static ast.LetStatement parseLetStatement()
{
ast.LetStatement stmt = new ast.LetStatement {
Token = curToken
};
if (!expectPeek(token.IDENT))
{
return(null);
}
stmt.Name = new ast.Identifier {
Token = curToken, Value = curToken.Literal
};
if (!expectPeek(token.ASSIGN))
{
return(null);
}
nextToken();
stmt.Value = parseExpression(LOWEST);
if (peekTokenIs(token.SEMICOLON))
{
nextToken();
}
return(stmt);
}
public static error Compile(ast.Node node)
{
if (node is ast.Program)
{
foreach (ast.Statement s in ((ast.Program)node).Statements)
{
error err = Compile(s);
if (err != null)
{
return(err);
}
}
return(null);
}
if (node is ast.ExpressionStatement)
{
error err = Compile(((ast.ExpressionStatement)node).Expression);
if (err != null)
{
return(err);
}
emit(code.OpPop);
return(null);
}
if (node is ast.InfixExpression)
{
ast.InfixExpression _node = (ast.InfixExpression)node;
error err;
if (_node.Operator == "<")
{
err = Compile(_node.Right);
if (err != null)
{
return(err);
}
err = Compile(_node.Left);
if (err != null)
{
return(err);
}
emit(code.OpGreaterThan);
return(null);
}
err = Compile(_node.Left);
if (err != null)
{
return(err);
}
err = Compile(_node.Right);
if (err != null)
{
return(err);
}
switch (_node.Operator)
{
case "+":
emit(code.OpAdd);
break;
case "-":
emit(code.OpSub);
break;
case "*":
emit(code.OpMul);
break;
case "/":
emit(code.OpDiv);
break;
case ">":
emit(code.OpGreaterThan);
break;
case "==":
emit(code.OpEqual);
break;
case "!=":
emit(code.OpNotEqual);
break;
default:
return(string.Format("unknown operator {0}", _node.Operator));
}
return(null);
}
if (node is ast.IntegerLiteral)
{
Object.Integer integer = new Object.Integer {
Value = ((ast.IntegerLiteral)node).Value
};
emit(code.OpConstant, (Opcode)addConstant(integer));
return(null);
}
if (node is ast.Boolean)
{
if (((ast.Boolean)node).Value)
{
emit(code.OpTrue);
}
else
{
emit(code.OpFalse);
}
return(null);
}
if (node is ast.PrefixExpression)
{
ast.PrefixExpression _node = (ast.PrefixExpression)node;
error err = Compile(_node.Right);
if (err != null)
{
return(err);
}
switch (_node.Operator)
{
case "!":
emit(code.OpBang);
break;
case "-":
emit(code.OpMinus);
break;
default:
return(string.Format("unknown operator {0}", _node.Operator));
}
return(null);
}
if (node is ast.IfExpression)
{
ast.IfExpression _node = (ast.IfExpression)node;
error err = Compile(_node.Condition);
if (err != null)
{
return(err);
}
//Emit an 'OpJumpNotTruthy' with bogus value
int jumpNotTruthyPos = emit(code.OpJumpNotTruthy, 9999);
err = Compile(_node.Consequence);
if (err != null)
{
return(err);
}
if (lastInstructionIs(code.OpPop))
{
removeLastPop();
}
// Emit an 'OpJump' with a bogus value
int jumpPos = emit(code.OpJump, 9999);
int afterConsequencePos = currentInstructions().Count;
changeOperand(jumpNotTruthyPos, afterConsequencePos);
if (_node.Alternative == null)
{
emit(code.OpNull);
}
else
{
err = Compile(_node.Alternative);
if (err != null)
{
return(err);
}
if (lastInstructionIs(code.OpPop))
{
removeLastPop();
}
}
int afterAlternativePos = currentInstructions().Count;
changeOperand(jumpPos, afterAlternativePos);
return(null);
}
if (node is ast.BlockStatement)
{
foreach (ast.Statement s in ((ast.BlockStatement)node).Statements)
{
error err = Compile(s);
if (err != null)
{
return(err);
}
}
return(null);
}
if (node is ast.LetStatement)
{
ast.LetStatement _node = (ast.LetStatement)node;
symbol_table.Symbol symbol = symbol_table.Define(ref c.symbolTable, _node.Name.Value);
error err = Compile(_node.Value);
if (err != null)
{
return(err);
}
if (symbol.Scope == symbol_table.GlobalScope)
{
emit(code.OpSetGlobal, symbol.Index);
}
else
{
emit(code.OpSetLocal, symbol.Index);
}
return(null);
}
if (node is ast.Identifier)
{
ast.Identifier _node = (ast.Identifier)node;
symbol_table.Symbol symbol = symbol_table.Resolve(ref c.symbolTable, _node.Value);
if (symbol == null)
{
return(string.Format("undefined variable {0}", _node.Value));
}
loadSymbols(symbol);
return(null);
}
if (node is ast.StringLiteral)
{
ast.StringLiteral _node = (ast.StringLiteral)node;
Object.String str = new Object.String {
Value = _node.Value
};
emit(code.OpConstant, addConstant(str));
return(null);
}
if (node is ast.ArrayLiteral)
{
ast.ArrayLiteral _node = (ast.ArrayLiteral)node;
foreach (ast.Expression el in _node.Elements)
{
error err = Compile(el);
if (err != null)
{
return(err);
}
}
emit(code.OpArray, _node.Elements.Count);
return(null);
}
if (node is ast.HashLiteral)
{
ast.HashLiteral _node = (ast.HashLiteral)node;
// the sorting is not strictly needed and was only done to pass the test
// since the test assumes a specific order for the keys
foreach (KeyValuePair <Expression, Expression> k in _node.Pairs)
{
error err = Compile(k.Key);
if (err != null)
{
return(err);
}
err = Compile(_node.Pairs[k.Key]);
if (err != null)
{
return(err);
}
}
emit(code.OpHash, _node.Pairs.Count * 2);
return(null);
}
if (node is ast.IndexExpression)
{
ast.IndexExpression _node = (ast.IndexExpression)node;
error err = Compile(_node.Left);
if (err != null)
{
return(err);
}
err = Compile(_node.Index);
if (err != null)
{
return(err);
}
emit(code.OpIndex);
return(null);
}
if (node is ast.FunctionLiteral)
{
ast.FunctionLiteral _node = (ast.FunctionLiteral)node;
enterScope();
if (_node.Name != null && _node.Name != "")
{
symbol_table.DefineFunctionName(ref c.symbolTable, _node.Name);
}
foreach (ast.Identifier p in _node.Parameters)
{
symbol_table.Define(ref c.symbolTable, p.Value);
}
error err = Compile(_node.Body);
if (err != null)
{
return(err);
}
if (lastInstructionIs(code.OpPop))
{
replaceLastPopWithReturn();
}
if (!lastInstructionIs(code.OpReturnValue))
{
emit(code.OpReturn);
}
List <symbol_table.Symbol> freeSymbols = c.symbolTable.FreeSymbols;
int numLocals = c.symbolTable.numDefinitions;
Instructions instructions = leaveScope();
foreach (symbol_table.Symbol s in freeSymbols)
{
loadSymbols(s);
}
Object.CompiledFunction compiledFn = new Object.CompiledFunction
{
Instructions = instructions,
NumLocals = numLocals,
NumParameters = _node.Parameters.Count,
};
int fnIndex = addConstant(compiledFn);
emit(code.OpClosure, fnIndex, freeSymbols.Count);
return(null);
}
if (node is ast.ReturnStatement)
{
ast.ReturnStatement _node = (ast.ReturnStatement)node;
error err = Compile(_node.ReturnValue);
if (err != null)
{
return(err);
}
emit(code.OpReturnValue);
return(null);
}
if (node is ast.CallExpression)
{
ast.CallExpression _node = (ast.CallExpression)node;
error err = Compile(_node.Function);
if (err != null)
{
return(err);
}
foreach (Expression a in _node.Arguments)
{
err = Compile(a);
if (err != null)
{
return(err);
}
}
emit(code.OpCall, _node.Arguments.Count);
return(null);
}
return(null);
}