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108 lines
2.7 KiB
108 lines
2.7 KiB
/*
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* @(#)IdentificationTable.java 2.1 2003/10/07
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*
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* Copyright (C) 1999, 2003 D.A. Watt and D.F. Brown
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* Dept. of Computing Science, University of Glasgow, Glasgow G12 8QQ Scotland
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* and School of Computer and Math Sciences, The Robert Gordon University,
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* St. Andrew Street, Aberdeen AB25 1HG, Scotland.
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* All rights reserved.
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*
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* This software is provided free for educational use only. It may
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* not be used for commercial purposes without the prior written permission
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* of the authors.
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*/
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package Triangle.ContextualAnalyzer;
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import Triangle.AbstractSyntaxTrees.Declaration;
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public final class IdentificationTable {
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private int level;
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private IdEntry latest;
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public IdentificationTable() {
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level = 0;
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latest = null;
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}
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// Opens a new level in the identification table, 1 higher than the
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// current topmost level.
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public void openScope() {
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level++;
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}
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// Closes the topmost level in the identification table, discarding
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// all entries belonging to that level.
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public void closeScope() {
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IdEntry entry, local;
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// Presumably, idTable.level > 0.
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entry = this.latest;
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while (entry.level == this.level) {
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local = entry;
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entry = local.previous;
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}
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this.level--;
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this.latest = entry;
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}
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// Makes a new entry in the identification table for the given identifier
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// and attribute. The new entry belongs to the current level.
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// duplicated is set to to true iff there is already an entry for the
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// same identifier at the current level.
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public void enter(String id, Declaration attr) {
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IdEntry entry = this.latest;
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boolean present = false, searching = true;
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// Check for duplicate entry ...
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while (searching) {
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if (entry == null || entry.level < this.level)
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searching = false;
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else if (entry.id.equals(id)) {
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present = true;
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searching = false;
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} else
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entry = entry.previous;
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}
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attr.duplicated = present;
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// Add new entry ...
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entry = new IdEntry(id, attr, this.level, this.latest);
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this.latest = entry;
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}
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// Finds an entry for the given identifier in the identification table,
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// if any. If there are several entries for that identifier, finds the
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// entry at the highest level, in accordance with the scope rules.
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// Returns null iff no entry is found.
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// otherwise returns the attribute field of the entry found.
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public Declaration retrieve(String id) {
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IdEntry entry;
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Declaration attr = null;
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boolean present = false, searching = true;
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entry = this.latest;
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while (searching) {
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if (entry == null)
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searching = false;
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else if (entry.id.equals(id)) {
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present = true;
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searching = false;
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attr = entry.attr;
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} else
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entry = entry.previous;
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}
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return attr;
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}
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}
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