internal void Reference(LabelScopeInfo block)
{
_references.Add(block);
if (HasDefinitions)
{
ValidateJump(block);
}
}
private LabelScopeInfo FirstDefinition()
{
LabelScopeInfo scope = _definitions as LabelScopeInfo;
if (scope != null)
{
return(scope);
}
return(((HashSet <LabelScopeInfo>)_definitions).First());
}
private void ValidateJump(LabelScopeInfo reference)
{
// look for a simple jump out
for (LabelScopeInfo j = reference; j != null; j = j.Parent)
{
if (DefinedIn(j))
{
// found it, jump is valid!
return;
}
if (j.Kind == LabelScopeKind.Filter)
{
break;
}
}
_acrossBlockJump = true;
if (HasMultipleDefinitions)
{
throw new InvalidOperationException(String.Format("Ambiguous jump {0}", _node.Name));
}
// We didn't find an outward jump. Look for a jump across blocks
LabelScopeInfo def = FirstDefinition();
LabelScopeInfo common = CommonNode(def, reference, b => b.Parent);
// Validate that we aren't jumping across a finally
for (LabelScopeInfo j = reference; j != common; j = j.Parent)
{
if (j.Kind == LabelScopeKind.Filter)
{
throw new InvalidOperationException("Control cannot leave filter test");
}
}
// Valdiate that we aren't jumping into a catch or an expression
for (LabelScopeInfo j = def; j != common; j = j.Parent)
{
if (!j.CanJumpInto)
{
if (j.Kind == LabelScopeKind.Expression)
{
throw new InvalidOperationException("Control cannot enter an expression");
}
else
{
throw new InvalidOperationException("Control cannot enter try");
}
}
}
}
private bool DefinedIn(LabelScopeInfo scope)
{
if (_definitions == scope)
{
return(true);
}
if (_definitions is HashSet <LabelScopeInfo> definitions)
{
return(definitions.Contains(scope));
}
return(false);
}
private void AddDefinition(LabelScopeInfo scope)
{
if (_definitions == null)
{
_definitions = scope;
}
else
{
if (!(_definitions is HashSet <LabelScopeInfo> set))
{
_definitions = set = new HashSet <LabelScopeInfo>()
{
(LabelScopeInfo)_definitions
};
}
set.Add(scope);
}
}
internal void Define(LabelScopeInfo block)
{
// Prevent the label from being shadowed, which enforces cleaner
// trees. Also we depend on this for simplicity (keeping only one
// active IL Label per LabelInfo)
for (LabelScopeInfo j = block; j != null; j = j.Parent)
{
if (j.ContainsTarget(_node))
{
throw new InvalidOperationException(String.Format("Label target already defined: {0}", _node.Name));
}
}
AddDefinition(block);
block.AddLabelInfo(_node, this);
// Once defined, validate all jumps
if (HasDefinitions && !HasMultipleDefinitions)
{
foreach (var r in _references)
{
ValidateJump(r);
}
}
else
{
// Was just redefined, if we had any across block jumps, they're
// now invalid
if (_acrossBlockJump)
{
throw new InvalidOperationException("Ambiguous jump");
}
// For local jumps, we need a new IL label
// This is okay because:
// 1. no across block jumps have been made or will be made
// 2. we don't allow the label to be shadowed
_label = null;
}
}
internal LabelScopeInfo(LabelScopeInfo parent, LabelScopeKind kind)
{
Parent = parent;
Kind = kind;
}