private static Object EvaluateIdentifierExpression(Expression expression, IEnvironment env)
{
var value = (string)((IdentifierExpression)expression).Value;
var identifier = env.Get(value);
if (identifier != default(Object))
{
return(identifier);
}
var builtIn = Functions.GetByName(value);
if (builtIn != default(Object))
{
return(builtIn);
}
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.IdentifierExpressionEvaluation,
Offenders = new List <object> {
value
},
Kind = ErrorKind.InvalidIdentifier,
Source = ErrorSource.Evaluator
})));
}
private static Object EvaluateHashIndexExpression(Object hash, Object key)
{
if (key.Kind != ObjectKind.Integer && key.Kind != ObjectKind.Boolean && key.Kind != ObjectKind.String)
{
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.HashIndexExpressionEvaluation,
Offenders = new List <object> {
hash, key
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
var hashtable = (Dictionary <string, Object>)hash.Value;
var keyValue = key.Value.ToString();
if (hashtable.Count == 0 || keyValue == String.Empty)
{
return(Object.Create(ObjectKind.Null, null));
}
var hashKey = hashtable.Keys.Where(item => item == keyValue).FirstOrDefault();
if (hashKey == default(string))
{
return(Object.Create(ObjectKind.Null, null));
}
return(hashtable[keyValue]);
}
private void ExecuteHashOperation()
{
var count = DecodeOperand(2);
var hash = new Dictionary <string, Object>();
var keys = new List <string>();
var values = new List <Object>();
internalState.CurrentFrame.InstructionPointer += 2;
for (var i = 0; i < count; i++)
{
values.Add(internalState.Stack.Pop());
keys.Add(internalState.Stack.Pop().Value.ToString().ToLower());
}
keys.Reverse();
values.Reverse();
for (var i = 0; i < keys.Count; i++)
{
hash.Add(keys[i], values[i]);
}
internalState.Stack.Push(Object.Create(ObjectKind.Hash, hash));
}
private static Object EvaluatePrefixExpression(Expression expression, IEnvironment env)
{
var prefixExpression = (PrefixExpression)expression;
var op = ((InfixExpression)prefixExpression.Left).Operator;
switch (op.Kind)
{
case SyntaxKind.Bang:
return(EvaluateBangOperatorExpression(prefixExpression.Right, env));
case SyntaxKind.Minus:
return(EvaluateMinusOperatorExpression(prefixExpression.Right, env));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.UnknownOperator,
Offenders = new List <object> {
op
},
Kind = ErrorKind.UnknownOperator,
Source = ErrorSource.Evaluator
})));
}
}
private static Object EvaluateStringInfixExpression(string left, Token op, string right)
{
switch (op.Kind)
{
case SyntaxKind.Plus:
return(Object.Create(ObjectKind.String, string.Join(String.Empty, left, right)));
case SyntaxKind.Equal:
return(Object.Create(ObjectKind.Boolean, left == right));
case SyntaxKind.NotEqual:
return(Object.Create(ObjectKind.Boolean, left != right));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.StringExpressionOperatorEvaluation,
Offenders = new List <object> {
left, op, right
},
Kind = ErrorKind.UnknownOperator,
Source = ErrorSource.Evaluator
})));
}
}
private void ExecuteBinaryIntegerOperation(byte op, int left, int right)
{
switch (op)
{
case 2: // Opcode.Add
internalState.Stack.Push(Object.Create(ObjectKind.Integer, left + right));
break;
case 4: // Opcode.Subtract
internalState.Stack.Push(Object.Create(ObjectKind.Integer, left - right));
break;
case 5: // Opcode.Multiply
internalState.Stack.Push(Object.Create(ObjectKind.Integer, left * right));
break;
case 6: // Opcode.Divide
internalState.Stack.Push(Object.Create(ObjectKind.Integer, left / right));
break;
case 9: // Opcode.Equal
internalState.Stack.Push(left == right ? Invariants[true] : Invariants[false]);
break;
case 10: // Opcode.NotEqual
internalState.Stack.Push(left != right ? Invariants[true] : Invariants[false]);
break;
case 11: // Opcode.GreaterThan
internalState.Stack.Push(left > right ? Invariants[true] : Invariants[false]);
break;
}
}
private static Object EvaluateCallExpression(Expression expression, IEnvironment env)
{
List <Object> args = new List <Object>();
CallExpression callExpression = (CallExpression)expression;
Object obj;
if (callExpression.Identifier != default(Token))
{
obj = env.Get(callExpression.Identifier.Literal);
obj = obj == default(Object) ? Functions.GetByName(callExpression.Identifier.Literal) : obj;
}
else
{
obj = Object.Create(ObjectKind.Function, callExpression.Function);
}
if (callExpression.Arguments != default(List <Expression>))
{
args = EvaluateExpressionList(callExpression.Arguments, env);
}
if (obj.Kind == ObjectKind.BuiltIn)
{
var fn = (Func <List <Object>, Object>)obj.Value;
return(fn(args));
}
else
{
return(ApplyFunction(obj, args));
}
}
private static Object EvaluateFunctionExpression(Expression expression, IEnvironment env)
{
var obj = Object.Create(ObjectKind.Function, expression);
obj.Environment = env;
return(obj);
}
private void ExecuteBinaryStringOperation(byte op, string left, string right)
{
switch (op)
{
case 2: // Opcode.Add
internalState.Stack.Push(Object.Create(ObjectKind.String, string.Join(String.Empty, left, right)));
break;
}
}
private static Object EvaluateInfixExpression(Expression expression, IEnvironment env)
{
var infixExpression = (InfixExpression)expression;
var left = EvaluateExpression(infixExpression.Left, env);
if (left.Kind == ObjectKind.Error)
{
return(left);
}
var right = EvaluateExpression(infixExpression.Right, env);
if (right.Kind == ObjectKind.Error)
{
return(right);
}
if (left.Kind != right.Kind)
{
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.InfixExpressionEvaluation,
Offenders = new List <object> {
left, right
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
switch (left.Kind)
{
case ObjectKind.Integer:
return(EvaluateIntegerInfixExpression((int)left.Value, infixExpression.Operator, (int)right.Value));
case ObjectKind.Boolean:
return(EvaluateBooleanInfixExpression((bool)left.Value, infixExpression.Operator, (bool)right.Value));
case ObjectKind.String:
return(EvaluateStringInfixExpression((string)left.Value, infixExpression.Operator, (string)right.Value));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.InfixExpressionOperatorEvaluation,
Offenders = new List <object> {
left, infixExpression.Operator, right
},
Kind = ErrorKind.UnknownOperator,
Source = ErrorSource.Evaluator
})));
}
}
private CompilerState CompileStringExpression(Expression expression, CompilerState previousState)
{
var stringExpression = (StringExpression)expression;
var index = DetermineConstantIndex(expression, previousState);
return(Factory.CompilerState()
.Assign(Emit((byte)Opcode.Name.Constant, new List <int> {
index
}, previousState))
.Constant(index, Object.Create(ObjectKind.String, stringExpression.Value))
.Create());
}
private void ExecuteMinusOperation()
{
Object operand = internalState.Stack.Pop();
if (operand.Kind != ObjectKind.Integer)
{
return;
}
int value = (int)operand.Value;
internalState.Stack.Push(Object.Create(ObjectKind.Integer, -value));
}
private static Object EvaluateStatements(List <Statement> statements, IEnvironment env)
{
var obj = Object.Create(ObjectKind.Null, null);
foreach (var statement in statements)
{
obj = EvaluateNode(statement, env);
if (obj.Kind == ObjectKind.Error || obj.Kind == ObjectKind.Return)
{
return(obj);
}
}
return(obj);
}
private void ExecuteArrayOperation()
{
var count = DecodeOperand(2);
var elements = new List <Object>();
internalState.CurrentFrame.InstructionPointer += 2;
for (var i = 0; i < count; i++)
{
elements.Add(internalState.Stack.Pop());
}
elements.Reverse();
internalState.Stack.Push(Object.Create(ObjectKind.Array, elements));
}
private static Object ApplyFunction(Object obj, List <Object> args)
{
var functionExpression = (FunctionExpression)obj.Value;
IEnvironment env = obj.Environment;
if (functionExpression.Parameters != default(List <Token>) && args != default(List <Object>))
{
env = EncloseEnvironment(functionExpression.Parameters, args, env);
}
if (functionExpression.Body != default(BlockStatement))
{
return(EvaluateStatements(functionExpression.Body.Statements, env));
}
return(Object.Create(ObjectKind.Null, null));
}
private static Object EvaluateExpression(Expression expression, IEnvironment env)
{
switch (expression.Kind)
{
case ExpressionKind.Integer:
return(EvaluateIntegerExpression(expression));
case ExpressionKind.Boolean:
return(EvaluateBooleanExpression(expression));
case ExpressionKind.String:
return(EvaluateStringExpression(expression));
case ExpressionKind.Identifier:
return(EvaluateIdentifierExpression(expression, env));
case ExpressionKind.Prefix:
return(EvaluatePrefixExpression(expression, env));
case ExpressionKind.Infix:
return(EvaluateInfixExpression(expression, env));
case ExpressionKind.IfElse:
return(EvaluateIfElseExpression(expression, env));
case ExpressionKind.Function:
return(EvaluateFunctionExpression(expression, env));
case ExpressionKind.Call:
return(EvaluateCallExpression(expression, env));
case ExpressionKind.Array:
return(EvaluateArrayExpression(expression, env));
case ExpressionKind.Hash:
return(EvaluateHashExpression(expression, env));
case ExpressionKind.Index:
return(EvaluateIndexExpression(expression, env));
default:
return(Object.Create(ObjectKind.Null, null));
}
}
private static Object EvaluateNode(Node node, IEnvironment env)
{
switch (node.Kind)
{
case NodeKind.Program:
return(EvaluateStatements(((Program)node).Statements, env));
case NodeKind.Let:
return(EvaluateLetStatement((Statement)node, env));
case NodeKind.Return:
return(EvaluateReturnStatement((Statement)node, env));
case NodeKind.Expression:
return(EvaluateExpression(((Statement)node).Expression, env));
default:
return(Object.Create(ObjectKind.Null, null));
}
}
private static Object EvaluateLetStatement(Statement statement, IEnvironment env)
{
var obj = Object.Create(ObjectKind.Null, null);
if (statement.Identifier == default(Token) || statement.Expression == default(Expression))
{
return(obj);
}
var value = EvaluateExpression(statement.Expression, env);
if (value.Kind == ObjectKind.Error)
{
return(value);
}
env.Set(statement.Identifier.Literal, value);
return(obj);
}
static Functions()
{
List = new List <BuiltIn>
{
new BuiltIn {
Name = "len", Function = Object.Create(ObjectKind.BuiltIn, Len)
},
new BuiltIn {
Name = "first", Function = Object.Create(ObjectKind.BuiltIn, First)
},
new BuiltIn {
Name = "last", Function = Object.Create(ObjectKind.BuiltIn, Last)
},
new BuiltIn {
Name = "rest", Function = Object.Create(ObjectKind.BuiltIn, Rest)
},
new BuiltIn {
Name = "push", Function = Object.Create(ObjectKind.BuiltIn, Push)
}
};
}
private static Object EvaluateIntegerInfixExpression(int left, Token op, int right)
{
switch (op.Kind)
{
case SyntaxKind.Plus:
return(Object.Create(ObjectKind.Integer, left + right));
case SyntaxKind.Minus:
return(Object.Create(ObjectKind.Integer, left - right));
case SyntaxKind.Asterisk:
return(Object.Create(ObjectKind.Integer, left * right));
case SyntaxKind.Slash:
return(Object.Create(ObjectKind.Integer, left / right));
case SyntaxKind.GreaterThan:
return(Object.Create(ObjectKind.Boolean, left > right));
case SyntaxKind.LessThan:
return(Object.Create(ObjectKind.Boolean, left < right));
case SyntaxKind.Equal:
return(Object.Create(ObjectKind.Boolean, left == right));
case SyntaxKind.NotEqual:
return(Object.Create(ObjectKind.Boolean, left != right));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.InfixExpressionOperatorEvaluation,
Offenders = new List <object> {
left, op, right
},
Kind = ErrorKind.UnknownOperator,
Source = ErrorSource.Evaluator
})));
}
}
private void ExecuteClosureOperation()
{
var index = DecodeOperand(2);
internalState.CurrentFrame.InstructionPointer += 2;
var freeCount = DecodeOperand(1);
internalState.CurrentFrame.InstructionPointer += 1;
var frees = new List <Object>();
for (var i = 0; i < freeCount; i++)
{
frees.Add(internalState.Stack[internalState.Stack.Count - freeCount + i]);
}
var fn = internalState.Constants[index];
var closure = Object.Create(ObjectKind.Closure, new Closure((List <byte>)fn.Value, frees));
internalState.Stack.Push(closure);
}
private static Object EvaluateBooleanInfixExpression(bool left, Token op, bool right)
{
switch (op.Kind)
{
case SyntaxKind.Equal:
return(Object.Create(ObjectKind.Boolean, left == right));
case SyntaxKind.NotEqual:
return(Object.Create(ObjectKind.Boolean, left != right));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.BooleanInfixExpressionEvaluation,
Offenders = new List <object> {
left, op, right
},
Kind = ErrorKind.UnknownOperator,
Source = ErrorSource.Evaluator
})));
}
}
private static Object EvaluateArrayIndexExpression(Object array, Object index)
{
if (array.Kind != ObjectKind.Array)
{
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.ArrayExpressionEvaluation,
Offenders = new List <object> {
array, index
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
if (index.Kind != ObjectKind.Integer)
{
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.ArrayIndexExpressionEvaluation,
Offenders = new List <object> {
array, index
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
var elements = (List <Object>)array.Value;
var indexValue = (int)index.Value;
if (elements.Count == 0 || indexValue < 0 || indexValue > elements.Count - 1)
{
return(Object.Create(ObjectKind.Null, null));
}
return(elements[indexValue]);
}
private void ExecuteBinaryOperation(byte op)
{
Object right = internalState.Stack.Pop();
Object left = internalState.Stack.Pop();
if (left.Kind != right.Kind)
{
var info = new ErrorInfo
{
Code = ErrorCode.BinaryOperationInvalidOperand,
Kind = ErrorKind.InvalidType,
Offenders = new List <object> {
left, op, right
},
Position = 2, // Consider right side as the offender
Source = ErrorSource.VM
};
internalState.Stack.Push(Object.Create(ObjectKind.Error, Error.Create(info)));
return;
}
switch (left.Kind)
{
case ObjectKind.Boolean:
ExecuteBinaryBooleanOperation(op, (bool)left.Value, (bool)right.Value);
break;
case ObjectKind.String:
ExecuteBinaryStringOperation(op, left.Value.ToString(), right.Value.ToString());
break;
default:
ExecuteBinaryIntegerOperation(op, (int)left.Value, (int)right.Value);
break;
}
}
private static Object EvaluateMinusOperatorExpression(Expression expression, IEnvironment env)
{
var value = EvaluateExpression(expression, env);
if (value.Kind == ObjectKind.Error)
{
return(value);
}
if (value.Kind != ObjectKind.Integer)
{
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.MinusOperatorExpressionEvaluation,
Offenders = new List <object> {
value
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
return(Object.Create(ObjectKind.Integer, -(int)value.Value));
}
private static Object EvaluateIfElseExpression(Expression expression, IEnvironment env)
{
var ifElseExpression = (IfElseExpression)expression;
var condition = EvaluateExpression(ifElseExpression.Condition, env);
if (condition.Kind == ObjectKind.Error)
{
return(condition);
}
if (IsTruthy(condition))
{
return(EvaluateStatements(ifElseExpression.Consequence.Statements, env));
}
else if (ifElseExpression.Alternative != default(BlockStatement))
{
return(EvaluateStatements(ifElseExpression.Alternative.Statements, env));
}
else
{
return(Object.Create(ObjectKind.Null, null));
}
}
private static Object EvaluateBangOperatorExpression(Expression expression, IEnvironment env)
{
var obj = EvaluateExpression(expression, env);
switch (obj.Kind)
{
case ObjectKind.Integer:
return(Object.Create(ObjectKind.Boolean, !((int)obj.Value != 0)));
case ObjectKind.Boolean:
return(Object.Create(ObjectKind.Boolean, !(bool)obj.Value));
default:
return(Object.Create(ObjectKind.Error, Error.Create(new ErrorInfo
{
Code = ErrorCode.BangOperatorExpressionEvaluation,
Offenders = new List <object> {
obj
},
Kind = ErrorKind.InvalidType,
Source = ErrorSource.Evaluator
})));
}
}
private static Object EvaluateHashExpression(Expression expression, IEnvironment env)
{
var hashExpression = (HashExpression)expression;
var hash = new Dictionary <string, Object>();
for (var i = 0; i < hashExpression.Keys.Count; i++)
{
var key = EvaluateExpression(hashExpression.Keys[i], env);
var value = EvaluateExpression(hashExpression.Values[i], env);
var previousKey = hash.Keys.Where(item => item == key.Value.ToString()).FirstOrDefault();
if (previousKey != default(string))
{
hash[previousKey] = Object.Create(value.Kind, value.Value);
}
else
{
hash.Add(key.Value.ToString(), Object.Create(value.Kind, value.Value));
}
}
return(Object.Create(ObjectKind.Hash, hash));
}
private static Object EvaluateArrayExpression(Expression expression, IEnvironment env)
{
var arrayExpression = (ArrayExpression)expression;
return(Object.Create(ObjectKind.Array, EvaluateExpressionList(arrayExpression.Elements, env)));
}
private static Object EvaluateStringExpression(Expression expression)
{
return(Object.Create(ObjectKind.String, ((StringExpression)expression).Value));
}
