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Diffstat (limited to 'antlr-3.4/runtime/C/src/antlr3cyclicdfa.c')
| -rw-r--r-- | antlr-3.4/runtime/C/src/antlr3cyclicdfa.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/antlr-3.4/runtime/C/src/antlr3cyclicdfa.c b/antlr-3.4/runtime/C/src/antlr3cyclicdfa.c new file mode 100644 index 0000000..82e7222 --- /dev/null +++ b/antlr-3.4/runtime/C/src/antlr3cyclicdfa.c @@ -0,0 +1,204 @@ +/** 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; +} |