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