ThisExpression.java :  » 6.0-JDK-Modules-sun » tools » sun » tools » tree » Java Open Source

/*
 * Copyright 1994-2003 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package sun.tools.tree;

import sun.tools.java.*;
import sun.tools.asm.Assembler;
import java.io.PrintStream;
import java.util.Hashtable;

/**
 * WARNING: The contents of this source file are not part of any
 * supported API.  Code that depends on them does so at its own risk:
 * they are subject to change or removal without notice.
 */
public
class ThisExpression extends Expression {
    LocalMember field;
    Expression implementation;
    Expression outerArg;

    /**
     * Constructor
     */
    public ThisExpression(long where) {
  super(THIS, where, Type.tObject);
    }
    protected ThisExpression(int op, long where) {
  super(op, where, Type.tObject);
    }
    public ThisExpression(long where, LocalMember field) {
  super(THIS, where, Type.tObject);
  this.field = field;
  field.readcount++;
    }
    public ThisExpression(long where, Context ctx) {
  super(THIS, where, Type.tObject);
  field = ctx.getLocalField(idThis);
  field.readcount++;
    }
    
    /**
     * Constructor for "x.this()"
     */
    public ThisExpression(long where, Expression outerArg) {
  this(where);
  this.outerArg = outerArg;
    }

    public Expression getImplementation() {
  if (implementation != null)
      return implementation;
  return this;
    } 

    /**
     * From the 'this' in an expression of the form outer.this(...),
     * or the 'super' in an expression of the form outer.super(...),
     * return the "outer" expression, or null if there is none.
     */
    public Expression getOuterArg() {
  return outerArg;
    }

    /**
     * Check expression
     */
    public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable exp) {
  if (ctx.field.isStatic()) {
      env.error(where, "undef.var", opNames[op]);
      type = Type.tError;
      return vset;
  }
  if (field == null) {
      field = ctx.getLocalField(idThis);
      field.readcount++;
  }
  if (field.scopeNumber < ctx.frameNumber) {
      // get a "this$C" copy via the current object
      implementation = ctx.makeReference(env, field);
  }
  if (!vset.testVar(field.number)) {
      env.error(where, "access.inst.before.super", opNames[op]);
  }
  if (field == null) {
      type = ctx.field.getClassDeclaration().getType();
  } else {
      type = field.getType();
  }
  return vset;
    }

    public boolean isNonNull() {
  return true;
    }

    // A 'ThisExpression' node can never appear on the LHS of an assignment in a correct
    // program, but handle this case anyhow to provide a safe error recovery.

    public FieldUpdater getAssigner(Environment env, Context ctx) {
  return null;
    }

    public FieldUpdater getUpdater(Environment env, Context ctx) {
  return null;
    }

    /**
     * Inline
     */
    public Expression inlineValue(Environment env, Context ctx) {
  if (implementation != null)
      return implementation.inlineValue(env, ctx);
  if (field != null && field.isInlineable(env, false)) {
      Expression e = (Expression)field.getValue(env);
      //System.out.println("INLINE = "+ e + ", THIS");
      if (e != null) {
    e = e.copyInline(ctx);
    e.type = type;  // in case op==SUPER
    return e;
      }
  }
  return this;
    }

    /**
     * Create a copy of the expression for method inlining
     */
    public Expression copyInline(Context ctx) {
  if (implementation != null)
      return implementation.copyInline(ctx);
  ThisExpression e = (ThisExpression)clone();
  if (field == null) {
      // The expression is copied into the context of a method
      e.field = ctx.getLocalField(idThis);
      e.field.readcount++;
  } else {
      e.field = field.getCurrentInlineCopy(ctx);
  }
  if (outerArg != null) {
      e.outerArg = outerArg.copyInline(ctx);
  }
  return e;  
    }

    /**
     * Code
     */
    public void codeValue(Environment env, Context ctx, Assembler asm) {
  asm.add(where, opc_aload, new Integer(field.number));
    }

    /**
     * Print
     */
    public void print(PrintStream out) {
  if (outerArg != null) {
      out.print("(outer=");
      outerArg.print(out);
      out.print(" ");
  }
  String pfx = (field == null) ? ""
      : field.getClassDefinition().getName().getFlatName().getName()+".";
  pfx += opNames[op];
  out.print(pfx + "#" + ((field != null) ? field.hashCode() : 0));
  if (outerArg != null)
      out.print(")");
    }
}