ICCItem *CCodeChain::EvaluateArgs (CEvalContext *pCtx, ICCItem *pArgs, const CString &sArgValidation)
// EvaluateArgs
//
// Evaluate arguments and validate their types
{
ICCItem *pArg;
ICCItem *pNew;
ICCItem *pError;
CCLinkedList *pEvalList;
char *pValidation;
int i;
BOOL bNoEval;
// If the argument list if quoted, then it means that the arguments
// have already been evaluated. This happens if we've been called by
// (apply).
bNoEval = pArgs->IsQuoted();
// Create a list to hold the results
pNew = CreateLinkedList();
if (pNew->IsError())
return pNew;
pEvalList = dynamic_cast<CCLinkedList *>(pNew);
// Start parsing at the beginning
pValidation = sArgValidation.GetPointer();
// If there is a '*' in the validation, figure out
// how many arguments it represents
int iVarArgs = Max(0, pArgs->GetCount() - (sArgValidation.GetLength() - 1));
// Loop over each argument
for (i = 0; i < pArgs->GetCount(); i++)
{
ICCItem *pResult;
pArg = pArgs->GetElement(i);
// If we're processing variable args, see if we're done
if (*pValidation == '*')
{
if (iVarArgs == 0)
pValidation++;
else
iVarArgs--;
}
// Evaluate the item. If the arg is 'q' or 'u' then we
// don't evaluate it.
if (bNoEval || *pValidation == 'q' || *pValidation == 'u')
pResult = pArg->Reference();
// If the arg is 'c' then we don't evaluate unless it is
// a lambda expression (or an identifier)
else if (*pValidation == 'c' && !pArg->IsLambdaExpression() && !pArg->IsIdentifier())
pResult = pArg->Reference();
// Evaluate
else
{
pResult = Eval(pCtx, pArg);
// We don't want to return on error because some functions
// might want to pass errors around
if (*pValidation != 'v' && *pValidation != '*')
{
if (pResult->IsError())
{
pEvalList->Discard(this);
return pResult;
}
}
}
// Check to see if the item is valid
switch (*pValidation)
{
// We expect a function...
case 'f':
{
if (!pResult->IsFunction())
{
pError = CreateError(LITERAL("Function expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a numeral...
//
// NOTE: We treat integer the same a numeral because it's not always
// clear to the user when they've created a double or an integer.
// It is up to the actual function to use the integer or double
// value appropriately.
case 'i':
case 'n':
{
if (!pResult->IsDouble() && !pResult->IsInteger())
{
pError = CreateError(LITERAL("Numeral expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a double...
case 'd':
{
if (!pResult->IsDouble())
{
pError = CreateError(LITERAL("Double expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a vEctor...
case 'e':
{
if (!(pResult->GetValueType() == ICCItem::Vector))
{
pError = CreateError(LITERAL("Vector expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a linked list
case 'k':
{
if (pResult->GetClass()->GetObjID() != OBJID_CCLINKEDLIST)
{
pError = CreateError(LITERAL("Linked-list expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a list
case 'l':
{
if (!pResult->IsList())
{
pError = CreateError(LITERAL("List expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect an identifier
case 's':
case 'q':
{
if (!pResult->IsIdentifier())
{
pError = CreateError(LITERAL("Identifier expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect an atom table
case 'x':
{
if (!pResult->IsAtomTable())
{
pError = CreateError(LITERAL("Atom table expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect a symbol table
case 'y':
{
if (!pResult->IsSymbolTable())
{
pError = CreateError(LITERAL("Symbol table expected"), pResult);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
break;
}
// We expect anything
case 'c':
case 'u':
case 'v':
break;
// We expect any number of anythings...
case '*':
break;
// Too many arguments
case '\0':
{
pError = CreateError(LITERAL("Too many arguments"), NULL);
pResult->Discard(this);
pEvalList->Discard(this);
return pError;
}
default:
ASSERT(FALSE);
}
// Add the result to the list
pEvalList->Append(*this, pResult);
pResult->Discard(this);
// Next validation sequence (note that *pValidation can never
// be '\0' because we return above if we find it)
if (*pValidation != '*')
pValidation++;
}
// Make sure we have enough arguments
if (*pValidation != '\0' && *pValidation != '*')
{
pError = CreateError(LITERAL("Insufficient arguments"), NULL);
pEvalList->Discard(this);
return pError;
}
// Return the evaluation list
return pEvalList;
}
ICCItem *fnApply (CEvalContext *pCtx, ICCItem *pArguments, DWORD dwData)
// fnApply
//
// Applies the given parameter list to the lambda expression
//
// (apply exp arg1 arg2 ... argn list)
{
CCodeChain *pCC = pCtx->pCC;
ICCItem *pArgs;
ICCItem *pResult;
ICCItem *pFunction;
ICCItem *pLast;
CCLinkedList *pList;
int i;
// Evaluate the arguments and validate them
pArgs = pCC->EvaluateArgs(pCtx, pArguments, CONSTLIT("v*"));
if (pArgs->IsError())
return pArgs;
// We better have at least two arguments
if (pArgs->GetCount() < 2)
{
pArgs->Discard(pCC);
return pCC->CreateError(CONSTLIT("apply needs a function and a list of arguments."), NULL);
}
// The last argument better be a list
pLast = pArgs->GetElement(pArgs->GetCount() - 1);
if (!pLast->IsList())
{
pArgs->Discard(pCC);
return pCC->CreateError(CONSTLIT("Last argument for apply must be a list."), NULL);
}
// The first argument is the function
pFunction = pArgs->Head(pCC);
// Create a new list to store the arguments in
pResult = pCC->CreateLinkedList();
if (pResult->IsError())
{
pArgs->Discard(pCC);
return pResult;
}
pList = (CCLinkedList *)pResult;
// Add each of the arguments except the last
for (i = 1; i < pArgs->GetCount() - 1; i++)
{
pList->Append(pCC, pArgs->GetElement(i), &pResult);
if (pResult->IsError())
{
pList->Discard(pCC);
pArgs->Discard(pCC);
return pResult;
}
pResult->Discard(pCC);
}
// Add each of the elements of the last list
for (i = 0; i < pLast->GetCount(); i++)
{
pList->Append(pCC, pLast->GetElement(i), &pResult);
if (pResult->IsError())
{
pList->Discard(pCC);
pArgs->Discard(pCC);
return pResult;
}
pResult->Discard(pCC);
}
// Set the literal flag to indicate that the arguments should
// not be evaluated.
pList->SetQuoted();
// Execute the function
if (pFunction->IsFunction())
pResult = pFunction->Execute(pCtx, pList);
else
pResult = pFunction->Reference();
pList->Discard(pCC);
// Done
pArgs->Discard(pCC);
return pResult;
}
ICCItem *CCodeChain::Eval (CEvalContext *pEvalCtx, ICCItem *pItem)
// Eval
//
// Evaluates the given item and returns a result
{
// Errors always evaluate to themselves
if (pItem->IsError())
return pItem->Reference();
// If this item is quoted, then return an unquoted item
if (pItem->IsQuoted())
{
// If this is a literal symbol table then we need to evaluate its
// values.
if (pItem->IsSymbolTable())
return EvalLiteralStruct(pEvalCtx, pItem);
// HACK: We clone the item so that when we try to modify a literal list we
// mody a copy instead of the original.
else
{
ICCItem *pResult = pItem->Clone(this);
pResult->ClearQuoted();
return pResult;
}
}
// Evaluate differently depending on whether or not
// this is an atom or a list. If it is an atom, either return
// the value or look up the atom in a symbol table. If the item
// is a list, try to evaluate as a function
else if (pItem->IsIdentifier())
return Lookup(pEvalCtx, pItem);
// If this is an expression (a list with multiple terms) then we
// try to evaluate it.
else if (pItem->IsExpression())
{
ICCItem *pFunctionName;
ICCItem *pFunction;
ICCItem *pArgs;
ICCItem *pResult;
// The first element of the list is the function
pFunctionName = pItem->Head(this);
// We must have a first element since this is a list (but not Nil)
ASSERT(pFunctionName);
// If this is an identifier, then look up the function
// in the global symbols
if (pFunctionName->IsIdentifier())
pFunction = LookupFunction(pEvalCtx, pFunctionName);
// Otherwise, evaluate it
else
pFunction = Eval(pEvalCtx, pFunctionName);
// If we get an error, return it
if (pFunction->IsError())
return pFunction;
// Make sure this is a function
if (!pFunction->IsFunction())
{
pFunction->Discard(this);
return CreateError(LITERAL("Function name expected"), pFunctionName);
}
// Get the arguments
pArgs = pItem->Tail(this);
// Do it
pResult = pFunction->Execute(pEvalCtx, pArgs);
// Handle error by appending the function call that failed
if (pResult->IsError())
{
CCString *pError = dynamic_cast<CCString *>(pResult);
if (pError)
{
CString sError = pError->GetValue();
if (!sError.IsBlank())
{
char *pPos = sError.GetASCIIZPointer() + sError.GetLength() - 1;
if (*pPos != '#')
{
sError.Append(strPatternSubst(CONSTLIT(" ### %s ###"), pItem->Print(this)));
pError->SetValue(sError);
}
}
}
}
// Done
pFunction->Discard(this);
pArgs->Discard(this);
return pResult;
}
// Anything else is a literal so we return it.
else
return pItem->Reference();
}