/// Starts a subroutine block. For this, we create a separate symbol table
/// to supplement the main one.
ParseNode KSubFunc(SymClass klass, string methodName, SymFullType returnType)
{
ProcedureParseNode node = new ProcedureParseNode();
EnsureNoLabel();
// Add the name to the global scope, ensuring it hasn't already been
// defined.
if (methodName == null) {
IdentifierToken identToken = ExpectIdentifierToken();
if (identToken == null) {
SkipToEndOfLine();
return null;
}
methodName = identToken.Name;
}
Symbol method = _globalSymbols.Get(methodName);
if (method != null && method.Defined && !method.IsExternal) {
_messages.Error(MessageCode.SUBFUNCDEFINED, String.Format("{0} already defined", methodName));
SkipToEndOfLine();
return null;
}
// Reset the COMMON indexes for this program unit
foreach (Symbol sym in _globalSymbols) {
if (sym.Type == SymType.COMMON) {
sym.CommonIndex = 0;
}
}
// New local symbol table for this block
_localSymbols = new SymbolCollection("Local");
_hasReturn = false;
// Parameter list allowed for subroutines and functions, but
// not the main program.
Collection<Symbol> parameters = null;
int alternateReturnCount = 0;
switch (klass) {
case SymClass.PROGRAM:
parameters = new Collection<Symbol>();
klass = SymClass.SUBROUTINE;
methodName = _entryPointName;
break;
case SymClass.FUNCTION:
parameters = ParseParameterDecl(_localSymbols, SymScope.PARAMETER, out alternateReturnCount);
break;
case SymClass.SUBROUTINE:
parameters = ParseParameterDecl(_localSymbols, SymScope.PARAMETER, out alternateReturnCount);
if (alternateReturnCount > 0) {
returnType = new SymFullType(SymType.INTEGER);
}
break;
}
// Don't allow alternate returns for anything except subroutines
if (alternateReturnCount > 0 && klass != SymClass.SUBROUTINE) {
_messages.Error(MessageCode.ALTRETURNNOTALLOWED, "Alternate return only permitted for subroutines");
}
// Add this method to the global symbol table now.
if (method == null) {
method = _globalSymbols.Add(methodName, new SymFullType(), klass, null, _ls.LineNumber);
}
method.Parameters = parameters;
method.Defined = true;
method.Class = klass;
if (returnType.Type != SymType.NONE) {
method.FullType = returnType;
}
if (methodName == _entryPointName) {
method.Modifier |= SymModifier.ENTRYPOINT;
_hasProgram = true;
}
// Special case for functions. Create a local symbol with the same
// name to be used for the return value.
if (klass == SymClass.FUNCTION || alternateReturnCount > 0) {
method.RetVal = _localSymbols.Add(methodName, returnType, SymClass.VAR, null, _ls.LineNumber);
method.RetVal.Modifier = SymModifier.RETVAL;
}
node.ProcedureSymbol = method;
node.LocalSymbols = _localSymbols;
node.LabelList = new Collection<ParseNode>();
_currentProcedure = node;
_currentProcedure.AlternateReturnCount = alternateReturnCount;
_initList = new CollectionParseNode();
node.InitList = _initList;
// Compile the body of the procedure
SimpleToken token = _ls.GetKeyword();
while (token.ID != TokenID.ENDOFFILE) {
if (token.ID != TokenID.EOL) {
ParseNode labelNode = CheckLabel();
if (labelNode != null) {
node.Add(labelNode);
}
if (token.ID == TokenID.KEND) {
break;
}
ParseNode lineNode = Statement(token);
if (lineNode != null) {
node.Add(MarkLine());
node.Add(lineNode);
}
ExpectEndOfLine();
}
token = _ls.GetKeyword();
}
// If we hit the end of the file first then we're missing
// a mandatory END statement.
if (token.ID != TokenID.KEND) {
_messages.Error(MessageCode.MISSINGENDSTATEMENT, "Missing END statement");
}
// Make sure we have a RETURN statement.
if (!_hasReturn) {
node.Add(new ReturnParseNode());
}
// Validate the block.
foreach (Symbol sym in _localSymbols) {
if (sym.IsLabel && !sym.Defined) {
_messages.Error(MessageCode.UNDEFINEDLABEL, sym.RefLine, String.Format("Undefined label {0}", sym.Name));
}
if (_saveAll && sym.IsLocal) {
sym.Modifier |= SymModifier.STATIC;
}
// For non-array characters, if there's no value, set the empty string
if (sym.Type == SymType.FIXEDCHAR && !sym.IsArray && !sym.Value.HasValue) {
sym.Value = new Variant(string.Empty);
}
if (!sym.IsReferenced && !(sym.Modifier.HasFlag(SymModifier.RETVAL))) {
string scopeName = (sym.IsParameter) ? "parameter" : (sym.IsLabel) ? "label" : "variable";
_messages.Warning(MessageCode.UNUSEDVARIABLE,
3,
sym.RefLine,
String.Format("Unused {0} {1} in function", scopeName, sym.Name));
}
}
ValidateBlock(0, node);
_state = BlockState.SPECIFICATION;
return node;
}
// Internal generation logic for a subroutine or function call.
SymType InternalGenerate(CodeGenerator cg, SymClass callType, string callName)
{
Symbol sym = ProcName.Symbol;
SymType thisType = SymType.NONE;
if (!sym.Defined) {
cg.Error(sym.RefLine, String.Format("Undefined {0} {1}", callName, sym.Name));
}
if (sym.Class != callType) {
cg.Error(sym.RefLine, String.Format("{0} is not a {1}", sym.Name, callName));
}
Type[] paramTypes = Parameters.Generate(cg, sym);
if (sym.IsParameter) {
ProcName.Generate(cg);
cg.Emitter.CallIndirect(sym.Type, paramTypes);
thisType = sym.Type;
} else {
if (sym.Info != null) {
Debug.Assert(sym.Info is MethodInfo);
cg.Emitter.Call((MethodInfo)sym.Info);
thisType = sym.Type;
}
}
// Sanity check, make sure alternate return labels are only specified
// for subroutines.
if (AlternateReturnLabels.Count > 0 && sym.Class != SymClass.SUBROUTINE) {
throw new CodeGeneratorException("Codegen error: Alternate return labels only permitted for subroutines");
}
// Post-alternate return branching
if (AlternateReturnLabels.Count > 0) {
Label [] jumpTable = new Label[AlternateReturnLabels.Count];
for (int c = 0; c < AlternateReturnLabels.Count; ++c) {
Symbol symLabel = AlternateReturnLabels[c];
jumpTable[c] = (Label)symLabel.Info;
}
cg.Emitter.LoadInteger(1);
cg.Emitter.Sub(SymType.INTEGER);
cg.Emitter.Switch(jumpTable);
}
Parameters.FreeLocalDescriptors();
return thisType;
}
