public VariableId RegisterVariableForcedReDeclaration(AType type, string name, Token throwToken)
{
if (this.idsByVar.ContainsKey(name))
{
throw new ParserException(throwToken, "This variable has already been used in this scope.");
}
VariableId varId = new VariableId(type, name);
this.idsByVar[name] = varId;
this.rootScope.usedVariableNames.Add(name);
this.variableToUseIfNotFoundInDirectParent[name] = varId;
this.rootScope.rootScopeOrder.Add(varId);
return(varId);
}
public VariableId RegisterVariable(AType type, string name, bool allowSameScopeCollisions)
{
// Before anything else, check to see if this is coming from the closure.
VariableScope closureWalker = this.closureScope;
while (closureWalker != null)
{
VariableId closureVarId;
if (closureWalker.idsByVar.TryGetValue(name, out closureVarId))
{
MarkVarAsClosureVarThroughParentChain(this, closureWalker, closureVarId);
return(closureVarId);
}
closureWalker = closureWalker.closureScope;
}
VariableId varId;
// Check if variable is already declared in this or a parent scope already.
if (rootScope.usedVariableNames.Contains(name))
{
// The above if statement is a quick check to see if variable used before, anywhere,
// even if in a parallel branch. This will prevent many unnecessary walks up the parent chain.
// Variable is already known by this scope. Nothing to do.
if (this.idsByVar.TryGetValue(name, out varId))
{
return(varId);
}
if (this.variableToUseIfNotFoundInDirectParent.TryGetValue(name, out varId))
{
return(varId);
}
// Check to see if this variable was used by this or any parent scope.
VariableScope walker = this.parentScope;
while (walker != null)
{
if (walker.idsByVar.TryGetValue(name, out varId))
{
// cache this value in the current scope to make the lookup faster in the future
this.idsByVar[name] = varId;
return(varId);
}
walker = walker.parentScope;
}
// Do it again but using the fuzzy fallback
walker = this;
while (walker != null)
{
if (walker.variableToUseIfNotFoundInDirectParent.ContainsKey(name))
{
varId = walker.variableToUseIfNotFoundInDirectParent[name];
this.idsByVar[name] = varId;
return(varId);
}
}
// This should not happen.
#if DEBUG
throw new System.InvalidOperationException("Couldn't find variable declaration: " + name);
#endif
}
// Variable has never been used anywhere. Create a new one and put it in the root bookkeeping.
varId = new VariableId(type, name);
this.variableToUseIfNotFoundInDirectParent.Add(name, varId);
this.idsByVar[name] = varId;
this.rootScope.usedVariableNames.Add(name);
this.rootScope.rootScopeOrder.Add(varId);
return(varId);
}
private void MarkVarAsClosureVarThroughParentChain(VariableScope fromScope, VariableScope toScope, VariableId varId)
{
if (!varId.UsedByClosure)
{
varId.ClosureID = fromScope.closureRootScope.closureIdAlloc++;
varId.UsedByClosure = true;
}
do
{
fromScope.idsByVar[varId.Name] = varId;
fromScope = fromScope.closureScope;
} while (fromScope != toScope);
}