persistence.antlr.ParseTreeRule Maven / Gradle / Ivy
package persistence.antlr;
/* ANTLR Translator Generator
* Project led by Terence Parr at http://www.jGuru.com
* Software rights: http://www.antlr.org/license.html
*/
import persistence.antlr.Token;
import persistence.antlr.collections.AST;
public class ParseTreeRule extends ParseTree {
public static final int INVALID_ALT = -1;
protected String ruleName;
protected int altNumber; // unused until I modify antlr to record this
public ParseTreeRule(String ruleName) {
this(ruleName,INVALID_ALT);
}
public ParseTreeRule(String ruleName, int altNumber) {
this.ruleName = ruleName;
this.altNumber = altNumber;
}
public String getRuleName() {
return ruleName;
}
/** Do a step-first walk, building up a buffer of tokens until
* you've reached a particular step and print out any rule subroots
* insteads of descending.
*/
protected int getLeftmostDerivation(StringBuffer buf, int step) {
int numReplacements = 0;
if ( step<=0 ) {
buf.append(' ');
buf.append(toString());
return numReplacements;
}
AST child = getFirstChild();
numReplacements = 1;
// walk child printing them out, descending into at most one
while ( child!=null ) {
if ( numReplacements>=step || child instanceof ParseTreeToken ) {
buf.append(' ');
buf.append(child.toString());
}
else {
// descend for at least one more derivation; update count
int remainingReplacements = step-numReplacements;
int n = ((ParseTree)child).getLeftmostDerivation(buf,
remainingReplacements);
numReplacements += n;
}
child = child.getNextSibling();
}
return numReplacements;
}
public String toString() {
if ( altNumber==INVALID_ALT ) {
return '<'+ruleName+'>';
}
else {
return '<'+ruleName+"["+altNumber+"]>";
}
}
}