4198578702 2010-11-07        kinaba: /*
4198578702 2010-11-07        kinaba:  * Authors: k.inaba
4198578702 2010-11-07        kinaba:  * License: NYSL 0.9982 http://www.kmonos.net/nysl/
4198578702 2010-11-07        kinaba:  *
4198578702 2010-11-07        kinaba:  * Parser for Polemy programming language
423f308350 2010-11-07        kinaba:  */
4198578702 2010-11-07        kinaba: module polemy.parse;
4198578702 2010-11-07        kinaba: import polemy._common;
423f308350 2010-11-07        kinaba: import polemy.lex;
423f308350 2010-11-07        kinaba: import polemy.ast;
423f308350 2010-11-07        kinaba: import std.bigint;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: /// Parsing Failure
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: class ParserException : Exception
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: private:
423f308350 2010-11-07        kinaba: 	this(string msg) { super(msg); }
423f308350 2010-11-07        kinaba: 	static ParserException create(Lexer)(Lexer lex, string msg)
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		return new ParserException(sprintf!"[%s] %s"(
423f308350 2010-11-07        kinaba: 			lex.empty ? "EOF" : to!string(lex.front.pos), msg));
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: /// Named Constructor of Parser
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: auto parserFromLexer(Lexer)(Lexer lex)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	return new Parser!Lexer(lex);
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: /// Named Constructor of Parser (just fwd to lexerFromString)
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: auto parserFromString(T...)(T params)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	return parserFromLexer(polemy.lex.lexerFromString(params));
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: /// Named Constructor of Parser (just fwd to lexerFromFile)
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: auto parserFromFile(T...)(T params)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	return parserFromLexer(polemy.lex.lexerFromFile(params));
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: /// Parser
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: class Parser(Lexer)
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	this(Lexer lex)
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		this.lex = lex;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Program parseProgram()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		Program p;
423f308350 2010-11-07        kinaba: 		while( !lex.empty )
423f308350 2010-11-07        kinaba: 			p ~= parseStatement();
423f308350 2010-11-07        kinaba: 		return p;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Statement parseStatement()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		auto saved = lex.save;
423f308350 2010-11-07        kinaba: 		scope(failure) lex = saved;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		if( lex.empty )
423f308350 2010-11-07        kinaba: 			throw new ParserException("EOF during parsing a statement");
423f308350 2010-11-07        kinaba: 		auto pos = lex.front.pos;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		if( lex.front.kind==Token.Kind.identifier && lex.front.str=="var" )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			// "var" Var "=" Expression ";"
423f308350 2010-11-07        kinaba: 			lex.popFront;
423f308350 2010-11-07        kinaba: 			string var = lex.front.str;
423f308350 2010-11-07        kinaba: 			lex.popFront;
423f308350 2010-11-07        kinaba: 			eat("=", "for variable declaration");
423f308350 2010-11-07        kinaba: 			auto parsed = new DeclStatement(pos, var, parseExpression());
423f308350 2010-11-07        kinaba: 			eat(";", "after variable declaration");
423f308350 2010-11-07        kinaba: 			return parsed;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 		else
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			// Expression ";"
423f308350 2010-11-07        kinaba: 			auto parsed = new ExprStatement(pos, parseExpression());
423f308350 2010-11-07        kinaba: 			eat(";", "after statement");
423f308350 2010-11-07        kinaba: 			return parsed;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Expression parseExpression()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		auto saved = lex.save;
423f308350 2010-11-07        kinaba: 		scope(failure) lex = saved;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		// Expr ::= E0
423f308350 2010-11-07        kinaba: 		// E0 ::= (E1 "=")* E1
423f308350 2010-11-07        kinaba: 		// E1 ::= (E2 "+"|"-")* E2
423f308350 2010-11-07        kinaba: 		// E2 ::= (E3 "*"|"/")* E3
423f308350 2010-11-07        kinaba: 		// E3 ::= int | str | id | "(" Expr ")"
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		return parseE0();
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Expression parseE0()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		auto lhs = parseE1();
423f308350 2010-11-07        kinaba: 		if( tryEat("=") )
423f308350 2010-11-07        kinaba: 			lhs = new BinOpExpression(lhs.pos, "=", lhs, parseE0());
423f308350 2010-11-07        kinaba: 		return lhs;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Expression parseE1()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		for(auto lhs = parseE2();;)
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			if( tryEat("+") )
423f308350 2010-11-07        kinaba: 				lhs = new BinOpExpression(lhs.pos, "+", lhs, parseE2());
423f308350 2010-11-07        kinaba: 			else if( tryEat("-") )
423f308350 2010-11-07        kinaba: 				lhs = new BinOpExpression(lhs.pos, "-", lhs, parseE2());
423f308350 2010-11-07        kinaba: 			else
423f308350 2010-11-07        kinaba: 				return lhs;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Expression parseE2()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		for(auto lhs = parseE3();;)
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			if( tryEat("*") )
423f308350 2010-11-07        kinaba: 				lhs = new BinOpExpression(lhs.pos, "*", lhs, parseE3());
423f308350 2010-11-07        kinaba: 			else if( tryEat("/") )
423f308350 2010-11-07        kinaba: 				lhs = new BinOpExpression(lhs.pos, "/", lhs, parseE3());
423f308350 2010-11-07        kinaba: 			else
423f308350 2010-11-07        kinaba: 				return lhs;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Expression parseE3()
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		if( lex.empty )
423f308350 2010-11-07        kinaba: 			throw new ParserException("EOF during parsing an expression");
423f308350 2010-11-07        kinaba: 		auto pos = lex.front.pos;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 		if( lex.front.kind == Token.Kind.number )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			scope(exit) lex.popFront;
423f308350 2010-11-07        kinaba: 			return new IntLiteralExpression(pos, BigInt(cast(string)lex.front.str));
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 		if( lex.front.kind == Token.Kind.stringLiteral )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			scope(exit) lex.popFront;
423f308350 2010-11-07        kinaba: 			return new StrLiteralExpression(pos, lex.front.str);
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 		if( tryEat("(") )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			auto e = parseE0();
423f308350 2010-11-07        kinaba: 			eat(")", "after parenthesized expression");
423f308350 2010-11-07        kinaba: 			return e;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 		scope(exit) lex.popFront;
423f308350 2010-11-07        kinaba: 		return new VarExpression(pos, lex.front.str);
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: private:
423f308350 2010-11-07        kinaba: 	Lexer lex;
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	void eat(string kwd, lazy string msg)
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		if( !tryEat(kwd) )
423f308350 2010-11-07        kinaba: 		{
423f308350 2010-11-07        kinaba: 			auto e = ParserException.create(lex, "'"~kwd~"' is expected "~msg~" but '"
423f308350 2010-11-07        kinaba: 				~(lex.empty ? "EOF" : lex.front.str)~"' occured");
423f308350 2010-11-07        kinaba: 			throw e;
423f308350 2010-11-07        kinaba: 		}
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	bool tryEat(string kwd)
423f308350 2010-11-07        kinaba: 	{
423f308350 2010-11-07        kinaba: 		if( lex.empty || lex.front.kind!=Token.Kind.identifier || lex.front.str!=kwd )
423f308350 2010-11-07        kinaba: 			return false;
423f308350 2010-11-07        kinaba: 		lex.popFront;
423f308350 2010-11-07        kinaba: 		return true;
423f308350 2010-11-07        kinaba: 	}
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: unittest
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	auto p = parserFromString(`
423f308350 2010-11-07        kinaba: 		var x = 100;
423f308350 2010-11-07        kinaba: 		var y = 200;
423f308350 2010-11-07        kinaba: 	`);
423f308350 2010-11-07        kinaba: 	Program prog = p.parseProgram();
423f308350 2010-11-07        kinaba: 	assert( prog.length == 2 );
423f308350 2010-11-07        kinaba: 	auto p0 = cast(DeclStatement)prog[0];
423f308350 2010-11-07        kinaba: 	auto p1 = cast(DeclStatement)prog[1];
423f308350 2010-11-07        kinaba: 	assert( p0.var == "x" );
423f308350 2010-11-07        kinaba: 	assert( p1.var == "y" );
423f308350 2010-11-07        kinaba: 	assert( (cast(IntLiteralExpression)p0.expr).data == 100 );
423f308350 2010-11-07        kinaba: 	assert( (cast(IntLiteralExpression)p1.expr).data == 200 );
423f308350 2010-11-07        kinaba: }
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: unittest
423f308350 2010-11-07        kinaba: {
423f308350 2010-11-07        kinaba: 	auto p = parserFromString(`
423f308350 2010-11-07        kinaba: 		var zzz = 100; # comment
423f308350 2010-11-07        kinaba: 		zzz = zzz + zzz * "fo\no"; # comment
423f308350 2010-11-07        kinaba: 			42;
423f308350 2010-11-07        kinaba: 	`);
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	auto s0 = new DeclStatement(null, "zzz", new IntLiteralExpression(null, BigInt(100)));
423f308350 2010-11-07        kinaba: 	auto s1 = new ExprStatement(null, new BinOpExpression(null, "=",
423f308350 2010-11-07        kinaba: 		new VarExpression(null, "zzz"),
423f308350 2010-11-07        kinaba: 		new BinOpExpression(null, "+",
423f308350 2010-11-07        kinaba: 			new VarExpression(null, "zzz"),
423f308350 2010-11-07        kinaba: 			new BinOpExpression(null, "*",
423f308350 2010-11-07        kinaba: 				new VarExpression(null, "zzz"),
423f308350 2010-11-07        kinaba: 				new StrLiteralExpression(null, "fo\\no")
423f308350 2010-11-07        kinaba: 				))));
423f308350 2010-11-07        kinaba: 	auto s2 = new ExprStatement(null, new IntLiteralExpression(null, BigInt(42)));
423f308350 2010-11-07        kinaba: 
423f308350 2010-11-07        kinaba: 	Program prog = p.parseProgram();
423f308350 2010-11-07        kinaba: 	assert( prog.length == 3 );
423f308350 2010-11-07        kinaba: 	assert( prog[0] == s0 );
423f308350 2010-11-07        kinaba: 	assert( prog[1] == s1 );
423f308350 2010-11-07        kinaba: 	assert( prog[2] == s2 );
423f308350 2010-11-07        kinaba: }