public ILocalBuilder PushInnerLocal([NotNull] IRoutineBuilder rb, [NotNull] ZilAtom atom,
LocalBindingType reason, ISourceLine src)
{
if (Locals.TryGetValue(atom, out var prev))
{
// save the old binding
if (OuterLocals.TryGetValue(atom, out var stk) == false)
{
stk = new Stack <LocalBindingRecord>();
OuterLocals.Add(atom, stk);
}
stk.Push(prev);
}
ILocalBuilder result;
if (SpareLocals.Count > 0)
{
// reuse a spare variable
result = SpareLocals.Pop();
}
else
{
// allocate a new variable with a unique name
var tempName = MakeUniqueVariableName(atom);
try
{
result = rb.DefineLocal(tempName.Text);
}
catch (InvalidOperationException)
{
throw new CompilerError(CompilerMessages.Expression_Needs_Temporary_Variables_Not_Allowed_Here);
}
TempLocalNames.Add(tempName);
}
var lbr = new LocalBindingRecord(reason, src, atom.Text, result);
Locals[atom] = lbr;
AllLocalBindingRecords.Add(lbr);
return(result);
}
void BuildRoutine([NotNull] ZilRoutine routine, [NotNull] IRoutineBuilder rb, bool entryPoint, bool traceRoutines)
{
// give the user a chance to rewrite the routine
routine = MaybeRewriteRoutine(Context, routine);
// set up arguments and locals
ClearLocalsAndBlocks();
if (Context.TraceRoutines)
{
rb.EmitPrint("[" + routine.Name, false);
}
DefineLocalsFromArgSpec();
if (Context.TraceRoutines)
{
rb.EmitPrint("]\n", false);
}
// define a block for the routine
Blocks.Clear();
Blocks.Push(new Block
{
Name = routine.ActivationAtom,
AgainLabel = rb.RoutineStart,
ReturnLabel = null,
Flags = BlockFlags.None
});
// generate code for routine body
int i = 1;
foreach (var stmt in routine.Body)
{
// only want the result of the last statement
// and we never want results in the entry routine, since it can't return
CompileStmt(rb, stmt, !entryPoint && i == routine.BodyLength);
i++;
}
// the entry point has to quit instead of returning
if (entryPoint)
{
rb.EmitQuit();
}
// clean up
WarnAboutUnusedLocals();
ClearLocalsAndBlocks();
// helpers
void DefineLocalsFromArgSpec()
{
foreach (var arg in routine.ArgSpec)
{
var originalArgName = arg.Atom;
var uniqueArgName = MakeUniqueVariableName(originalArgName);
if (uniqueArgName != originalArgName)
{
/* When a parameter has to be renamed because of a conflict, use TempLocalNames
* to reserve the new name so we don't collide with it later. For example:
*
* <GLOBAL FOO <>>
* <ROUTINE BLAH (FOO)
* <PROG ((FOO)) ...>>
*
* We rename the local variable to FOO?1 to avoid shadowing the global.
* Now the temporary variable bound by the PROG has to be FOO?2.
* ZIL code only sees the name FOO: the local is shadowed inside the PROG,
* and the global can always be accessed with SETG and GVAL.
*/
TempLocalNames.Add(uniqueArgName);
}
var lb = MakeLocalBuilder(arg, uniqueArgName.Text);
if (traceRoutines && arg.Type == ArgItem.ArgType.Required)
{
// TODO: print OPT parameters when tracing routine execution too
rb.EmitPrint(" " + originalArgName + "=", false);
rb.EmitPrint(PrintOp.Number, lb);
}
var lbr = new LocalBindingRecord(arg.Type.ToLocalBindingType(), routine.SourceLine, originalArgName.Text, lb);
Locals.Add(originalArgName, lbr);
AllLocalBindingRecords.Add(lbr);
SetOrEmitDefaultValue(lb, arg);
}
}
ILocalBuilder MakeLocalBuilder(ArgItem arg, string uniqueArgName)
{
ILocalBuilder lb;
switch (arg.Type)
{
case ArgItem.ArgType.Required:
try
{
lb = rb.DefineRequiredParameter(uniqueArgName);
}
catch (InvalidOperationException)
{
throw new CompilerError(
CompilerMessages.Expression_Needs_Temporary_Variables_Not_Allowed_Here);
}
break;
case ArgItem.ArgType.Optional:
lb = rb.DefineOptionalParameter(uniqueArgName);
break;
case ArgItem.ArgType.Auxiliary:
lb = rb.DefineLocal(uniqueArgName);
break;
default:
throw UnhandledCaseException.FromEnum(arg.Type);
}
return(lb);
}
void SetOrEmitDefaultValue(ILocalBuilder lb, ArgItem arg)
{
if (arg.DefaultValue == null)
{
return;
}
Debug.Assert(arg.Type == ArgItem.ArgType.Optional || arg.Type == ArgItem.ArgType.Auxiliary);
// setting any default value counts as a write
MarkVariableAsWritten(lb);
lb.DefaultValue = CompileConstant(arg.DefaultValue);
if (lb.DefaultValue != null)
{
return;
}
ILabel nextLabel = null;
// ReSharper disable once SwitchStatementMissingSomeCases
switch (arg.Type)
{
case ArgItem.ArgType.Optional when !rb.HasArgCount:
// not a constant
throw new CompilerError(routine.SourceLine,
CompilerMessages.Optional_Args_With_Nonconstant_Defaults_Not_Supported_For_This_Target);
case ArgItem.ArgType.Optional:
nextLabel = rb.DefineLabel();
rb.Branch(Condition.ArgProvided, lb, null, nextLabel, true);
goto default;
default:
var val = CompileAsOperand(rb, arg.DefaultValue, routine.SourceLine, lb);
if (val != lb)
{
rb.EmitStore(lb, val);
}
break;
}
if (nextLabel != null)
{
rb.MarkLabel(nextLabel);
}
}
void WarnAboutUnusedLocals()
{
foreach (var lbr in AllLocalBindingRecords)
{
if (lbr.IsEverRead || lbr.IsEverWritten)
{
continue;
}
if (lbr.Type == LocalBindingType.CompilerTemporary)
{
continue;
}
//XXX not sure about this
if (lbr.Type == LocalBindingType.RoutineRequired)
{
continue;
}
var warning = new CompilerError(
lbr.Definition,
CompilerMessages.Local_Variable_0_Is_Never_Used,
lbr.BoundName);
Context.HandleError(warning);
}
}
}
public void MarkVariableAsReadAndWritten([NotNull] LocalBindingRecord lbr) => lbr.IsEverRead = lbr.IsEverWritten = true;
public void MarkVariableAsRead([NotNull] LocalBindingRecord lbr) => lbr.IsEverRead = true;