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/** Support functions for traversing cyclic DFA states as laid
* out in static initialized structures by the code generator.
*
* A DFA implemented as a set of transition tables.
*
* Any state that has a semantic predicate edge is special; those states
* are generated with if-then-else structures in a ->specialStateTransition()
* which is generated by cyclicDFA template.
*
* There are at most 32767 states (16-bit signed short).
* Could get away with byte sometimes but would have to generate different
* types and the simulation code too. For a point of reference, the Java
* lexer's Tokens rule DFA has 326 states roughly.
*/
// [The "BSD licence"]
// Copyright (c) 2005-2009 Jim Idle, Temporal Wave LLC
// http://www.temporal-wave.com
// http://www.linkedin.com/in/jimidle
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. The name of the author may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <antlr3defs.h>
#include <antlr3cyclicdfa.h>
#ifdef ANTLR3_WINDOWS
#pragma warning( disable : 4100 )
#endif
static void
noViableAlt(pANTLR3_BASE_RECOGNIZER rec, pANTLR3_CYCLIC_DFA cdfa, ANTLR3_UINT32 s)
{
// In backtracking mode, we just set the failed flag so that the
// alt can just exit right now. If we are parsing though, then
// we want the exception to be raised.
//
if (rec->state->backtracking > 0)
{
rec->state->failed = ANTLR3_TRUE;
}
else
{
rec->exConstruct(rec);
rec->state->exception->type = ANTLR3_NO_VIABLE_ALT_EXCEPTION;
rec->state->exception->message = cdfa->description;
rec->state->exception->decisionNum = cdfa->decisionNumber;
rec->state->exception->state = s;
}
}
/** From the input stream, predict what alternative will succeed
* using this DFA (representing the covering regular approximation
* to the underlying CFL). Return an alternative number 1..n. Throw
* an exception upon error.
*/
ANTLR3_API ANTLR3_INT32
antlr3dfapredict (void * ctx, pANTLR3_BASE_RECOGNIZER rec, pANTLR3_INT_STREAM is, pANTLR3_CYCLIC_DFA cdfa)
{
ANTLR3_MARKER mark;
ANTLR3_INT32 s;
ANTLR3_INT32 specialState;
ANTLR3_INT32 c;
mark = is->mark(is); /* Store where we are right now */
s = 0; /* Always start with state 0 */
for (;;)
{
/* Pick out any special state entry for this state
*/
specialState = cdfa->special[s];
/* Transition the special state and consume an input token
*/
if (specialState >= 0)
{
s = cdfa->specialStateTransition(ctx, rec, is, cdfa, specialState);
// Error?
//
if (s<0)
{
// If the predicate/rule raised an exception then we leave it
// in tact, else we have an NVA.
//
if (rec->state->error != ANTLR3_TRUE)
{
noViableAlt(rec,cdfa, s);
}
is->rewind(is, mark);
return 0;
}
is->consume(is);
continue;
}
/* Accept state?
*/
if (cdfa->accept[s] >= 1)
{
is->rewind(is, mark);
return cdfa->accept[s];
}
/* Look for a normal transition state based upon the input token element
*/
c = is->_LA(is, 1);
/* Check against min and max for this state
*/
if (c>= cdfa->min[s] && c <= cdfa->max[s])
{
ANTLR3_INT32 snext;
/* What is the next state?
*/
snext = cdfa->transition[s][c - cdfa->min[s]];
if (snext < 0)
{
/* Was in range but not a normal transition
* must check EOT, which is like the else clause.
* eot[s]>=0 indicates that an EOT edge goes to another
* state.
*/
if (cdfa->eot[s] >= 0)
{
s = cdfa->eot[s];
is->consume(is);
continue;
}
noViableAlt(rec,cdfa, s);
is->rewind(is, mark);
return 0;
}
/* New current state - move to it
*/
s = snext;
is->consume(is);
continue;
}
/* EOT Transition?
*/
if (cdfa->eot[s] >= 0)
{
s = cdfa->eot[s];
is->consume(is);
continue;
}
/* EOF transition to accept state?
*/
if ( c == ANTLR3_TOKEN_EOF && cdfa->eof[s] >= 0)
{
is->rewind(is, mark);
return cdfa->accept[cdfa->eof[s]];
}
/* No alt, so bomb
*/
noViableAlt(rec, cdfa, s);
is->rewind(is, mark);
return 0;
}
}
/** Default special state implementation
*/
ANTLR3_API ANTLR3_INT32
antlr3dfaspecialStateTransition (void * ctx, pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, pANTLR3_CYCLIC_DFA dfa, ANTLR3_INT32 s)
{
return -1;
}
/* Default special transition implementation
*/
ANTLR3_API ANTLR3_INT32
antlr3dfaspecialTransition (void * ctx, pANTLR3_BASE_RECOGNIZER recognizer, pANTLR3_INT_STREAM is, pANTLR3_CYCLIC_DFA dfa, ANTLR3_INT32 s)
{
return 0;
}
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