/** This code is factored out from mismatched token and mismatched set
* recovery. It handles "single token insertion" error recovery for
* both. No tokens are consumed to recover from insertions. Return
* true if recovery was possible else return false.
*/
static ANTLR3_BOOLEAN
recoverFromMismatchedElement (pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_BITSET follow)
{
pANTLR3_BITSET viableToksFollowingRule;
pANTLR3_BITSET newFollow;
pANTLR3_PARSER parser;
pANTLR3_TREE_PARSER tparser;
pANTLR3_INT_STREAM is;
switch (recognizer->type)
{
case ANTLR3_TYPE_PARSER:
parser = (pANTLR3_PARSER) (recognizer->super);
tparser = NULL;
is = parser->tstream->istream;
break;
case ANTLR3_TYPE_TREE_PARSER:
tparser = (pANTLR3_TREE_PARSER) (recognizer->super);
parser = NULL;
is = tparser->ctnstream->tnstream->istream;
break;
default:
fprintf(stderr, "Base recognizerfunction recover called by unknown paresr type - provide override for this function\n");
return ANTLR3_FALSE;
break;
}
newFollow = NULL;
if (follow == NULL)
{
/* The follow set is NULL, which means we don't know what can come
* next, so we "hit and hope" by just signifying that we cannot
* recover, which will just cause the next token to be consumed,
* which might dig us out.
*/
return ANTLR3_FALSE;
}
/* We have a bitmap for the follow set, hence we can compute
* what can follow this grammar element reference.
*/
if (follow->isMember(follow, ANTLR3_EOR_TOKEN_TYPE) == ANTLR3_TRUE)
{
/* First we need to know which of the available tokens are viable
* to follow this reference.
*/
viableToksFollowingRule = recognizer->computeCSRuleFollow(recognizer);
/* Knowing that, we can or in the follow set
*/
newFollow = follow->or(follow, viableToksFollowingRule);
/* Remove the EOR token, which we do not wish to compute with
*/
newFollow->remove(follow, ANTLR3_EOR_TOKEN_TYPE);
viableToksFollowingRule->free(viableToksFollowingRule);
/* We now have the computed set of what can follow the current token
*/
follow = newFollow;
}
/* We can now see if the current token works with the set of tokens
* that could follow the current grammar reference. If it looks like it
* is consistent, then we can "insert" that token by not throwing
* an exception and assumimng that we saw it.
*/
if ( follow->isMember(follow, is->_LA(is, 1)) == ANTLR3_TRUE)
{
/* report the error, but don't cause any rules to abort and stuff
*/
recognizer->reportError(recognizer);
if (newFollow != NULL)
{
newFollow->free(newFollow);
}
recognizer->error = ANTLR3_FALSE;
recognizer->failed = ANTLR3_FALSE;
return ANTLR3_TRUE; /* Success in recovery */
}
if (newFollow != NULL)
{
newFollow->free(newFollow);
}
/* We could not find anything viable to do, so this is going to
* cause an exception.
*/
return ANTLR3_FALSE;
}
