/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.jack.dx.rop.code;

import com.android.jack.dx.util.FixedSizeList;

/**
 * List of {@link Insn} instances.
 */
public final class InsnList extends FixedSizeList {
  /**
   * Constructs an instance. All indices initially contain {@code null}.
   *
   * @param size the size of the list
   */
  public InsnList(int size) {
    super(size);
  }

  /**
   * Gets the element at the given index. It is an error to call
   * this with the index for an element which was never set; if you
   * do that, this will throw {@code NullPointerException}.
   *
   * @param n {@code >= 0, < size();} which index
   * @return {@code non-null;} element at that index
   */
  public Insn get(int n) {
    return (Insn) get0(n);
  }

  /**
   * Sets the instruction at the given index.
   *
   * @param n {@code >= 0, < size();} which index
   * @param insn {@code non-null;} the instruction to set at {@code n}
   */
  public void set(int n, Insn insn) {
    set0(n, insn);
  }

  /**
   * Gets the last instruction. This is just a convenient shorthand for
   * {@code get(size() - 1)}.
   *
   * @return {@code non-null;} the last instruction
   */
  public Insn getLast() {
    return get(size() - 1);
  }

  /**
   * Visits each instruction in the list, in order.
   *
   * @param visitor {@code non-null;} visitor to use
   */
  public void forEach(Insn.Visitor visitor) {
    int sz = size();

    for (int i = 0; i < sz; i++) {
      get(i).accept(visitor);
    }
  }

  /**
   * Compares the contents of this {@code InsnList} with another.
   * The blocks must have the same number of insns, and each Insn must
   * also return true to {@code Insn.contentEquals()}.
   *
   * @param b to compare
   * @return true in the case described above.
   */
  public boolean contentEquals(InsnList b) {
    if (b == null) {
      return false;
    }

    int sz = size();

    if (sz != b.size()) {
      return false;
    }

    for (int i = 0; i < sz; i++) {
      if (!get(i).contentEquals(b.get(i))) {
        return false;
      }
    }

    return true;
  }

  /**
   * Returns an instance that is identical to this one, except that
   * the registers in each instruction are offset by the given
   * amount. Mutability of the result is inherited from the
   * original.
   *
   * @param delta the amount to offset register numbers by
   * @return {@code non-null;} an appropriately-constructed instance
   */
  public InsnList withRegisterOffset(int delta) {
    int sz = size();
    InsnList result = new InsnList(sz);

    for (int i = 0; i < sz; i++) {
      Insn one = (Insn) get0(i);
      if (one != null) {
        result.set0(i, one.withRegisterOffset(delta));
      }
    }

    if (isImmutable()) {
      result.setImmutable();
    }

    return result;
  }
}