public AstNode Parse(CompilerContext context, IEnumerable <TokenAst> tokenStream)
{
_context = context;
Reset();
_input = tokenStream.GetEnumerator();
NextToken();
while (true)
{
if (_currentState == Data.FinalState)
{
AstNode result = _stack[0].Node;
_stack.Reset();
return(result);
}
if (_currentToken.Terminal.Category == TokenCategory.Error)
{
ReportScannerError();
return(null);
}
ActionRecord action = GetCurrentAction();
if (action == null)
{
ReportParserError();
return(null);
}
//TODO: perform conflict resolving
//if (action.HasConflict())
switch (action.ActionType)
{
case ParserActionType.Operator:
if (GetActionTypeForOperation(_currentToken) == ParserActionType.Shift)
{
goto case ParserActionType.Shift;
}
else
{
goto case ParserActionType.Reduce;
}
case ParserActionType.Shift:
ExecuteShiftAction(action);
break;
case ParserActionType.Reduce:
ExecuteReduceAction(action);
break;
}
}
}
private AstNode CreateNode(ActionRecord reduceAction, SourceSpan sourceSpan, AstNodeList childNodes)
{
NonTerminal nonTeminal = reduceAction.NonTerminal;
AstNode result;
AstNodeArgs args = new AstNodeArgs(nonTeminal, sourceSpan, childNodes);
Type defaultNodeType = _context.Compiler.Data.DefaultNodeType;
Type ntNodeType = nonTeminal.NodeType ?? defaultNodeType ?? typeof(AstNode);
bool isList = nonTeminal.IsSet(TermOptions.IsList);
if (isList && childNodes.Count > 1 && childNodes[0].Term == nonTeminal)
{
result = childNodes[0];
AstNode newChild = childNodes[childNodes.Count - 1];
newChild.Parent = result;
result.ChildNodes.Add(newChild);
return(result);
}
if (nonTeminal.IsSet(TermOptions.IsStarList) && childNodes.Count == 1)
{
childNodes = childNodes[0].ChildNodes;
}
if (!isList && !nonTeminal.IsSet(TermOptions.IsPunctuation) && childNodes.Count == 1)
{
Type childNodeType = childNodes[0].Term.NodeType ?? defaultNodeType ?? typeof(AstNode);
if (childNodeType == ntNodeType || childNodeType.IsSubclassOf(ntNodeType))
{
return(childNodes[0]);
}
}
result = null;
if (ntNodeType == typeof(AstNode))
{
result = new AstNode(args);
}
else
{
ConstructorInfo ctor = ntNodeType.GetConstructor(new Type[] { typeof(AstNodeArgs) });
if (ctor == null)
{
throw new Exception("Failed to located constructor: " + ntNodeType.ToString() + "(AstNodeArgs args)");
}
result = (AstNode)ctor.Invoke(new object[] { args });
}
return(result);
}
private void ExecuteReduceAction(ActionRecord action)
{
ParserState oldState = _currentState;
int popCnt = action.PopCount;
AstNodeList childNodes = new AstNodeList();
for (int i = 0; i < action.PopCount; i++)
{
AstNode child = _stack[_stack.Count - popCnt + i].Node;
if (!child.Term.IsSet(TermOptions.IsPunctuation))
{
childNodes.Add(child);
}
}
SourceSpan newNodeSpan;
if (popCnt == 0)
{
newNodeSpan = new SourceSpan(_currentToken.Location, 0);
}
else
{
SourceLocation firstPopLoc = _stack[_stack.Count - popCnt].Node.Location;
int lastPopEndPos = _stack[_stack.Count - 1].Node.Span.EndPos;
newNodeSpan = new SourceSpan(firstPopLoc, lastPopEndPos - firstPopLoc.Position);
_currentState = _stack[_stack.Count - popCnt].State;
_stack.Pop(popCnt);
}
AstNode node = CreateNode(action, newNodeSpan, childNodes);
_stack.Push(node, _currentState);
ActionRecord gotoAction;
if (_currentState.Actions.TryGetValue(action.NonTerminal.Key, out gotoAction))
{
_currentState = gotoAction.NewState;
}
else
{
throw new CompilerException(string.Format("Cannot find transition for input {0}; state: {1}, popped state: {2}",
action.NonTerminal, oldState, _currentState));
}
}
private ActionRecord GetCurrentAction()
{
ActionRecord action = null;
if (_currentToken.MatchByValue)
{
if (_currentState.Actions.TryGetValue(_currentToken.Text, out action))
{
return(action);
}
}
if (_currentToken.MatchByType && _currentState.Actions.TryGetValue(_currentToken.Terminal.Key, out action))
{
return(action);
}
return(null);
}
private AstNode CreateNode(ActionRecord reduceAction, SourceSpan sourceSpan, AstNodeList childNodes)
{
NonTerminal nonTeminal = reduceAction.NonTerminal;
AstNode result;
AstNodeArgs args = new AstNodeArgs(nonTeminal, sourceSpan, childNodes);
Type defaultNodeType = _context.Compiler.Data.DefaultNodeType;
Type ntNodeType = nonTeminal.NodeType ?? defaultNodeType ?? typeof(AstNode);
bool isList = nonTeminal.IsSet(TermOptions.IsList);
if (isList && childNodes.Count > 1 && childNodes[0].Term == nonTeminal)
{
result = childNodes[0];
AstNode newChild = childNodes[childNodes.Count - 1];
newChild.Parent = result;
result.ChildNodes.Add(newChild);
return result;
}
if (nonTeminal.IsSet(TermOptions.IsStarList) && childNodes.Count == 1)
{
childNodes = childNodes[0].ChildNodes;
}
if (!isList && !nonTeminal.IsSet(TermOptions.IsPunctuation) && childNodes.Count == 1)
{
Type childNodeType = childNodes[0].Term.NodeType ?? defaultNodeType ?? typeof(AstNode);
if (childNodeType == ntNodeType || childNodeType.IsSubclassOf(ntNodeType))
return childNodes[0];
}
result = null;
if (ntNodeType == typeof(AstNode))
{
result = new AstNode(args);
}
else
{
ConstructorInfo ctor = ntNodeType.GetConstructor(new Type[] { typeof(AstNodeArgs) });
if (ctor == null)
throw new Exception("Failed to located constructor: " + ntNodeType.ToString() + "(AstNodeArgs args)");
result = (AstNode)ctor.Invoke(new object[] { args });
}
return result;
}
private void ExecuteReduceAction(ActionRecord action)
{
ParserState oldState = _currentState;
int popCnt = action.PopCount;
AstNodeList childNodes = new AstNodeList();
for (int i = 0; i < action.PopCount; i++)
{
AstNode child = _stack[_stack.Count - popCnt + i].Node;
if (!child.Term.IsSet(TermOptions.IsPunctuation))
childNodes.Add(child);
}
SourceSpan newNodeSpan;
if (popCnt == 0)
{
newNodeSpan = new SourceSpan(_currentToken.Location, 0);
}
else
{
SourceLocation firstPopLoc = _stack[_stack.Count - popCnt].Node.Location;
int lastPopEndPos = _stack[_stack.Count - 1].Node.Span.EndPos;
newNodeSpan = new SourceSpan(firstPopLoc, lastPopEndPos - firstPopLoc.Position);
_currentState = _stack[_stack.Count - popCnt].State;
_stack.Pop(popCnt);
}
AstNode node = CreateNode(action, newNodeSpan, childNodes);
_stack.Push(node, _currentState);
ActionRecord gotoAction;
if (_currentState.Actions.TryGetValue(action.NonTerminal.Key, out gotoAction))
{
_currentState = gotoAction.NewState;
}
else
throw new CompilerException(string.Format("Cannot find transition for input {0}; state: {1}, popped state: {2}",
action.NonTerminal, oldState, _currentState));
}
private void ExecuteShiftAction(ActionRecord action)
{
_stack.Push(_currentToken, _currentState);
_currentState = action.NewState;
NextToken();
}
private void ExecuteShiftAction(ActionRecord action)
{
_stack.Push(_currentToken, _currentState);
_currentState = action.NewState;
NextToken();
}