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ASM: a very small and fast Java bytecode manipulation framework Copyright (c) 2000-2007 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. 
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 package org.objectweb.asm;

A visitor to visit a Java method. The methods of this interface must be called in the following order: [ visitAnnotationDefault ] ( visitAnnotation | visitParameterAnnotation | visitAttribute )* [ visitCode ( visitFrame | visitXInsn | visitLabel | visitTryCatchBlock | visitLocalVariable | visitLineNumber)* visitMaxs ] visitEnd. In addition, the visitXInsn and visitLabel methods must be called in the sequential order of the bytecode instructions of the visited code, visitTryCatchBlock must be called before the labels passed as arguments have been visited, and the visitLocalVariable and visitLineNumber methods must be called after the labels passed as arguments have been visited.

Author(s):
Eric Bruneton
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 public interface MethodVisitor {
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     // -------------------------------------------------------------------------
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     // Annotations and non standard attributes
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     // -------------------------------------------------------------------------
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Visits the default value of this annotation interface method.

Returns:
a visitor to the visit the actual default value of this annotation interface method, or null if this visitor is not interested in visiting this default value. The 'name' parameters passed to the methods of this annotation visitor are ignored. Moreover, exacly one visit method must be called on this annotation visitor, followed by visitEnd.
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Visits an annotation of this method.

Parameters:
desc the class descriptor of the annotation class.
visible true if the annotation is visible at runtime.
Returns:
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
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     AnnotationVisitor visitAnnotation(String desc, boolean visible);

    
Visits an annotation of a parameter this method.

Parameters:
parameter the parameter index.
desc the class descriptor of the annotation class.
visible true if the annotation is visible at runtime.
Returns:
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
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         int parameter,
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         String desc,
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         boolean visible);

    
Visits a non standard attribute of this method.

Parameters:
attr an attribute.
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     void visitAttribute(Attribute attr);

    
Starts the visit of the method's code, if any (i.e. non abstract method). 
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    void visitCode();

    
Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i that follows an unconditionnal branch instruction such as GOTO or THROW, that is the target of a jump instruction, or that starts an exception handler block. The visited types must describe the values of the local variables and of the operand stack elements just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to V1_6.

Packed frames are basically "deltas" from the state of the previous frame (very first frame is implicitly defined by the method's parameters and access flags):
  • Opcodes.F_SAME representing frame with exactly the same locals as the previous frame and with the empty stack.
  • Opcodes.F_SAME1 representing frame with exactly the same locals as the previous frame and with single value on the stack (nStack is 1 and stack[0] contains value for the type of the stack item).
  • Opcodes.F_APPEND representing frame with current locals are the same as the locals in the previous frame, except that additional locals are defined (nLocal is 1, 2 or 3 and local elements contains values representing added types).
  • Opcodes.F_CHOP representing frame with current locals are the same as the locals in the previous frame, except that the last 1-3 locals are absent and with the empty stack (nLocals is 1, 2 or 3).
  • Opcodes.F_FULL representing complete frame data.

Parameters:
type the type of this stack map frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.
nLocal the number of local variables in the visited frame.
local the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes.TOP, Opcodes.INTEGER, Opcodes.FLOAT, Opcodes.LONG, Opcodes.DOUBLE,Opcodes.NULL or Opcodes.UNINITIALIZED_THIS (long and double are represented by a single element). Reference types are represented by String objects (representing internal names), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).
nStack the number of operand stack elements in the visited frame.
stack the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.
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    void visitFrame(
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        int type,
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        int nLocal,
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        Object[] local,
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        int nStack,
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        Object[] stack);
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    // -------------------------------------------------------------------------
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    // Normal instructions
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    // -------------------------------------------------------------------------
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Visits a zero operand instruction.

Parameters:
opcode the opcode of the instruction to be visited. This opcode is either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE, POP, POP2, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP, IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL, LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C, I2S, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW, MONITORENTER, or MONITOREXIT.
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    void visitInsn(int opcode);

    
Visits an instruction with a single int operand.

Parameters:
opcode the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.
operand the operand of the instruction to be visited.
When opcode is BIPUSH, operand value should be between Byte.MIN_VALUE and Byte.MAX_VALUE.
When opcode is SIPUSH, operand value should be between Short.MIN_VALUE and Short.MAX_VALUE.
When opcode is NEWARRAY, operand value should be one of Opcodes.T_BOOLEAN, Opcodes.T_CHAR, Opcodes.T_FLOAT, Opcodes.T_DOUBLE, Opcodes.T_BYTE, Opcodes.T_SHORT, Opcodes.T_INT or Opcodes.T_LONG.
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    void visitIntInsn(int opcode, int operand);

    
Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.

Parameters:
opcode the opcode of the local variable instruction to be visited. This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE, ASTORE or RET.
var the operand of the instruction to be visited. This operand is the index of a local variable.
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    void visitVarInsn(int opcode, int var);

    
Visits a type instruction. A type instruction is an instruction that takes the internal name of a class as parameter.

Parameters:
opcode the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
type the operand of the instruction to be visited. This operand must be the internal name of an object or array class (see Type.getInternalName()).
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    void visitTypeInsn(int opcode, String type);

    
Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.

Parameters:
opcode the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
owner the internal name of the field's owner class (see Type.getInternalName()).
name the field's name.
desc the field's descriptor (see Type).
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    void visitFieldInsn(int opcode, String owner, String name, String desc);

    
Visits a method instruction. A method instruction is an instruction that invokes a method.

Parameters:
opcode the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
owner the internal name of the method's owner class (see Type.getInternalName()).
name the method's name.
desc the method's descriptor (see Type).
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    void visitMethodInsn(int opcode, String owner, String name, String desc);

    
Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.

Parameters:
opcode the opcode of the type instruction to be visited. This opcode is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE, GOTO, JSR, IFNULL or IFNONNULL.
label the operand of the instruction to be visited. This operand is a label that designates the instruction to which the jump instruction may jump.
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    void visitJumpInsn(int opcode, Label label);

    
Visits a label. A label designates the instruction that will be visited just after it.

Parameters:
label a Label object.
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    void visitLabel(Label label);
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    // -------------------------------------------------------------------------
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    // Special instructions
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    // -------------------------------------------------------------------------
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Visits a LDC instruction.

Parameters:
cst the constant to be loaded on the stack. This parameter must be a non null java.lang.Integer, a java.lang.Float, a java.lang.Long, a java.lang.Double a java.lang.String (or a Type for .class constants, for classes whose version is 49.0 or more).
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    void visitLdcInsn(Object cst);

    
Visits an IINC instruction.

Parameters:
var index of the local variable to be incremented.
increment amount to increment the local variable by.
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    void visitIincInsn(int var, int increment);

    
Visits a TABLESWITCH instruction.

Parameters:
min the minimum key value.
max the maximum key value.
dflt beginning of the default handler block.
labels beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.
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    void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels);

    
Visits a LOOKUPSWITCH instruction.

Parameters:
dflt beginning of the default handler block.
keys the values of the keys.
labels beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.
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    void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels);

    
Visits a MULTIANEWARRAY instruction.

Parameters:
desc an array type descriptor (see Type).
dims number of dimensions of the array to allocate.
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    void visitMultiANewArrayInsn(String desc, int dims);
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    // -------------------------------------------------------------------------
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    // Exceptions table entries, debug information, max stack and max locals
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    // -------------------------------------------------------------------------
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Visits a try catch block.

Parameters:
start beginning of the exception handler's scope (inclusive).
end end of the exception handler's scope (exclusive).
handler beginning of the exception handler's code.
type internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).
Throws:
java.lang.IllegalArgumentException if one of the labels has already been visited by this visitor (by the visitLabel method).
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    void visitTryCatchBlock(Label start, Label end, Label handler, String type);

    
Visits a local variable declaration.

Parameters:
name the name of a local variable.
desc the type descriptor of this local variable.
signature the type signature of this local variable. May be null if the local variable type does not use generic types.
start the first instruction corresponding to the scope of this local variable (inclusive).
end the last instruction corresponding to the scope of this local variable (exclusive).
index the local variable's index.
Throws:
java.lang.IllegalArgumentException if one of the labels has not already been visited by this visitor (by the visitLabel method).
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    void visitLocalVariable(
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        String name,
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        String desc,
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        String signature,
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        Label start,
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        Label end,
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        int index);

    
Visits a line number declaration.

Parameters:
line a line number. This number refers to the source file from which the class was compiled.
start the first instruction corresponding to this line number.
Throws:
java.lang.IllegalArgumentException if start has not already been visited by this visitor (by the visitLabel method).
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    void visitLineNumber(int line, Label start);

    
Visits the maximum stack size and the maximum number of local variables of the method.

Parameters:
maxStack maximum stack size of the method.
maxLocals maximum number of local variables for the method.
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    void visitMaxs(int maxStack, int maxLocals);

    
Visits the end of the method. This method, which is the last one to be called, is used to inform the visitor that all the annotations and attributes of the method have been visited. 
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    void visitEnd();
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