org.objectweb.asm.util
Class CheckMethodAdapter

java.lang.Object
  extended by org.objectweb.asm.MethodAdapter
      extended by org.objectweb.asm.util.CheckMethodAdapter
All Implemented Interfaces:
MethodVisitor

public class CheckMethodAdapter
extends MethodAdapter

A MethodAdapter that checks that its methods are properly used. More precisely this code adapter checks each instruction individually (i.e., each visit method checks some preconditions based only on its arguments - such as the fact that the given opcode is correct for a given visit method), but does not check the sequence of instructions. For example, in a method whose signature is void m (), the invalid instruction IRETURN, or the invalid sequence IADD L2I will not be detected by this code adapter.

Author:
Eric Bruneton

Field Summary
private  boolean endCode
          true if the visitMaxs method has been called.
private  boolean endMethod
          true if the visitEnd method has been called.
private  java.util.HashMap labels
          The already visited labels.
private  boolean startCode
          true if the visitCode method has been called.
private static int[] TYPE
          Code of the visit method to be used for each opcode.
 
Fields inherited from class org.objectweb.asm.MethodAdapter
mv
 
Constructor Summary
CheckMethodAdapter(MethodVisitor cv)
          Constructs a new CheckMethodAdapter object.
 
Method Summary
(package private) static void checkConstant(java.lang.Object cst)
          Checks that the given value is an Integer, aFloat, a Long, a Double or a String.
(package private) static void checkDesc(java.lang.String desc, boolean canBeVoid)
          Checks that the given string is a valid type descriptor.
(package private) static int checkDesc(java.lang.String desc, int start, boolean canBeVoid)
          Checks that a the given substring is a valid type descriptor.
(package private)  void checkEndCode()
          Checks that the visitMaxs method has not been called.
(package private)  void checkEndMethod()
          Checks that the visitEnd method has not been called.
(package private) static void checkIdentifier(java.lang.String name, int start, int end, java.lang.String msg)
          Checks that the given substring is a valid Java identifier.
(package private) static void checkIdentifier(java.lang.String name, java.lang.String msg)
          Checks that the given string is a valid Java identifier.
(package private) static void checkInternalName(java.lang.String name, int start, int end, java.lang.String msg)
          Checks that the given substring is a valid internal class name.
(package private) static void checkInternalName(java.lang.String name, java.lang.String msg)
          Checks that the given string is a valid internal class name.
(package private)  void checkLabel(Label label, boolean checkVisited, java.lang.String msg)
          Checks that the given label is not null.
(package private) static void checkMethodDesc(java.lang.String desc)
          Checks that the given string is a valid method descriptor.
(package private) static void checkMethodIdentifier(java.lang.String name, java.lang.String msg)
          Checks that the given string is a valid Java identifier or is equal to '<init>' or '<clinit>'.
(package private) static void checkOpcode(int opcode, int type)
          Checks that the type of the given opcode is equal to the given type.
(package private) static void checkSignedByte(int value, java.lang.String msg)
          Checks that the given value is a signed byte.
(package private) static void checkSignedShort(int value, java.lang.String msg)
          Checks that the given value is a signed short.
(package private)  void checkStartCode()
          Checks that the visitCode method has been called.
(package private) static void checkUnsignedShort(int value, java.lang.String msg)
          Checks that the given value is an unsigned short.
 AnnotationVisitor visitAnnotation(java.lang.String desc, boolean visible)
          Visits an annotation of this method.
 AnnotationVisitor visitAnnotationDefault()
          Visits the default value of this annotation interface method.
 void visitAttribute(Attribute attr)
          Visits a non standard attribute of this method.
 void visitCode()
          Starts the visit of the method's code, if any (i.e.
 void visitEnd()
          Visits the end of the method.
 void visitFieldInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc)
          Visits a field instruction.
 void visitFrame(int type, int nLocal, java.lang.Object[] local, int nStack, java.lang.Object[] stack)
          Visits the current state of the local variables and operand stack elements.
 void visitIincInsn(int var, int increment)
          Visits an IINC instruction.
 void visitInsn(int opcode)
          Visits a zero operand instruction.
 void visitIntInsn(int opcode, int operand)
          Visits an instruction with a single int operand.
 void visitJumpInsn(int opcode, Label label)
          Visits a jump instruction.
 void visitLabel(Label label)
          Visits a label.
 void visitLdcInsn(java.lang.Object cst)
          Visits a LDC instruction.
 void visitLineNumber(int line, Label start)
          Visits a line number declaration.
 void visitLocalVariable(java.lang.String name, java.lang.String desc, java.lang.String signature, Label start, Label end, int index)
          Visits a local variable declaration.
 void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
          Visits a LOOKUPSWITCH instruction.
 void visitMaxs(int maxStack, int maxLocals)
          Visits the maximum stack size and the maximum number of local variables of the method.
 void visitMethodInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc)
          Visits a method instruction.
 void visitMultiANewArrayInsn(java.lang.String desc, int dims)
          Visits a MULTIANEWARRAY instruction.
 AnnotationVisitor visitParameterAnnotation(int parameter, java.lang.String desc, boolean visible)
          Visits an annotation of a parameter this method.
 void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels)
          Visits a TABLESWITCH instruction.
 void visitTryCatchBlock(Label start, Label end, Label handler, java.lang.String type)
          Visits a try catch block.
 void visitTypeInsn(int opcode, java.lang.String desc)
          Visits a type instruction.
 void visitVarInsn(int opcode, int var)
          Visits a local variable instruction.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

startCode

private boolean startCode
true if the visitCode method has been called.


endCode

private boolean endCode
true if the visitMaxs method has been called.


endMethod

private boolean endMethod
true if the visitEnd method has been called.


labels

private java.util.HashMap labels
The already visited labels. This map associate Integer values to Label keys.


TYPE

private static final int[] TYPE
Code of the visit method to be used for each opcode.

Constructor Detail

CheckMethodAdapter

public CheckMethodAdapter(MethodVisitor cv)
Constructs a new CheckMethodAdapter object.

Parameters:
cv - the code visitor to which this adapter must delegate calls.
Method Detail

visitAnnotation

public AnnotationVisitor visitAnnotation(java.lang.String desc,
                                         boolean visible)
Description copied from interface: MethodVisitor
Visits an annotation of this method.

Specified by:
visitAnnotation in interface MethodVisitor
Overrides:
visitAnnotation in class MethodAdapter
Parameters:
desc - the class descriptor of the annotation class.
visible - true if the annotation is visible at runtime.
Returns:
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

visitAnnotationDefault

public AnnotationVisitor visitAnnotationDefault()
Description copied from interface: MethodVisitor
Visits the default value of this annotation interface method.

Specified by:
visitAnnotationDefault in interface MethodVisitor
Overrides:
visitAnnotationDefault in class MethodAdapter
Returns:
a visitor to the visit the actual default value of this annotation interface method, or null 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.

visitParameterAnnotation

public AnnotationVisitor visitParameterAnnotation(int parameter,
                                                  java.lang.String desc,
                                                  boolean visible)
Description copied from interface: MethodVisitor
Visits an annotation of a parameter this method.

Specified by:
visitParameterAnnotation in interface MethodVisitor
Overrides:
visitParameterAnnotation in class MethodAdapter
Parameters:
parameter - the parameter index.
desc - the class descriptor of the annotation class.
visible - true if the annotation is visible at runtime.
Returns:
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

visitAttribute

public void visitAttribute(Attribute attr)
Description copied from interface: MethodVisitor
Visits a non standard attribute of this method.

Specified by:
visitAttribute in interface MethodVisitor
Overrides:
visitAttribute in class MethodAdapter
Parameters:
attr - an attribute.

visitCode

public void visitCode()
Description copied from interface: MethodVisitor
Starts the visit of the method's code, if any (i.e. non abstract method).

Specified by:
visitCode in interface MethodVisitor
Overrides:
visitCode in class MethodAdapter

visitFrame

public void visitFrame(int type,
                       int nLocal,
                       java.lang.Object[] local,
                       int nStack,
                       java.lang.Object[] stack)
Description copied from interface: MethodVisitor
Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i 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 block. The visited types must describe the values of the local variables and of the operand stack elements just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to V1_6.

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):

Specified by:
visitFrame in interface MethodVisitor
Overrides:
visitFrame in class MethodAdapter
Parameters:
type - the type of this stack map frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.
nLocal - the number of local variables in the visited frame.
local - the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes.TOP, Opcodes.INTEGER, Opcodes.FLOAT, Opcodes.LONG, Opcodes.DOUBLE,Opcodes.NULL or 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).
nStack - the number of operand stack elements in the visited frame.
stack - the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.

visitInsn

public void visitInsn(int opcode)
Description copied from interface: MethodVisitor
Visits a zero operand instruction.

Specified by:
visitInsn in interface MethodVisitor
Overrides:
visitInsn in class MethodAdapter
Parameters:
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.

visitIntInsn

public void visitIntInsn(int opcode,
                         int operand)
Description copied from interface: MethodVisitor
Visits an instruction with a single int operand.

Specified by:
visitIntInsn in interface MethodVisitor
Overrides:
visitIntInsn in class MethodAdapter
Parameters:
opcode - the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.
operand - the operand of the instruction to be visited.
When opcode is BIPUSH, operand value should be between Byte.MIN_VALUE and Byte.MAX_VALUE.
When opcode is SIPUSH, operand value should be between Short.MIN_VALUE and Short.MAX_VALUE.
When opcode is NEWARRAY, operand value should be one of Opcodes.T_BOOLEAN, Opcodes.T_CHAR, Opcodes.T_FLOAT, Opcodes.T_DOUBLE, Opcodes.T_BYTE, Opcodes.T_SHORT, Opcodes.T_INT or Opcodes.T_LONG.

visitVarInsn

public void visitVarInsn(int opcode,
                         int var)
Description copied from interface: MethodVisitor
Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.

Specified by:
visitVarInsn in interface MethodVisitor
Overrides:
visitVarInsn in class MethodAdapter
Parameters:
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.
var - the operand of the instruction to be visited. This operand is the index of a local variable.

visitTypeInsn

public void visitTypeInsn(int opcode,
                          java.lang.String desc)
Description copied from interface: MethodVisitor
Visits a type instruction. A type instruction is an instruction that takes a type descriptor as parameter.

Specified by:
visitTypeInsn in interface MethodVisitor
Overrides:
visitTypeInsn in class MethodAdapter
Parameters:
opcode - the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
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 Type).

visitFieldInsn

public void visitFieldInsn(int opcode,
                           java.lang.String owner,
                           java.lang.String name,
                           java.lang.String desc)
Description copied from interface: MethodVisitor
Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.

Specified by:
visitFieldInsn in interface MethodVisitor
Overrides:
visitFieldInsn in class MethodAdapter
Parameters:
opcode - the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
owner - the internal name of the field's owner class (see getInternalName).
name - the field's name.
desc - the field's descriptor (see Type).

visitMethodInsn

public void visitMethodInsn(int opcode,
                            java.lang.String owner,
                            java.lang.String name,
                            java.lang.String desc)
Description copied from interface: MethodVisitor
Visits a method instruction. A method instruction is an instruction that invokes a method.

Specified by:
visitMethodInsn in interface MethodVisitor
Overrides:
visitMethodInsn in class MethodAdapter
Parameters:
opcode - the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
owner - the internal name of the method's owner class (see getInternalName).
name - the method's name.
desc - the method's descriptor (see Type).

visitJumpInsn

public void visitJumpInsn(int opcode,
                          Label label)
Description copied from interface: MethodVisitor
Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.

Specified by:
visitJumpInsn in interface MethodVisitor
Overrides:
visitJumpInsn in class MethodAdapter
Parameters:
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.
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.

visitLabel

public void visitLabel(Label label)
Description copied from interface: MethodVisitor
Visits a label. A label designates the instruction that will be visited just after it.

Specified by:
visitLabel in interface MethodVisitor
Overrides:
visitLabel in class MethodAdapter
Parameters:
label - a Label object.

visitLdcInsn

public void visitLdcInsn(java.lang.Object cst)
Description copied from interface: MethodVisitor
Visits a LDC instruction.

Specified by:
visitLdcInsn in interface MethodVisitor
Overrides:
visitLdcInsn in class MethodAdapter
Parameters:
cst - the constant to be loaded on the stack. This parameter must be a non null Integer, a Float, a Long, a Double a String (or a Type for .class constants, for classes whose version is 49.0 or more).

visitIincInsn

public void visitIincInsn(int var,
                          int increment)
Description copied from interface: MethodVisitor
Visits an IINC instruction.

Specified by:
visitIincInsn in interface MethodVisitor
Overrides:
visitIincInsn in class MethodAdapter
Parameters:
var - index of the local variable to be incremented.
increment - amount to increment the local variable by.

visitTableSwitchInsn

public void visitTableSwitchInsn(int min,
                                 int max,
                                 Label dflt,
                                 Label[] labels)
Description copied from interface: MethodVisitor
Visits a TABLESWITCH instruction.

Specified by:
visitTableSwitchInsn in interface MethodVisitor
Overrides:
visitTableSwitchInsn in class MethodAdapter
Parameters:
min - the minimum key value.
max - the maximum key value.
dflt - beginning of the default handler block.
labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.

visitLookupSwitchInsn

public void visitLookupSwitchInsn(Label dflt,
                                  int[] keys,
                                  Label[] labels)
Description copied from interface: MethodVisitor
Visits a LOOKUPSWITCH instruction.

Specified by:
visitLookupSwitchInsn in interface MethodVisitor
Overrides:
visitLookupSwitchInsn in class MethodAdapter
Parameters:
dflt - beginning of the default handler block.
keys - the values of the keys.
labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.

visitMultiANewArrayInsn

public void visitMultiANewArrayInsn(java.lang.String desc,
                                    int dims)
Description copied from interface: MethodVisitor
Visits a MULTIANEWARRAY instruction.

Specified by:
visitMultiANewArrayInsn in interface MethodVisitor
Overrides:
visitMultiANewArrayInsn in class MethodAdapter
Parameters:
desc - an array type descriptor (see Type).
dims - number of dimensions of the array to allocate.

visitTryCatchBlock

public void visitTryCatchBlock(Label start,
                               Label end,
                               Label handler,
                               java.lang.String type)
Description copied from interface: MethodVisitor
Visits a try catch block.

Specified by:
visitTryCatchBlock in interface MethodVisitor
Overrides:
visitTryCatchBlock in class MethodAdapter
Parameters:
start - beginning of the exception handler's scope (inclusive).
end - end of the exception handler's scope (exclusive).
handler - beginning of the exception handler's code.
type - internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).

visitLocalVariable

public void visitLocalVariable(java.lang.String name,
                               java.lang.String desc,
                               java.lang.String signature,
                               Label start,
                               Label end,
                               int index)
Description copied from interface: MethodVisitor
Visits a local variable declaration.

Specified by:
visitLocalVariable in interface MethodVisitor
Overrides:
visitLocalVariable in class MethodAdapter
Parameters:
name - the name of a local variable.
desc - the type descriptor of this local variable.
signature - the type signature of this local variable. May be null if the local variable type does not use generic types.
start - the first instruction corresponding to the scope of this local variable (inclusive).
end - the last instruction corresponding to the scope of this local variable (exclusive).
index - the local variable's index.

visitLineNumber

public void visitLineNumber(int line,
                            Label start)
Description copied from interface: MethodVisitor
Visits a line number declaration.

Specified by:
visitLineNumber in interface MethodVisitor
Overrides:
visitLineNumber in class MethodAdapter
Parameters:
line - a line number. This number refers to the source file from which the class was compiled.
start - the first instruction corresponding to this line number.

visitMaxs

public void visitMaxs(int maxStack,
                      int maxLocals)
Description copied from interface: MethodVisitor
Visits the maximum stack size and the maximum number of local variables of the method.

Specified by:
visitMaxs in interface MethodVisitor
Overrides:
visitMaxs in class MethodAdapter
Parameters:
maxStack - maximum stack size of the method.
maxLocals - maximum number of local variables for the method.

visitEnd

public void visitEnd()
Description copied from interface: MethodVisitor
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.

Specified by:
visitEnd in interface MethodVisitor
Overrides:
visitEnd in class MethodAdapter

checkStartCode

void checkStartCode()
Checks that the visitCode method has been called.


checkEndCode

void checkEndCode()
Checks that the visitMaxs method has not been called.


checkEndMethod

void checkEndMethod()
Checks that the visitEnd method has not been called.


checkOpcode

static void checkOpcode(int opcode,
                        int type)
Checks that the type of the given opcode is equal to the given type.

Parameters:
opcode - the opcode to be checked.
type - the expected opcode type.

checkSignedByte

static void checkSignedByte(int value,
                            java.lang.String msg)
Checks that the given value is a signed byte.

Parameters:
value - the value to be checked.
msg - an message to be used in case of error.

checkSignedShort

static void checkSignedShort(int value,
                             java.lang.String msg)
Checks that the given value is a signed short.

Parameters:
value - the value to be checked.
msg - an message to be used in case of error.

checkUnsignedShort

static void checkUnsignedShort(int value,
                               java.lang.String msg)
Checks that the given value is an unsigned short.

Parameters:
value - the value to be checked.
msg - an message to be used in case of error.

checkConstant

static void checkConstant(java.lang.Object cst)
Checks that the given value is an Integer, aFloat, a Long, a Double or a String.

Parameters:
cst - the value to be checked.

checkIdentifier

static void checkIdentifier(java.lang.String name,
                            java.lang.String msg)
Checks that the given string is a valid Java identifier.

Parameters:
name - the string to be checked.
msg - a message to be used in case of error.

checkIdentifier

static void checkIdentifier(java.lang.String name,
                            int start,
                            int end,
                            java.lang.String msg)
Checks that the given substring is a valid Java identifier.

Parameters:
name - the string to be checked.
start - index of the first character of the identifier (inclusive).
end - index of the last character of the identifier (exclusive). -1 is equivalent to name.length() if name is not null.
msg - a message to be used in case of error.

checkMethodIdentifier

static void checkMethodIdentifier(java.lang.String name,
                                  java.lang.String msg)
Checks that the given string is a valid Java identifier or is equal to '<init>' or '<clinit>'.

Parameters:
name - the string to be checked.
msg - a message to be used in case of error.

checkInternalName

static void checkInternalName(java.lang.String name,
                              java.lang.String msg)
Checks that the given string is a valid internal class name.

Parameters:
name - the string to be checked.
msg - a message to be used in case of error.

checkInternalName

static void checkInternalName(java.lang.String name,
                              int start,
                              int end,
                              java.lang.String msg)
Checks that the given substring is a valid internal class name.

Parameters:
name - the string to be checked.
start - index of the first character of the identifier (inclusive).
end - index of the last character of the identifier (exclusive). -1 is equivalent to name.length() if name is not null.
msg - a message to be used in case of error.

checkDesc

static void checkDesc(java.lang.String desc,
                      boolean canBeVoid)
Checks that the given string is a valid type descriptor.

Parameters:
desc - the string to be checked.
canBeVoid - true if V can be considered valid.

checkDesc

static int checkDesc(java.lang.String desc,
                     int start,
                     boolean canBeVoid)
Checks that a the given substring is a valid type descriptor.

Parameters:
desc - the string to be checked.
start - index of the first character of the identifier (inclusive).
canBeVoid - true if V can be considered valid.
Returns:
the index of the last character of the type decriptor, plus one.

checkMethodDesc

static void checkMethodDesc(java.lang.String desc)
Checks that the given string is a valid method descriptor.

Parameters:
desc - the string to be checked.

checkLabel

void checkLabel(Label label,
                boolean checkVisited,
                java.lang.String msg)
Checks that the given label is not null. This method can also check that the label has been visited.

Parameters:
label - the label to be checked.
checkVisited - true to check that the label has been visited.
msg - a message to be used in case of error.