Java example source code file (ConstantPoolGen.java)
The ConstantPoolGen.java Java example source code
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package com.sun.org.apache.bcel.internal.generic;
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import com.sun.org.apache.bcel.internal.Constants;
import com.sun.org.apache.bcel.internal.classfile.*;
import java.util.HashMap;
/**
* 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.
*
* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
* @see Constant
*/
public class ConstantPoolGen implements java.io.Serializable {
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 final String METHODREF_DELIM = ":";
private static final String IMETHODREF_DELIM = "#";
private static final String FIELDREF_DELIM = "&";
private static final String NAT_DELIM = "%";
private static class Index implements java.io.Serializable {
int index;
Index(int i) { index = i; }
}
/**
* 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() + NAT_DELIM + u8_2.getBytes(), new Index(i));
} else if(c instanceof ConstantUtf8) {
ConstantUtf8 u = (ConstantUtf8)c;
utf8_table.put(u.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();
String delim = METHODREF_DELIM;
if(c instanceof ConstantInterfaceMethodref)
delim = IMETHODREF_DELIM;
else if(c instanceof ConstantFieldref)
delim = FIELDREF_DELIM;
cp_table.put(class_name + delim + method_name + delim + signature, new Index(i));
}
}
}
/**
* Initialize with given constant pool.
*/
public ConstantPoolGen(ConstantPool cp) {
this(cp.getConstantPool());
}
/**
* Create empty constant pool.
*/
public ConstantPoolGen() {}
/** 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);
}
}
private HashMap string_table = new HashMap();
/**
* 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;
}
/**
* 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
int utf8 = addUtf8(str);
adjustSize();
ConstantString s = new ConstantString(utf8);
ret = index;
constants[index++] = s;
string_table.put(str, new Index(ret));
return ret;
}
private HashMap class_table = new HashMap();
/**
* 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.replace('.', '/'));
return (index != null)? index.index : -1;
}
private int addClass_(String clazz) {
int ret;
if((ret = lookupClass(clazz)) != -1)
return ret; // Already in CP
adjustSize();
ConstantClass c = new ConstantClass(addUtf8(clazz));
ret = index;
constants[index++] = c;
class_table.put(clazz, new Index(ret));
return ret;
}
/**
* 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('.', '/'));
}
/**
* 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 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());
}
/**
* 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;
}
/**
* 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;
}
/**
* Look for ConstantFloat in ConstantPool.
*
* @param n Float number to look for
* @return index on success, -1 otherwise
*/
public int lookupFloat(float n) {
int bits = Float.floatToIntBits(n);
for(int i=1; i < index; i++) {
if(constants[i] instanceof ConstantFloat) {
ConstantFloat c = (ConstantFloat)constants[i];
if(Float.floatToIntBits(c.getBytes()) == bits)
return i;
}
}
return -1;
}
/**
* 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;
}
private HashMap utf8_table = new HashMap();
/**
* Look for ConstantUtf8 in ConstantPool.
*
* @param n Utf8 string to look for
* @return index on success, -1 otherwise
*/
public int lookupUtf8(String n) {
Index index = (Index)utf8_table.get(n);
return (index != null)? index.index : -1;
}
/**
* 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);
utf8_table.put(n, new Index(ret));
return ret;
}
/**
* 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;
}
/**
* 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;
}
/**
* Look for ConstantDouble in ConstantPool.
*
* @param n Double number to look for
* @return index on success, -1 otherwise
*/
public int lookupDouble(double n) {
long bits = Double.doubleToLongBits(n);
for(int i=1; i < index; i++) {
if(constants[i] instanceof ConstantDouble) {
ConstantDouble c = (ConstantDouble)constants[i];
if(Double.doubleToLongBits(c.getBytes()) == bits)
return i;
}
}
return -1;
}
/**
* 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;
}
private HashMap n_a_t_table = new HashMap();
/**
* 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 + NAT_DELIM + signature);
return (index != null)? index.index : -1;
}
/**
* 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 + NAT_DELIM + signature, new Index(ret));
return ret;
}
private HashMap cp_table = new HashMap();
/**
* 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 + METHODREF_DELIM + method_name +
METHODREF_DELIM + signature);
return (index != null)? index.index : -1;
}
public int lookupMethodref(MethodGen method) {
return lookupMethodref(method.getClassName(), method.getName(),
method.getSignature());
}
/**
* 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 + METHODREF_DELIM + method_name +
METHODREF_DELIM + signature, new Index(ret));
return ret;
}
public int addMethodref(MethodGen method) {
return addMethodref(method.getClassName(), method.getName(),
method.getSignature());
}
/**
* 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 + IMETHODREF_DELIM + method_name +
IMETHODREF_DELIM + signature);
return (index != null)? index.index : -1;
}
public int lookupInterfaceMethodref(MethodGen method) {
return lookupInterfaceMethodref(method.getClassName(), method.getName(),
method.getSignature());
}
/**
* 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 + IMETHODREF_DELIM + method_name +
IMETHODREF_DELIM + signature, new Index(ret));
return ret;
}
public int addInterfaceMethodref(MethodGen method) {
return addInterfaceMethodref(method.getClassName(), method.getName(),
method.getSignature());
}
/**
* 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 + FIELDREF_DELIM + field_name +
FIELDREF_DELIM + signature);
return (index != null)? index.index : -1;
}
/**
* 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 + FIELDREF_DELIM + field_name + FIELDREF_DELIM + signature, new Index(ret));
return ret;
}
/**
* @param i index in constant pool
* @return constant pool entry at index i
*/
public Constant getConstant(int i) { return constants[i]; }
/**
* 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 intermediate constant pool
*/
public ConstantPool getConstantPool() {
return new ConstantPool(constants);
}
/**
* @return current size of constant pool
*/
public int getSize() {
return index;
}
/**
* @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 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();
}
/** Import constant from another ConstantPool and return new index.
*/
public int addConstant(Constant c, ConstantPoolGen cp) {
Constant[] constants = cp.getConstantPool().getConstantPool();
switch(c.getTag()) {
case Constants.CONSTANT_String: {
ConstantString s = (ConstantString)c;
ConstantUtf8 u8 = (ConstantUtf8)constants[s.getStringIndex()];
return addString(u8.getBytes());
}
case Constants.CONSTANT_Class: {
ConstantClass s = (ConstantClass)c;
ConstantUtf8 u8 = (ConstantUtf8)constants[s.getNameIndex()];
return addClass(u8.getBytes());
}
case Constants.CONSTANT_NameAndType: {
ConstantNameAndType n = (ConstantNameAndType)c;
ConstantUtf8 u8 = (ConstantUtf8)constants[n.getNameIndex()];
ConstantUtf8 u8_2 = (ConstantUtf8)constants[n.getSignatureIndex()];
return addNameAndType(u8.getBytes(), u8_2.getBytes());
}
case Constants.CONSTANT_Utf8:
return addUtf8(((ConstantUtf8)c).getBytes());
case Constants.CONSTANT_Double:
return addDouble(((ConstantDouble)c).getBytes());
case Constants.CONSTANT_Float:
return addFloat(((ConstantFloat)c).getBytes());
case Constants.CONSTANT_Long:
return addLong(((ConstantLong)c).getBytes());
case Constants.CONSTANT_Integer:
return addInteger(((ConstantInteger)c).getBytes());
case Constants.CONSTANT_InterfaceMethodref: case Constants.CONSTANT_Methodref:
case Constants.CONSTANT_Fieldref: {
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 name = u8.getBytes();
u8 = (ConstantUtf8)constants[n.getSignatureIndex()];
String signature = u8.getBytes();
switch(c.getTag()) {
case Constants.CONSTANT_InterfaceMethodref:
return addInterfaceMethodref(class_name, name, signature);
case Constants.CONSTANT_Methodref:
return addMethodref(class_name, name, signature);
case Constants.CONSTANT_Fieldref:
return addFieldref(class_name, name, signature);
default: // Never reached
throw new RuntimeException("Unknown constant type " + c);
}
}
default: // Never reached
throw new RuntimeException("Unknown constant type " + c);
}
}
}
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