/**
* Guard a rule's previous context from being reused.
* <p>
* This routine will check whether a given parser rule needs to be rerun, or if
* we already have context that can be reused for this parse.
*/
public IncrementalParserRuleContext guardRule(IncrementalParserRuleContext parentCtx, int state, int ruleIndex)
{
// If we have no previous parse data, the rule needs to be run.
if (this.parseData == null)
{
return(null);
}
Console.WriteLine($"guardRule() state = {state.ToString()}, ruleIndex = {ruleIndex.ToString()}");
// See if we have seen this state before at this starting point.
IncrementalParserRuleContext existingCtx = this.parseData.tryGetContext(
parentCtx != null ? parentCtx.Depth() + 1 : 1, State, ruleIndex,
this._input.LT(1).TokenIndex);
// We haven't see it, so we need to rerun this rule.
if (existingCtx == null)
{
return(null);
}
// We have seen it, see if it was affected by the parse
if (this.parseData.ruleAffectedByTokenChanges(existingCtx))
{
return(null);
}
// Everything checked out, reuse the rule context - we add it to the
// parent context as enterRule would have;
if (this._ctx != null)
{
IncrementalParserRuleContext parent = (IncrementalParserRuleContext)this._ctx;
// add current context to parent if we have a parent
parent?.AddChild(existingCtx);
}
return(existingCtx);
}
private String getKeyFromContext(IncrementalParserRuleContext ctx)
{
return(getKey(ctx.Depth(), ctx.invokingState, ctx.RuleIndex, ctx.Start.TokenIndex));
}
