code: /**
   * Copyright (c) 2005, Regents of the University of California
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the University of California, Los Angeles nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Creation date: Nov 29, 2005
   */
  
  package avrora.test.sim;
  
  import avrora.core.Program;
  import avrora.core.SourceMapping;
  
  /**
   * @author Ben L. Titzer
   */
  abstract class TestExpr {
      public abstract int evaluate(StateAccessor access);
      public void set(StateAccessor access, int val) {
          // do nothing.
      }
  
      static class Index extends TestExpr {
          final String name;
          final TestExpr index;
          Index(String name, TestExpr i) {
              this.name = name;
              this.index = i;
          }
          public int evaluate(StateAccessor access) {
              int indv = index.evaluate(access);
              return access.getIndex(name, indv);
          }
          public String toString() {
              return name+"["+index+"]";
          }
          public void set(StateAccessor access, int val) {
              int indv = index.evaluate(access);
              access.setIndex(name, indv, val);
          }
      }
  
      static class Var extends TestExpr {
          final String name;
          Var(String name) {
              this.name = name;
          }
          public int evaluate(StateAccessor access) {
              return access.get(name);
          }
          public String toString() {
              return name;
          }
          public void set(StateAccessor access, int val) {
              access.set(name, val);
          }
      }
  
      static class Label extends TestExpr {
          String name;
  
          Label(String n) {
              name = n;
          }
  
          public int evaluate(StateAccessor access) {
              Program p = access.getProgram();
              SourceMapping smap = p.getSourceMapping();
              SourceMapping.Location l = smap.getLocation(name);
              if (l == null) throw new UnknownLabel(name);
              return l.lma_addr;
          }
  
          public String toString() {
              return name;
          }
      }
  
      static class Const extends TestExpr {
          int value;
  
          Const(int v) {
              value = v;
          }
  
          public int evaluate(StateAccessor access) {
              return value;
          }
  
          public String toString() {
              return Integer.toString(value);
          }
      }
  
      abstract static class BinOp extends TestExpr {
          TestExpr left, right;
          String op;
  
          BinOp(TestExpr l, TestExpr r, String o) {
              left = l;
              right = r;
              op = o;
          }
  
          public String toString() {
              return left + op + right;
          }
      }
  
      static class Add extends BinOp {
  
          Add(TestExpr l, TestExpr r) {
              super(l, r, "+");
          }
  
          public int evaluate(StateAccessor access) {
              int lval = left.evaluate(access);
              int rval = right.evaluate(access);
              return lval + rval;
          }
      }
  
      static class Subtract extends BinOp {
  
          Subtract(TestExpr l, TestExpr r) {
              super(l, r, "-");
          }
  
          public int evaluate(StateAccessor access) {
              int lval = left.evaluate(access);
              int rval = right.evaluate(access);
              return lval - rval;
          }
      }
  
      static class UnknownLabel extends RuntimeException {
          
          private static final long serialVersionUID = 1L;
          
          String name;
  
          UnknownLabel(String n) {
              name = n;
          }
      }
  }
  