/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 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.mvel2.asm;

/**
 * A visitor to visit a Java method. The methods of this interface 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 interface MethodVisitor {

  // -------------------------------------------------------------------------
  // 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.
   */
  AnnotationVisitor visitAnnotationDefault();

  /**
   * 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.
   */
  AnnotationVisitor visitAnnotation(String desc, boolean visible);

  /**
   * 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.
   */
  AnnotationVisitor visitParameterAnnotation(
      int parameter,
      String desc,
      boolean visible);

  /**
   * Visits a non standard attribute of this method.
   *
   * @param attr an attribute.
   */
  void visitAttribute(Attribute attr);

  /**
   * Starts the visit of the method's code, if any (i.e. non abstract method).
   */
  void 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 unconditionnal branch instruction
   * such as GOTO or THROW, that is the target of a jump instruction, or that
   * starts an exception handler ast. 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> Packed frames are basically
   * "deltas" from the state of the previous frame (very first frame is
   * implicitly defined by the method's parameters and access flags): <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>
   *
   * @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, or type
   *               descriptors for array types), 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.
   */
  void visitFrame(
      int type,
      int nLocal,
      Object[] local,
      int nStack,
      Object[] 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.
   */
  void visitInsn(int 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}.
   */
  void visitIntInsn(int opcode, int 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.
   */
  void visitVarInsn(int opcode, int var);

  /**
   * Visits a type instruction. A type instruction is an instruction that
   * takes a type descriptor as parameter.
   *
   * @param opcode the opcode of the type instruction to be visited. This
   *               opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
   * @param desc   the operand of the instruction to be visited. This operand is
   *               must be a fully qualified class name in internal form, or the type
   *               descriptor of an array type (see {@link Type Type}).
   */
  void visitTypeInsn(int opcode, String desc);

  /**
   * 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}).
   */
  void visitFieldInsn(int opcode, String owner, String name, String 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}).
   */
  void visitMethodInsn(int opcode, String owner, String name, String desc);

  /**
   * 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.
   */
  void visitJumpInsn(int opcode, Label label);

  /**
   * Visits a label. A label designates the instruction that will be visited
   * just after it.
   *
   * @param label a {@link Label Label} object.
   */
  void visitLabel(Label label);

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

  /**
   * Visits a LDC instruction.
   *
   * @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} (or a {@link Type} for
   *            <tt>.class</tt> constants, for classes whose version is 49.0 or
   *            more).
   */
  void visitLdcInsn(Object cst);

  /**
   * Visits an IINC instruction.
   *
   * @param var       index of the local variable to be incremented.
   * @param increment amount to increment the local variable by.
   */
  void visitIincInsn(int var, int increment);

  /**
   * Visits a TABLESWITCH instruction.
   *
   * @param min    the minimum key value.
   * @param max    the maximum key value.
   * @param dflt   beginning of the default handler ast.
   * @param labels beginnings of the handler blocks. <tt>labels[i]</tt> is
   *               the beginning of the handler ast for the <tt>min + i</tt> key.
   */
  void visitTableSwitchInsn(int min, int max, Label dflt, Label labels[]);

  /**
   * Visits a LOOKUPSWITCH instruction.
   *
   * @param dflt   beginning of the default handler ast.
   * @param keys   the values of the keys.
   * @param labels beginnings of the handler blocks. <tt>labels[i]</tt> is
   *               the beginning of the handler ast for the <tt>keys[i]</tt> key.
   */
  void visitLookupSwitchInsn(Label dflt, int keys[], Label 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.
   */
  void visitMultiANewArrayInsn(String desc, int dims);

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

  /**
   * Visits a try catch ast.
   *
   * @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).
   */
  void visitTryCatchBlock(Label start, Label end, Label handler, String 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).
   */
  void visitLocalVariable(
      String name,
      String desc,
      String signature,
      Label start,
      Label end,
      int 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).
   */
  void visitLineNumber(int line, Label 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.
   */
  void visitMaxs(int maxStack, int 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.
   */
  void visitEnd();
}
