public bool Validate(List <Flag> flags, CancellationToken cancel, bool isCompilerAction = false)
{
if (myComprData != null && myComprData.Depth > MaxDepth)
{
var flag = new Flag(
SeverityKind.Error,
AST.Node,
Constants.BadSyntax.ToString(
string.Format("Comprehension nesting too deep. Maximum nesting depth is {0}.", MaxDepth)),
Constants.BadSyntax.Code);
flags.Add(flag);
return(RecordValidationResult(false));
}
IEnumerable <Node> heads = null;
IEnumerable <Body> bodies = null;
switch (AST.Node.NodeKind)
{
case NodeKind.Compr:
heads = ((Compr)AST.Node).Heads;
bodies = ((Compr)AST.Node).Bodies;
break;
case NodeKind.Rule:
heads = ((Rule)AST.Node).Heads;
bodies = ((Rule)AST.Node).Bodies;
break;
default:
throw new NotImplementedException();
}
if (heads.IsEmpty <Node>())
{
var flag = new Flag(
SeverityKind.Error,
AST.Node,
Constants.BadSyntax.ToString("The expression has no heads."),
Constants.BadSyntax.Code);
flags.Add(flag);
return(RecordValidationResult(false));
}
//// Step 1.a. If the body is empty, treat it like a TRUE body.
var result = true;
if (bodies.IsEmpty <Body>())
{
bodies = EnumerableMethods.GetEnumerable <Body>(MkTrueBody(heads.First <Node>().Span));
}
//// Step 1.b. Otherwise, find all the variables (possibly) with selectors
//// occurring in all the heads. These will be registered with the bodies.
var varList = new LinkedList <Id>();
foreach (var h in heads)
{
FindVarLikeIds(h, varList);
}
//// Step 2. Expand heads / bodies.
Term type;
TypeEnvironment bodyEnv;
foreach (var b in bodies)
{
bodyEnv = TypeEnvironment.AddChild(b);
var cs = new ConstraintSystem(Index, b, bodyEnv, myComprData);
if (!cs.Validate(flags, varList, cancel))
{
result = false;
continue;
}
foreach (var v in cs.Variables)
{
if (cs.TryGetType(v, out type))
{
bodyEnv.SetType(v, type);
}
}
foreach (var h in heads)
{
var act = new Action(h, cs, TypeEnvironment, myComprData, AST.Node);
if (act.Validate(flags, cancel, isCompilerAction))
{
actions.AddLast(act);
}
else
{
result = false;
}
if (cancel.IsCancellationRequested)
{
return(RecordValidationResult(false));
}
}
}
if (result && !cancel.IsCancellationRequested)
{
TypeEnvironment.JoinTypes();
Contract.Assert(AST.Node.CompilerData == null);
AST.Node.CompilerData = TypeEnvironment;
return(RecordValidationResult(true));
}
else
{
return(RecordValidationResult(false));
}
}
