public bool VisitDereference(Dereference dereference)
{
if (!IsExpressionValid(dereference.Expression))
{
return(false);
}
return(Typer.GetExpressionType(_context, _environment, dereference.Expression) != null);
}
public static IType GetExpressionType(
Context context,
Scope environment,
IExpression expression)
{
var self = new Typer(context, environment);
return(self.GetExpressionType(expression));
}
public bool VisitArrayLiteral(ArrayLiteral arrayLiteral)
{
var isValid = arrayLiteral.Elements.Aggregate(
true,
(current, element) => current & IsExpressionValid(element));
if (!isValid)
{
return(false);
}
return(Typer.GetExpressionType(_context, _environment, arrayLiteral) != null);
}
public bool VisitFunctionCall(FunctionCall functionCall)
{
var calleeType = Typer.GetExpressionType(_context, _environment, functionCall.Callee);
if (calleeType == null)
{
return(false);
}
if (!(calleeType is FunctionType))
{
_context.Error(
functionCall.Span,
$"tried to call a non-callable type \"{calleeType}\"");
return(false);
}
var calleeFunctionType = (FunctionType)calleeType;
if (functionCall.Arity != calleeFunctionType.Arity)
{
var s = calleeFunctionType.Arity == 1 ? "" : "s";
var wasOrWere = functionCall.Arity == 1 ? "was" : "were";
_context.Error(
functionCall.Callee.Span,
$"expected {calleeFunctionType.Arity} argument{s}, " +
$"but {functionCall.Arity} {wasOrWere} given");
}
var argumentsToCheck = Math.Min(functionCall.Arity, calleeFunctionType.Arity);
var allArgumentsHaveCorrectType = true;
for (var i = 0; i < argumentsToCheck; i++)
{
var argument = functionCall.Arguments[i];
var argumentType = Typer.GetExpressionType(_context, _environment, argument);
var parameterType = calleeFunctionType.ParameterTypes[i];
if (parameterType.IsSame(argumentType))
{
continue;
}
_context.Error(
argument.Span,
"type mismatch between argument and parameter; " +
$"expected \"{parameterType}\", but found \"{argumentType}\"");
allArgumentsHaveCorrectType = false;
}
return(allArgumentsHaveCorrectType);
}
public bool VisitAddressOf(AddressOf addressOf)
{
if (!IsExpressionValid(addressOf.Expression))
{
return(false);
}
if (!SemanticAnalyzer.IsLValue(addressOf.Expression))
{
_context.Error(addressOf.Span, "cannot get the address of a temporary value");
return(false);
}
return(Typer.GetExpressionType(_context, _environment, addressOf.Expression) != null);
}
public bool VisitInfixOperation(InfixOperation infixOperation)
{
if (!(IsExpressionValid(infixOperation.LeftOperand) &&
IsExpressionValid(infixOperation.RightOperand)))
{
return(false);
}
if (infixOperation.LeftOperand is InfixOperation child &&
infixOperation.Operator.Node != child.Operator.Node)
{
_context.Error(
infixOperation.Operator.Span,
"operator precedence is not supported; parentheses required");
}
var leftOperandType = Typer.GetExpressionType(
_context,
_environment,
infixOperation.LeftOperand);
var rightOperandType = Typer.GetExpressionType(
_context,
_environment,
infixOperation.RightOperand);
if (leftOperandType != null &&
leftOperandType.GetInfixOperationResultType(infixOperation.Operator.Node) == null)
{
_context.Error(
infixOperation.Operator.Span,
$"infix operation \"{infixOperation.Operator.Node}\" " +
$"is not defined for types \"{leftOperandType}\" and \"{rightOperandType}\"");
return(false);
}
if (leftOperandType != null && leftOperandType.IsSame(rightOperandType))
{
return(true);
}
_context.Error(
infixOperation.Operator.Span,
"type mismatch between operands of a infix expression; " +
$"left is \"{leftOperandType}\", but right is \"{rightOperandType}\"");
return(false);
}
private void CheckIfCase(IExpression condition, Block body)
{
if (!ExpressionAnalyzer.IsExpressionValid(_context, _currentScope, condition))
{
return;
}
var conditionType = Typer.GetExpressionType(_context, _currentScope, condition);
if (conditionType != null && !(conditionType is BooleanType))
{
_context.Error(
condition.Span,
"condition does not evaluate to \"bool\" type");
}
AnalyzeBlock(body);
}
public bool VisitSubscriptExpression(SubscriptExpression subscriptExpression)
{
if (!IsExpressionValid(subscriptExpression.Operand) ||
!IsExpressionValid(subscriptExpression.Index))
{
return(false);
}
var operandType = Typer.GetExpressionType(
_context,
_environment,
subscriptExpression.Operand);
if (operandType == null)
{
return(false);
}
if (!(operandType is ArrayType))
{
_context.Error(
subscriptExpression.Span,
$"cannot index into a non-array type \"{operandType}\"");
return(false);
}
var indexType = Typer.GetExpressionType(
_context,
_environment,
subscriptExpression.Index);
if (indexType == null)
{
return(false);
}
if (!(indexType is IntegerType))
{
_context.Error(
subscriptExpression.Span,
$"type \"{operandType}\" cannot be indexed by type \"{indexType}\"");
return(false);
}
return(true);
}
public void VisitAssignmentStatement(AssignmentStatement assignmentStatement)
{
if (!ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
assignmentStatement.Target) ||
!ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
assignmentStatement.Value))
{
return;
}
if (!IsLValue(assignmentStatement.Target))
{
_context.Error(
assignmentStatement.Target.Span,
"left-hand of the assignment is not assignable");
return;
}
var targetType = Typer.GetExpressionType(
_context,
_currentScope,
assignmentStatement.Target);
var valueType = Typer.GetExpressionType(
_context,
_currentScope,
assignmentStatement.Value);
if (targetType == null || valueType == null)
{
return;
}
if (!targetType.IsSame(valueType))
{
_context.Error(
assignmentStatement.Value.Span,
$"type mismatch; expected \"{targetType}\", but found \"{valueType}\"");
}
}
public void VisitAssertStatement(AssertStatement assertStatement)
{
if (!ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
assertStatement.Condition))
{
return;
}
var conditionType = Typer.GetExpressionType(
_context,
_currentScope,
assertStatement.Condition);
if (conditionType != null && !(conditionType is BooleanType))
{
_context.Error(
assertStatement.Condition.Span,
$"type mismatch; expected \"bool\", but found \"{conditionType}\"");
}
}
public void VisitWhileStatement(WhileStatement whileStatement)
{
if (ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
whileStatement.Condition))
{
var conditionType = Typer.GetExpressionType(
_context,
_currentScope,
whileStatement.Condition);
if (conditionType != null && !conditionType.IsSame(new BooleanType()))
{
_context.Error(
whileStatement.Condition.Span,
"while loop condition does not evaluate to type \"bool\"");
}
}
_loopNestLevel++;
AnalyzeBlock(whileStatement.Body);
_loopNestLevel--;
}
public bool VisitPrefixOperation(PrefixOperation prefixOperation)
{
if (!IsExpressionValid(prefixOperation.Operand))
{
return(false);
}
var operandType = Typer.GetExpressionType(
_context,
_environment,
prefixOperation.Operand);
if (operandType == null ||
operandType.GetPrefixOperationResultType(prefixOperation.Operator.Node) != null)
{
return(true);
}
_context.Error(
prefixOperation.Span,
"cannot apply unary operator " +
$"{prefixOperation.Operator.Node.GetDescription()} to type \"{operandType}\"");
return(false);
}
public void VisitVariableDefinition(VariableDefinition variableDefinition)
{
if (variableDefinition.TypeSignature != null && variableDefinition.Initializer != null)
{
var variableType = TypeSignatureParser.ParseTypeSignature(
_context,
variableDefinition.TypeSignature);
if (!ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
variableDefinition.Initializer))
{
return;
}
var initializerType = Typer.GetExpressionType(
_context,
_currentScope,
variableDefinition.Initializer);
if (variableType != null && !variableType.IsSame(initializerType))
{
// We made sure in the StatementParser that a definition without both initializer
// and type signature is not a valid AST item and discarded it with an error.
Debug.Assert(variableDefinition.Initializer != null);
_context.Error(
variableDefinition.Initializer.Span,
$"expected type \"{variableType}\", but found \"{initializerType}\"");
}
_astContext.AddNodeType(variableDefinition.NodeId, variableType);
}
else if (variableDefinition.TypeSignature != null &&
variableDefinition.Initializer == null)
{
var variableType =
TypeSignatureParser.ParseTypeSignature(
_context,
variableDefinition.TypeSignature);
_astContext.AddNodeType(variableDefinition.NodeId, variableType);
}
else // variableDefinition.TypeSignature == null && variableDefinition.Initializer != null
{
if (!ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
variableDefinition.Initializer))
{
return;
}
var initializerType = Typer.GetExpressionType(
_context,
_currentScope,
variableDefinition.Initializer);
switch (initializerType)
{
case VoidType _:
// Again, the linter is overly sensitive. There's no way for the Initializer
// field to be null at this point.
Debug.Assert(variableDefinition.Initializer != null);
_context.Error(
variableDefinition.Initializer.Span,
"type \"void\" cannot be assigned to a variable");
break;
case null:
return;
default:
_astContext.AddNodeType(variableDefinition.NodeId, initializerType);
break;
}
}
if (!_currentScope.DefineSymbol(
variableDefinition,
_astContext.GetNodeType(variableDefinition.NodeId)))
{
_context.Error(
variableDefinition.Span,
$"redefined previously defined symbol \"{variableDefinition.Identifier}\"");
}
}