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: Oct 4, 2005
   */
  
  package jintgen.jigir;
  
  import cck.parser.SourcePoint;
  import jintgen.isdl.parser.Token;
  import jintgen.types.*;
  
  /**
   * The <code>UnOp</code> inner class represents an operation on a single integer value. For example, the
   * bitwise complement and the negation of an integer are operations on a single integer that produce a
   * single integer result.
   */
  public class UnOpExpr extends Expr {
      /**
       * The <code>operation</code> field stores the string name of the operation being performed on the
       * expression. For example, '~' represents bitwise negation.
       */
      public final Token operation;
  
      /**
       * The <code>operand</code> field stores a reference to the expression operand of this operation.
       */
      public final Expr expr;
  
      /**
       * The <code>unop</code> field stores a reference to the actual unary operator implementation.
       */
      protected UnOpImpl unop;
  
      /**
       * The constructor of the <code>UnOp</code> class initializes the public final fields that form the
       * structure of this expression.
       *
       * @param op the string name of the operation
       * @param o  the operand of this operation
       */
      public UnOpExpr(Token op, Expr o) {
          expr = o;
          operation = op;
      }
  
      /**
       * The <code>isConstantExpr()</code> method tests whether this expression is a constant expression
       * (i.e. it is reducable to a constant and has no references to variables, maps, etc).
       *
       * @return true if this expression can be evaluated to a constant; false otherwise
       */
      public boolean isConstantExpr() {
          return expr.isConstantExpr();
      }
  
      /**
       * The <code>toString()</code> method recursively converts this expression to a string. For binary
       * operations, inner expressions will be nested within parentheses if their precedence is lower than
       * the precedence of the parent expression.
       *
       * @return a string representation of this expression
       */
      public String toString() {
          return operation + innerString(expr);
      }
  
      /**
       * The <code>getPrecedence()</code> method gets the binding precedence for this expression. This is
       * used to compute when inner expressions must be nested within parentheses in order to preserve the
       * implied order of evaluation.
       *
       * @return an integer representing the precedence of this expression; higher numbers are higher
       *         precedence
       */
      public int getPrecedence() {
          return PREC_UN;
      }
  
      /**
       * The <code>getSourcePoint()</code> method returns a reference to a <code>SourcePoint</code>
       * instance that represents the location in the source program of this expression.
       * @return a <code>SourcePoint</code> instance that represents this expression in the
       * source program
       */
      public SourcePoint getSourcePoint() {
          return operation.getSourcePoint();
      }
  
      public SourcePoint getSourceRange() {
          return new SourcePoint(operation.getSourcePoint(), expr.getSourcePoint());
      }
  
      /**
       * The <code>getUnOp()</code> method gets a reference to the unary operation implementation
       * associated with this syntax tree node.
       * @return a reference to the unary operator implementation corresponding to this node
       */
      public UnOpImpl getUnOp() {
          return unop;
      }
  
      /**
       * The <code>setUnOp()</code> method allows update of the unary operation implementation for
       * this syntax tree node. For example, during typechecking, it is necessary to resolve the
       * correct unary operation for a particular node, based on the types, e.g.
       * @param un the unary operator implementation
       */
      public void setUnOp(UnOpImpl un) {
          unop = un;
      }
  
      /**
       * The <code>accept()</code> method implements one half of the visitor pattern so that client visitors
       * can traverse the syntax tree easily and in an extensible way.
       *
       * @param v the visitor to accept
       */
      public void accept(CodeVisitor v) {
          v.visit(this);
      }
  
      /**
       * The <code>accept()</code> method implements one half of the visitor pattern for rebuilding of
       * expressions. This visitor allows code to be slightly modified while only writing visit methods for
       * the parts of the syntax tree affected.
       *
       * @param r the rebuilder to accept
       * @return the result of calling the appropriate <code>visit()</code> method of the rebuilder
       */
      public <Res, Env> Res accept(CodeAccumulator<Res, Env> r, Env env) {
          return r.visit(this, env);
      }
  
      /**
       * The <code>UnOpImpl</code> class represents a unary operation implementation. Descendants
       * of this class implement the functionality of an unary operator, including typechecking,
       * constant evaluation, etc.
       */
      public abstract static class UnOpImpl implements TypeCon.UnOp {
          public final String operation;
          public final int prec;
  
          protected UnOpImpl(String op, int p) {
              operation = op;
              prec = p;
          }
  
          public String getOperation() {
              return operation;
          }
  
          public abstract Literal evaluate(Literal inner);
          public abstract Type typeCheck(TypeEnv env, Typeable inner);
      }
  }
  