfState* st = new IfState();
	st->ast = ast;
	st->is_in_else = false;
	st->num_nest = num_if_nest_;
	if_stack_.push(st);
	out_asts_ = &ast->true_asts;
	}

	void ParseIfdef(StringPiece line, StringPiece directive) {
	IfAST* ast = new IfAST();
	ast->set_loc(loc_);
	ast->op = directive[2] == 'n' ? CondOp::IFNDEF : CondOp::IFDEF;
	ast->lhs = ParseExpr(line);
	ast->rhs = NULL;
	out_asts_->push_back(ast);
	EnterIf(ast);
	}

	bool ParseIfEqCond(StringPiece s, IfAST* ast) {
	if (s.empty()) {
	return false;
	}

	if (s[0] == '(' && s[s.size() - 1] == ')') {
	s = s.substr(1, s.size() - 2);
	char terms[] = {',', '\0'};
	size_t n;
	ast->lhs = ParseExprImpl(s, terms, ParseExprOpt::NORMAL, &n, true);
	if (s[n] != ',')
	return false;
	s = TrimLeftSpace(s.substr(n+1));
	ast->rhs = ParseExprImpl(s, NULL, ParseExprOpt::NORMAL, &n);
	s = TrimLeftSpace(s.substr(n));
	} else {
	for (int i = 0; i < 2; i++) {
	if (s.empty())
	return false;
	char quote = s[0];
	if (quote != '\'' && quote != '"')
	return false;
	size_t end = s.find(quote, 1);
	if (end == string::npos)
	return false;
	Value* v = ParseExpr(s.substr(1, end - 1), ParseExprOpt::NORMAL);
	if (i == 0)
	ast->lhs = v;
	else
	ast->rhs = v;
	s = TrimLeftSpace(s.substr(end+1));
	}
	}
	if (!s.empty()) {
	Error("extraneous text after `ifeq' directive");
	}
	return true;
	}

	void ParseIfeq(StringPiece line, StringPiece directive) {
	IfAST* ast = new IfAST();
	ast->set_loc(loc_);
	ast->op = directive[2] == 'n' ? CondOp::IFNEQ : CondOp::IFEQ;

	if (!ParseIfEqCond(line, ast)) {
	Error("*** invalid syntax in conditional.");
	}

	out_asts_->push_back(ast);
	EnterIf(ast);
	}

	void ParseElse(StringPiece line, StringPiece) {
	CheckIfStack("else");
	IfState* st = if_stack_.top();
	if (st->is_in_else)
	Error("*** only one `else' per conditional.");
	st->is_in_else = true;
	out_asts_ = &st->ast->false_asts;

	StringPiece next_if = TrimLeftSpace(line);
	if (next_if.empty())
	return;

	num_if_nest_ = st->num_nest + 1;
	if (!HandleDirective(next_if, else_if_directives_)) {
	WARN("%s:%d: extraneous text after `else' directive", LOCF(loc_));
	}
	num_if_nest_ = 0;
	}

	void ParseEndif(StringPiece line, StringPiece) {
	CheckIfStack("endif");
	if (!line.empty())
	Error("extraneous text after `endif` directive");
	IfState st = *if_stack_.top();
	for (int t = 0; t <= st.num_nest; t++) {
	delete if_stack_.top();
	if_stack_.pop();
	if (if_stack_.empty()) {
	out_asts_ = asts_;
	} else {
	IfState* st = if_stack_.top();
	if (st->is_in_else)
	out_asts_ = &st->ast->false_asts;
	else
	out_asts_ = &st->ast->true_asts;
	}
	}
	}

	void CheckIfStack(const char* keyword) {
	if (if_stack_.empty()) {
	Error(StringPrintf("*** extraneous `%s'.", keyword));
	}
	}

	StringPiece RemoveComment(StringPiece line) {
	size_t i = FindOutsideParen(line, '#');
	if (i == string::npos)
	return line;
	return line.substr(0, i);
	}

	StringPiece GetDirective(StringPiece line) {
	if (line.size() < shortest_directive_len_)
	return StringPiece();
	StringPiece prefix = line.substr(0, longest_directive_len_ + 1);
	size_t space_index = prefix.find_first_of(" \t#");
	return prefix.substr(0, space_index);
	}

	bool HandleDirective(StringPiece line, const DirectiveMap* directive_map) {
	StringPiece directive = GetDirective(line);
	auto found = directive_map->find(directive);
	if (found == directive_map->end())
	return false;

	StringPiece rest = TrimRightSpace(RemoveComment(TrimLeftSpace(
	line.substr(directive.size()))));
	(this->*found->second)(rest, directive);
	return true;
	}

	StringPiece buf_;
	size_t l_;
	ParserState state_;

	vector<AST> asts_;
	vector<AST> out_asts_;

	StringPiece define_name_;
	size_t define_start_;
	int define_start_line_;

	int num_if_nest_;
	stack<IfState*> if_stack_;

	Loc loc_;
	bool fixed_lineno_;

	static DirectiveMap* make_directives_;
	static DirectiveMap* else_if_directives_;
	static size_t shortest_directive_len_;
	static size_t longest_directive_len_;
	};

	void Parse(Makefile* mk) {
	Parser parser(StringPiece(mk->buf(), mk->len()),
	mk->filename().c_str(),
	mk->mutable_asts());
	parser.Parse();
	}

	void Parse(StringPiece buf, const Loc& loc, vector<AST> out_asts) {
	Parser parser(buf, loc, out_asts);
	parser.Parse();
	}

	void InitParser() {
	Parser::Init();
	}

	void QuitParser() {
	Parser::Quit();
	}

	Parser::DirectiveMap* Parser::make_directives_;
	Parser::DirectiveMap* Parser::else_if_directives_;
	size_t Parser::shortest_directive_len_;
	size_t Parser::longest_directive_len_;

	void ParseAssignStatement(StringPiece line, size_t sep,
	StringPiece* lhs, StringPiece* rhs, AssignOp* op) {
	CHECK(sep != 0);
	*op = AssignOp::EQ;
	size_t lhs_end = sep;
	switch (line[sep-1]) {
	case ':':
	lhs_end--;
	*op = AssignOp::COLON_EQ;
	break;
	case '+':
	lhs_end--;
	*op = AssignOp::PLUS_EQ;
	break;
	case '?':
	lhs_end--;
	*op = AssignOp::QUESTION_EQ;
	break;
	}
	*lhs = TrimSpace(line.substr(0, lhs_end));
	*rhs = TrimSpace(line.substr(sep + 1));
	}