public static bool IsExpressionValid(
Context context,
Scope environment,
IExpression expression)
{
var self = new ExpressionAnalyzer(context, environment);
return(expression.Accept(self));
}
public void VisitReturnStatement(ReturnStatement returnStatement)
{
if (_functionContext == null)
{
_context.Error(returnStatement.Span, "return statement outside of a function");
}
ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
returnStatement.Expression);
}
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 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 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}\"");
}
}
public void VisitExpressionStatement(ExpressionStatement expressionStatement) =>
ExpressionAnalyzer.IsExpressionValid(
_context,
_currentScope,
expressionStatement.Expression);