| /* |
| * [The "BSD license"] |
| * Copyright (c) 2010 Terence Parr |
| * 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. |
| */ |
| package org.antlr.analysis; |
| |
| import org.antlr.misc.Utils; |
| |
| /** An NFA state, predicted alt, and syntactic/semantic context. |
| * The syntactic context is a pointer into the rule invocation |
| * chain used to arrive at the state. The semantic context is |
| * the unordered set semantic predicates encountered before reaching |
| * an NFA state. |
| */ |
| public class NFAConfiguration { |
| /** The NFA state associated with this configuration */ |
| public int state; |
| |
| /** What alt is predicted by this configuration */ |
| public int alt; |
| |
| /** What is the stack of rule invocations that got us to state? */ |
| public NFAContext context; |
| |
| /** The set of semantic predicates associated with this NFA |
| * configuration. The predicates were found on the way to |
| * the associated NFA state in this syntactic context. |
| * Set<AST>: track nodes in grammar containing the predicate |
| * for error messages and such (nice to know where the predicate |
| * came from in case of duplicates etc...). By using a set, |
| * the equals() method will correctly show {pred1,pred2} as equals() |
| * to {pred2,pred1}. |
| */ |
| public SemanticContext semanticContext = SemanticContext.EMPTY_SEMANTIC_CONTEXT; |
| |
| /** Indicate that this configuration has been resolved and no further |
| * DFA processing should occur with it. Essentially, this is used |
| * as an "ignore" bit so that upon a set of nondeterministic configurations |
| * such as (s|2) and (s|3), I can set (s|3) to resolved=true (and any |
| * other configuration associated with alt 3). |
| */ |
| protected boolean resolved; |
| |
| /** This bit is used to indicate a semantic predicate will be |
| * used to resolve the conflict. Method |
| * DFA.findNewDFAStatesAndAddDFATransitions will add edges for |
| * the predicates after it performs the reach operation. The |
| * nondeterminism resolver sets this when it finds a set of |
| * nondeterministic configurations (as it does for "resolved" field) |
| * that have enough predicates to resolve the conflit. |
| */ |
| protected boolean resolveWithPredicate; |
| |
| /** Lots of NFA states have only epsilon edges (1 or 2). We can |
| * safely consider only n>0 during closure. |
| */ |
| protected int numberEpsilonTransitionsEmanatingFromState; |
| |
| /** Indicates that the NFA state associated with this configuration |
| * has exactly one transition and it's an atom (not epsilon etc...). |
| */ |
| protected boolean singleAtomTransitionEmanating; |
| |
| //protected boolean addedDuringClosure = true; |
| |
| public NFAConfiguration(int state, |
| int alt, |
| NFAContext context, |
| SemanticContext semanticContext) |
| { |
| this.state = state; |
| this.alt = alt; |
| this.context = context; |
| this.semanticContext = semanticContext; |
| } |
| |
| /** An NFA configuration is equal to another if both have |
| * the same state, the predict the same alternative, and |
| * syntactic/semantic contexts are the same. I don't think |
| * the state|alt|ctx could be the same and have two different |
| * semantic contexts, but might as well define equals to be |
| * everything. |
| */ |
| public boolean equals(Object o) { |
| if ( o==null ) { |
| return false; |
| } |
| NFAConfiguration other = (NFAConfiguration)o; |
| return this.state==other.state && |
| this.alt==other.alt && |
| this.context.equals(other.context)&& |
| this.semanticContext.equals(other.semanticContext); |
| } |
| |
| public int hashCode() { |
| int h = state + alt + context.hashCode(); |
| return h; |
| } |
| |
| public String toString() { |
| return toString(true); |
| } |
| |
| public String toString(boolean showAlt) { |
| StringBuffer buf = new StringBuffer(); |
| buf.append(state); |
| if ( showAlt ) { |
| buf.append("|"); |
| buf.append(alt); |
| } |
| if ( context.parent!=null ) { |
| buf.append("|"); |
| buf.append(context); |
| } |
| if ( semanticContext!=null && |
| semanticContext!=SemanticContext.EMPTY_SEMANTIC_CONTEXT ) { |
| buf.append("|"); |
| String escQuote = Utils.replace(semanticContext.toString(), "\"", "\\\""); |
| buf.append(escQuote); |
| } |
| if ( resolved ) { |
| buf.append("|resolved"); |
| } |
| if ( resolveWithPredicate ) { |
| buf.append("|resolveWithPredicate"); |
| } |
| return buf.toString(); |
| } |
| } |