Package org.apache.bcel.generic

Class Instruction

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static InstructionComparator cmp  
      protected short length
      Deprecated.
      (since 6.0) will be made private; do not access directly, use getter/setter
      protected short opcode
      Deprecated.
      (since 6.0) will be made private; do not access directly, use getter/setter

    • Constructor Summary

      Constructors 
      Constructor Description
      Instruction()
      Empty constructor needed for Instruction.readInstruction.
      Instruction​(short opcode, short length)  

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      abstract void accept​(Visitor v)
      Call corresponding visitor method(s).
      int consumeStack​(ConstantPoolGen cpg)
      This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
      Instruction copy()
      Use with caution, since `BranchInstruction's have a `target' reference which is not copied correctly (only basic types are).
      (package private) void dispose()
      Some instructions may be reused, so don't do anything by default.
      void dump​(java.io.DataOutputStream out)
      Dump instruction as byte code to stream out.
      boolean equals​(java.lang.Object that)
      Check for equality, delegated to comparator
      static InstructionComparator getComparator()
      Deprecated.
      (6.0) use the built in comparator, or wrap this class in another object that implements these methods
      int getLength()  
      java.lang.String getName()  
      short getOpcode()  
      int hashCode()
      calculate the hashCode of this object
      protected void initFromFile​(ByteSequence bytes, boolean wide)
      Read needed data (e.g.
      static boolean isValidByte​(int value)
      Check if the value can fit in a byte (signed)
      static boolean isValidShort​(int value)
      Check if the value can fit in a short (signed)
      int produceStack​(ConstantPoolGen cpg)
      This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
      static Instruction readInstruction​(ByteSequence bytes)
      Read an instruction from (byte code) input stream and return the appropiate object.
      static void setComparator​(InstructionComparator c)
      Deprecated.
      (6.0) use the built in comparator, or wrap this class in another object that implements these methods
      (package private) void setLength​(int length)
      Needed in readInstruction and subclasses in this package
      (package private) void setOpcode​(short opcode)
      Needed in readInstruction and subclasses in this package
      java.lang.String toString()  
      java.lang.String toString​(boolean verbose)
      Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")"
      java.lang.String toString​(ConstantPool cp)  

      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    • Field Detail

      • length

        @Deprecated
protected short length
        Deprecated.
        (since 6.0) will be made private; do not access directly, use getter/setter

      • opcode

        @Deprecated
protected short opcode
        Deprecated.
        (since 6.0) will be made private; do not access directly, use getter/setter

    • Constructor Detail

      • Instruction

        Instruction()
        Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.

      • Instruction

        public Instruction​(short opcode,
                   short length)

    • Method Detail

      • dump

        public void dump​(java.io.DataOutputStream out)
          throws java.io.IOException
        Dump instruction as byte code to stream out.
        Parameters:
        out - Output stream
        Throws:
        java.io.IOException

      • getName

        public java.lang.String getName()
        Returns:
        name of instruction, i.e., opcode name

      • toString

        public java.lang.String toString​(boolean verbose)
        Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")"
        Parameters:
        verbose - long/short format switch
        Returns:
        mnemonic for instruction

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object
        Returns:
        mnemonic for instruction in verbose format

      • toString

        public java.lang.String toString​(ConstantPool cp)
        Returns:
        mnemonic for instruction with sumbolic references resolved

      • copy

        public Instruction copy()
        Use with caution, since `BranchInstruction's have a `target' reference which is not copied correctly (only basic types are). This also applies for `Select' instructions with their multiple branch targets.
        Returns:
        (shallow) copy of an instruction
        See Also:
        BranchInstruction

      • initFromFile

        protected void initFromFile​(ByteSequence bytes,
                            boolean wide)
                     throws java.io.IOException
        Read needed data (e.g. index) from file.
        Parameters:
        bytes - byte sequence to read from
        wide - "wide" instruction flag
        Throws:
        java.io.IOException - may be thrown if the implementation needs to read data from the file

      • readInstruction

        public static Instruction readInstruction​(ByteSequence bytes)
                                   throws java.io.IOException
        Read an instruction from (byte code) input stream and return the appropiate object.

        If the Instruction is defined in InstructionConst, then the singleton instance is returned.

        Parameters:
        bytes - input stream bytes
        Returns:
        instruction object being read
        Throws:
        java.io.IOException
        See Also:
        InstructionConst.getInstruction(int)

      • consumeStack

        public int consumeStack​(ConstantPoolGen cpg)
        This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
        Returns:
        Number of words consumed from stack by this instruction, or Constants.UNPREDICTABLE, if this can not be computed statically

      • produceStack

        public int produceStack​(ConstantPoolGen cpg)
        This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
        Returns:
        Number of words produced onto stack by this instruction, or Constants.UNPREDICTABLE, if this can not be computed statically

      • getOpcode

        public short getOpcode()
        Returns:
        this instructions opcode

      • getLength

        public int getLength()
        Returns:
        length (in bytes) of instruction

      • setOpcode

        final void setOpcode​(short opcode)
        Needed in readInstruction and subclasses in this package

      • setLength

        final void setLength​(int length)
        Needed in readInstruction and subclasses in this package
        Since:
        6.0

      • dispose

        void dispose()
        Some instructions may be reused, so don't do anything by default.

      • accept

        public abstract void accept​(Visitor v)
        Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
        Parameters:
        v - Visitor object

      • getComparator

        @Deprecated
public static InstructionComparator getComparator()
        Deprecated.
        (6.0) use the built in comparator, or wrap this class in another object that implements these methods
        Get Comparator object used in the equals() method to determine equality of instructions.
        Returns:
        currently used comparator for equals()

      • setComparator

        @Deprecated
public static void setComparator​(InstructionComparator c)
        Deprecated.
        (6.0) use the built in comparator, or wrap this class in another object that implements these methods
        Set comparator to be used for equals().

      • equals

        public boolean equals​(java.lang.Object that)
        Check for equality, delegated to comparator
        Overrides:
        equals in class java.lang.Object
        Returns:
        true if that is an Instruction and has the same opcode

      • hashCode

        public int hashCode()
        calculate the hashCode of this object
        Overrides:
        hashCode in class java.lang.Object
        Returns:
        the hashCode
        Since:
        6.0

      • isValidByte

        public static boolean isValidByte​(int value)
        Check if the value can fit in a byte (signed)
        Parameters:
        value - the value to check
        Returns:
        true if the value is in range
        Since:
        6.0

      • isValidShort

        public static boolean isValidShort​(int value)
        Check if the value can fit in a short (signed)
        Parameters:
        value - the value to check
        Returns:
        true if the value is in range
        Since:
        6.0