https://github.com/spring-projects/spring-framework: Spring Core (Spring IO)
  • Juergen Hoeller 
// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 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 org.springframework.asm;


A visitor to visit a Java method. The methods of this class must be called in the following order: ( visitParameter )* [ visitAnnotationDefault ] ( visitAnnotation | visitAnnotableParameterCount | visitParameterAnnotation 
visitTypeAnnotation | visitAttribute )* [ visitCode ( visitFrame | visit<i>X</i>Insn | visitLabel | visitInsnAnnotation | 
visitTryCatchBlock | visitTryCatchAnnotation | visitLocalVariable | 
visitLocalVariableAnnotation | visitLineNumber )* visitMaxs ] visitEnd. In addition, the visit<i>X</i>Insn and visitLabel methods must be called in the sequential order of the bytecode instructions of the visited code, visitInsnAnnotation must be called after the annotated instruction, visitTryCatchBlock must be called before the labels passed as arguments have been visited, 
visitTryCatchBlockAnnotation must be called after the corresponding try catch block has been visited, and the visitLocalVariable, visitLocalVariableAnnotation and 
visitLineNumber methods must be called after the labels passed as arguments have been
visited.

Author:Eric Bruneton
/**
 * A visitor to visit a Java method. The methods of this class must be called in the following
 * order: ( {@code visitParameter} )* [ {@code visitAnnotationDefault} ] ( {@code visitAnnotation} |
 * {@code visitAnnotableParameterCount} | {@code visitParameterAnnotation} {@code
 * visitTypeAnnotation} | {@code visitAttribute} )* [ {@code visitCode} ( {@code visitFrame} |
 * {@code visit<i>X</i>Insn} | {@code visitLabel} | {@code visitInsnAnnotation} | {@code
 * visitTryCatchBlock} | {@code visitTryCatchAnnotation} | {@code visitLocalVariable} | {@code
 * visitLocalVariableAnnotation} | {@code visitLineNumber} )* {@code visitMaxs} ] {@code visitEnd}.
 * In addition, the {@code visit<i>X</i>Insn} and {@code visitLabel} methods must be called in the
 * sequential order of the bytecode instructions of the visited code, {@code visitInsnAnnotation}
 * must be called <i>after</i> the annotated instruction, {@code visitTryCatchBlock} must be called
 * <i>before</i> the labels passed as arguments have been visited, {@code
 * visitTryCatchBlockAnnotation} must be called <i>after</i> the corresponding try catch block has
 * been visited, and the {@code visitLocalVariable}, {@code visitLocalVariableAnnotation} and {@code
 * visitLineNumber} methods must be called <i>after</i> the labels passed as arguments have been
 * visited.
 *
 * @author Eric Bruneton
 */
public abstract class MethodVisitor {

  private static final String REQUIRES_ASM5 = "This feature requires ASM5";

  
The ASM API version implemented by this visitor. The value of this field must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7. 
/**
   * The ASM API version implemented by this visitor. The value of this field must be one of {@link
   * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
   */
  protected final int api;

  
The method visitor to which this visitor must delegate method calls. May be null. 
/**
   * The method visitor to which this visitor must delegate method calls. May be {@literal null}.
   */
  protected MethodVisitor mv;

  
Constructs a new MethodVisitor. 
Params:
/**
   * Constructs a new {@link MethodVisitor}.
   *
   * @param api the ASM API version implemented by this visitor. Must be one of {@link
   *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
   */
  public MethodVisitor(final int api) {
    this(api, null);
  }

  
Constructs a new MethodVisitor. 
Params:
/**
   * Constructs a new {@link MethodVisitor}.
   *
   * @param api the ASM API version implemented by this visitor. Must be one of {@link
   *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
   * @param methodVisitor the method visitor to which this visitor must delegate method calls. May
   *     be null.
   */
  public MethodVisitor(final int api, final MethodVisitor methodVisitor) {
    if (api != Opcodes.ASM9
        && api != Opcodes.ASM8
        && api != Opcodes.ASM7
        && api != Opcodes.ASM6
        && api != Opcodes.ASM5
        && api != Opcodes.ASM4
        && api != Opcodes.ASM10_EXPERIMENTAL) {
      throw new IllegalArgumentException("Unsupported api " + api);
    }
    // SPRING PATCH: no preview mode check for ASM 9 experimental
    this.api = api;
    this.mv = methodVisitor;
  }

  // -----------------------------------------------------------------------------------------------
  // Parameters, annotations and non standard attributes
  // -----------------------------------------------------------------------------------------------

  
Visits a parameter of this method.

Params:
  • name – parameter name or null if none is provided.
  • access – the parameter's access flags, only ACC_FINAL, ACC_SYNTHETIC or/and ACC_MANDATED are allowed (see Opcodes).
/**
   * Visits a parameter of this method.
   *
   * @param name parameter name or {@literal null} if none is provided.
   * @param access the parameter's access flags, only {@code ACC_FINAL}, {@code ACC_SYNTHETIC}
   *     or/and {@code ACC_MANDATED} are allowed (see {@link Opcodes}).
   */
  public void visitParameter(final String name, final int access) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      mv.visitParameter(name, access);
    }
  }

  
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.
/**
   * Visits the default value of this annotation interface method.
   *
   * @return a visitor to the visit the actual default value of this annotation interface method, or
   *     {@literal 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.
   */
  public AnnotationVisitor visitAnnotationDefault() {
    if (mv != null) {
      return mv.visitAnnotationDefault();
    }
    return null;
  }

  
Visits an annotation of this method.

Params:
  • descriptor – 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.
/**
   * Visits an annotation of this method.
   *
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
    if (mv != null) {
      return mv.visitAnnotation(descriptor, visible);
    }
    return null;
  }

  
Visits an annotation on a type in the method signature.

Params:
Returns:a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
/**
   * Visits an annotation on a type in the method signature.
   *
   * @param typeRef a reference to the annotated type. The sort of this type reference must be
   *     {@link TypeReference#METHOD_TYPE_PARAMETER}, {@link
   *     TypeReference#METHOD_TYPE_PARAMETER_BOUND}, {@link TypeReference#METHOD_RETURN}, {@link
   *     TypeReference#METHOD_RECEIVER}, {@link TypeReference#METHOD_FORMAL_PARAMETER} or {@link
   *     TypeReference#THROWS}. See {@link TypeReference}.
   * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
   *     static inner type within 'typeRef'. May be {@literal null} if the annotation targets
   *     'typeRef' as a whole.
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitTypeAnnotation(
      final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      return mv.visitTypeAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  
Visits the number of method parameters that can have annotations. By default (i.e. when this
method is not called), all the method parameters defined by the method descriptor can have
annotations.

Params:
  • parameterCount – the number of method parameters than can have annotations. This number
    must be less or equal than the number of parameter types in the method descriptor. It can
    be strictly less when a method has synthetic parameters and when these parameters are
    ignored when computing parameter indices for the purpose of parameter annotations (see
    https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
  • visible – true to define the number of method parameters that can have annotations visible at runtime, false to define the number of method parameters that can have annotations invisible at runtime.
/**
   * Visits the number of method parameters that can have annotations. By default (i.e. when this
   * method is not called), all the method parameters defined by the method descriptor can have
   * annotations.
   *
   * @param parameterCount the number of method parameters than can have annotations. This number
   *     must be less or equal than the number of parameter types in the method descriptor. It can
   *     be strictly less when a method has synthetic parameters and when these parameters are
   *     ignored when computing parameter indices for the purpose of parameter annotations (see
   *     https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
   * @param visible {@literal true} to define the number of method parameters that can have
   *     annotations visible at runtime, {@literal false} to define the number of method parameters
   *     that can have annotations invisible at runtime.
   */
  public void visitAnnotableParameterCount(final int parameterCount, final boolean visible) {
    if (mv != null) {
      mv.visitAnnotableParameterCount(parameterCount, visible);
    }
  }

  
Visits an annotation of a parameter this method.

Params:
  • parameter – the parameter index. This index must be strictly smaller than the number of parameters in the method descriptor, and strictly smaller than the parameter count specified in visitAnnotableParameterCount. Important note: a parameter index i
    is not required to correspond to the i'th parameter descriptor in the method
    descriptor, in particular in case of synthetic parameters (see
    https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
  • descriptor – 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.
/**
   * Visits an annotation of a parameter this method.
   *
   * @param parameter the parameter index. This index must be strictly smaller than the number of
   *     parameters in the method descriptor, and strictly smaller than the parameter count
   *     specified in {@link #visitAnnotableParameterCount}. Important note: <i>a parameter index i
   *     is not required to correspond to the i'th parameter descriptor in the method
   *     descriptor</i>, in particular in case of synthetic parameters (see
   *     https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitParameterAnnotation(
      final int parameter, final String descriptor, final boolean visible) {
    if (mv != null) {
      return mv.visitParameterAnnotation(parameter, descriptor, visible);
    }
    return null;
  }

  
Visits a non standard attribute of this method.

Params:
  • attribute – an attribute.
/**
   * Visits a non standard attribute of this method.
   *
   * @param attribute an attribute.
   */
  public void visitAttribute(final Attribute attribute) {
    if (mv != null) {
      mv.visitAttribute(attribute);
    }
  }

  
Starts the visit of the method's code, if any (i.e. non abstract method). 
/** Starts the visit of the method's code, if any (i.e. non abstract method). */
  public void visitCode() {
    if (mv != null) {
      mv.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 unconditional 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 Opcodes.V1_6. 



The frames of a method must be given either in expanded form, or in compressed form (all frames
must use the same format, i.e. you must not mix expanded and compressed frames within a single
method):

    
  
  • In expanded form, all frames must have the F_NEW type.
  
  • In compressed form, frames are basically "deltas" from the state of the previous frame:
      
      
        
    • 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 ( numStack 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 (
            numLocal 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 (numLocal is 1, 2 or 3).
        
    • Opcodes.F_FULL representing complete frame data. 
    




In both cases the first frame, corresponding to the method's parameters and access flags, is
implicit and must not be visited. Also, it is illegal to visit two or more frames for the same
code location (i.e., at least one instruction must be visited between two calls to visitFrame).

Params:
Throws:
  • IllegalStateException – if a frame is visited just after another one, without any
    instruction between the two (unless this frame is a Opcodes#F_SAME frame, in which case it
    is silently ignored).
/**
   * Visits the current state of the local variables and operand stack elements. This method must(*)
   * be called <i>just before</i> any instruction <b>i</b> that follows an unconditional 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 <i>just before</i> <b>i</b> is executed.<br>
   * <br>
   * (*) this is mandatory only for classes whose version is greater than or equal to {@link
   * Opcodes#V1_6}. <br>
   * <br>
   * The frames of a method must be given either in expanded form, or in compressed form (all frames
   * must use the same format, i.e. you must not mix expanded and compressed frames within a single
   * method):
   *
   * <ul>
   *   <li>In expanded form, all frames must have the F_NEW type.
   *   <li>In compressed form, frames are basically "deltas" from the state of the previous frame:
   *       <ul>
   *         <li>{@link Opcodes#F_SAME} representing frame with exactly the same locals as the
   *             previous frame and with the empty stack.
   *         <li>{@link Opcodes#F_SAME1} representing frame with exactly the same locals as the
   *             previous frame and with single value on the stack ( <code>numStack</code> is 1 and
   *             <code>stack[0]</code> contains value for the type of the stack item).
   *         <li>{@link Opcodes#F_APPEND} representing frame with current locals are the same as the
   *             locals in the previous frame, except that additional locals are defined (<code>
   *             numLocal</code> is 1, 2 or 3 and <code>local</code> elements contains values
   *             representing added types).
   *         <li>{@link 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 (<code>numLocal</code> is 1, 2 or 3).
   *         <li>{@link Opcodes#F_FULL} representing complete frame data.
   *       </ul>
   * </ul>
   *
   * <br>
   * In both cases the first frame, corresponding to the method's parameters and access flags, is
   * implicit and must not be visited. Also, it is illegal to visit two or more frames for the same
   * code location (i.e., at least one instruction must be visited between two calls to visitFrame).
   *
   * @param type the type of this stack map frame. Must be {@link Opcodes#F_NEW} for expanded
   *     frames, or {@link Opcodes#F_FULL}, {@link Opcodes#F_APPEND}, {@link Opcodes#F_CHOP}, {@link
   *     Opcodes#F_SAME} or {@link Opcodes#F_APPEND}, {@link Opcodes#F_SAME1} for compressed frames.
   * @param numLocal the number of local variables in the visited frame.
   * @param local the local variable types in this frame. This array must not be modified. Primitive
   *     types are represented by {@link Opcodes#TOP}, {@link Opcodes#INTEGER}, {@link
   *     Opcodes#FLOAT}, {@link Opcodes#LONG}, {@link Opcodes#DOUBLE}, {@link Opcodes#NULL} or
   *     {@link 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).
   * @param numStack the number of operand stack elements in the visited frame.
   * @param stack the operand stack types in this frame. This array must not be modified. Its
   *     content has the same format as the "local" array.
   * @throws IllegalStateException if a frame is visited just after another one, without any
   *     instruction between the two (unless this frame is a Opcodes#F_SAME frame, in which case it
   *     is silently ignored).
   */
  public void visitFrame(
      final int type,
      final int numLocal,
      final Object[] local,
      final int numStack,
      final Object[] stack) {
    if (mv != null) {
      mv.visitFrame(type, numLocal, local, numStack, stack);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // Normal instructions
  // -----------------------------------------------------------------------------------------------

  
Visits a zero operand instruction.

Params:
  • 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.
/**
   * Visits a zero operand instruction.
   *
   * @param 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.
   */
  public void visitInsn(final int opcode) {
    if (mv != null) {
      mv.visitInsn(opcode);
    }
  }

  
Visits an instruction with a single int operand.

Params:
/**
   * Visits an instruction with a single int operand.
   *
   * @param opcode the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH
   *     or NEWARRAY.
   * @param operand the operand of the instruction to be visited.<br>
   *     When opcode is BIPUSH, operand value should be between Byte.MIN_VALUE and Byte.MAX_VALUE.
   *     <br>
   *     When opcode is SIPUSH, operand value should be between Short.MIN_VALUE and Short.MAX_VALUE.
   *     <br>
   *     When opcode is NEWARRAY, operand value should be one of {@link Opcodes#T_BOOLEAN}, {@link
   *     Opcodes#T_CHAR}, {@link Opcodes#T_FLOAT}, {@link Opcodes#T_DOUBLE}, {@link Opcodes#T_BYTE},
   *     {@link Opcodes#T_SHORT}, {@link Opcodes#T_INT} or {@link Opcodes#T_LONG}.
   */
  public void visitIntInsn(final int opcode, final int operand) {
    if (mv != null) {
      mv.visitIntInsn(opcode, operand);
    }
  }

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

Params:
  • 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.
/**
   * Visits a local variable instruction. A local variable instruction is an instruction that loads
   * or stores the value of a local variable.
   *
   * @param 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.
   * @param var the operand of the instruction to be visited. This operand is the index of a local
   *     variable.
   */
  public void visitVarInsn(final int opcode, final int var) {
    if (mv != null) {
      mv.visitVarInsn(opcode, var);
    }
  }

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

Params:
  • 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()).
/**
   * Visits a type instruction. A type instruction is an instruction that takes the internal name of
   * a class as parameter.
   *
   * @param opcode the opcode of the type instruction to be visited. This opcode is either NEW,
   *     ANEWARRAY, CHECKCAST or INSTANCEOF.
   * @param type the operand of the instruction to be visited. This operand must be the internal
   *     name of an object or array class (see {@link Type#getInternalName()}).
   */
  public void visitTypeInsn(final int opcode, final String type) {
    if (mv != null) {
      mv.visitTypeInsn(opcode, type);
    }
  }

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

Params:
  • 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.
  • descriptor – the field's descriptor (see Type).
/**
   * Visits a field instruction. A field instruction is an instruction that loads or stores the
   * value of a field of an object.
   *
   * @param opcode the opcode of the type instruction to be visited. This opcode is either
   *     GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
   * @param owner the internal name of the field's owner class (see {@link Type#getInternalName()}).
   * @param name the field's name.
   * @param descriptor the field's descriptor (see {@link Type}).
   */
  public void visitFieldInsn(
      final int opcode, final String owner, final String name, final String descriptor) {
    if (mv != null) {
      mv.visitFieldInsn(opcode, owner, name, descriptor);
    }
  }

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

Params:
  • 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.
  • descriptor – the method's descriptor (see Type).
Deprecated:use visitMethodInsn(int, String, String, String, boolean) instead.
/**
   * Visits a method instruction. A method instruction is an instruction that invokes a method.
   *
   * @param opcode the opcode of the type instruction to be visited. This opcode is either
   *     INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
   * @param owner the internal name of the method's owner class (see {@link
   *     Type#getInternalName()}).
   * @param name the method's name.
   * @param descriptor the method's descriptor (see {@link Type}).
   * @deprecated use {@link #visitMethodInsn(int, String, String, String, boolean)} instead.
   */
  @Deprecated
  public void visitMethodInsn(
      final int opcode, final String owner, final String name, final String descriptor) {
    int opcodeAndSource = opcode | (api < Opcodes.ASM5 ? Opcodes.SOURCE_DEPRECATED : 0);
    visitMethodInsn(opcodeAndSource, owner, name, descriptor, opcode == Opcodes.INVOKEINTERFACE);
  }

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

Params:
  • 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.
  • descriptor – the method's descriptor (see Type).
  • isInterface – if the method's owner class is an interface.
/**
   * Visits a method instruction. A method instruction is an instruction that invokes a method.
   *
   * @param opcode the opcode of the type instruction to be visited. This opcode is either
   *     INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
   * @param owner the internal name of the method's owner class (see {@link
   *     Type#getInternalName()}).
   * @param name the method's name.
   * @param descriptor the method's descriptor (see {@link Type}).
   * @param isInterface if the method's owner class is an interface.
   */
  public void visitMethodInsn(
      final int opcode,
      final String owner,
      final String name,
      final String descriptor,
      final boolean isInterface) {
    if (api < Opcodes.ASM5 && (opcode & Opcodes.SOURCE_DEPRECATED) == 0) {
      if (isInterface != (opcode == Opcodes.INVOKEINTERFACE)) {
        throw new UnsupportedOperationException("INVOKESPECIAL/STATIC on interfaces requires ASM5");
      }
      visitMethodInsn(opcode, owner, name, descriptor);
      return;
    }
    if (mv != null) {
      mv.visitMethodInsn(opcode & ~Opcodes.SOURCE_MASK, owner, name, descriptor, isInterface);
    }
  }

  
Visits an invokedynamic instruction.

Params:
  • name – the method's name.
  • descriptor – the method's descriptor (see Type).
  • bootstrapMethodHandle – the bootstrap method.
  • bootstrapMethodArguments – the bootstrap method constant arguments. Each argument must be an Integer, Float, Long, Double, String, Type, Handle or ConstantDynamic value. This method is allowed to modify the content of the array so a caller should expect that this array may change.
/**
   * Visits an invokedynamic instruction.
   *
   * @param name the method's name.
   * @param descriptor the method's descriptor (see {@link Type}).
   * @param bootstrapMethodHandle the bootstrap method.
   * @param bootstrapMethodArguments the bootstrap method constant arguments. Each argument must be
   *     an {@link Integer}, {@link Float}, {@link Long}, {@link Double}, {@link String}, {@link
   *     Type}, {@link Handle} or {@link ConstantDynamic} value. This method is allowed to modify
   *     the content of the array so a caller should expect that this array may change.
   */
  public void visitInvokeDynamicInsn(
      final String name,
      final String descriptor,
      final Handle bootstrapMethodHandle,
      final Object... bootstrapMethodArguments) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      mv.visitInvokeDynamicInsn(name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments);
    }
  }

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

Params:
  • 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.
/**
   * Visits a jump instruction. A jump instruction is an instruction that may jump to another
   * instruction.
   *
   * @param 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.
   * @param 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.
   */
  public void visitJumpInsn(final int opcode, final Label label) {
    if (mv != null) {
      mv.visitJumpInsn(opcode, label);
    }
  }

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

Params:
  • label – a Label object.
/**
   * Visits a label. A label designates the instruction that will be visited just after it.
   *
   * @param label a {@link Label} object.
   */
  public void visitLabel(final Label label) {
    if (mv != null) {
      mv.visitLabel(label);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // Special instructions
  // -----------------------------------------------------------------------------------------------

  
Visits a LDC instruction. Note that new constant types may be added in future versions of the
Java Virtual Machine. To easily detect new constant types, implementations of this method
should check for unexpected constant types, like this:

if (cst instanceof Integer) {
    // ...
} else if (cst instanceof Float) {
    // ...
} else if (cst instanceof Long) {
    // ...
} else if (cst instanceof Double) {
    // ...
} else if (cst instanceof String) {
    // ...
} else if (cst instanceof Type) {
    int sort = ((Type) cst).getSort();
    if (sort == Type.OBJECT) {
        // ...
    } else if (sort == Type.ARRAY) {
        // ...
    } else if (sort == Type.METHOD) {
        // ...
    } else {
        // throw an exception
    }
} else if (cst instanceof Handle) {
    // ...
} else if (cst instanceof ConstantDynamic) {
    // ...
} else {
    // throw an exception
}



Params:
  • value – the constant to be loaded on the stack. This parameter must be a non null Integer, a Float, a Long, a Double, a String, a Type of OBJECT or ARRAY sort for .class constants, for classes whose version is 49, a Type of METHOD sort for MethodType, a Handle for MethodHandle constants, for classes whose version is 51 or a ConstantDynamic for a constant dynamic for classes whose version is 55.
/**
   * Visits a LDC instruction. Note that new constant types may be added in future versions of the
   * Java Virtual Machine. To easily detect new constant types, implementations of this method
   * should check for unexpected constant types, like this:
   *
   * <pre>
   * if (cst instanceof Integer) {
   *     // ...
   * } else if (cst instanceof Float) {
   *     // ...
   * } else if (cst instanceof Long) {
   *     // ...
   * } else if (cst instanceof Double) {
   *     // ...
   * } else if (cst instanceof String) {
   *     // ...
   * } else if (cst instanceof Type) {
   *     int sort = ((Type) cst).getSort();
   *     if (sort == Type.OBJECT) {
   *         // ...
   *     } else if (sort == Type.ARRAY) {
   *         // ...
   *     } else if (sort == Type.METHOD) {
   *         // ...
   *     } else {
   *         // throw an exception
   *     }
   * } else if (cst instanceof Handle) {
   *     // ...
   * } else if (cst instanceof ConstantDynamic) {
   *     // ...
   * } else {
   *     // throw an exception
   * }
   * </pre>
   *
   * @param value the constant to be loaded on the stack. This parameter must be a non null {@link
   *     Integer}, a {@link Float}, a {@link Long}, a {@link Double}, a {@link String}, a {@link
   *     Type} of OBJECT or ARRAY sort for {@code .class} constants, for classes whose version is
   *     49, a {@link Type} of METHOD sort for MethodType, a {@link Handle} for MethodHandle
   *     constants, for classes whose version is 51 or a {@link ConstantDynamic} for a constant
   *     dynamic for classes whose version is 55.
   */
  public void visitLdcInsn(final Object value) {
    if (api < Opcodes.ASM5
        && (value instanceof Handle
            || (value instanceof Type && ((Type) value).getSort() == Type.METHOD))) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (api < Opcodes.ASM7 && value instanceof ConstantDynamic) {
      throw new UnsupportedOperationException("This feature requires ASM7");
    }
    if (mv != null) {
      mv.visitLdcInsn(value);
    }
  }

  
Visits an IINC instruction.

Params:
  • var – index of the local variable to be incremented.
  • increment – amount to increment the local variable by.
/**
   * Visits an IINC instruction.
   *
   * @param var index of the local variable to be incremented.
   * @param increment amount to increment the local variable by.
   */
  public void visitIincInsn(final int var, final int increment) {
    if (mv != null) {
      mv.visitIincInsn(var, increment);
    }
  }

  
Visits a TABLESWITCH instruction.

Params:
  • 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.
/**
   * Visits a TABLESWITCH instruction.
   *
   * @param min the minimum key value.
   * @param max the maximum key value.
   * @param dflt beginning of the default handler block.
   * @param labels beginnings of the handler blocks. {@code labels[i]} is the beginning of the
   *     handler block for the {@code min + i} key.
   */
  public void visitTableSwitchInsn(
      final int min, final int max, final Label dflt, final Label... labels) {
    if (mv != null) {
      mv.visitTableSwitchInsn(min, max, dflt, labels);
    }
  }

  
Visits a LOOKUPSWITCH instruction.

Params:
  • 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.
/**
   * Visits a LOOKUPSWITCH instruction.
   *
   * @param dflt beginning of the default handler block.
   * @param keys the values of the keys.
   * @param labels beginnings of the handler blocks. {@code labels[i]} is the beginning of the
   *     handler block for the {@code keys[i]} key.
   */
  public void visitLookupSwitchInsn(final Label dflt, final int[] keys, final Label[] labels) {
    if (mv != null) {
      mv.visitLookupSwitchInsn(dflt, keys, labels);
    }
  }

  
Visits a MULTIANEWARRAY instruction.

Params:
  • descriptor – an array type descriptor (see Type).
  • numDimensions – the number of dimensions of the array to allocate.
/**
   * Visits a MULTIANEWARRAY instruction.
   *
   * @param descriptor an array type descriptor (see {@link Type}).
   * @param numDimensions the number of dimensions of the array to allocate.
   */
  public void visitMultiANewArrayInsn(final String descriptor, final int numDimensions) {
    if (mv != null) {
      mv.visitMultiANewArrayInsn(descriptor, numDimensions);
    }
  }

  
Visits an annotation on an instruction. This method must be called just after the
annotated instruction. It can be called several times for the same instruction.

Params:
Returns:a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
/**
   * Visits an annotation on an instruction. This method must be called just <i>after</i> the
   * annotated instruction. It can be called several times for the same instruction.
   *
   * @param typeRef a reference to the annotated type. The sort of this type reference must be
   *     {@link TypeReference#INSTANCEOF}, {@link TypeReference#NEW}, {@link
   *     TypeReference#CONSTRUCTOR_REFERENCE}, {@link TypeReference#METHOD_REFERENCE}, {@link
   *     TypeReference#CAST}, {@link TypeReference#CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT}, {@link
   *     TypeReference#METHOD_INVOCATION_TYPE_ARGUMENT}, {@link
   *     TypeReference#CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or {@link
   *     TypeReference#METHOD_REFERENCE_TYPE_ARGUMENT}. See {@link TypeReference}.
   * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
   *     static inner type within 'typeRef'. May be {@literal null} if the annotation targets
   *     'typeRef' as a whole.
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitInsnAnnotation(
      final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      return mv.visitInsnAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  // -----------------------------------------------------------------------------------------------
  // Exceptions table entries, debug information, max stack and max locals
  // -----------------------------------------------------------------------------------------------

  
Visits a try catch block.

Params:
  • start – the beginning of the exception handler's scope (inclusive).
  • end – the end of the exception handler's scope (exclusive).
  • handler – the beginning of the exception handler's code.
  • type – the internal name of the type of exceptions handled by the handler, or 
    null to catch any exceptions (for "finally" blocks).
Throws:
/**
   * Visits a try catch block.
   *
   * @param start the beginning of the exception handler's scope (inclusive).
   * @param end the end of the exception handler's scope (exclusive).
   * @param handler the beginning of the exception handler's code.
   * @param type the internal name of the type of exceptions handled by the handler, or {@literal
   *     null} to catch any exceptions (for "finally" blocks).
   * @throws IllegalArgumentException if one of the labels has already been visited by this visitor
   *     (by the {@link #visitLabel} method).
   */
  public void visitTryCatchBlock(
      final Label start, final Label end, final Label handler, final String type) {
    if (mv != null) {
      mv.visitTryCatchBlock(start, end, handler, type);
    }
  }

  
Visits an annotation on an exception handler type. This method must be called after the visitTryCatchBlock for the annotated exception handler. It can be called several times for the same exception handler. 
Params:
  • typeRef – a reference to the annotated type. The sort of this type reference must be TypeReference.EXCEPTION_PARAMETER. See TypeReference.
  • typePath – the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.
  • descriptor – 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.
/**
   * Visits an annotation on an exception handler type. This method must be called <i>after</i> the
   * {@link #visitTryCatchBlock} for the annotated exception handler. It can be called several times
   * for the same exception handler.
   *
   * @param typeRef a reference to the annotated type. The sort of this type reference must be
   *     {@link TypeReference#EXCEPTION_PARAMETER}. See {@link TypeReference}.
   * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
   *     static inner type within 'typeRef'. May be {@literal null} if the annotation targets
   *     'typeRef' as a whole.
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitTryCatchAnnotation(
      final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      return mv.visitTryCatchAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  
Visits a local variable declaration.

Params:
  • name – the name of a local variable.
  • descriptor – 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:
/**
   * Visits a local variable declaration.
   *
   * @param name the name of a local variable.
   * @param descriptor the type descriptor of this local variable.
   * @param signature the type signature of this local variable. May be {@literal null} if the local
   *     variable type does not use generic types.
   * @param start the first instruction corresponding to the scope of this local variable
   *     (inclusive).
   * @param end the last instruction corresponding to the scope of this local variable (exclusive).
   * @param index the local variable's index.
   * @throws IllegalArgumentException if one of the labels has not already been visited by this
   *     visitor (by the {@link #visitLabel} method).
   */
  public void visitLocalVariable(
      final String name,
      final String descriptor,
      final String signature,
      final Label start,
      final Label end,
      final int index) {
    if (mv != null) {
      mv.visitLocalVariable(name, descriptor, signature, start, end, index);
    }
  }

  
Visits an annotation on a local variable type.

Params:
  • typeRef – a reference to the annotated type. The sort of this type reference must be TypeReference.LOCAL_VARIABLE or TypeReference.RESOURCE_VARIABLE. See TypeReference.
  • typePath – the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.
  • start – the fist instructions corresponding to the continuous ranges that make the scope
    of this local variable (inclusive).
  • end – the last instructions corresponding to the continuous ranges that make the scope of
    this local variable (exclusive). This array must have the same size as the 'start' array.
  • index – the local variable's index in each range. This array must have the same size as
    the 'start' array.
  • descriptor – 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.
/**
   * Visits an annotation on a local variable type.
   *
   * @param typeRef a reference to the annotated type. The sort of this type reference must be
   *     {@link TypeReference#LOCAL_VARIABLE} or {@link TypeReference#RESOURCE_VARIABLE}. See {@link
   *     TypeReference}.
   * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
   *     static inner type within 'typeRef'. May be {@literal null} if the annotation targets
   *     'typeRef' as a whole.
   * @param start the fist instructions corresponding to the continuous ranges that make the scope
   *     of this local variable (inclusive).
   * @param end the last instructions corresponding to the continuous ranges that make the scope of
   *     this local variable (exclusive). This array must have the same size as the 'start' array.
   * @param index the local variable's index in each range. This array must have the same size as
   *     the 'start' array.
   * @param descriptor the class descriptor of the annotation class.
   * @param visible {@literal true} if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or {@literal null} if this visitor is not
   *     interested in visiting this annotation.
   */
  public AnnotationVisitor visitLocalVariableAnnotation(
      final int typeRef,
      final TypePath typePath,
      final Label[] start,
      final Label[] end,
      final int[] index,
      final String descriptor,
      final boolean visible) {
    if (api < Opcodes.ASM5) {
      throw new UnsupportedOperationException(REQUIRES_ASM5);
    }
    if (mv != null) {
      return mv.visitLocalVariableAnnotation(
          typeRef, typePath, start, end, index, descriptor, visible);
    }
    return null;
  }

  
Visits a line number declaration.

Params:
  • 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:
/**
   * Visits a line number declaration.
   *
   * @param line a line number. This number refers to the source file from which the class was
   *     compiled.
   * @param start the first instruction corresponding to this line number.
   * @throws IllegalArgumentException if {@code start} has not already been visited by this visitor
   *     (by the {@link #visitLabel} method).
   */
  public void visitLineNumber(final int line, final Label start) {
    if (mv != null) {
      mv.visitLineNumber(line, start);
    }
  }

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

Params:
  • maxStack – maximum stack size of the method.
  • maxLocals – maximum number of local variables for the method.
/**
   * Visits the maximum stack size and the maximum number of local variables of the method.
   *
   * @param maxStack maximum stack size of the method.
   * @param maxLocals maximum number of local variables for the method.
   */
  public void visitMaxs(final int maxStack, final int maxLocals) {
    if (mv != null) {
      mv.visitMaxs(maxStack, 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.

/**
   * 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.
   */
  public void visitEnd() {
    if (mv != null) {
      mv.visitEnd();
    }
  }
}