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From hyun...@apache.org
Subject [17/25] TAJO-906: Runtime code generation for evaluating expression trees.
Date Sat, 23 Aug 2014 17:38:06 GMT
http://git-wip-us.apache.org/repos/asf/tajo/blob/7603a3d4/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/Label.java
----------------------------------------------------------------------
diff --git a/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/Label.java b/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/Label.java
new file mode 100644
index 0000000..bf061ba
--- /dev/null
+++ b/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/Label.java
@@ -0,0 +1,560 @@
+/***
+ * 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.apache.tajo.org.objectweb.asm;
+
+/**
+ * A label represents a position in the bytecode of a method. Labels are used
+ * for jump, goto, and switch instructions, and for try catch blocks. A label
+ * designates the <i>instruction</i> that is just after. Note however that there
+ * can be other elements between a label and the instruction it designates (such
+ * as other labels, stack map frames, line numbers, etc.).
+ * 
+ * @author Eric Bruneton
+ */
+public class Label {
+
+    /**
+     * Indicates if this label is only used for debug attributes. Such a label
+     * is not the start of a basic block, the target of a jump instruction, or
+     * an exception handler. It can be safely ignored in control flow graph
+     * analysis algorithms (for optimization purposes).
+     */
+    static final int DEBUG = 1;
+
+    /**
+     * Indicates if the position of this label is known.
+     */
+    static final int RESOLVED = 2;
+
+    /**
+     * Indicates if this label has been updated, after instruction resizing.
+     */
+    static final int RESIZED = 4;
+
+    /**
+     * Indicates if this basic block has been pushed in the basic block stack.
+     * See {@link MethodWriter#visitMaxs visitMaxs}.
+     */
+    static final int PUSHED = 8;
+
+    /**
+     * Indicates if this label is the target of a jump instruction, or the start
+     * of an exception handler.
+     */
+    static final int TARGET = 16;
+
+    /**
+     * Indicates if a stack map frame must be stored for this label.
+     */
+    static final int STORE = 32;
+
+    /**
+     * Indicates if this label corresponds to a reachable basic block.
+     */
+    static final int REACHABLE = 64;
+
+    /**
+     * Indicates if this basic block ends with a JSR instruction.
+     */
+    static final int JSR = 128;
+
+    /**
+     * Indicates if this basic block ends with a RET instruction.
+     */
+    static final int RET = 256;
+
+    /**
+     * Indicates if this basic block is the start of a subroutine.
+     */
+    static final int SUBROUTINE = 512;
+
+    /**
+     * Indicates if this subroutine basic block has been visited by a
+     * visitSubroutine(null, ...) call.
+     */
+    static final int VISITED = 1024;
+
+    /**
+     * Indicates if this subroutine basic block has been visited by a
+     * visitSubroutine(!null, ...) call.
+     */
+    static final int VISITED2 = 2048;
+
+    /**
+     * Field used to associate user information to a label. Warning: this field
+     * is used by the ASM tree package. In order to use it with the ASM tree
+     * package you must override the
+     * {@link org.apache.tajo.org.objectweb.asm.tree.MethodNode#getLabelNode} method.
+     */
+    public Object info;
+
+    /**
+     * Flags that indicate the status of this label.
+     * 
+     * @see #DEBUG
+     * @see #RESOLVED
+     * @see #RESIZED
+     * @see #PUSHED
+     * @see #TARGET
+     * @see #STORE
+     * @see #REACHABLE
+     * @see #JSR
+     * @see #RET
+     */
+    int status;
+
+    /**
+     * The line number corresponding to this label, if known.
+     */
+    int line;
+
+    /**
+     * The position of this label in the code, if known.
+     */
+    int position;
+
+    /**
+     * Number of forward references to this label, times two.
+     */
+    private int referenceCount;
+
+    /**
+     * Informations about forward references. Each forward reference is
+     * described by two consecutive integers in this array: the first one is the
+     * position of the first byte of the bytecode instruction that contains the
+     * forward reference, while the second is the position of the first byte of
+     * the forward reference itself. In fact the sign of the first integer
+     * indicates if this reference uses 2 or 4 bytes, and its absolute value
+     * gives the position of the bytecode instruction. This array is also used
+     * as a bitset to store the subroutines to which a basic block belongs. This
+     * information is needed in {@linked MethodWriter#visitMaxs}, after all
+     * forward references have been resolved. Hence the same array can be used
+     * for both purposes without problems.
+     */
+    private int[] srcAndRefPositions;
+
+    // ------------------------------------------------------------------------
+
+    /*
+     * Fields for the control flow and data flow graph analysis algorithms (used
+     * to compute the maximum stack size or the stack map frames). A control
+     * flow graph contains one node per "basic block", and one edge per "jump"
+     * from one basic block to another. Each node (i.e., each basic block) is
+     * represented by the Label object that corresponds to the first instruction
+     * of this basic block. Each node also stores the list of its successors in
+     * the graph, as a linked list of Edge objects.
+     * 
+     * The control flow analysis algorithms used to compute the maximum stack
+     * size or the stack map frames are similar and use two steps. The first
+     * step, during the visit of each instruction, builds information about the
+     * state of the local variables and the operand stack at the end of each
+     * basic block, called the "output frame", <i>relatively</i> to the frame
+     * state at the beginning of the basic block, which is called the "input
+     * frame", and which is <i>unknown</i> during this step. The second step, in
+     * {@link MethodWriter#visitMaxs}, is a fix point algorithm that computes
+     * information about the input frame of each basic block, from the input
+     * state of the first basic block (known from the method signature), and by
+     * the using the previously computed relative output frames.
+     * 
+     * The algorithm used to compute the maximum stack size only computes the
+     * relative output and absolute input stack heights, while the algorithm
+     * used to compute stack map frames computes relative output frames and
+     * absolute input frames.
+     */
+
+    /**
+     * Start of the output stack relatively to the input stack. The exact
+     * semantics of this field depends on the algorithm that is used.
+     * 
+     * When only the maximum stack size is computed, this field is the number of
+     * elements in the input stack.
+     * 
+     * When the stack map frames are completely computed, this field is the
+     * offset of the first output stack element relatively to the top of the
+     * input stack. This offset is always negative or null. A null offset means
+     * that the output stack must be appended to the input stack. A -n offset
+     * means that the first n output stack elements must replace the top n input
+     * stack elements, and that the other elements must be appended to the input
+     * stack.
+     */
+    int inputStackTop;
+
+    /**
+     * Maximum height reached by the output stack, relatively to the top of the
+     * input stack. This maximum is always positive or null.
+     */
+    int outputStackMax;
+
+    /**
+     * Information about the input and output stack map frames of this basic
+     * block. This field is only used when {@link ClassWriter#COMPUTE_FRAMES}
+     * option is used.
+     */
+    Frame frame;
+
+    /**
+     * The successor of this label, in the order they are visited. This linked
+     * list does not include labels used for debug info only. If
+     * {@link ClassWriter#COMPUTE_FRAMES} option is used then, in addition, it
+     * does not contain successive labels that denote the same bytecode position
+     * (in this case only the first label appears in this list).
+     */
+    Label successor;
+
+    /**
+     * The successors of this node in the control flow graph. These successors
+     * are stored in a linked list of {@link Edge Edge} objects, linked to each
+     * other by their {@link Edge#next} field.
+     */
+    Edge successors;
+
+    /**
+     * The next basic block in the basic block stack. This stack is used in the
+     * main loop of the fix point algorithm used in the second step of the
+     * control flow analysis algorithms. It is also used in
+     * {@link #visitSubroutine} to avoid using a recursive method.
+     * 
+     * @see MethodWriter#visitMaxs
+     */
+    Label next;
+
+    // ------------------------------------------------------------------------
+    // Constructor
+    // ------------------------------------------------------------------------
+
+    /**
+     * Constructs a new label.
+     */
+    public Label() {
+    }
+
+    // ------------------------------------------------------------------------
+    // Methods to compute offsets and to manage forward references
+    // ------------------------------------------------------------------------
+
+    /**
+     * Returns the offset corresponding to this label. This offset is computed
+     * from the start of the method's bytecode. <i>This method is intended for
+     * {@link Attribute} sub classes, and is normally not needed by class
+     * generators or adapters.</i>
+     * 
+     * @return the offset corresponding to this label.
+     * @throws IllegalStateException
+     *             if this label is not resolved yet.
+     */
+    public int getOffset() {
+        if ((status & RESOLVED) == 0) {
+            throw new IllegalStateException(
+                    "Label offset position has not been resolved yet");
+        }
+        return position;
+    }
+
+    /**
+     * Puts a reference to this label in the bytecode of a method. If the
+     * position of the label is known, the offset is computed and written
+     * directly. Otherwise, a null offset is written and a new forward reference
+     * is declared for this label.
+     * 
+     * @param owner
+     *            the code writer that calls this method.
+     * @param out
+     *            the bytecode of the method.
+     * @param source
+     *            the position of first byte of the bytecode instruction that
+     *            contains this label.
+     * @param wideOffset
+     *            <tt>true</tt> if the reference must be stored in 4 bytes, or
+     *            <tt>false</tt> if it must be stored with 2 bytes.
+     * @throws IllegalArgumentException
+     *             if this label has not been created by the given code writer.
+     */
+    void put(final MethodWriter owner, final ByteVector out, final int source,
+            final boolean wideOffset) {
+        if ((status & RESOLVED) == 0) {
+            if (wideOffset) {
+                addReference(-1 - source, out.length);
+                out.putInt(-1);
+            } else {
+                addReference(source, out.length);
+                out.putShort(-1);
+            }
+        } else {
+            if (wideOffset) {
+                out.putInt(position - source);
+            } else {
+                out.putShort(position - source);
+            }
+        }
+    }
+
+    /**
+     * Adds a forward reference to this label. This method must be called only
+     * for a true forward reference, i.e. only if this label is not resolved
+     * yet. For backward references, the offset of the reference can be, and
+     * must be, computed and stored directly.
+     * 
+     * @param sourcePosition
+     *            the position of the referencing instruction. This position
+     *            will be used to compute the offset of this forward reference.
+     * @param referencePosition
+     *            the position where the offset for this forward reference must
+     *            be stored.
+     */
+    private void addReference(final int sourcePosition,
+            final int referencePosition) {
+        if (srcAndRefPositions == null) {
+            srcAndRefPositions = new int[6];
+        }
+        if (referenceCount >= srcAndRefPositions.length) {
+            int[] a = new int[srcAndRefPositions.length + 6];
+            System.arraycopy(srcAndRefPositions, 0, a, 0,
+                    srcAndRefPositions.length);
+            srcAndRefPositions = a;
+        }
+        srcAndRefPositions[referenceCount++] = sourcePosition;
+        srcAndRefPositions[referenceCount++] = referencePosition;
+    }
+
+    /**
+     * Resolves all forward references to this label. This method must be called
+     * when this label is added to the bytecode of the method, i.e. when its
+     * position becomes known. This method fills in the blanks that where left
+     * in the bytecode by each forward reference previously added to this label.
+     * 
+     * @param owner
+     *            the code writer that calls this method.
+     * @param position
+     *            the position of this label in the bytecode.
+     * @param data
+     *            the bytecode of the method.
+     * @return <tt>true</tt> if a blank that was left for this label was to
+     *         small to store the offset. In such a case the corresponding jump
+     *         instruction is replaced with a pseudo instruction (using unused
+     *         opcodes) using an unsigned two bytes offset. These pseudo
+     *         instructions will need to be replaced with true instructions with
+     *         wider offsets (4 bytes instead of 2). This is done in
+     *         {@link MethodWriter#resizeInstructions}.
+     * @throws IllegalArgumentException
+     *             if this label has already been resolved, or if it has not
+     *             been created by the given code writer.
+     */
+    boolean resolve(final MethodWriter owner, final int position,
+            final byte[] data) {
+        boolean needUpdate = false;
+        this.status |= RESOLVED;
+        this.position = position;
+        int i = 0;
+        while (i < referenceCount) {
+            int source = srcAndRefPositions[i++];
+            int reference = srcAndRefPositions[i++];
+            int offset;
+            if (source >= 0) {
+                offset = position - source;
+                if (offset < Short.MIN_VALUE || offset > Short.MAX_VALUE) {
+                    /*
+                     * changes the opcode of the jump instruction, in order to
+                     * be able to find it later (see resizeInstructions in
+                     * MethodWriter). These temporary opcodes are similar to
+                     * jump instruction opcodes, except that the 2 bytes offset
+                     * is unsigned (and can therefore represent values from 0 to
+                     * 65535, which is sufficient since the size of a method is
+                     * limited to 65535 bytes).
+                     */
+                    int opcode = data[reference - 1] & 0xFF;
+                    if (opcode <= Opcodes.JSR) {
+                        // changes IFEQ ... JSR to opcodes 202 to 217
+                        data[reference - 1] = (byte) (opcode + 49);
+                    } else {
+                        // changes IFNULL and IFNONNULL to opcodes 218 and 219
+                        data[reference - 1] = (byte) (opcode + 20);
+                    }
+                    needUpdate = true;
+                }
+                data[reference++] = (byte) (offset >>> 8);
+                data[reference] = (byte) offset;
+            } else {
+                offset = position + source + 1;
+                data[reference++] = (byte) (offset >>> 24);
+                data[reference++] = (byte) (offset >>> 16);
+                data[reference++] = (byte) (offset >>> 8);
+                data[reference] = (byte) offset;
+            }
+        }
+        return needUpdate;
+    }
+
+    /**
+     * Returns the first label of the series to which this label belongs. For an
+     * isolated label or for the first label in a series of successive labels,
+     * this method returns the label itself. For other labels it returns the
+     * first label of the series.
+     * 
+     * @return the first label of the series to which this label belongs.
+     */
+    Label getFirst() {
+        return !ClassReader.FRAMES || frame == null ? this : frame.owner;
+    }
+
+    // ------------------------------------------------------------------------
+    // Methods related to subroutines
+    // ------------------------------------------------------------------------
+
+    /**
+     * Returns true is this basic block belongs to the given subroutine.
+     * 
+     * @param id
+     *            a subroutine id.
+     * @return true is this basic block belongs to the given subroutine.
+     */
+    boolean inSubroutine(final long id) {
+        if ((status & Label.VISITED) != 0) {
+            return (srcAndRefPositions[(int) (id >>> 32)] & (int) id) != 0;
+        }
+        return false;
+    }
+
+    /**
+     * Returns true if this basic block and the given one belong to a common
+     * subroutine.
+     * 
+     * @param block
+     *            another basic block.
+     * @return true if this basic block and the given one belong to a common
+     *         subroutine.
+     */
+    boolean inSameSubroutine(final Label block) {
+        if ((status & VISITED) == 0 || (block.status & VISITED) == 0) {
+            return false;
+        }
+        for (int i = 0; i < srcAndRefPositions.length; ++i) {
+            if ((srcAndRefPositions[i] & block.srcAndRefPositions[i]) != 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Marks this basic block as belonging to the given subroutine.
+     * 
+     * @param id
+     *            a subroutine id.
+     * @param nbSubroutines
+     *            the total number of subroutines in the method.
+     */
+    void addToSubroutine(final long id, final int nbSubroutines) {
+        if ((status & VISITED) == 0) {
+            status |= VISITED;
+            srcAndRefPositions = new int[(nbSubroutines - 1) / 32 + 1];
+        }
+        srcAndRefPositions[(int) (id >>> 32)] |= (int) id;
+    }
+
+    /**
+     * Finds the basic blocks that belong to a given subroutine, and marks these
+     * blocks as belonging to this subroutine. This method follows the control
+     * flow graph to find all the blocks that are reachable from the current
+     * block WITHOUT following any JSR target.
+     * 
+     * @param JSR
+     *            a JSR block that jumps to this subroutine. If this JSR is not
+     *            null it is added to the successor of the RET blocks found in
+     *            the subroutine.
+     * @param id
+     *            the id of this subroutine.
+     * @param nbSubroutines
+     *            the total number of subroutines in the method.
+     */
+    void visitSubroutine(final Label JSR, final long id, final int nbSubroutines) {
+        // user managed stack of labels, to avoid using a recursive method
+        // (recursivity can lead to stack overflow with very large methods)
+        Label stack = this;
+        while (stack != null) {
+            // removes a label l from the stack
+            Label l = stack;
+            stack = l.next;
+            l.next = null;
+
+            if (JSR != null) {
+                if ((l.status & VISITED2) != 0) {
+                    continue;
+                }
+                l.status |= VISITED2;
+                // adds JSR to the successors of l, if it is a RET block
+                if ((l.status & RET) != 0) {
+                    if (!l.inSameSubroutine(JSR)) {
+                        Edge e = new Edge();
+                        e.info = l.inputStackTop;
+                        e.successor = JSR.successors.successor;
+                        e.next = l.successors;
+                        l.successors = e;
+                    }
+                }
+            } else {
+                // if the l block already belongs to subroutine 'id', continue
+                if (l.inSubroutine(id)) {
+                    continue;
+                }
+                // marks the l block as belonging to subroutine 'id'
+                l.addToSubroutine(id, nbSubroutines);
+            }
+            // pushes each successor of l on the stack, except JSR targets
+            Edge e = l.successors;
+            while (e != null) {
+                // if the l block is a JSR block, then 'l.successors.next' leads
+                // to the JSR target (see {@link #visitJumpInsn}) and must
+                // therefore not be followed
+                if ((l.status & Label.JSR) == 0 || e != l.successors.next) {
+                    // pushes e.successor on the stack if it not already added
+                    if (e.successor.next == null) {
+                        e.successor.next = stack;
+                        stack = e.successor;
+                    }
+                }
+                e = e.next;
+            }
+        }
+    }
+
+    // ------------------------------------------------------------------------
+    // Overriden Object methods
+    // ------------------------------------------------------------------------
+
+    /**
+     * Returns a string representation of this label.
+     * 
+     * @return a string representation of this label.
+     */
+    @Override
+    public String toString() {
+        return "L" + System.identityHashCode(this);
+    }
+}

http://git-wip-us.apache.org/repos/asf/tajo/blob/7603a3d4/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/MethodVisitor.java
----------------------------------------------------------------------
diff --git a/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/MethodVisitor.java b/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/MethodVisitor.java
new file mode 100644
index 0000000..1d6758e
--- /dev/null
+++ b/tajo-thirdparty/asm/src/main/java/org/apache/tajo/org/objectweb/asm/MethodVisitor.java
@@ -0,0 +1,662 @@
+/***
+ * 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.apache.tajo.org.objectweb.asm;
+
+/**
+ * A visitor to visit a Java method. The methods of this class must be called in
+ * the following order: [ <tt>visitAnnotationDefault</tt> ] (
+ * <tt>visitAnnotation</tt> | <tt>visitParameterAnnotation</tt> |
+ * <tt>visitAttribute</tt> )* [ <tt>visitCode</tt> ( <tt>visitFrame</tt> |
+ * <tt>visit</tt><i>X</i>Insn</tt> | <tt>visitLabel</tt> |
+ * <tt>visitTryCatchBlock</tt> | <tt>visitLocalVariable</tt> |
+ * <tt>visitLineNumber</tt> )* <tt>visitMaxs</tt> ] <tt>visitEnd</tt>. In
+ * addition, the <tt>visit</tt><i>X</i>Insn</tt> and <tt>visitLabel</tt> methods
+ * must be called in the sequential order of the bytecode instructions of the
+ * visited code, <tt>visitTryCatchBlock</tt> must be called <i>before</i> the
+ * labels passed as arguments have been visited, and the
+ * <tt>visitLocalVariable</tt> and <tt>visitLineNumber</tt> methods must be
+ * called <i>after</i> the labels passed as arguments have been visited.
+ * 
+ * @author Eric Bruneton
+ */
+public abstract class MethodVisitor {
+
+    /**
+     * The ASM API version implemented by this visitor. The value of this field
+     * must be one of {@link Opcodes#ASM4}.
+     */
+    protected final int api;
+
+    /**
+     * The method visitor to which this visitor must delegate method calls. May
+     * be null.
+     */
+    protected MethodVisitor mv;
+
+    /**
+     * Constructs a new {@link MethodVisitor}.
+     * 
+     * @param api
+     *            the ASM API version implemented by this visitor. Must be one
+     *            of {@link Opcodes#ASM4}.
+     */
+    public MethodVisitor(final int api) {
+        this(api, null);
+    }
+
+    /**
+     * Constructs a new {@link MethodVisitor}.
+     * 
+     * @param api
+     *            the ASM API version implemented by this visitor. Must be one
+     *            of {@link Opcodes#ASM4}.
+     * @param mv
+     *            the method visitor to which this visitor must delegate method
+     *            calls. May be null.
+     */
+    public MethodVisitor(final int api, final MethodVisitor mv) {
+        if (api != Opcodes.ASM4) {
+            throw new IllegalArgumentException();
+        }
+        this.api = api;
+        this.mv = mv;
+    }
+
+    // -------------------------------------------------------------------------
+    // Annotations and non standard attributes
+    // -------------------------------------------------------------------------
+
+    /**
+     * 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 <tt>null</tt> 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.
+     * 
+     * @param desc
+     *            the class descriptor of the annotation class.
+     * @param visible
+     *            <tt>true</tt> if the annotation is visible at runtime.
+     * @return a visitor to visit the annotation values, or <tt>null</tt> if
+     *         this visitor is not interested in visiting this annotation.
+     */
+    public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
+        if (mv != null) {
+            return mv.visitAnnotation(desc, visible);
+        }
+        return null;
+    }
+
+    /**
+     * Visits an annotation of a parameter this method.
+     * 
+     * @param parameter
+     *            the parameter index.
+     * @param desc
+     *            the class descriptor of the annotation class.
+     * @param visible
+     *            <tt>true</tt> if the annotation is visible at runtime.
+     * @return a visitor to visit the annotation values, or <tt>null</tt> if
+     *         this visitor is not interested in visiting this annotation.
+     */
+    public AnnotationVisitor visitParameterAnnotation(int parameter,
+            String desc, boolean visible) {
+        if (mv != null) {
+            return mv.visitParameterAnnotation(parameter, desc, visible);
+        }
+        return null;
+    }
+
+    /**
+     * Visits a non standard attribute of this method.
+     * 
+     * @param attr
+     *            an attribute.
+     */
+    public void visitAttribute(Attribute attr) {
+        if (mv != null) {
+            mv.visitAttribute(attr);
+        }
+    }
+
+    /**
+     * 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 <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 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>
+     * <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>
+     * <li>{@link Opcodes#F_SAME1} representing frame with exactly the same
+     * locals as the previous frame and with single value on the stack (
+     * <code>nStack</code> is 1 and <code>stack[0]</code> contains value for the
+     * type of the stack item).</li>
+     * <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>nLocal</code> is 1, 2 or 3 and
+     * <code>local</code> elements contains values representing added types).</li>
+     * <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>nLocals</code> is 1, 2 or 3).</li>
+     * <li>{@link Opcodes#F_FULL} representing complete frame data.</li></li>
+     * </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 nLocal
+     *            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 nStack
+     *            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(int type, int nLocal, Object[] local, int nStack,
+            Object[] stack) {
+        if (mv != null) {
+            mv.visitFrame(type, nLocal, local, nStack, stack);
+        }
+    }
+
+    // -------------------------------------------------------------------------
+    // Normal instructions
+    // -------------------------------------------------------------------------
+
+    /**
+     * 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(int opcode) {
+        if (mv != null) {
+            mv.visitInsn(opcode);
+        }
+    }
+
+    /**
+     * 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(int opcode, 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.
+     * 
+     * @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(int opcode, 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.
+     * 
+     * @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() getInternalName}).
+     */
+    public void visitTypeInsn(int opcode, 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.
+     * 
+     * @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() getInternalName}).
+     * @param name
+     *            the field's name.
+     * @param desc
+     *            the field's descriptor (see {@link Type Type}).
+     */
+    public void visitFieldInsn(int opcode, String owner, String name,
+            String desc) {
+        if (mv != null) {
+            mv.visitFieldInsn(opcode, owner, name, desc);
+        }
+    }
+
+    /**
+     * 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() getInternalName}).
+     * @param name
+     *            the method's name.
+     * @param desc
+     *            the method's descriptor (see {@link Type Type}).
+     */
+    public void visitMethodInsn(int opcode, String owner, String name,
+            String desc) {
+        if (mv != null) {
+            mv.visitMethodInsn(opcode, owner, name, desc);
+        }
+    }
+
+    /**
+     * Visits an invokedynamic instruction.
+     * 
+     * @param name
+     *            the method's name.
+     * @param desc
+     *            the method's descriptor (see {@link Type Type}).
+     * @param bsm
+     *            the bootstrap method.
+     * @param bsmArgs
+     *            the bootstrap method constant arguments. Each argument must be
+     *            an {@link Integer}, {@link Float}, {@link Long},
+     *            {@link Double}, {@link String}, {@link Type} or {@link Handle}
+     *            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(String name, String desc, Handle bsm,
+            Object... bsmArgs) {
+        if (mv != null) {
+            mv.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
+        }
+    }
+
+    /**
+     * 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(int opcode, Label label) {
+        if (mv != null) {
+            mv.visitJumpInsn(opcode, label);
+        }
+    }
+
+    /**
+     * Visits a label. A label designates the instruction that will be visited
+     * just after it.
+     * 
+     * @param label
+     *            a {@link Label Label} object.
+     */
+    public void visitLabel(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:
+     * 
+     * <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 {
+     *     // throw an exception
+     * }
+     * </pre>
+     * 
+     * @param cst
+     *            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 <tt>.class</tt> constants, for classes whose
+     *            version is 49.0, a {@link Type} of METHOD sort or a
+     *            {@link Handle} for MethodType and MethodHandle constants, for
+     *            classes whose version is 51.0.
+     */
+    public void visitLdcInsn(Object cst) {
+        if (mv != null) {
+            mv.visitLdcInsn(cst);
+        }
+    }
+
+    /**
+     * 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(int var, int increment) {
+        if (mv != null) {
+            mv.visitIincInsn(var, increment);
+        }
+    }
+
+    /**
+     * 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. <tt>labels[i]</tt> is the
+     *            beginning of the handler block for the <tt>min + i</tt> key.
+     */
+    public void visitTableSwitchInsn(int min, int max, Label dflt,
+            Label... labels) {
+        if (mv != null) {
+            mv.visitTableSwitchInsn(min, max, dflt, labels);
+        }
+    }
+
+    /**
+     * 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. <tt>labels[i]</tt> is the
+     *            beginning of the handler block for the <tt>keys[i]</tt> key.
+     */
+    public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) {
+        if (mv != null) {
+            mv.visitLookupSwitchInsn(dflt, keys, labels);
+        }
+    }
+
+    /**
+     * Visits a MULTIANEWARRAY instruction.
+     * 
+     * @param desc
+     *            an array type descriptor (see {@link Type Type}).
+     * @param dims
+     *            number of dimensions of the array to allocate.
+     */
+    public void visitMultiANewArrayInsn(String desc, int dims) {
+        if (mv != null) {
+            mv.visitMultiANewArrayInsn(desc, dims);
+        }
+    }
+
+    // -------------------------------------------------------------------------
+    // Exceptions table entries, debug information, max stack and max locals
+    // -------------------------------------------------------------------------
+
+    /**
+     * Visits a try catch block.
+     * 
+     * @param start
+     *            beginning of the exception handler's scope (inclusive).
+     * @param end
+     *            end of the exception handler's scope (exclusive).
+     * @param handler
+     *            beginning of the exception handler's code.
+     * @param type
+     *            internal name of the type of exceptions handled by the
+     *            handler, or <tt>null</tt> 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 visitLabel} method).
+     */
+    public void visitTryCatchBlock(Label start, Label end, Label handler,
+            String type) {
+        if (mv != null) {
+            mv.visitTryCatchBlock(start, end, handler, type);
+        }
+    }
+
+    /**
+     * Visits a local variable declaration.
+     * 
+     * @param name
+     *            the name of a local variable.
+     * @param desc
+     *            the type descriptor of this local variable.
+     * @param signature
+     *            the type signature of this local variable. May be
+     *            <tt>null</tt> 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 visitLabel} method).
+     */
+    public void visitLocalVariable(String name, String desc, String signature,
+            Label start, Label end, int index) {
+        if (mv != null) {
+            mv.visitLocalVariable(name, desc, signature, start, end, index);
+        }
+    }
+
+    /**
+     * 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 <tt>start</tt> has not already been visited by this
+     *             visitor (by the {@link #visitLabel visitLabel} method).
+     */
+    public void visitLineNumber(int line, Label start) {
+        if (mv != null) {
+            mv.visitLineNumber(line, start);
+        }
+    }
+
+    /**
+     * 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(int maxStack, 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.
+     */
+    public void visitEnd() {
+        if (mv != null) {
+            mv.visitEnd();
+        }
+    }
+}


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