Compiling Expressions 17

src/clox/parser.d

@@ -0,0 +1,66 @@
+module clox.parser;
+
+import clox.compiler;
+import clox.value;
+import clox.scanner;
+import clox.parserules;
+
+struct Parser{
+	Compiler* compiler;
+	Token current, previous;
+	bool hadError, panicMode;
+	void errorAtCurrent(string message){
+		errorAt(current, message);
+	}
+	void error(string message){
+		errorAt(previous, message);
+	}
+	void errorAt(in ref Token token, string message){
+		import core.stdc.stdio;
+		if(panicMode)
+			return;
+		panicMode = true;
+		fprintf(stderr, "[line %d] Error", token.line);
+		if(token.type == Token.Type.EOF){
+			fprintf(stderr, " at end");
+		} else if(token.type != Token.Type.Error){
+			fprintf(stderr, " at '%.*s'", cast(int)token.lexeme.length, token.lexeme.ptr);
+		}
+		fprintf(stderr, ": %.*s\n", cast(int)message.length, message.ptr);
+		hadError = true;
+	}
+	auto consume(Token.Type type, string msg){
+		if(current.type == type){
+			advance();
+			return;
+		}
+		errorAtCurrent(msg);
+	}
+	void advance(){
+		previous = current;
+		while(true){
+			current = compiler.scanner.scan();
+			if(current.type != Token.Type.Error)
+				break;
+			errorAtCurrent(current.lexeme);
+		}
+	}
+
+	void expression(){
+		parsePrecedence(Precedence.Assignment);
+	}
+	void parsePrecedence(Precedence precedence){
+		advance();
+		ParseFn prefixRule = ParseRule.get(previous.type).prefix;
+		if(prefixRule == null){
+			error("Expect expression.");
+			return;
+		}
+		prefixRule(compiler);
+		while(precedence <= ParseRule.get(current.type).precedence){
+			advance();
+			ParseFn infixRule = ParseRule.get(previous.type).infix;
+			infixRule(compiler);
+		}
+	}
+}