public override AstNode Visit(SubscriptAccess node)
{
// Begin the node
builder.BeginNode(node);
// Get the array expression.
Expression array = node.GetArray();
// Visit it.
array.Accept(this);
// Get the array and coercion type.
IChelaType arrayType = array.GetNodeType();
IChelaType coercionType = node.GetCoercionType();
// Perform array coercion.
if(arrayType != coercionType)
Cast(node, array.GetNodeValue(), arrayType, coercionType);
// Visit and coerce each index.
IChelaType[] indexCoercions = node.GetIndexCoercions();
Expression index = node.GetIndex();
int indexId = 0;
while(index != null)
{
// Visit it.
index.Accept(this);
// Get the index type.
IChelaType indexType = index.GetNodeType();
// Get or compute the index coercion type.
IChelaType indexCoercion = null;
if(indexCoercions != null && indexCoercions.Length != 0)
{
indexCoercion = indexCoercions[indexId];
}
else
{
// Remove the reference and constant layer.
indexCoercion = indexType;
if(indexCoercion.IsReference())
indexCoercion = DeReferenceType(indexCoercion);
if(indexCoercion.IsConstant())
indexCoercion = DeConstType(indexCoercion);
}
if(indexType != indexCoercion)
Cast(index, index.GetNodeValue(), indexType, indexCoercion);
// Process the next index.
++indexId;
index = (Expression)index.GetNext();
}
return builder.EndNode();
}
public override AstNode Visit(SubscriptAccess node)
{
// Evaluate the base reference.
Expression arrayExpr = node.GetArray();
arrayExpr.Accept(this);
// Get the base reference type.
IChelaType arrayType = arrayExpr.GetNodeType();
IChelaType objectType = null;
if(arrayType.IsReference())
{
// Get the referenced type.
ReferenceType refType = (ReferenceType) arrayType;
objectType = refType.GetReferencedType();
// Dereference again (object variable).
if(objectType.IsReference())
{
refType = (ReferenceType) objectType;
arrayType = refType;
objectType = refType.GetReferencedType();
}
else if(objectType.IsStructure())
{
arrayType = objectType;
}
if(objectType.IsPointer())
{
arrayType = objectType;
}
}
// Check the array type.
if(!arrayType.IsPointer() && !arrayType.IsReference() && !arrayType.IsStructure())
Error(node, "expected pointer/array/object.");
// Get the object type.
IChelaType[] indexCoercionsType = null;
IChelaType usedArrayType = arrayType;
int dimensions = 1;
bool arraySlot = false;
if(arrayType.IsPointer())
{
PointerType pointer = (PointerType) arrayType;
objectType = pointer.GetPointedType();
arraySlot = true;
}
else if(objectType != null && objectType.IsArray())
{
ArrayType array = (ArrayType)objectType;
dimensions = array.GetDimensions();
usedArrayType = array;
objectType = array.GetValueType();
if(objectType.IsPassedByReference())
objectType = ReferenceType.Create(objectType);
arraySlot = true;
}
else if(objectType.IsClass() || objectType.IsStructure() || objectType.IsInterface())
{
// Find the indexer.
Structure building = (Structure)objectType;
// TODO: support indexer overloading.
ScopeMember member = building.FindMemberRecursive("Op_Index");
if(!member.IsProperty())
Error(node, "object has invalid indexer.");
// Check the indices type.
PropertyVariable indexer = (PropertyVariable)member;
dimensions = indexer.GetIndexCount();
if(dimensions == 0)
Error(node, "Expected an intexer with at leas one dimension.");
// Use the indexer as the node value.
node.SetNodeValue(indexer);
// Set the index coercion type.
indexCoercionsType = new IChelaType[dimensions];
for(int i = 0; i < dimensions; ++i)
indexCoercionsType[i] = indexer.GetIndexType(i);
node.SetIndexCoercions(indexCoercionsType);
// Use the indexer type.
objectType = indexer.GetVariableType();
}
else
{
Error(node, "unexpected object.");
}
// Set the coercion type.
node.SetCoercionType(arrayType);
// Set the node type.
node.SetNodeType(ReferenceType.Create(objectType));
// Create the "variable" for arrays.
if(arraySlot)
{
ArraySlot variable = new ArraySlot(objectType, usedArrayType);
node.SetNodeValue(variable);
}
// Check the index expressions.
int indexId = 0;
Expression index = node.GetIndex();
while(index != null)
{
// Don't allow more indices than dimensions.
if(indexId == dimensions)
Error(index, "cannot use more indices than dimensions.");
// Visit it.
index.Accept(this);
// Get the index type.
IChelaType indexType = index.GetNodeType();
if(indexCoercionsType != null)
{
// Perform the index coercion.
IChelaType coercionType = indexCoercionsType[indexId];
if(Coerce(index, coercionType, indexType, index.GetNodeValue()) != coercionType)
Error(index, "expected an index of type {0}.", coercionType.GetDisplayName());
}
else
{
// Dereference.
if(indexType.IsReference())
{
ReferenceType indexRef = (ReferenceType) indexType;
indexType = indexRef.GetReferencedType();
}
// Deconst.
if(indexType.IsConstant())
indexType = DeConstType(indexType);
if(!indexType.IsInteger())
Error(node, "expected integer index.");
}
// Check the next index.
++indexId;
index = (Expression)index.GetNext();
}
// Don't allow less indices than dimensions.
if(indexId < dimensions)
Error(index, "cannot use less indices than dimensions.");
return node;
}