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ConstantPoolGen.java

package de.fub.bytecode.generic;

import de.fub.bytecode.Constants;
import de.fub.bytecode.classfile.*;
import java.util.Hashtable;

/** 
 * This class is used to build up a constant pool. The user adds
 * constants via `addXXX' methods, `addString', `addClass',
 * etc.. These methods return an index into the constant
 * pool. Finally, `getFinalConstantPool()' returns the constant pool
 * built up. Intermediate versions of the constant pool can be
 * obtained with `getConstantPool()'. A constant pool has capacity for
 * Constants.MAX_SHORT entries. Note that the first (0) is used by the
 * JVM and that Double and Long constants need two slots.
 *
 * @version $Id: ConstantPoolGen.java,v 1.1.1.1 2002/01/24 03:44:04 pserver Exp $
 * @author  <A HREF="http://www.inf.fu-berlin.de/~dahm">M. Dahm</A>
 * @see Constant
 */
public class ConstantPoolGen implements Constants {
  protected int        size      = 1024; // Inital size, sufficient in most cases
  protected Constant[] constants = new Constant[size];
  protected int        index     = 1; // First entry (0) used by JVM

  private static class Index {
    int index;
    Index(int i) { index = i; }
  }

  private Hashtable string_table = new Hashtable();

  private Hashtable class_table = new Hashtable();

  private Hashtable n_a_t_table = new Hashtable();

  private Hashtable cp_table = new Hashtable();

  /**
   * Create empty constant pool.
   */
  public ConstantPoolGen() {}  
  /**
   * Initialize with given array of constants.
   *
   * @param c array of given constants, new ones will be appended
   */
  public ConstantPoolGen(Constant[] cs) {
    if(cs.length > size) {
      size      = cs.length;
      constants = new Constant[size];
    }

    System.arraycopy(cs, 0, constants, 0, cs.length);

    if(cs.length > 0)
      index = cs.length;

    for(int i=1; i < index; i++) {
      Constant c = constants[i];

      if(c instanceof ConstantString) {
    ConstantString s  = (ConstantString)c;
    ConstantUtf8   u8 = (ConstantUtf8)constants[s.getStringIndex()];

    string_table.put(u8.getBytes(), new Index(i));
      } else if(c instanceof ConstantClass) {
    ConstantClass s  = (ConstantClass)c;
    ConstantUtf8  u8 = (ConstantUtf8)constants[s.getNameIndex()];

    class_table.put(u8.getBytes(), new Index(i));
      } else if(c instanceof ConstantNameAndType) {
    ConstantNameAndType n    = (ConstantNameAndType)c;
    ConstantUtf8        u8   = (ConstantUtf8)constants[n.getNameIndex()];
    ConstantUtf8        u8_2 = (ConstantUtf8)constants[n.getSignatureIndex()];

    n_a_t_table.put(u8.getBytes() + ":" + u8_2.getBytes(), new Index(i));
      } else if(c instanceof ConstantCP) {
    ConstantCP          m     = (ConstantCP)c;
    ConstantClass       clazz = (ConstantClass)constants[m.getClassIndex()];
    ConstantNameAndType n     = (ConstantNameAndType)constants[m.getNameAndTypeIndex()];
    
        ConstantUtf8 u8         = (ConstantUtf8)constants[clazz.getNameIndex()];
        String       class_name = u8.getBytes().replace('/', '.');

    u8 = (ConstantUtf8)constants[n.getNameIndex()];
    String method_name = u8.getBytes();

    u8 = (ConstantUtf8)constants[n.getSignatureIndex()];
    String signature = u8.getBytes();

    cp_table.put(class_name + ":" + method_name + ":" + signature, new Index(i));
      }
    }
  }  
  /**
   * Initialize with given constant pool.
   */
  public ConstantPoolGen(ConstantPool cp) {
    this(cp.getConstantPool());
  }  
  /**
   * Add a reference to an array class (e.g. String[][]) as needed by MULTIANEWARRAY
   * instruction, e.g. to the ConstantPool.
   *
   * @param type type of array class
   * @return index of entry
   */
  public int addArrayClass(ArrayType type) {
    return addClass_(type.getSignature());
  }  
  /**
   * Add a new Class reference to the ConstantPool for a given type.
   *
   * @param str Class to add
   * @return index of entry
   */
  public int addClass(ObjectType type) {
    return addClass(type.getClassName());
  }  
  /**
   * Add a new Class reference to the ConstantPool, if it is not already in there.
   *
   * @param str Class to add
   * @return index of entry
   */
  public int addClass(String str) {
    return addClass_(str.replace('.', '/'));
  }  
  private int addClass_(String clazz) {
    int    ret;

    if((ret = lookupClass(clazz)) != -1)
      return ret; // Already in CP

    adjustSize();

    ConstantUtf8  u8 = new ConstantUtf8(clazz);
    ConstantClass c  = new ConstantClass(index);

    constants[index++] = u8;
    ret = index;
    constants[index++] = c;

    class_table.put(clazz, new Index(ret));

    return ret;
  }  
  /**
   * Add a new double constant to the ConstantPool, if it is not already in there.
   *
   * @param n Double number to add
   * @return index of entry
   */
  public int addDouble(double n) {
    int  ret;

    if((ret = lookupDouble(n)) != -1)
      return ret; // Already in CP

    adjustSize();

    ret = index;
    constants[index] = new ConstantDouble(n);
    index += 2;   // Wastes one entry according to spec

    return ret;
  }  
  /**
   * Add a new Fieldref constant to the ConstantPool, if it is not already 
   * in there.
   *
   * @param n Fieldref string to add
   * @return index of entry
   */
  public int addFieldref(String class_name, String field_name,
                   String signature) {
    int  ret;
    int  class_index, name_and_type_index;

    if((ret = lookupFieldref(class_name, field_name, signature)) != -1)
      return ret; // Already in CP

    adjustSize();

    class_index         = addClass(class_name);
    name_and_type_index = addNameAndType(field_name, signature);
    ret = index;
    constants[index++] = new ConstantFieldref(class_index, name_and_type_index);

    cp_table.put(class_name + "&" + field_name + "&" + signature, new Index(ret));

    return ret;
  }  
  /**
   * Add a new Float constant to the ConstantPool, if it is not already in there.
   *
   * @param n Float number to add
   * @return index of entry
   */
  public int addFloat(float n) {
    int  ret;

    if((ret = lookupFloat(n)) != -1)
      return ret; // Already in CP

    adjustSize();

    ret = index;
    constants[index++] = new ConstantFloat(n);

    return ret;
  }  
  /* Suggested ...
     public final int addConstant(Constant c)
  {
    int  ret;

    adjustSize();

    ret = index;
    constants[index++] = c;

    return ret;
  }
  */

  /**
   * Add a new Integer constant to the ConstantPool, if it is not already in there.
   *
   * @param n integer number to add
   * @return index of entry
   */
  public int addInteger(int n) {
    int  ret;

    if((ret = lookupInteger(n)) != -1)
      return ret; // Already in CP

    adjustSize();

    ret = index;
    constants[index++] = new ConstantInteger(n);

    return ret;
  }  
  public int addInterfaceMethodref(MethodGen method) {
    return addInterfaceMethodref(method.getClassName(), method.getMethodName(),
                 method.getMethodSignature());
  }  
  /**
   * Add a new InterfaceMethodref constant to the ConstantPool, if it is not already 
   * in there.
   *
   * @param n InterfaceMethodref string to add
   * @return index of entry
   */
  public int addInterfaceMethodref(String class_name, String method_name, String signature) {
    int ret, class_index, name_and_type_index;

    if((ret = lookupInterfaceMethodref(class_name, method_name, signature)) != -1)
      return ret; // Already in CP

    adjustSize();

    class_index         = addClass(class_name);
    name_and_type_index = addNameAndType(method_name, signature);
    ret = index;
    constants[index++] = new ConstantInterfaceMethodref(class_index, name_and_type_index);

    cp_table.put(class_name + "#" + method_name + "#" + signature, new Index(ret));

    return ret;
  }  
  /**
   * Add a new long constant to the ConstantPool, if it is not already in there.
   *
   * @param n Long number to add
   * @return index of entry
   */
  public int addLong(long n) {
    int  ret;

    if((ret = lookupLong(n)) != -1)
      return ret; // Already in CP

    adjustSize();

    ret = index;
    constants[index] = new ConstantLong(n);
    index += 2;   // Wastes one entry according to spec

    return ret;
  }  
  public int addMethodref(MethodGen method) {
    return addMethodref(method.getClassName(), method.getMethodName(),
            method.getMethodSignature());
  }  
  /**
   * Add a new Methodref constant to the ConstantPool, if it is not already 
   * in there.
   *
   * @param n Methodref string to add
   * @return index of entry
   */
  public int addMethodref(String class_name, String method_name, String signature) {
    int  ret, class_index, name_and_type_index;

    if((ret = lookupMethodref(class_name, method_name, signature)) != -1)
      return ret; // Already in CP

    adjustSize();

    name_and_type_index = addNameAndType(method_name, signature);
    class_index         = addClass(class_name);
    ret = index;
    constants[index++] = new ConstantMethodref(class_index, name_and_type_index);

    cp_table.put(class_name + ":" + method_name + ":" + signature, new Index(ret));

    return ret;
  }  
  /**
   * Add a new NameAndType constant to the ConstantPool if it is not already 
   * in there.
   *
   * @param n NameAndType string to add
   * @return index of entry
   */
  public int addNameAndType(String name, String signature) {
    int  ret;
    int  name_index, signature_index;

    if((ret = lookupNameAndType(name, signature)) != -1)
      return ret; // Already in CP

    adjustSize();

    name_index      = addUtf8(name);
    signature_index = addUtf8(signature);
    ret = index;
    constants[index++] = new ConstantNameAndType(name_index, signature_index);

    n_a_t_table.put(name + ":" + signature, new Index(ret));
    return ret;
  }  
  /**
   * Add a new String constant to the ConstantPool, if it is not already in there.
   *
   * @param str String to add
   * @return index of entry
   */
  public int addString(String str) {
    int ret;
    
    if((ret = lookupString(str)) != -1)
      return ret; // Already in CP

    adjustSize();

    ConstantUtf8   u8 = new ConstantUtf8(str);
    ConstantString s  = new ConstantString(index);
       
    constants[index++] = u8;
    ret = index;
    constants[index++] = s;

    string_table.put(str, new Index(ret));

    return ret;
  }  
  /**
   * Add a new Utf8 constant to the ConstantPool, if it is not already in there.
   *
   * @param n Utf8 string to add
   * @return index of entry
   */
  public int addUtf8(String n) {
    int  ret;

    if((ret = lookupUtf8(n)) != -1)
      return ret; // Already in CP

    adjustSize();

    ret = index;
    constants[index++] = new ConstantUtf8(n);

    return ret;
  }  
  /** Resize internal array of constants.
   */
  protected void adjustSize() {
    if(index + 3 >= size) {
      Constant[] cs = constants;

      size      *= 2;
      constants  = new Constant[size];
      System.arraycopy(cs, 0, constants, 0, index);
    }
  }  
  /**
   * @param i index in constant pool
   * @return constant pool entry at index i
   */
  public Constant getConstant(int i) { return constants[i]; }  
  /**
   * @return intermediate constant pool
   */
  public ConstantPool getConstantPool() {
    return new ConstantPool(constants);
  }  
  /**
   * @return constant pool with proper length
   */
  public ConstantPool getFinalConstantPool() { 
    Constant[] cs = new Constant[index];
    
    System.arraycopy(constants, 0, cs, 0, index);

    return new ConstantPool(cs); 
  }  
  /**
   * @return current size of constant pool
   */
  public int getSize() {
    return index;
  }  
  /**
   * Look for ConstantClass in ConstantPool named `str'.
   *
   * @param str String to search for
   * @return index on success, -1 otherwise
   */
  public int lookupClass(String str) {
    Index index = (Index)class_table.get(str);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantDouble in ConstantPool.
   *
   * @param n Double number to look for
   * @return index on success, -1 otherwise
   */
  public int lookupDouble(double n) {
    for(int i=1; i < index; i++) {
      if(constants[i] instanceof ConstantDouble) {
    ConstantDouble c = (ConstantDouble)constants[i];

    if(c.getBytes() == n)
      return i;
      }
    }

    return -1;
  }  
  /** 
   * Look for ConstantFieldref in ConstantPool.
   *
   * @param class_name Where to find method
   * @param field_name Guess what
   * @param signature return and argument types
   * @return index on success, -1 otherwise
   */
  public int lookupFieldref(String class_name, String field_name, String signature) {
    Index index = (Index)cp_table.get(class_name + "&" + field_name + "&" + signature);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantFloat in ConstantPool.
   *
   * @param n Float number to look for
   * @return index on success, -1 otherwise
   */
  public int lookupFloat(float n) {
    for(int i=1; i < index; i++) {
      if(constants[i] instanceof ConstantFloat) {
    ConstantFloat c = (ConstantFloat)constants[i];

    if(c.getBytes() == n)
      return i;
      }
    }

    return -1;
  }  
  /** 
   * Look for ConstantInteger in ConstantPool.
   *
   * @param n integer number to look for
   * @return index on success, -1 otherwise
   */
  public int lookupInteger(int n) {
    for(int i=1; i < index; i++) {
      if(constants[i] instanceof ConstantInteger) {
    ConstantInteger c = (ConstantInteger)constants[i];

    if(c.getBytes() == n)
      return i;
      }
    }

    return -1;
  }  
  public int lookupInterfaceMethodref(MethodGen method) {
    return lookupInterfaceMethodref(method.getClassName(), method.getMethodName(),
                    method.getMethodSignature());
  }  
  /** 
   * Look for ConstantInterfaceMethodref in ConstantPool.
   *
   * @param class_name Where to find method
   * @param method_name Guess what
   * @param signature return and argument types
   * @return index on success, -1 otherwise
   */
  public int lookupInterfaceMethodref(String class_name, String method_name, String signature) {
    Index index = (Index)cp_table.get(class_name + "#" + method_name + "#" + signature);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantLong in ConstantPool.
   *
   * @param n Long number to look for
   * @return index on success, -1 otherwise
   */
  public int lookupLong(long n) {
    for(int i=1; i < index; i++) {
      if(constants[i] instanceof ConstantLong) {
    ConstantLong c = (ConstantLong)constants[i];

    if(c.getBytes() == n)
      return i;
      }
    }

    return -1;
  }  
  public int lookupMethodref(MethodGen method) {
    return lookupMethodref(method.getClassName(), method.getMethodName(),
              method.getMethodSignature());
  }  
  /** 
   * Look for ConstantMethodref in ConstantPool.
   *
   * @param class_name Where to find method
   * @param method_name Guess what
   * @param signature return and argument types
   * @return index on success, -1 otherwise
   */
  public int lookupMethodref(String class_name, String method_name, String signature) {
    Index index = (Index)cp_table.get(class_name + ":" + method_name + ":" + signature);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantNameAndType in ConstantPool.
   *
   * @param name of variable/method
   * @param signature of variable/method
   * @return index on success, -1 otherwise
   */
  public int lookupNameAndType(String name, String signature) {
    Index index = (Index)n_a_t_table.get(name + ":" + signature);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantString in ConstantPool containing String `str'.
   *
   * @param str String to search for
   * @return index on success, -1 otherwise
   */
  public int lookupString(String str) {
    Index index = (Index)string_table.get(str);
    return (index != null)? index.index : -1;
  }  
  /** 
   * Look for ConstantUtf8 in ConstantPool.
   *
   * @param n Utf8 string to look for
   * @return index on success, -1 otherwise
   */
  public int lookupUtf8(String n) {
    for(int i=1; i < index; i++) {
      if(constants[i] instanceof ConstantUtf8) {
    ConstantUtf8 c = (ConstantUtf8)constants[i];

    if(c.getBytes().equals(n))
      return i;
      }
    }

    return -1;
  }  
  /**
   * Use with care!
   *
   * @param i index in constant pool
   * @param c new constant pool entry at index i
   */
  public void setConstant(int i, Constant c) { constants[i] = c; }  
  /**
   * @return String representation.
   */
  public String toString() {
    StringBuffer buf = new StringBuffer();

    for(int i=1; i < index; i++)
      buf.append(i + ")" + constants[i] + "\n");

    return buf.toString();
  }  
}

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