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51 lines
1.3 KiB
51 lines
1.3 KiB
5 years ago
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package com.fr.third.antlr;
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/* ANTLR Translator Generator
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* Project led by Terence Parr at http://www.cs.usfca.edu
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* Software rights: http://www.antlr.org/license.html
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*/
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import com.fr.third.antlr.collections.AST;
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public abstract class ParseTree extends BaseAST {
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/** Walk parse tree and return requested number of derivation steps.
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* If steps <= 0, return node text. If steps == 1, return derivation
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* string at step.
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*/
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public String getLeftmostDerivationStep(int step) {
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if ( step<=0 ) {
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return toString();
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}
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StringBuffer buf = new StringBuffer(2000);
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getLeftmostDerivation(buf, step);
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return buf.toString();
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}
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public String getLeftmostDerivation(int maxSteps) {
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StringBuffer buf = new StringBuffer(2000);
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buf.append(" "+this.toString());
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buf.append('\n');
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for (int d=1; d<maxSteps; d++) {
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buf.append(" =>");
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buf.append(getLeftmostDerivationStep(d));
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buf.append('\n');
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}
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return buf.toString();
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}
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/** Get derivation and return how many you did (less than requested for
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* subtree roots.
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*/
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protected abstract int getLeftmostDerivation(StringBuffer buf, int step);
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// just satisfy BaseAST interface; unused as we manually create nodes
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public void initialize(int i, String s) {
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}
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public void initialize(AST ast) {
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}
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public void initialize(Token token) {
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}
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}
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