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a template-like script and engine, all writen with Java.
The newest version!
/**
* *
* ASM: a very small and fast Java bytecode manipulation framework Copyright (c)
* 2000,2002,2003 INRIA, France Telecom All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer. 2. Redistributions in
* binary form must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution. 3. Neither the name of the
* copyright holders nor the names of its contributors may be used to endorse or
* promote products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package webit.script.asm.lib;
import java.util.ArrayList;
import java.util.HashMap;
/**
* A {@link ClassVisitor ClassVisitor} that generates Java class files. More
* precisely this visitor generates a byte array conforming to the Java class
* file format. It can be used alone, to generate a Java class "from scratch",
* or with one or more {@link ClassReader ClassReader} and adapter class visitor
* to generate a modified class from one or more existing Java classes.
*
* @author Eric Bruneton
*/
public final class ClassWriter {
static final int[] EMPATY_INTS = new int[0];
/**
* The type of CONSTANT_Class constant pool items.
*/
static final int CLASS = 7;
/**
* The type of CONSTANT_Fieldref constant pool items.
*/
static final int FIELD = 9;
/**
* The type of CONSTANT_Methodref constant pool items.
*/
static final int METH = 10;
/**
* The type of CONSTANT_InterfaceMethodref constant pool items.
*/
static final int IMETH = 11;
/**
* The type of CONSTANT_String constant pool items.
*/
static final int STR = 8;
/**
* The type of CONSTANT_Integer constant pool items.
*/
static final int INT = 3;
/**
* The type of CONSTANT_Float constant pool items.
*/
static final int FLOAT = 4;
/**
* The type of CONSTANT_Long constant pool items.
*/
static final int LONG = 5;
/**
* The type of CONSTANT_Double constant pool items.
*/
static final int DOUBLE = 6;
/**
* The type of CONSTANT_NameAndType constant pool items.
*/
static final int NAME_TYPE = 12;
/**
* The type of CONSTANT_Utf8 constant pool items.
*/
static final int UTF8 = 1;
/**
* Minor and major version numbers of the class to be generated.
*/
private final int version;
/**
* The access flags of this class.
*/
private final int access;
/**
* The constant pool item that contains the internal name of this class.
*/
private final int name;
/**
* The constant pool item that contains the internal name of the super class
* of this class.
*/
private final int superName;
/**
* The interfaces implemented or extended by this class or interface. More
* precisely, this array contains the indexes of the constant pool items
* that contain the internal names of these interfaces.
*/
private final int[] interfaces;
// /**
// * Number of fields of this class.
// */
// private int fieldCount;
//
// /**
// * The fields of this class.
// */
// private ByteBuffer fields;
/**
* The methods of this class. These methods are stored in a linked list of
* {@link MethodWriter MethodWriter} objects, linked to each other by their {@link
* CodeWriter#next} field. This field stores the first element of this list.
*/
private final ArrayList methods;
/**
* The constant pool of this class.
*/
private final ByteBuffer pool;
/**
* The constant pool's hash table data.
*/
private final HashMap items;
/**
* Index of the next item to be added in the constant pool.
*/
private short poolIndex;
/**
* A reusable key used to look for items in the hash {@link #items items}.
*/
private final Item key;
private final Item key2;
private final Item key3;
// /**
// * The type of instructions without any label.
// */
// static final int NOARG_INSN = 0;
//
// /**
// * The type of instructions with an signed byte label.
// */
// static final int SBYTE_INSN = 1;
//
// /**
// * The type of instructions with an signed short label.
// */
// static final int SHORT_INSN = 2;
//
// /**
// * The type of instructions with a local variable index label.
// */
// static final int VAR_INSN = 3;
//
// /**
// * The type of instructions with an implicit local variable index label.
// */
// static final int IMPLVAR_INSN = 4;
//
// /**
// * The type of instructions with a type descriptor argument.
// */
// static final int TYPE_INSN = 5;
//
// /**
// * The type of field and method invocations instructions.
// */
// static final int FIELDORMETH_INSN = 6;
//
// /**
// * The type of the INVOKEINTERFACE instruction.
// */
// static final int ITFMETH_INSN = 7;
//
// /**
// * The type of instructions with a 2 bytes bytecode offset label.
// */
// static final int LABEL_INSN = 8;
//
// /**
// * The type of instructions with a 4 bytes bytecode offset label.
// */
// static final int LABELW_INSN = 9;
//
// /**
// * The type of the LDC instruction.
// */
// static final int LDC_INSN = 10;
//
// /**
// * The type of the LDC_W and LDC2_W instructions.
// */
// static final int LDCW_INSN = 11;
//
// /**
// * The type of the IINC instruction.
// */
// static final int IINC_INSN = 12;
//
// /**
// * The type of the TABLESWITCH instruction.
// */
// static final int TABL_INSN = 13;
//
// /**
// * The type of the LOOKUPSWITCH instruction.
// */
// static final int LOOK_INSN = 14;
//
//// /**
//// * The type of the MULTIANEWARRAY instruction.
//// */
//// static final int MANA_INSN = 15;
//
// /**
// * The type of the WIDE instruction.
// */
// static final int WIDE_INSN = 16;
//
// /**
// * The instruction types of all JVM opcodes.
// */
// static final byte[] TYPE;
//
// // --------------------------------------------------------------------------
// // Static initializer
// // --------------------------------------------------------------------------
// /**
// * Computes the instruction types of JVM opcodes.
// */
// static {
// int i, len;
// byte[] b = new byte[220];
// String s
// = "AAAAAAAAAAAAAAAABCKLLDDDDDEEEEEEEEEEEEEEEEEEEEAAAAAAAADDDDDEEEEEEEEE"
// + "EEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAMAAA"
// + "AAAAAAAAAAAAAAAAAIIIIIIIIIIIIIIIIDNOAAAAAAGGGGGGGHAFBFAAFFAAQPIIJJII"
// + "IIIIIIIIIIIIIIII";
// for (i = 0, len = b.length; i < len; ++i) {
// b[i] = (byte) (s.charAt(i) - 'A');
// }
// TYPE = b;
//
// /* code to generate the above string
//
// // SBYTE_INSN instructions
// b[Constants.NEWARRAY] = SBYTE_INSN;
// b[Constants.BIPUSH] = SBYTE_INSN;
//
// // SHORT_INSN instructions
// b[Constants.SIPUSH] = SHORT_INSN;
//
// // (IMPL)VAR_INSN instructions
// b[Constants.RET] = VAR_INSN;
// for (i = Constants.ILOAD; i <= Constants.ALOAD; ++i) {
// b[i] = VAR_INSN;
// }
// for (i = Constants.ISTORE; i <= Constants.ASTORE; ++i) {
// b[i] = VAR_INSN;
// }
// for (i = 26; i <= 45; ++i) { // ILOAD_0 to ALOAD_3
// b[i] = IMPLVAR_INSN;
// }
// for (i = 59; i <= 78; ++i) { // ISTORE_0 to ASTORE_3
// b[i] = IMPLVAR_INSN;
// }
//
// // TYPE_INSN instructions
// b[Constants.NEW] = TYPE_INSN;
// b[Constants.ANEWARRAY] = TYPE_INSN;
// b[Constants.CHECKCAST] = TYPE_INSN;
// b[Constants.INSTANCEOF] = TYPE_INSN;
//
// // (Set)FIELDORMETH_INSN instructions
// for (i = Constants.GETSTATIC; i <= Constants.INVOKESTATIC; ++i) {
// b[i] = FIELDORMETH_INSN;
// }
// b[Constants.INVOKEINTERFACE] = ITFMETH_INSN;
//
// // LABEL(W)_INSN instructions
// for (i = Constants.IFEQ; i <= Constants.JSR; ++i) {
// b[i] = LABEL_INSN;
// }
// b[Constants.IFNULL] = LABEL_INSN;
// b[Constants.IFNONNULL] = LABEL_INSN;
// b[200] = LABELW_INSN; // GOTO_W
// b[201] = LABELW_INSN; // JSR_W
// // temporary opcodes used internally by ASM - see Label and MethodWriter
// for (i = 202; i < 220; ++i) {
// b[i] = LABEL_INSN;
// }
//
// // LDC(_W) instructions
// b[Constants.LDC] = LDC_INSN;
// b[19] = LDCW_INSN; // LDC_W
// b[20] = LDCW_INSN; // LDC2_W
//
// // special instructions
// b[Constants.IINC] = IINC_INSN;
// b[Constants.TABLESWITCH] = TABL_INSN;
// b[Constants.LOOKUPSWITCH] = LOOK_INSN;
// b[Constants.MULTIANEWARRAY] = MANA_INSN;
// b[196] = WIDE_INSN; // WIDE
//
// for (i = 0; i < b.length; ++i) {
// System.err.print((char)('A' + b[i]));
// }
// System.err.println();
// */
// }
public ClassWriter(
final int version,
final int access,
final String name,
final String superName,
final String[] interfaces) {
poolIndex = 1;
pool = new ByteBuffer();
items = new HashMap(64);
methods = new ArrayList();
key = new Item();
key2 = new Item();
key3 = new Item();
this.version = version;
this.access = access;
this.name = newClass(name);
this.superName = superName == null ? 0 : newClass(superName);
if (interfaces != null) {
int interfaceCount = interfaces.length;
this.interfaces = new int[interfaceCount];
for (int i = 0; i < interfaceCount; ++i) {
this.interfaces[i] = newClass(interfaces[i]);
}
} else {
this.interfaces = EMPATY_INTS;
}
// if ((access & Constants.ACC_DEPRECATED) != 0) {
// newUTF8("Deprecated");
// }
// if ((access & Constants.ACC_SYNTHETIC) != 0) {
// newUTF8("Synthetic");
// }
}
// public void visitField(
// final int access,
// final String name,
// final String desc,
// final Object value) {
// ++fieldCount;
// if (fields == null) {
// fields = new ByteBuffer();
// }
// fields.putShort(access).putShort(newUTF8(name)).putShort(newUTF8(desc));
// int attributeCount = 0;
// if (value != null) {
// ++attributeCount;
// }
// if ((access & Constants.ACC_SYNTHETIC) != 0) {
// ++attributeCount;
// }
// if ((access & Constants.ACC_DEPRECATED) != 0) {
// ++attributeCount;
// }
// fields.putShort(attributeCount);
// if (value != null) {
// fields.putShort(newUTF8("ConstantValue"));
// fields.putInt(2).putShort(newConstItem(value).index);
// }
// if ((access & Constants.ACC_SYNTHETIC) != 0) {
// fields.putShort(newUTF8("Synthetic")).putInt(0);
// }
// if ((access & Constants.ACC_DEPRECATED) != 0) {
// fields.putShort(newUTF8("Deprecated")).putInt(0);
// }
// }
public MethodWriter visitMethod(
final int access,
final String name,
final String desc,
final String[] exceptions) {
MethodWriter cw = new MethodWriter(this, access, name, desc, exceptions);
this.methods.add(cw);
return cw;
}
/**
* Returns the bytecode of the class that was build with this class writer.
*
* @return the bytecode of the class that was build with this class writer.
*/
public byte[] toByteArray() {
// computes the real size of the bytecode of this class
final int interfaceCount = interfaces.length;
int size = 24 + 2 * interfaceCount;
// if (fields != null) {
// size += fields.length;
// }
for (MethodWriter cb : this.methods) {
size += cb.getSize();
}
// int attributeCount = 0;
// if ((access & Constants.ACC_DEPRECATED) != 0) {
// ++attributeCount;
// size += 6;
// }
// if ((access & Constants.ACC_SYNTHETIC) != 0) {
// ++attributeCount;
// size += 6;
// }
size += pool.length;
// allocates a byte vector of this size, in order to avoid unnecessary
// arraycopy operations in the ByteBuffer.enlarge() method
final ByteBuffer out = new ByteBuffer(size);
out.putInt(0xCAFEBABE).putInt(version);
out.putShort(poolIndex).put(pool);
out.putShort(access).putShort(name).putShort(superName);
out.putShort(interfaceCount);
for (int i = 0; i < interfaceCount; ++i) {
out.putShort(interfaces[i]);
}
out.putShort(0); //out.putShort(fieldCount);
// if (fields != null) {
// out.put(fields);
// }
out.putShort(this.methods.size());
for (MethodWriter cb : this.methods) {
cb.renderTo(out);
}
out.putShort(0 /* attributeCount */);
// if ((access & Constants.ACC_DEPRECATED) != 0) {
// out.putShort(newUTF8("Deprecated")).putInt(0);
// }
// if ((access & Constants.ACC_SYNTHETIC) != 0) {
// out.putShort(newUTF8("Synthetic")).putInt(0);
// }
return out.data;
}
// --------------------------------------------------------------------------
// Utility methods: constant pool management
// --------------------------------------------------------------------------
/**
* Adds a number or string constant to the constant pool of the class being
* build. Does nothing if the constant pool already contains a similar item.
*
* @param cst the value of the constant to be added to the constant pool.
* This parameter must be an {@link java.lang.Integer Integer}, a {@link
* java.lang.Float Float}, a {@link java.lang.Long Long}, a {@link
* java.lang.Double Double}, a {@link String String} or a {@link Type}.
* @return a new or already existing constant item with the given value.
*/
Item newConstItem(final Object cst) {
if (cst instanceof Integer) {
return newInteger((Integer) cst);
} else if (cst instanceof Byte) {
return newInteger((Byte) cst);
} else if (cst instanceof Character) {
return newInteger((Character) cst);
} else if (cst instanceof Short) {
return newInteger((Short) cst);
} else if (cst instanceof Boolean) {
return newInteger(((Boolean) cst) ? 1 : 0);
} else if (cst instanceof Float) {
return newFloat((Float) cst);
} else if (cst instanceof Long) {
return newLong((Long) cst);
} else if (cst instanceof Double) {
return newDouble((Double) cst);
} else if (cst instanceof String) {
return newString((String) cst);
} else if (cst instanceof Item) {
return (Item) cst;
} else {
throw new IllegalArgumentException("value " + cst);
}
}
/**
* Adds an UTF8 string to the constant pool of the class being build. Does
* nothing if the constant pool already contains a similar item. This
* method is intended for {@link Attribute} sub classes, and is normally not
* needed by class generators or adapters.
*
* @param value the String value.
* @return the index of a new or already existing UTF8 item.
*/
int newUTF8(final String value) {
Item result = get(key.set(UTF8, value, null, null));
if (result == null) {
pool.putByte(UTF8).putUTF8(value);
result = new Item(poolIndex++, key);
put(result);
}
return result.index;
}
/**
* Adds a class reference to the constant pool of the class being build.
* Does nothing if the constant pool already contains a similar item.
* This method is intended for {@link Attribute} sub classes, and is
* normally not needed by class generators or adapters.
*
* @param value the internal name of the class.
* @return the index of a new or already existing class reference item.
*/
int newClass(final String value) {
return newClassItem(value).index;
}
/**
* Adds a class reference to the constant pool of the class being build.
* Does nothing if the constant pool already contains a similar item.
* This method is intended for {@link Attribute} sub classes, and is
* normally not needed by class generators or adapters.
*
* @param value the internal name of the class.
* @return a new or already existing class reference item.
*/
Item newClassItem(final String value) {
Item result = get(key2.set(CLASS, value, null, null));
if (result == null) {
pool.putBS(CLASS, newUTF8(value));
result = new Item(poolIndex++, key2);
put(result);
}
return result;
}
/**
* Adds a field reference to the constant pool of the class being build.
* Does nothing if the constant pool already contains a similar item.
* This method is intended for {@link Attribute} sub classes, and is
* normally not needed by class generators or adapters.
*
* @param owner the internal name of the field's owner class.
* @param name the field's name.
* @param desc the field's descriptor.
* @return the index of a new or already existing field reference item.
*/
public int newField(
final String owner,
final String name,
final String desc) {
Item result = get(key3.set(FIELD, owner, name, desc));
if (result == null) {
put122(FIELD, newClass(owner), newNameType(name, desc));
result = new Item(poolIndex++, key3);
put(result);
}
return result.index;
}
/**
* Adds a method reference to the constant pool of the class being build.
* Does nothing if the constant pool already contains a similar item.
*
* @param owner the internal name of the method's owner class.
* @param name the method's name.
* @param desc the method's descriptor.
* @param itf true if owner is an interface.
* @return a new or already existing method reference item.
*/
Item newMethodItem(
final String owner,
final String name,
final String desc,
final boolean itf) {
Item result = get(key3.set(itf ? IMETH : METH, owner, name, desc));
if (result == null) {
put122(itf ? IMETH : METH, newClass(owner), newNameType(name, desc));
result = new Item(poolIndex++, key3);
put(result);
}
return result;
}
/**
* Adds an integer to the constant pool of the class being build. Does
* nothing if the constant pool already contains a similar item.
*
* @param value the int value.
* @return a new or already existing int item.
*/
private Item newInteger(final int value) {
Item result = get(key.set(INT, value));
if (result == null) {
pool.putByte(INT).putInt(value);
result = new Item(poolIndex++, key);
put(result);
}
return result;
}
/**
* Adds a float to the constant pool of the class being build. Does nothing
* if the constant pool already contains a similar item.
*
* @param value the float value.
* @return a new or already existing float item.
*/
private Item newFloat(final float value) {
Item result = get(key.set(FLOAT, value));
if (result == null) {
pool.putByte(FLOAT).putInt(Float.floatToIntBits(value));
result = new Item(poolIndex++, key);
put(result);
}
return result;
}
/**
* Adds a long to the constant pool of the class being build. Does nothing
* if the constant pool already contains a similar item.
*
* @param value the long value.
* @return a new or already existing long item.
*/
private Item newLong(final long value) {
Item result = get(key.set(LONG, value));
if (result == null) {
pool.putByte(LONG).putLong(value);
result = new Item(poolIndex, key);
put(result);
poolIndex += 2;
}
return result;
}
/**
* Adds a double to the constant pool of the class being build. Does nothing
* if the constant pool already contains a similar item.
*
* @param value the double value.
* @return a new or already existing double item.
*/
private Item newDouble(final double value) {
Item result = get(key.set(DOUBLE, value));
if (result == null) {
pool.putByte(DOUBLE).putLong(Double.doubleToLongBits(value));
result = new Item(poolIndex, key);
put(result);
poolIndex += 2;
}
return result;
}
/**
* Adds a string to the constant pool of the class being build. Does nothing
* if the constant pool already contains a similar item.
*
* @param value the String value.
* @return a new or already existing string item.
*/
private Item newString(final String value) {
Item result = get(key2.set(STR, value, null, null));
if (result == null) {
pool.putBS(STR, newUTF8(value));
result = new Item(poolIndex++, key2);
put(result);
}
return result;
}
/**
* Adds a name and type to the constant pool of the class being build. Does
* nothing if the constant pool already contains a similar item. This
* method is intended for {@link Attribute} sub classes, and is normally not
* needed by class generators or adapters.
*
* @param name a name.
* @param desc a type descriptor.
* @return the index of a new or already existing name and type item.
*/
public int newNameType(final String name, final String desc) {
Item result = get(key2.set(NAME_TYPE, name, desc, null));
if (result == null) {
put122(NAME_TYPE, newUTF8(name), newUTF8(desc));
result = new Item(poolIndex++, key2);
put(result);
}
return result.index;
}
/**
* Returns the constant pool's hash table item which is equal to the given
* item.
*
* @param key a constant pool item.
* @return the constant pool's hash table item which is equal to the given
* item, or null if there is no such item.
*/
private Item get(final Item key) {
return items.get(key);
}
/**
* Puts the given item in the constant pool's hash table. The hash table
* must not already contains this item.
*
* @param i the item to be added to the constant pool's hash table.
*/
private void put(final Item i) {
this.items.put(i, i);
}
/**
* Puts one byte and two shorts into the constant pool.
*
* @param b a byte.
* @param s1 a short.
* @param s2 another short.
*/
private void put122(final int b, final int s1, final int s2) {
pool.putBS(b, s1).putShort(s2);
}
}