content: /***
   * ASM: a very small and fast Java bytecode manipulation framework
   * Copyright (c) 2000-2007 INRIA, France Telecom
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
   * THE POSSIBILITY OF SUCH DAMAGE.
   */
  package com.alibaba.fastjson.asm;
  
  /**
   * A {@link ClassVisitor} that generates classes in bytecode form. More precisely this visitor generates a byte array
   * conforming to the Java class file format. It can be used alone, to generate a Java class "from scratch", or with one
   * or more and adapter class visitor to generate a modified class from one or more existing Java classes.
   * 
   * @author Eric Bruneton
   */
  public class ClassWriter {
  
      /**
       * Flag to automatically compute the maximum stack size and the maximum number of local variables of methods. If
       * this flag is set, then the arguments of the {@link MethodVisitor#visitMaxs visitMaxs} method of the
       * {@link MethodVisitor} returned by the {@link #visitMethod visitMethod} method will be ignored, and computed
       * automatically from the signature and the bytecode of each method.
       * 
       * @see #ClassWriter(int)
       */
      public static final int COMPUTE_MAXS            = 1;
  
      /**
       * Flag to automatically compute the stack map frames of methods from scratch. If this flag is set, then the calls
       * to the {@link MethodVisitor#visitFrame} method are ignored, and the stack map frames are recomputed from the
       * methods bytecode. The arguments of the {@link MethodVisitor#visitMaxs visitMaxs} method are also ignored and
       * recomputed from the bytecode. In other words, computeFrames implies computeMaxs.
       * 
       * @see #ClassWriter(int)
       */
      public static final int COMPUTE_FRAMES          = 2;
  
      /**
       * Pseudo access flag to distinguish between the synthetic attribute and the synthetic access flag.
       */
      static final int        ACC_SYNTHETIC_ATTRIBUTE = 0x40000;
  
      /**
       * The type of instructions without any argument.
       */
      static final int        NOARG_INSN              = 0;
  
      /**
       * The type of instructions with an signed byte argument.
       */
      static final int        SBYTE_INSN              = 1;
  
      /**
       * The type of instructions with an signed short argument.
       */
      static final int        SHORT_INSN              = 2;
  
      /**
       * The type of instructions with a local variable index argument.
       */
      static final int        VAR_INSN                = 3;
  
      /**
       * The type of instructions with an implicit local variable index argument.
       */
      static final int        IMPLVAR_INSN            = 4;
  
      /**
       * The type of instructions with a type descriptor argument.
       */
      static final int        TYPE_INSN               = 5;
  
      /**
       * The type of field and method invocations instructions.
       */
      static final int        FIELDORMETH_INSN        = 6;
  
      /**
       * The type of the INVOKEINTERFACE/INVOKEDYNAMIC instruction.
       */
      static final int        ITFDYNMETH_INSN         = 7;
  
      /**
       * The type of instructions with a 2 bytes bytecode offset label.
       */
      static final int        LABEL_INSN              = 8;
  
      /**
       * The type of instructions with a 4 bytes bytecode offset label.
       */
      static final int        LABELW_INSN             = 9;
  
      /**
       * The type of the LDC instruction.
       */
      static final int        LDC_INSN                = 10;
  
      /**
       * The type of the LDC_W and LDC2_W instructions.
       */
      static final int        LDCW_INSN               = 11;
  
      /**
       * The type of the IINC instruction.
       */
      static final int        IINC_INSN               = 12;
  
      /**
       * The type of the TABLESWITCH instruction.
       */
      static final int        TABL_INSN               = 13;
  
      /**
       * The type of the LOOKUPSWITCH instruction.
       */
      static final int        LOOK_INSN               = 14;
  
      /**
       * The type of the MULTIANEWARRAY instruction.
       */
      static final int        MANA_INSN               = 15;
  
      /**
       * The type of the WIDE instruction.
       */
      static final int        WIDE_INSN               = 16;
  
      /**
       * The instruction types of all JVM opcodes.
       */
      static final byte[]     TYPE;
  
      /**
       * The type of CONSTANT_Class constant pool items.
       */
      static final int        CLASS                   = 7;
  
      /**
       * The type of CONSTANT_Fieldref constant pool items.
       */
      static final int        FIELD                   = 9;
  
      /**
       * The type of CONSTANT_Methodref constant pool items.
       */
      static final int        METH                    = 10;
  
      /**
       * The type of CONSTANT_InterfaceMethodref constant pool items.
       */
      static final int        IMETH                   = 11;
  
      /**
       * The type of CONSTANT_String constant pool items.
       */
      static final int        STR                     = 8;
  
      /**
       * The type of CONSTANT_Integer constant pool items.
       */
      static final int        INT                     = 3;
  
      /**
       * The type of CONSTANT_Float constant pool items.
       */
      static final int        FLOAT                   = 4;
  
      /**
       * The type of CONSTANT_Long constant pool items.
       */
      static final int        LONG                    = 5;
  
      /**
       * The type of CONSTANT_Double constant pool items.
       */
      static final int        DOUBLE                  = 6;
  
      /**
       * The type of CONSTANT_NameAndType constant pool items.
       */
      static final int        NAME_TYPE               = 12;
  
      /**
       * The type of CONSTANT_Utf8 constant pool items.
       */
      static final int        UTF8                    = 1;
  
      /**
       * Normal type Item stored in the ClassWriter {@link ClassWriter#typeTable}, instead of the constant pool, in order
       * to avoid clashes with normal constant pool items in the ClassWriter constant pool's hash table.
       */
      static final int        TYPE_NORMAL             = 13;
  
      /**
       * Uninitialized type Item stored in the ClassWriter {@link ClassWriter#typeTable}, instead of the constant pool, in
       * order to avoid clashes with normal constant pool items in the ClassWriter constant pool's hash table.
       */
      static final int        TYPE_UNINIT             = 14;
  
      /**
       * Merged type Item stored in the ClassWriter {@link ClassWriter#typeTable}, instead of the constant pool, in order
       * to avoid clashes with normal constant pool items in the ClassWriter constant pool's hash table.
       */
      static final int        TYPE_MERGED             = 15;
  
      /**
       * Minor and major version numbers of the class to be generated.
       */
      int                     version;
  
      /**
       * Index of the next item to be added in the constant pool.
       */
      int                     index;
  
      /**
       * The constant pool of this class.
       */
      final ByteVector        pool;
  
      /**
       * The constant pool's hash table data.
       */
      Item[]                  items;
  
      /**
       * The threshold of the constant pool's hash table.
       */
      int                     threshold;
  
      /**
       * A reusable key used to look for items in the {@link #items} hash table.
       */
      final Item              key;
  
      /**
       * A reusable key used to look for items in the {@link #items} hash table.
       */
      final Item              key2;
  
      /**
       * A reusable key used to look for items in the {@link #items} hash table.
       */
      final Item              key3;
  
      /**
       * A type table used to temporarily store internal names that will not necessarily be stored in the constant pool.
       * This type table is used by the control flow and data flow analysis algorithm used to compute stack map frames
       * from scratch. This array associates to each index <tt>i</tt> the Item whose index is <tt>i</tt>. All Item objects
       * stored in this array are also stored in the {@link #items} hash table. These two arrays allow to retrieve an Item
       * from its index or, conversely, to get the index of an Item from its value. Each Item stores an internal name in
       * its {@link Item#strVal1} field.
       */
      Item[]                  typeTable;
  
      /**
       * The access flags of this class.
       */
      private int             access;
  
      /**
       * The constant pool item that contains the internal name of this class.
       */
      private int             name;
  
      /**
       * The internal name of this class.
       */
      String                  thisName;
  
      /**
       * The constant pool item that contains the internal name of the super class of this class.
       */
      private int             superName;
  
      /**
       * Number of interfaces implemented or extended by this class or interface.
       */
      private int             interfaceCount;
  
      /**
       * The interfaces implemented or extended by this class or interface. More precisely, this array contains the
       * indexes of the constant pool items that contain the internal names of these interfaces.
       */
      private int[]           interfaces;
  
      /**
       * The fields of this class. These fields are stored in a linked list of {@link FieldWriter} objects, linked to each
       * other by their {@link FieldWriter#next} field. This field stores the first element of this list.
       */
      FieldWriter             firstField;
  
      /**
       * The fields of this class. These fields are stored in a linked list of {@link FieldWriter} objects, linked to each
       * other by their {@link FieldWriter#next} field. This field stores the last element of this list.
       */
      FieldWriter             lastField;
  
      /**
       * The methods of this class. These methods are stored in a linked list of {@link MethodWriter} objects, linked to
       * each other by their {@link MethodWriter#next} field. This field stores the first element of this list.
       */
      MethodWriter            firstMethod;
  
      /**
       * The methods of this class. These methods are stored in a linked list of {@link MethodWriter} objects, linked to
       * each other by their {@link MethodWriter#next} field. This field stores the last element of this list.
       */
      MethodWriter            lastMethod;
  
      // ------------------------------------------------------------------------
      // Static initializer
      // ------------------------------------------------------------------------
  
      /**
       * Computes the instruction types of JVM opcodes.
       */
      static {
          int i;
          byte[] b = new byte[220];
          String s = "AAAAAAAAAAAAAAAABCKLLDDDDDEEEEEEEEEEEEEEEEEEEEAAAAAAAADD" + "DDDEEEEEEEEEEEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" + "AAAAAAAAAAAAAAAAAMAAAAAAAAAAAAAAAAAAAAIIIIIIIIIIIIIIIIDNOAA" + "AAAAGGGGGGGHHFBFAAFFAAQPIIJJIIIIIIIIIIIIIIIIII";
          for (i = 0; i < b.length; ++i) {
              b[i] = (byte) (s.charAt(i) - 'A');
          }
          TYPE = b;
  
          // code to generate the above string
          //
          // // SBYTE_INSN instructions
          // b[Constants.NEWARRAY] = SBYTE_INSN;
          // b[Constants.BIPUSH] = SBYTE_INSN;
          //
          // // SHORT_INSN instructions
          // b[Constants.SIPUSH] = SHORT_INSN;
          //
          // // (IMPL)VAR_INSN instructions
          // b[Constants.RET] = VAR_INSN;
          // for (i = Constants.ILOAD; i <= Constants.ALOAD; ++i) {
          // b[i] = VAR_INSN;
          // }
          // for (i = Constants.ISTORE; i <= Constants.ASTORE; ++i) {
          // b[i] = VAR_INSN;
          // }
          // for (i = 26; i <= 45; ++i) { // ILOAD_0 to ALOAD_3
          // b[i] = IMPLVAR_INSN;
          // }
          // for (i = 59; i <= 78; ++i) { // ISTORE_0 to ASTORE_3
          // b[i] = IMPLVAR_INSN;
          // }
          //
          // // TYPE_INSN instructions
          // b[Constants.NEW] = TYPE_INSN;
          // b[Constants.ANEWARRAY] = TYPE_INSN;
          // b[Constants.CHECKCAST] = TYPE_INSN;
          // b[Constants.INSTANCEOF] = TYPE_INSN;
          //
          // // (Set)FIELDORMETH_INSN instructions
          // for (i = Constants.GETSTATIC; i <= Constants.INVOKESTATIC; ++i) {
          // b[i] = FIELDORMETH_INSN;
          // }
          // b[Constants.INVOKEINTERFACE] = ITFDYNMETH_INSN;
          // b[Constants.INVOKEDYNAMIC] = ITFDYNMETH_INSN;
          //
          // // LABEL(W)_INSN instructions
          // for (i = Constants.IFEQ; i <= Constants.JSR; ++i) {
          // b[i] = LABEL_INSN;
          // }
          // b[Constants.IFNULL] = LABEL_INSN;
          // b[Constants.IFNONNULL] = LABEL_INSN;
          // b[200] = LABELW_INSN; // GOTO_W
          // b[201] = LABELW_INSN; // JSR_W
          // // temporary opcodes used internally by ASM - see Label and
          // MethodWriter
          // for (i = 202; i < 220; ++i) {
          // b[i] = LABEL_INSN;
          // }
          //
          // // LDC(_W) instructions
          // b[Constants.LDC] = LDC_INSN;
          // b[19] = LDCW_INSN; // LDC_W
          // b[20] = LDCW_INSN; // LDC2_W
          //
          // // special instructions
          // b[Constants.IINC] = IINC_INSN;
          // b[Constants.TABLESWITCH] = TABL_INSN;
          // b[Constants.LOOKUPSWITCH] = LOOK_INSN;
          // b[Constants.MULTIANEWARRAY] = MANA_INSN;
          // b[196] = WIDE_INSN; // WIDE
          //
          // for (i = 0; i < b.length; ++i) {
          // System.err.print((char)('A' + b[i]));
          // }
          // System.err.println();
      }
  
      // ------------------------------------------------------------------------
      // Constructor
      // ------------------------------------------------------------------------
  
      public ClassWriter(){
          this(0);
      }
  
      /**
       * Constructs a new {@link ClassWriter} object.
       * 
       * @param flags option flags that can be used to modify the default behavior of this class. See
       * {@link #COMPUTE_MAXS}, {@link #COMPUTE_FRAMES}.
       */
      private ClassWriter(final int flags){
          index = 1;
          pool = new ByteVector();
          items = new Item[256];
          threshold = (int) (0.75d * items.length);
          key = new Item();
          key2 = new Item();
          key3 = new Item();
      }
  
      // ------------------------------------------------------------------------
      // Implementation of the ClassVisitor interface
      // ------------------------------------------------------------------------
  
      public void visit(final int version, final int access, final String name, final String superName, final String[] interfaces) {
          this.version = version;
          this.access = access;
          this.name = newClass(name);
          thisName = name;
          this.superName = superName == null ? 0 : newClass(superName);
          if (interfaces != null && interfaces.length > 0) {
              interfaceCount = interfaces.length;
              this.interfaces = new int[interfaceCount];
              for (int i = 0; i < interfaceCount; ++i) {
                  this.interfaces[i] = newClass(interfaces[i]);
              }
          }
      }
  
      public FieldVisitor visitField(final int access, final String name, final String desc) {
          return new FieldWriter(this, access, name, desc);
      }
  
      public MethodVisitor visitMethod(final int access, final String name, final String desc, final String signature, final String[] exceptions) {
          return new MethodWriter(this, access, name, desc, signature, exceptions);
      }
  
      public void visitEnd() {
      }
  
      // ------------------------------------------------------------------------
      // Other public methods
      // ------------------------------------------------------------------------
  
      /**
       * Returns the bytecode of the class that was build with this class writer.
       * 
       * @return the bytecode of the class that was build with this class writer.
       */
      public byte[] toByteArray() {
          // computes the real size of the bytecode of this class
          int size = 24 + 2 * interfaceCount;
          int nbFields = 0;
          FieldWriter fb = firstField;
          while (fb != null) {
              ++nbFields;
              size += fb.getSize();
              fb = fb.next;
          }
          int nbMethods = 0;
          MethodWriter mb = firstMethod;
          while (mb != null) {
              ++nbMethods;
              size += mb.getSize();
              mb = mb.next;
          }
          int attributeCount = 0;
          size += pool.length;
          // allocates a byte vector of this size, in order to avoid unnecessary
          // arraycopy operations in the ByteVector.enlarge() method
          ByteVector out = new ByteVector(size);
          out.putInt(0xCAFEBABE).putInt(version);
          out.putShort(index).putByteArray(pool.data, 0, pool.length);
          int mask = Opcodes.ACC_DEPRECATED | ClassWriter.ACC_SYNTHETIC_ATTRIBUTE | ((access & ClassWriter.ACC_SYNTHETIC_ATTRIBUTE) / (ClassWriter.ACC_SYNTHETIC_ATTRIBUTE / Opcodes.ACC_SYNTHETIC));
          out.putShort(access & ~mask).putShort(name).putShort(superName);
          out.putShort(interfaceCount);
          for (int i = 0; i < interfaceCount; ++i) {
              out.putShort(interfaces[i]);
          }
          out.putShort(nbFields);
          fb = firstField;
          while (fb != null) {
              fb.put(out);
              fb = fb.next;
          }
          out.putShort(nbMethods);
          mb = firstMethod;
          while (mb != null) {
              mb.put(out);
              mb = mb.next;
          }
          out.putShort(attributeCount);
          return out.data;
      }
  
      // ------------------------------------------------------------------------
      // Utility methods: constant pool management
      // ------------------------------------------------------------------------
  
      /**
       * Adds a number or string constant to the constant pool of the class being build. Does nothing if the constant pool
       * already contains a similar item.
       * 
       * @param cst the value of the constant to be added to the constant pool. This parameter must be an {@link Integer},
       * a {@link Float}, a {@link Long}, a {@link Double}, a {@link String} or a {@link Type}.
       * @return a new or already existing constant item with the given value.
       */
      Item newConstItem(final Object cst) {
          if (cst instanceof Integer) {
              int val = ((Integer) cst).intValue();
              return newInteger(val);
          } else if (cst instanceof String) {
              return newString((String) cst);
          } else if (cst instanceof Type) {
              Type t = (Type) cst;
              return newClassItem(t.getSort() == Type.OBJECT ? t.getInternalName() : t.getDescriptor());
          } else {
              throw new IllegalArgumentException("value " + cst);
          }
      }
      
      Item newInteger(final int value) {
          key.set(value);
          Item result = get(key);
          if (result == null) {
              pool.putByte(INT).putInt(value);
              result = new Item(index++, key);
              put(result);
          }
          return result;
      }
  
      public int newUTF8(final String value) {
          key.set(UTF8, value, null, null);
          Item result = get(key);
          if (result == null) {
              pool.putByte(UTF8).putUTF8(value);
              result = new Item(index++, key);
              put(result);
          }
          return result.index;
      }
  
      Item newClassItem(final String value) {
          key2.set(CLASS, value, null, null);
          Item result = get(key2);
          if (result == null) {
              pool.put12(CLASS, newUTF8(value));
              result = new Item(index++, key2);
              put(result);
          }
          return result;
      }
  
      public int newClass(final String value) {
          return newClassItem(value).index;
      }
  
      /**
       * Adds a field reference to the constant pool of the class being build. Does nothing if the constant pool already
       * contains a similar item.
       * 
       * @param owner the internal name of the field's owner class.
       * @param name the field's name.
       * @param desc the field's descriptor.
       * @return a new or already existing field reference item.
       */
      Item newFieldItem(final String owner, final String name, final String desc) {
          key3.set(FIELD, owner, name, desc);
          Item result = get(key3);
          if (result == null) {
              put122(FIELD, newClass(owner), newNameType(name, desc));
              result = new Item(index++, key3);
              put(result);
          }
          return result;
      }
  
      /**
       * Adds a method reference to the constant pool of the class being build. Does nothing if the constant pool already
       * contains a similar item.
       * 
       * @param owner the internal name of the method's owner class.
       * @param name the method's name.
       * @param desc the method's descriptor.
       * @param itf <tt>true</tt> if <tt>owner</tt> is an interface.
       * @return a new or already existing method reference item.
       */
      Item newMethodItem(final String owner, final String name, final String desc, final boolean itf) {
          int type = itf ? IMETH : METH;
          key3.set(type, owner, name, desc);
          Item result = get(key3);
          if (result == null) {
              put122(type, newClass(owner), newNameType(name, desc));
              result = new Item(index++, key3);
              put(result);
          }
          return result;
      }
  
      /**
       * Adds a string to the constant pool of the class being build. Does nothing if the constant pool already contains a
       * similar item.
       * 
       * @param value the String value.
       * @return a new or already existing string item.
       */
      private Item newString(final String value) {
          key2.set(STR, value, null, null);
          Item result = get(key2);
          if (result == null) {
              pool.put12(STR, newUTF8(value));
              result = new Item(index++, key2);
              put(result);
          }
          return result;
      }
  
      public int newNameType(final String name, final String desc) {
          return newNameTypeItem(name, desc).index;
      }
  
      /**
       * Adds a name and type to the constant pool of the class being build. Does nothing if the constant pool already
       * contains a similar item.
       * 
       * @param name a name.
       * @param desc a type descriptor.
       * @return a new or already existing name and type item.
       */
      Item newNameTypeItem(final String name, final String desc) {
          key2.set(NAME_TYPE, name, desc, null);
          Item result = get(key2);
          if (result == null) {
              put122(NAME_TYPE, newUTF8(name), newUTF8(desc));
              result = new Item(index++, key2);
              put(result);
          }
          return result;
      }
  
      /**
       * Returns the constant pool's hash table item which is equal to the given item.
       * 
       * @param key a constant pool item.
       * @return the constant pool's hash table item which is equal to the given item, or <tt>null</tt> if there is no
       * such item.
       */
      private Item get(final Item key) {
          Item i = items[key.hashCode % items.length];
          while (i != null && (i.type != key.type || !key.isEqualTo(i))) {
              i = i.next;
          }
          return i;
      }
  
      /**
       * Puts the given item in the constant pool's hash table. The hash table <i>must</i> not already contains this item.
       * 
       * @param i the item to be added to the constant pool's hash table.
       */
      private void put(final Item i) {
          if (index > threshold) {
              int ll = items.length;
              int nl = ll * 2 + 1;
              Item[] newItems = new Item[nl];
              for (int l = ll - 1; l >= 0; --l) {
                  Item j = items[l];
                  while (j != null) {
                      int index = j.hashCode % newItems.length;
                      Item k = j.next;
                      j.next = newItems[index];
                      newItems[index] = j;
                      j = k;
                  }
              }
              items = newItems;
              threshold = (int) (nl * 0.75);
          }
          int index = i.hashCode % items.length;
          i.next = items[index];
          items[index] = i;
      }
  
      /**
       * Puts one byte and two shorts into the constant pool.
       * 
       * @param b a byte.
       * @param s1 a short.
       * @param s2 another short.
       */
      private void put122(final int b, final int s1, final int s2) {
          pool.put12(b, s1).putShort(s2);
      }
  }
  