Package org.apache.bcel.generic

Class MethodGen

  • All Implemented Interfaces:
    java.lang.Cloneable, NamedAndTyped
    public class MethodGen
extends FieldGenOrMethodGen
    Template class for building up a method. This is done by defining exception handlers, adding thrown exceptions, local variables and attributes, whereas the 'LocalVariableTable' and 'LineNumberTable' attributes will be set automatically for the code. Use stripAttributes() if you don't like this. While generating code it may be necessary to insert NOP operations. You can use the 'removeNOPs' method to get rid off them. The resulting method object can be obtained via the 'getMethod()' method.
    See Also:
    InstructionList, Method

    • Field Detail

      • className

        private java.lang.String className

      • argTypes

        private Type[] argTypes

      • argNames

        private java.lang.String[] argNames

      • maxLocals

        private int maxLocals

      • maxStack

        private int maxStack

      • stripAttributes

        private boolean stripAttributes

      • lineNumberList

        private final java.util.List<LineNumberGen> lineNumberList

      • throwsList

        private final java.util.List<java.lang.String> throwsList

      • codeAttrsList

        private final java.util.List<Attribute> codeAttrsList

      • hasParameterAnnotations

        private boolean hasParameterAnnotations

      • haveUnpackedParameterAnnotations

        private boolean haveUnpackedParameterAnnotations

    • Constructor Detail

      • MethodGen

        public MethodGen​(int accessFlags,
                 Type returnType,
                 Type[] argTypes,
                 java.lang.String[] argNames,
                 java.lang.String methodName,
                 java.lang.String className,
                 InstructionList il,
                 ConstantPoolGen cp)
        Declare method. If the method is non-static the constructor automatically declares a local variable '$this' in slot 0. The actual code is contained in the 'il' parameter, which may further manipulated by the user. But they must take care not to remove any instruction (handles) that are still referenced from this object. For example one may not add a local variable and later remove the instructions it refers to without causing havoc. It is safe however if you remove that local variable, too.
        Parameters:
        accessFlags - access qualifiers.
        returnType - method type.
        argTypes - argument types.
        argNames - argument names (if this is null, default names will be provided for them).
        methodName - name of method.
        className - class name containing this method (may be null, if you don't care).
        il - instruction list associated with this method, may be null only for abstract or native methods.
        cp - constant pool.

      • MethodGen

        public MethodGen​(Method method,
                 java.lang.String className,
                 ConstantPoolGen cp)
        Instantiate from existing method.
        Parameters:
        method - method.
        className - class name containing this method.
        cp - constant pool.

    • Method Detail

      • getByteCodes

        private static byte[] getByteCodes​(Method method)

      • getMaxStack

        public static int getMaxStack​(ConstantPoolGen cp,
                              InstructionList il,
                              CodeExceptionGen[] et)
        Computes stack usage of an instruction list by performing control flow analysis.
        Parameters:
        cp - the constant pool generator.
        il - the instruction list.
        et - the exception handlers.
        Returns:
        maximum stack depth used by method.

      • setComparator

        public static void setComparator​(BCELComparator<FieldGenOrMethodGen> comparator)
        Sets the comparison strategy object.
        Parameters:
        comparator - Comparison strategy object.

      • addAnnotationsAsAttribute

        public void addAnnotationsAsAttribute​(ConstantPoolGen cp)
        Adds annotations as an attribute.
        Parameters:
        cp - the constant pool generator.
        Since:
        6.0

      • addCodeAttribute

        public void addCodeAttribute​(Attribute a)
        Add an attribute to the code. Currently, the JVM knows about the LineNumberTable, LocalVariableTable and StackMap attributes, where the former two will be generated automatically and the latter is used for the MIDP only. Other attributes will be ignored by the JVM but do no harm.
        Parameters:
        a - attribute to be added.

      • addException

        public void addException​(java.lang.String className)
        Add an exception possibly thrown by this method.
        Parameters:
        className - (fully qualified) name of exception.

      • addExceptionHandler

        public CodeExceptionGen addExceptionHandler​(InstructionHandle startPc,
                                            InstructionHandle endPc,
                                            InstructionHandle handlerPc,
                                            ObjectType catchType)
        Add an exception handler, that is, specify region where a handler is active and an instruction where the actual handling is done.
        Parameters:
        startPc - Start of region (inclusive).
        endPc - End of region (inclusive).
        handlerPc - Where handling is done.
        catchType - class type of handled exception or null if any exception is handled.
        Returns:
        new exception handler object.

      • addLineNumber

        public LineNumberGen addLineNumber​(InstructionHandle ih,
                                   int srcLine)
        Give an instruction a line number corresponding to the source code line.
        Parameters:
        ih - instruction to tag.
        srcLine - the source line number.
        Returns:
        new line number object.
        See Also:
        LineNumber

      • addLocalVariable

        public LocalVariableGen addLocalVariable​(java.lang.String name,
                                         Type type,
                                         InstructionHandle start,
                                         InstructionHandle end)
        Adds a local variable to this method and assigns an index automatically.
        Parameters:
        name - variable name.
        type - variable type.
        start - from where the variable is valid, if this is null, it is valid from the start.
        end - until where the variable is valid, if this is null, it is valid to the end.
        Returns:
        new local variable object.
        See Also:
        LocalVariable

      • addLocalVariable

        public LocalVariableGen addLocalVariable​(java.lang.String name,
                                         Type type,
                                         int slot,
                                         InstructionHandle start,
                                         InstructionHandle end)
        Adds a local variable to this method.
        Parameters:
        name - variable name.
        type - variable type.
        slot - the index of the local variable, if type is long or double, the next available index is slot+2.
        start - from where the variable is valid.
        end - until where the variable is valid.
        Returns:
        new local variable object.
        See Also:
        LocalVariable

      • addLocalVariable

        public LocalVariableGen addLocalVariable​(java.lang.String name,
                                         Type type,
                                         int slot,
                                         InstructionHandle start,
                                         InstructionHandle end,
                                         int origIndex)
        Adds a local variable to this method.
        Parameters:
        name - variable name.
        type - variable type.
        slot - the index of the local variable, if type is long or double, the next available index is slot+2.
        start - from where the variable is valid.
        end - until where the variable is valid.
        origIndex - the index of the local variable prior to any modifications.
        Returns:
        new local variable object.
        See Also:
        LocalVariable

      • addObserver

        public void addObserver​(MethodObserver o)
        Add observer for this object.
        Parameters:
        o - the observer to add.

      • addParameterAnnotation

        public void addParameterAnnotation​(int parameterIndex,
                                   AnnotationEntryGen annotation)
        Adds a parameter annotation.
        Parameters:
        parameterIndex - the parameter index.
        annotation - the annotation.

      • addParameterAnnotationsAsAttribute

        public void addParameterAnnotationsAsAttribute​(ConstantPoolGen cp)
        Adds parameter annotations as an attribute.
        Parameters:
        cp - the constant pool generator.
        Since:
        6.0

      • addRuntimeParameterAnnotationsAsAttribute

        private Attribute[] addRuntimeParameterAnnotationsAsAttribute​(ConstantPoolGen cp)

      • adjustLocalVariableTypeTable

        private void adjustLocalVariableTypeTable​(LocalVariableTable lvt)

      • copy

        public MethodGen copy​(java.lang.String className,
                      ConstantPoolGen cp)
        Creates a deep copy of this method.
        Parameters:
        className - the class name.
        cp - the constant pool generator.
        Returns:
        deep copy of this method.

      • ensureExistingParameterAnnotationsUnpacked

        private void ensureExistingParameterAnnotationsUnpacked()
        Goes through the attributes on the method and identifies any that are RuntimeParameterAnnotations, extracting their contents and storing them as parameter annotations. There are two kinds of parameter annotation - visible and invisible. Once they have been unpacked, these attributes are deleted. (The annotations will be rebuilt as attributes when someone builds a Method object out of this MethodGen object).

      • equals

        public boolean equals​(java.lang.Object obj)
        Return value as defined by given BCELComparator strategy. By default two MethodGen objects are said to be equal when their names and signatures are equal.
        Overrides:
        equals in class java.lang.Object
        See Also:
        Object.equals(Object)

      • getAnnotationsOnParameter

        public java.util.List<AnnotationEntryGen> getAnnotationsOnParameter​(int i)
        Return a list of AnnotationGen objects representing parameter annotations.
        Parameters:
        i - the parameter index.
        Returns:
        list of AnnotationGen objects.
        Since:
        6.0

      • getArgumentName

        public java.lang.String getArgumentName​(int i)
        Gets the argument name at the specified index.
        Parameters:
        i - the argument index.
        Returns:
        the argument name.

      • getArgumentNames

        public java.lang.String[] getArgumentNames()
        Gets all argument names.
        Returns:
        array of argument names.

      • getArgumentType

        public Type getArgumentType​(int i)
        Gets the argument type at the specified index.
        Parameters:
        i - the argument index.
        Returns:
        the argument type.

      • getArgumentTypes

        public Type[] getArgumentTypes()
        Gets all argument types.
        Returns:
        array of argument types.

      • getClassName

        public java.lang.String getClassName()
        Gets the class that contains this method.
        Returns:
        class that contains this method.

      • getCodeAttributes

        public Attribute[] getCodeAttributes()
        Gets all attributes of this method.
        Returns:
        all attributes of this method.

      • getCodeExceptions

        private CodeException[] getCodeExceptions()
        Returns:
        code exceptions for 'Code' attribute.

      • getExceptionHandlers

        public CodeExceptionGen[] getExceptionHandlers()
        Gets array of declared exception handlers.
        Returns:
        array of declared exception handlers.

      • getExceptions

        public java.lang.String[] getExceptions()
        Gets array of thrown exceptions.
        Returns:
        array of thrown exceptions.

      • getExceptionTable

        private ExceptionTable getExceptionTable​(ConstantPoolGen cp)
        Returns:
        'Exceptions' attribute of all the exceptions thrown by this method.

      • getInstructionList

        public InstructionList getInstructionList()
        Gets the instruction list.
        Returns:
        the instruction list.

      • getLineNumbers

        public LineNumberGen[] getLineNumbers()
        Gets array of line numbers.
        Returns:
        array of line numbers.

      • getLineNumberTable

        public LineNumberTable getLineNumberTable​(ConstantPoolGen cp)
        Gets the 'LineNumberTable' attribute of all the local variables of this method.
        Parameters:
        cp - the constant pool generator.
        Returns:
        'LineNumberTable' attribute of all the local variables of this method.

      • getLocalVariables

        public LocalVariableGen[] getLocalVariables()
        Gets array of declared local variables sorted by index. If the range of the variable has not been set yet, it will be set to be valid from the start to the end of the instruction list.
        Returns:
        array of declared local variables sorted by index.

      • getLocalVariableTable

        public LocalVariableTable getLocalVariableTable​(ConstantPoolGen cp)
        Gets the 'LocalVariableTable' attribute of all the local variables of this method.
        Parameters:
        cp - the constant pool generator.
        Returns:
        'LocalVariableTable' attribute of all the local variables of this method.

      • getLocalVariableTypeTable

        public LocalVariableTypeTable getLocalVariableTypeTable()
        Gets the 'LocalVariableTypeTable' attribute of this method.
        Returns:
        'LocalVariableTypeTable' attribute of this method.

      • getMaxLocals

        public int getMaxLocals()
        Gets the maximum number of local variables.
        Returns:
        the maximum number of local variables.

      • getMaxStack

        public int getMaxStack()
        Gets the maximum stack size.
        Returns:
        the maximum stack size.

      • getMethod

        public Method getMethod()
        Gets method object. Never forget to call setMaxStack() or setMaxStack(max), respectively, before calling this method (the same applies for max locals).
        Returns:
        method object.

      • getReturnType

        public Type getReturnType()
        Gets the return type.
        Returns:
        the return type.

      • hashCode

        public int hashCode()
        Return value as defined by given BCELComparator strategy. By default return the hash code of the method's name XOR signature.
        Overrides:
        hashCode in class java.lang.Object
        See Also:
        Object.hashCode()

      • removeCodeAttribute

        public void removeCodeAttribute​(Attribute a)
        Remove a code attribute.
        Parameters:
        a - the attribute to remove.

      • removeCodeAttributes

        public void removeCodeAttributes()
        Remove all code attributes.

      • removeException

        public void removeException​(java.lang.String c)
        Remove an exception.
        Parameters:
        c - the exception to remove.

      • removeExceptionHandler

        public void removeExceptionHandler​(CodeExceptionGen c)
        Remove an exception handler.
        Parameters:
        c - the exception handler to remove.

      • removeExceptionHandlers

        public void removeExceptionHandlers()
        Remove all line numbers.

      • removeExceptions

        public void removeExceptions()
        Remove all exceptions.

      • removeLineNumber

        public void removeLineNumber​(LineNumberGen l)
        Remove a line number.
        Parameters:
        l - the line number to remove.

      • removeLineNumbers

        public void removeLineNumbers()
        Remove all line numbers.

      • removeLocalVariable

        public void removeLocalVariable​(LocalVariableGen l)
        Remove a local variable, its slot will not be reused, if you do not use addLocalVariable with an explicit index argument.
        Parameters:
        l - the local variable to remove.

      • removeLocalVariables

        public void removeLocalVariables()
        Remove all local variables.

      • removeLocalVariableTypeTable

        public void removeLocalVariableTypeTable()
        Remove the LocalVariableTypeTable

      • removeNOPs

        public void removeNOPs()
        Remove all NOPs from the instruction list (if possible) and update every object referring to them, that is, branch instructions, local variables and exception handlers.

      • removeObserver

        public void removeObserver​(MethodObserver o)
        Remove observer for this object.
        Parameters:
        o - the observer to remove.

      • removeRuntimeAttributes

        public void removeRuntimeAttributes​(Attribute[] attributes)
        Would prefer to make this private, but need a way to test if client is using BCEL version 6.5.0 or later that contains fix for BCEL-329.
        Parameters:
        attributes - the attributes to remove.
        Since:
        6.5.0

      • setArgumentName

        public void setArgumentName​(int i,
                            java.lang.String name)
        Sets the argument name at the specified index.
        Parameters:
        i - the argument index.
        name - the argument name.

      • setArgumentNames

        public void setArgumentNames​(java.lang.String[] argNames)
        Sets all argument names.
        Parameters:
        argNames - the argument names.

      • setArgumentType

        public void setArgumentType​(int i,
                            Type type)
        Sets the argument type at the specified index.
        Parameters:
        i - the argument index.
        type - the argument type.

      • setArgumentTypes

        public void setArgumentTypes​(Type[] argTypes)
        Sets all argument types.
        Parameters:
        argTypes - the argument types.

      • setClassName

        public void setClassName​(java.lang.String className)
        Sets the class name.
        Parameters:
        className - the class name.

      • setInstructionList

        public void setInstructionList​(InstructionList il)
        Sets the instruction list.
        Parameters:
        il - the instruction list.

      • setMaxLocals

        public void setMaxLocals()
        Compute maximum number of local variables.

      • setMaxLocals

        public void setMaxLocals​(int m)
        Sets maximum number of local variables.
        Parameters:
        m - the maximum number of local variables.

      • setMaxStack

        public void setMaxStack()
        Computes max. stack size by performing control flow analysis.

      • setMaxStack

        public void setMaxStack​(int m)
        Sets maximum stack size for this method.
        Parameters:
        m - the maximum stack size.

      • setReturnType

        public void setReturnType​(Type returnType)
        Sets the return type.
        Parameters:
        returnType - the return type.

      • stripAttributes

        public void stripAttributes​(boolean flag)
        Do not/Do produce attributes code attributesLineNumberTable and LocalVariableTable, like javac -O.
        Parameters:
        flag - whether to strip attributes.

      • toString

        public final java.lang.String toString()
        Return string representation close to declaration format, 'public static void main(String[]) throws IOException', for example.
        Overrides:
        toString in class java.lang.Object
        Returns:
        String representation of the method.

      • update

        public void update()
        Call notify() method on all observers. This method is not called automatically whenever the state has changed, but has to be called by the user after they have finished editing the object.

      • updateLocalVariableTable

        private void updateLocalVariableTable​(LocalVariableTable a)