public Loop(BoundedLoopContext blc, ZilAtom atom, ZilObject start, ZilObject end, ZilObject inc)
: base(blc)
{
this.atom = atom;
this.start = start;
this.end = end;
this.inc = inc;
}
public IBoundedLoop MakeLoop(BoundedLoopContext blc)
{
if (!blc.spec.HasLength(3, 4))
{
throw new CompilerError(
blc.src,
CompilerMessages._0_Expected_1_Element1s_In_Binding_List,
Name,
new CountableString("3 or 4", true));
}
if (!blc.spec.Matches(out ZilAtom atom, out ZilObject start, out ZilObject end, out ZilObject inc) &&
!blc.spec.Matches(out atom, out start, out end))
{
throw new CompilerError(
blc.src,
CompilerMessages._0_1_Element_In_Binding_List_Must_Be_2,
Name,
"first",
"an atom");
}
return(new Loop(blc, atom, start, end, inc));
}
private IOperand CompileBoundedLoop(
[NotNull] IRoutineBuilder rb, [NotNull] IBoundedLoopBuilder builder,
[NotNull] ZilListoidBase args, [NotNull] ISourceLine src,
bool wantResult, [CanBeNull] IVariable resultStorage)
{
// extract loop spec ("binding list", although we don't care about the bindings here)
// TODO: allow activation atoms in bounded loops?
if (!args.IsCons(out var first, out var rest) || !(first is ZilList spec))
{
throw new CompilerError(CompilerMessages.Expected_Binding_List_At_Start_Of_0, builder.Name);
}
// instantiate the loop and let it check binding syntax
var blc = new BoundedLoopContext(this, spec, src);
using (var loop = builder.MakeLoop(blc))
{
// look for the optional end statements
ZilListoidBase body;
if (rest.StartsWith(out ZilList endStmts))
{
(_, body) = rest;
}
else
{
body = rest;
}
// create block
resultStorage = wantResult ? (resultStorage ?? rb.Stack) : null;
var block = new Block
{
AgainLabel = rb.DefineLabel(),
ResultStorage = resultStorage,
ReturnLabel = rb.DefineLabel(),
Flags = wantResult ? BlockFlags.WantResult : 0
};
Blocks.Push(block);
try
{
var exhaustedLabel = rb.DefineLabel();
// let the loop initialize counters, etc.
loop.BeforeBlock(rb, block, exhaustedLabel);
// mark the top of the block ("again" label) and let the loop add prechecks, etc.
rb.MarkLabel(block.AgainLabel);
loop.BeforeBody();
// compile the body
CompileClauseBody(rb, body, false, null);
// let the loop add postchecks, etc., and mark the end of the block ("exhausted" label)
loop.AfterBody();
rb.MarkLabel(exhaustedLabel);
// compile the end statements if present, and provide a return value if requested
if (endStmts != null)
{
CompileClauseBody(rb, endStmts, false, null);
}
if (wantResult)
{
rb.EmitStore(resultStorage, Game.One);
}
// if <RETURN> was used inside the loop, mark the return label
if ((block.Flags & BlockFlags.Returned) != 0)
{
rb.MarkLabel(block.ReturnLabel);
}
}
finally
{
Blocks.Pop();
}
return(wantResult ? resultStorage : null);
}
}
protected BoundedLoop(BoundedLoopContext blc)
{
this.blc = blc;
}
