org.antlr.analysis.Transition Maven / Gradle / Ivy
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* Copyright (c) 2010 Terence Parr
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package org.antlr.analysis;
/** A generic transition between any two state machine states. It defines
* some special labels that indicate things like epsilon transitions and
* that the label is actually a set of labels or a semantic predicate.
* This is a one way link. It emanates from a state (usually via a list of
* transitions) and has a label/target pair. I have abstracted the notion
* of a Label to handle the various kinds of things it can be.
*/
public class Transition implements Comparable {
/** What label must be consumed to transition to target */
public Label label;
/** The target of this transition */
public State target;
public Transition(Label label, State target) {
this.label = label;
this.target = target;
}
public Transition(int label, State target) {
this.label = new Label(label);
this.target = target;
}
public boolean isEpsilon() {
return label.isEpsilon();
}
public boolean isAction() {
return label.isAction();
}
public boolean isSemanticPredicate() {
return label.isSemanticPredicate();
}
@Override
public int hashCode() {
return label.hashCode() + target.stateNumber;
}
@Override
public boolean equals(Object o) {
Transition other = (Transition)o;
return this.label.equals(other.label) &&
this.target.equals(other.target);
}
@Override
public int compareTo(Transition other) {
return this.label.compareTo(other.label);
}
@Override
public String toString() {
return label+"->"+target.stateNumber;
}
}
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