Parsing Expressions 6

.gitignore

@@ -14,3 +14,6 @@ lox-test-*
 *.o
 *.obj
 *.lst
+
+.msc/
+

src/jlox/expr.d

@@ -8,6 +8,7 @@ import taggedalgebraic;
 
 import jlox.token;
 import jlox.tokentype;
+import jlox.util;
 
 abstract class Expr{
 	interface Visitor(R){
@@ -20,10 +21,7 @@ abstract class Expr{
 	static foreach(T; rTypes)
 		abstract T accept(Visitor!T visitor);
 	private template defCtorAndAccept(){
-		this(Args...)(auto ref Args args){
+		mixin defaultCtor;
-			static foreach(i, a; args)
-				this.tupleof[i] = a;
-		}
 		static foreach(T; rTypes)
 			override T accept(Visitor!T visitor) => visitor.visit(this);
 	}

src/jlox/main.d

@@ -10,12 +10,21 @@ import commandr;
 import jlox.token;
 import jlox.tokentype;
 import jlox.scanner;
+import jlox.parser;
+import jlox.expr;
 
 static bool hadError = false;
 
 void error(int line, string message){
 	report(line, "", message);
 }
+void error(Token token, string message){
+	if (token.type == TokenType.EOF) {
+		report(token.line, " at end", message);
+	} else {
+		report(token.line, " at '" ~ token.lexeme ~ "'", message);
+	}
+}
 void report(int line, string where, string message){
 	stderr.writeln("[line " ~ line.to!string ~ "] Error" ~ where ~ ": " ~ message);
 	hadError = true;
@@ -25,8 +34,13 @@ void run(string source){
 	Scanner scanner = new Scanner(source);
 	Token[] tokens = scanner.scanTokens();
 
-	foreach(token; tokens)
+	Parser parser = new Parser(tokens);
-		writeln(token);
+	Expr expression = parser.parse();
+
+	if(hadError)
+		return;
+
+	writeln((new AstPrinter).print(expression));
 }
 
 void runFile(string path){

src/jlox/parser.d

@@ -0,0 +1,148 @@
+module jlox.parser;
+
+import std.stdio;
+
+import jlox.token;
+import jlox.tokentype;
+import jlox.util;
+import jlox.expr;
+import jlox.main : loxError = error;
+
+class Parser{
+	private Token[] tokens;
+	private int current = 0;
+
+	mixin defaultCtor;
+	Expr parse(){
+		try {
+			return expression();
+		} catch (ParseError error) {
+			return null;
+		}
+	}
+
+	private bool isAtEnd() => peek().type == EOF;
+	private Token peek() => tokens[current];
+	private Token previous() => tokens[current-1];
+	private bool check(TokenType type){
+		if(isAtEnd)
+			return false;
+		return peek().type == type;
+	}
+	private Token advance(){
+		if(!isAtEnd())
+			current++;
+		return previous();
+	}
+	private bool match(TokenType[] types...){
+		foreach(TokenType type; types){
+			if(check(type)){
+				advance();
+				return true;
+			}
+		}
+		return false;
+	}
+	private Token consume(TokenType type, string message){
+		if(check(type))
+			return advance();
+		throw error(peek(), message);
+	}
+	private static class ParseError : Exception {
+		this(string s){
+			super(s);
+		}
+	}
+	private ParseError error(Token token, string message){
+		loxError(token, message);
+		return new ParseError("hello");
+	}
+	private void synchronize(){
+		advance();
+		with(TokenType) while(!isAtEnd()){
+			if(previous().type == SEMICOLON)
+				return;
+			switch(peek().type){
+				case CLASS:
+				case FUN:
+				case VAR:
+				case FOR:
+				case IF:
+				case WHILE:
+				case PRINT:
+				case RETURN:
+					return;
+				default:
+					assert(0);
+			}
+			advance();
+		}
+	}
+
+
+	private Expr expression(){
+		return equality();
+	}
+	private Expr equality(){
+		Expr expr = comparison();
+		while(match(TokenType.BANG_EQUAL, TokenType.EQUAL_EQUAL)){
+			Token operator = previous();
+			Expr right = comparison();
+			expr = new Expr.Binary(expr, operator, right);
+		}
+		return expr;
+	}
+	private Expr comparison(){
+		Expr expr = term();
+		while(match(TokenType.GREATER, TokenType.GREATER_EQUAL, TokenType.LESS, TokenType.LESS_EQUAL)){
+			Token operator = previous();
+			Expr right = term();
+			expr = new Expr.Binary(expr, operator, right);
+		}
+		return expr;
+	}
+	private Expr term(){
+		Expr expr = factor();
+		while(match(TokenType.MINUS, TokenType.PLUS)){
+			Token operator = previous();
+			Expr right = factor();
+			expr = new Expr.Binary(expr, operator, right);
+		}
+		return expr;
+	}
+	private Expr factor(){
+		Expr expr = unary();
+		while(match(TokenType.SLASH, TokenType.STAR)){
+			Token operator = previous();
+			Expr right = unary();
+			expr = new Expr.Binary(expr, operator, right);
+		}
+		return expr;
+	}
+	private Expr unary(){
+		if(match(TokenType.BANG, TokenType.MINUS)){
+			Token operator = previous();
+			Expr right = unary();
+			return new Expr.Unary(operator, right);
+		}
+		return primary();
+	}
+	private Expr primary(){
+		if(match(TokenType.FALSE))
+			return new Expr.Literal(false);
+		if(match(TokenType.TRUE))
+			return new Expr.Literal(true);
+		if(match(TokenType.NIL))
+			return new Expr.Literal(null);
+		if(match(TokenType.NUMBER, TokenType.STRING))
+			return new Expr.Literal(previous().literal);
+		if(match(TokenType.LEFT_PAREN)){
+			Expr expr = expression();
+			consume(TokenType.RIGHT_PAREN, "Expect ')' after expression.");
+			return new Expr.Grouping(expr);
+		}
+		throw error(peek(), "Expect expression.");
+		assert(0);
+	}
+
+}

src/jlox/util.d

@@ -0,0 +1,8 @@
+module jlox.util;
+
+template defaultCtor(){
+	this(Args...)(auto ref Args args){
+		static foreach(i, a; args)
+			this.tupleof[i] = a;
+	}
+}