public override void Execute(ParsingContext context)
{
context.Status = ParserStatus.Error;
var grammar = context.Language.Grammar;
grammar.ReportParseError(context);
// Do not recover if we're already at EOF, or if we're in command line mode
if (context.CurrentParserInput.Term == grammar.Eof || context.Mode == ParseMode.CommandLine)
{
return;
}
//Try to recover from error
context.Status = ParserStatus.Recovering;
context.AddTrace(Resources.MsgTraceRecovering); // *** RECOVERING - searching for state with error shift ***
var recovered = TryRecoverFromError(context);
if (recovered)
{
context.AddTrace(Resources.MsgTraceRecoverSuccess); //add new trace entry
context.Status = ParserStatus.Parsing;
}
else
{
context.AddTrace(Resources.MsgTraceRecoverFailed);
context.Status = ParserStatus.Error;
}
}
//Completes reduce: pops child nodes from the stack and pushes result node into the stack
protected void CompleteReduce(ParsingContext context) {
var resultNode = context.CurrentParserInput;
var childCount = Production.RValues.Count;
//Pop stack
context.ParserStack.Pop(childCount);
//Copy comment block from first child; if comments precede child node, they precede the parent as well.
if (resultNode.ChildNodes.Count > 0)
resultNode.Comments = resultNode.ChildNodes[0].Comments;
//Inherit precedence and associativity, to cover a standard case: BinOp->+|-|*|/;
// BinOp node should inherit precedence from underlying operator symbol.
//TODO: this special case will be handled differently. A ToTerm method should be expanded to allow "combined" terms like "NOT LIKE".
// OLD COMMENT: A special case is SQL operator "NOT LIKE" which consists of 2 tokens. We therefore inherit "max" precedence from any children
if (Production.LValue.Flags.IsSet(TermFlags.InheritPrecedence))
InheritPrecedence(resultNode);
//Push new node into stack and move to new state
//First read the state from top of the stack
context.CurrentParserState = context.ParserStack.Top.State;
if (context.TracingEnabled)
context.AddTrace(Resources.MsgTracePoppedState, Production.LValue.Name);
#region comments on special case
//Special case: if a non-terminal is Transient (ex: BinOp), then result node is not this NonTerminal, but its its child (ex: symbol).
// Shift action will invoke OnShifting on actual term being shifted (symbol); we need to invoke Shifting even on NonTerminal itself
// - this would be more expected behavior in general. ImpliedPrecHint relies on this
#endregion
if (resultNode.Term != Production.LValue) //special case
Production.LValue.OnShifting(context.SharedParsingEventArgs);
// Shift to new state - execute shift over the non-terminal of the production.
var shift = context.CurrentParserState.Actions[Production.LValue];
// Execute shift to new state
shift.Execute(context);
//Invoke Reduce event
Production.LValue.OnReduced(context, Production, resultNode);
}
public override void Execute(ParsingContext context) {
context.Status = ParserStatus.Error;
var grammar = context.Language.Grammar;
grammar.ReportParseError(context);
// Do not recover if we're already at EOF, or if we're in command line mode
if (context.CurrentParserInput.Term == grammar.Eof || context.Mode == ParseMode.CommandLine)
return;
//Try to recover from error
context.Status = ParserStatus.Recovering;
context.AddTrace(Resources.MsgTraceRecovering); // *** RECOVERING - searching for state with error shift ***
var recovered = TryRecoverFromError(context);
if (recovered) {
context.AddTrace(Resources.MsgTraceRecoverSuccess); //add new trace entry
context.Status = ParserStatus.Parsing;
} else {
context.AddTrace(Resources.MsgTraceRecoverFailed);
context.Status = ParserStatus.Error;
}
}
public override void Execute(ParsingContext context)
{
var traceEnabled = context.TracingEnabled;
if (traceEnabled)
{
context.AddTrace("Conditional Parser Action.");
}
for (int i = 0; i < ConditionalEntries.Count; i++)
{
var ce = ConditionalEntries[i];
if (traceEnabled)
{
context.AddTrace(" Checking condition: " + ce.Description);
}
if (ce.Condition(context))
{
if (traceEnabled)
{
context.AddTrace(" Condition is TRUE, executing action: " + ce.Action.ToString());
}
ce.Action.Execute(context);
return;
}
}
//if no conditions matched, execute default action
if (DefaultAction == null)
{
context.AddParserError("Fatal parser error: no conditions matched in conditional parser action, and default action is null." +
" State: {0}", context.CurrentParserState.Name);
context.Parser.RecoverFromError();
return;
}
if (traceEnabled)
{
context.AddTrace(" All conditions failed, executing default action: " + DefaultAction.ToString());
}
DefaultAction.Execute(context);
} //method
public override void Execute(ParsingContext context) {
if (context.TracingEnabled)
context.AddTrace(Resources.MsgTraceExecCustomAction);
//States with DefaultAction do NOT read input, so we read it here
if (context.CurrentParserInput == null)
context.Parser.ReadInput();
// Remember old state and input; if they don't change after custom action - it is error, we may fall into an endless loop
var oldState = context.CurrentParserState;
var oldInput = context.CurrentParserInput;
ExecuteRef(context, this);
//Prevent from falling into an infinite loop
if (context.CurrentParserState == oldState && context.CurrentParserInput == oldInput) {
context.AddParserError(Resources.MsgErrorCustomActionDidNotAdvance);
context.Parser.RecoverFromError();
}
}//method
protected bool TryRecoverFromError(ParsingContext context)
{
var grammar = context.Language.Grammar;
var parser = context.Parser;
//1. We need to find a state in the stack that has a shift item based on error production (with error token),
// and error terminal is current. This state would have a shift action on error token.
ParserAction errorShiftAction = FindErrorShiftActionInStack(context);
if (errorShiftAction == null)
{
return(false); //we failed to recover
}
context.AddTrace(Resources.MsgTraceRecoverFoundState, context.CurrentParserState);
//2. Shift error token - execute shift action
context.AddTrace(Resources.MsgTraceRecoverShiftError, errorShiftAction);
errorShiftAction.Execute(context);
//4. Now we need to go along error production until the end, shifting tokens that CAN be shifted and ignoring others.
// We shift until we can reduce
context.AddTrace(Resources.MsgTraceRecoverShiftTillEnd);
while (true)
{
if (context.CurrentParserInput == null)
{
parser.ReadInput();
}
if (context.CurrentParserInput.Term == grammar.Eof)
{
return(false);
}
//Check if we can reduce
var nextAction = parser.GetNextAction();
if (nextAction == null)
{
parser.ReadInput();
continue;
}
if (nextAction is ReduceParserAction)
{
//We are reducing a fragment containing error - this is the end of recovery
//Clear all input token queues and buffered input, reset location back to input position token queues;
context.SetSourceLocation(context.CurrentParserInput.Span.Location);
//Reduce error production - it creates parent non-terminal that "hides" error inside
context.AddTrace(Resources.MsgTraceRecoverReducing);
context.AddTrace(Resources.MsgTraceRecoverAction, nextAction);
nextAction.Execute(context); //execute reduce
return(true); //we recovered
}
// If it is not reduce, simply execute it (it is most likely shift)
context.AddTrace(Resources.MsgTraceRecoverAction, nextAction);
nextAction.Execute(context); //shift input token
}
}//method
//Completes reduce: pops child nodes from the stack and pushes result node into the stack
protected void CompleteReduce(ParsingContext context)
{
var resultNode = context.CurrentParserInput;
var childCount = Production.RValues.Count;
//Pop stack
context.ParserStack.Pop(childCount);
//Copy comment block from first child; if comments precede child node, they precede the parent as well.
if (resultNode.ChildNodes.Count > 0)
{
resultNode.Comments = resultNode.ChildNodes[0].Comments;
}
//Inherit precedence and associativity, to cover a standard case: BinOp->+|-|*|/;
// BinOp node should inherit precedence from underlying operator symbol.
//TODO: this special case will be handled differently. A ToTerm method should be expanded to allow "combined" terms like "NOT LIKE".
// OLD COMMENT: A special case is SQL operator "NOT LIKE" which consists of 2 tokens. We therefore inherit "max" precedence from any children
if (Production.LValue.Flags.IsSet(TermFlags.InheritPrecedence))
{
InheritPrecedence(resultNode);
}
//Push new node into stack and move to new state
//First read the state from top of the stack
context.CurrentParserState = context.ParserStack.Top.State;
if (context.TracingEnabled)
{
context.AddTrace(Resources.MsgTracePoppedState, Production.LValue.Name);
}
#region comments on special case
//Special case: if a non-terminal is Transient (ex: BinOp), then result node is not this NonTerminal, but its its child (ex: symbol).
// Shift action will invoke OnShifting on actual term being shifted (symbol); we need to invoke Shifting even on NonTerminal itself
// - this would be more expected behavior in general. ImpliedPrecHint relies on this
#endregion
if (resultNode.Term != Production.LValue) //special case
{
Production.LValue.OnShifting(context.SharedParsingEventArgs);
}
// Shift to new state - execute shift over the non-terminal of the production.
var shift = context.CurrentParserState.Actions[Production.LValue];
// Execute shift to new state
shift.Execute(context);
//Invoke Reduce event
Production.LValue.OnReduced(context, Production, resultNode);
}
public override void Execute(ParsingContext context)
{
if (context.TracingEnabled)
{
context.AddTrace(Resources.MsgTraceExecCustomAction);
}
//States with DefaultAction do NOT read input, so we read it here
if (context.CurrentParserInput == null)
{
context.Parser.ReadInput();
}
// Remember old state and input; if they don't change after custom action - it is error, we may fall into an endless loop
var oldState = context.CurrentParserState;
var oldInput = context.CurrentParserInput;
ExecuteRef(context, this);
//Prevent from falling into an infinite loop
if (context.CurrentParserState == oldState && context.CurrentParserInput == oldInput)
{
context.AddParserError(Resources.MsgErrorCustomActionDidNotAdvance);
context.Parser.RecoverFromError();
}
}//method
protected bool TryRecoverFromError(ParsingContext context)
{
var grammar = context.Language.Grammar;
var parser = context.Parser;
//1. We need to find a state in the stack that has a shift item based on error production (with error token),
// and error terminal is current. This state would have a shift action on error token.
ParserAction errorShiftAction = FindErrorShiftActionInStack(context);
if (errorShiftAction == null) return false; //we failed to recover
context.AddTrace(Resources.MsgTraceRecoverFoundState, context.CurrentParserState);
//2. Shift error token - execute shift action
context.AddTrace(Resources.MsgTraceRecoverShiftError, errorShiftAction);
errorShiftAction.Execute(context);
//4. Now we need to go along error production until the end, shifting tokens that CAN be shifted and ignoring others.
// We shift until we can reduce
context.AddTrace(Resources.MsgTraceRecoverShiftTillEnd);
while (true) {
if (context.CurrentParserInput == null)
parser.ReadInput();
if (context.CurrentParserInput.Term == grammar.Eof)
return false;
//Check if we can reduce
var nextAction = parser.GetNextAction();
if (nextAction == null) {
parser.ReadInput();
continue;
}
if (nextAction is ReduceParserAction) {
//We are reducing a fragment containing error - this is the end of recovery
//Clear all input token queues and buffered input, reset location back to input position token queues;
context.SetSourceLocation(context.CurrentParserInput.Span.Location);
//Reduce error production - it creates parent non-terminal that "hides" error inside
context.AddTrace(Resources.MsgTraceRecoverReducing);
context.AddTrace(Resources.MsgTraceRecoverAction, nextAction);
nextAction.Execute(context); //execute reduce
return true; //we recovered
}
// If it is not reduce, simply execute it (it is most likely shift)
context.AddTrace(Resources.MsgTraceRecoverAction, nextAction);
nextAction.Execute(context); //shift input token
}
}
