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package com.sun.org.apache.bcel.internal.classfile;

/* ====================================================================

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import  com.sun.org.apache.bcel.internal.Constants;

import  java.io.*;

/**

 * This class represents the constant pool, i.e., a table of constants, of

 * a parsed classfile. It may contain null references, due to the JVM

 * specification that skips an entry after an 8-byte constant (double,

 * long) entry.  Those interested in generating constant pools

 * programatically should see <a href="../generic/ConstantPoolGen.html">

 * ConstantPoolGen</a>.

 * @see     Constant

 * @see     com.sun.org.apache.bcel.internal.generic.ConstantPoolGen

 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>

 */

public class ConstantPool implements Cloneable, Node, Serializable {

  private int        constant_pool_count;

  private Constant[] constant_pool;

  /**

   * @param constant_pool Array of constants

   */

  public ConstantPool(Constant[] constant_pool)

  {

    setConstantPool(constant_pool);

  }

  /**

   * Read constants from given file stream.

   *

   * @param file Input stream

   * @throws IOException

   * @throws ClassFormatException

   */

  ConstantPool(DataInputStream file) throws IOException, ClassFormatException

  {

    byte tag;

    constant_pool_count = file.readUnsignedShort();

    constant_pool       = new Constant[constant_pool_count];

    /* constant_pool[0] is unused by the compiler and may be used freely

     * by the implementation.

     */

    for(int i=1; i < constant_pool_count; i++) {

      constant_pool[i] = Constant.readConstant(file);

      /* Quote from the JVM specification:

       * "All eight byte constants take up two spots in the constant pool.

       * If this is the n'th byte in the constant pool, then the next item

       * will be numbered n+2"

       *

       * Thus we have to increment the index counter.

       */

      tag = constant_pool[i].getTag();

      if((tag == Constants.CONSTANT_Double) || (tag == Constants.CONSTANT_Long))

        i++;

    }

  }

  /**

   * Called by objects that are traversing the nodes of the tree implicitely

   * defined by the contents of a Java class. I.e., the hierarchy of methods,

   * fields, attributes, etc. spawns a tree of objects.

   *

   * @param v Visitor object

   */

  public void accept(Visitor v) {

    v.visitConstantPool(this);

  }

  /**

   * Resolve constant to a string representation.

   *

   * @param  constant Constant to be printed

   * @return String representation

   */

  public String constantToString(Constant c)

       throws ClassFormatException

  {

    String   str;

    int      i;

    byte     tag = c.getTag();

    switch(tag) {

    case Constants.CONSTANT_Class:

      i   = ((ConstantClass)c).getNameIndex();

      c   = getConstant(i, Constants.CONSTANT_Utf8);

      str = Utility.compactClassName(((ConstantUtf8)c).getBytes(), false);

      break;

    case Constants.CONSTANT_String:

      i   = ((ConstantString)c).getStringIndex();

      c   = getConstant(i, Constants.CONSTANT_Utf8);

      str = "\"" + escape(((ConstantUtf8)c).getBytes()) + "\"";

      break;

    case Constants.CONSTANT_Utf8:    str = ((ConstantUtf8)c).getBytes();         break;

    case Constants.CONSTANT_Double:  str = "" + ((ConstantDouble)c).getBytes();  break;

    case Constants.CONSTANT_Float:   str = "" + ((ConstantFloat)c).getBytes();   break;

    case Constants.CONSTANT_Long:    str = "" + ((ConstantLong)c).getBytes();    break;

    case Constants.CONSTANT_Integer: str = "" + ((ConstantInteger)c).getBytes(); break;

    case Constants.CONSTANT_NameAndType:

      str = (constantToString(((ConstantNameAndType)c).getNameIndex(),

                              Constants.CONSTANT_Utf8) + " " +

             constantToString(((ConstantNameAndType)c).getSignatureIndex(),

                              Constants.CONSTANT_Utf8));

      break;

    case Constants.CONSTANT_InterfaceMethodref: case Constants.CONSTANT_Methodref:

    case Constants.CONSTANT_Fieldref:

      str = (constantToString(((ConstantCP)c).getClassIndex(),

                              Constants.CONSTANT_Class) + "." +

             constantToString(((ConstantCP)c).getNameAndTypeIndex(),

                              Constants.CONSTANT_NameAndType));

      break;

    default: // Never reached

      throw new RuntimeException("Unknown constant type " + tag);

    }

    return str;

  }

  private static final String escape(String str) {

    int          len = str.length();

    StringBuffer buf = new StringBuffer(len + 5);

    char[]       ch  = str.toCharArray();

    for(int i=0; i < len; i++) {

      switch(ch[i]) {

      case '\n' : buf.append("\\n"); break;

      case '\r' : buf.append("\\r"); break;

      case '\t' : buf.append("\\t"); break;

      case '\b' : buf.append("\\b"); break;

      case '"'  : buf.append("\\\""); break;

      default: buf.append(ch[i]);

      }

    }

    return buf.toString();

  }

  /**

   * Retrieve constant at `index' from constant pool and resolve it to

   * a string representation.

   *

   * @param  index of constant in constant pool

   * @param  tag expected type

   * @return String representation

   */

  public String constantToString(int index, byte tag)

       throws ClassFormatException

  {

    Constant c = getConstant(index, tag);

    return constantToString(c);

  }

  /**

   * Dump constant pool to file stream in binary format.

   *

   * @param file Output file stream

   * @throws IOException

   */

  public void dump(DataOutputStream file) throws IOException

  {

    file.writeShort(constant_pool_count);

    for(int i=1; i < constant_pool_count; i++)

      if(constant_pool[i] != null)

        constant_pool[i].dump(file);

  }

  /**

   * Get constant from constant pool.

   *

   * @param  index Index in constant pool

   * @return Constant value

   * @see    Constant

   */

  public Constant getConstant(int index) {

    if (index >= constant_pool.length || index < 0)

      throw new ClassFormatException("Invalid constant pool reference: " +

                                 index + ". Constant pool size is: " +

                                 constant_pool.length);

    return constant_pool[index];

  }

  /**

   * Get constant from constant pool and check whether it has the

   * expected type.

   *

   * @param  index Index in constant pool

   * @param  tag Tag of expected constant, i.e., its type

   * @return Constant value

   * @see    Constant

   * @throws  ClassFormatException

   */

  public Constant getConstant(int index, byte tag)

       throws ClassFormatException

  {

    Constant c;

    c = getConstant(index);

    if(c == null)

      throw new ClassFormatException("Constant pool at index " + index + " is null.");

    if(c.getTag() == tag)

      return c;

    else

      throw new ClassFormatException("Expected class `" + Constants.CONSTANT_NAMES[tag] +

                                 "' at index " + index + " and got " + c);

  }

  /**

   * @return Array of constants.

   * @see    Constant

   */

  public Constant[] getConstantPool() { return constant_pool;  }

  /**

   * Get string from constant pool and bypass the indirection of

   * `ConstantClass' and `ConstantString' objects. I.e. these classes have

   * an index field that points to another entry of the constant pool of

   * type `ConstantUtf8' which contains the real data.

   *

   * @param  index Index in constant pool

   * @param  tag Tag of expected constant, either ConstantClass or ConstantString

   * @return Contents of string reference

   * @see    ConstantClass

   * @see    ConstantString

   * @throws  ClassFormatException

   */

  public String getConstantString(int index, byte tag)

       throws ClassFormatException

  {

    Constant c;

    int    i;

    c = getConstant(index, tag);

    /* This switch() is not that elegant, since the two classes have the

     * same contents, they just differ in the name of the index

     * field variable.

     * But we want to stick to the JVM naming conventions closely though

     * we could have solved these more elegantly by using the same

     * variable name or by subclassing.

     */

    switch(tag) {

    case Constants.CONSTANT_Class:  i = ((ConstantClass)c).getNameIndex();    break;

    case Constants.CONSTANT_String: i = ((ConstantString)c).getStringIndex(); break;

    default:

      throw new RuntimeException("getConstantString called with illegal tag " + tag);

    }

    // Finally get the string from the constant pool

    c = getConstant(i, Constants.CONSTANT_Utf8);

    return ((ConstantUtf8)c).getBytes();

  }

  /**

   * @return Length of constant pool.

   */

  public int getLength()

  {

    return constant_pool_count;

  }

  /**

   * @param constant Constant to set

   */

  public void setConstant(int index, Constant constant) {

    constant_pool[index] = constant;

  }

  /**

   * @param constant_pool

   */

  public void setConstantPool(Constant[] constant_pool) {

    this.constant_pool = constant_pool;

    constant_pool_count = (constant_pool == null)? 0 : constant_pool.length;

  }

  /**

   * @return String representation.

   */

  public String toString() {

    StringBuffer buf = new StringBuffer();

    for(int i=1; i < constant_pool_count; i++)

      buf.append(i + ")" + constant_pool[i] + "\n");

    return buf.toString();

  }

  /**

   * @return deep copy of this constant pool

   */

  public ConstantPool copy() {

    ConstantPool c = null;

    try {

      c = (ConstantPool)clone();

    } catch(CloneNotSupportedException e) {}

    c.constant_pool = new Constant[constant_pool_count];

    for(int i=1; i < constant_pool_count; i++) {

      if(constant_pool[i] != null)

        c.constant_pool[i] = constant_pool[i].copy();

    }

    return c;

  }

}