Statements and State 8

src/jlox/interpreter.d

@@ -8,10 +8,12 @@ import std.functional : ctEval;
 import taggedalgebraic;
 
 import jlox.expr;
+import jlox.stmt;
 import jlox.token;
 import jlox.tokentype;
 import jlox.token : TValue;
 import jlox.main;
+import jlox.environment;
 
 class RuntimeError : Exception{
 	const Token token;
@@ -21,15 +23,29 @@ class RuntimeError : Exception{
 	}
 }
 
-class Interpreter : Expr.Visitor!TValue{
-	void interpret(Expr expression) { 
+class Interpreter : Stmt.Visitor!void, Expr.Visitor!TValue {
+	private Environment environment = new Environment();
+	void interpret(Stmt[] statements){ 
 		try {
-			TValue value = evaluate(expression);
-			writeln(value);
+			foreach(statement; statements)
+				execute(statement);
 		} catch(RuntimeError error){
 			Lox.runtimeError(error);
 		}
 	}
+	private void execute(Stmt stmt){
+		stmt.accept(this);
+	}
+	private void executeBlock(Stmt[] statements, Environment environment){
+		Environment previous = this.environment;
+		try {
+			this.environment = environment;
+			foreach(Stmt statement; statements)
+				execute(statement);
+		} finally {
+			this.environment = previous;
+		}
+	}
 	private TValue evaluate(Expr expr){
 		return expr.accept(this);
 	}
@@ -51,13 +67,29 @@ class Interpreter : Expr.Visitor!TValue{
 			return;
 		throw new RuntimeError(operator, "Operand must be a number.");
 	}
+
+
+	void visit(Stmt.Block stmt){
+		executeBlock(stmt.statements, new Environment(environment));
+	}
+	void visit(Stmt.Expression stmt){
+		evaluate(stmt.expression);
+	}
+	void visit(Stmt.Print stmt){
+		TValue value = evaluate(stmt.expression);
+		writeln(tvalueToString(value));
+	}
+	void visit(Stmt.Var stmt){
+		environment.define(stmt.name.lexeme, stmt.initialiser is null ? TValue.nil(0) : evaluate(stmt.initialiser));
+	}
+
 	TValue visit(Expr.Literal expr){
 		return expr.value;
 	}
-	TValue visit(Expr.Grouping expr) {
+	TValue visit(Expr.Grouping expr){
 		return evaluate(expr.expression);
 	}
-	TValue visit(Expr.Unary expr) {
+	TValue visit(Expr.Unary expr){
 		TValue right = evaluate(expr.right);
 		switch(expr.operator.type){
 			case TokenType.MINUS:
@@ -104,5 +136,13 @@ class Interpreter : Expr.Visitor!TValue{
 				assert(0);
 		}
 	}
+	TValue visit(Expr.Variable expr){
+		return environment.get(expr.name);
+	}
+	TValue visit(Expr.Assign expr){
+		TValue value = evaluate(expr.value);
+		environment.assign(expr.name, value);
+		return value;
+	}
 }