Top Description Fields Constructors Methods
org.objectweb.asm.tree.analysis

public abstract Class Interpreter<V extends Value>

extends Object
Class Inheritance
Known Direct Subclasses
org.objectweb.asm.tree.analysis.SourceInterpreter, org.objectweb.asm.tree.analysis.BasicInterpreter
Type Parameters
<V>
type of the Value used for the analysis.
Imports
java.util.List, org.objectweb.asm.Opcodes, .Type, org.objectweb.asm.tree.AbstractInsnNode, .TryCatchBlockNode

A semantic bytecode interpreter. More precisely, this interpreter only manages the computation of values from other values: it does not manage the transfer of values to or from the stack, and to or from the local variables. This separation allows a generic bytecode Analyzer to work with various semantic interpreters, without needing to duplicate the code to simulate the transfer of values.
Author
Eric Bruneton

Field Summary

Modifier and TypeField and Description
protected final int
api

The ASM API version supported by this interpreter.

Constructor Summary

AccessConstructor and Description
protected
Interpreter(final int
the ASM API version supported by this interpreter. Must be one of the ASMx values in Opcodes.
api
)

Constructs a new Interpreter.

Method Summary

Modifier and TypeMethod and Description
public abstract V

Returns:

the result of the interpretation of the given instruction.
binaryOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
V
the first argument of the instruction to be interpreted.
value1
,
V
the second argument of the instruction to be interpreted.
value2
)

Interprets a bytecode instruction with two arguments.

public abstract V

Returns:

the result of the interpretation of the given instruction. The returned value must be equal to the given value.
copyOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
V
the value that must be moved by the instruction.
value
)

Interprets a bytecode instruction that moves a value on the stack or to or from local variables.

public abstract V

Returns:

the merged value. If the merged value is equal to value1, this method must return value1.
merge
(V
a value.
value1
,
V
another value.
value2
)

Merges two values.

public abstract V

Returns:

the result of the interpretation of the given instruction.
naryOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
List<? extends V>
the arguments of the instruction to be interpreted.
values
)

Interprets a bytecode instruction with a variable number of arguments.

public V

Returns:

a value representing an uninitialized value. The size of the returned value must be equal to 1.
newEmptyValue
(final int
the local variable index.
local
)

Creates a new uninitialized value for a local variable.

public V

Returns:

a value that represents the given exceptionType. The size of the returned value must be equal to 1.
newExceptionValue
(final TryCatchBlockNode
the exception handler.
tryCatchBlockNode
,
final Frame<V>
the exception handler frame.
handlerFrame
,
final Type
the exception type handled by this handler.
exceptionType
)

Creates a new value that represents the given exception type.

public abstract V

Returns:

the result of the interpretation of the given instruction.
newOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
)

Interprets a bytecode instruction without arguments.

public V

Returns:

a value that represents the given type. The size of the returned value must be equal to the size of the given type.
newParameterValue
(final boolean
true if the method is non-static.
isInstanceMethod
,
final int
the local variable index.
local
,
final Type
a primitive or reference type.
type
)

Creates a new value that represents the given parameter type.

public V

Returns:

a value that represents the given type. The size of the returned value must be equal to the size of the given type.
newReturnTypeValue
(final Type
a primitive or reference type.
type
)

Creates a new value that represents the given return type.

public abstract V

Returns:

a value that represents the given type. The size of the returned value must be equal to the size of the given type.
newValue
(Type
a primitive or reference type, or null to represent an uninitialized value.
type
)

Creates a new value that represents the given type.

public abstract void
returnOperation(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
V
the argument of the instruction to be interpreted.
value
,
V
the expected return type of the analyzed method.
expected
)

Interprets a bytecode return instruction.

public abstract V

Returns:

the result of the interpretation of the given instruction.
ternaryOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
V
the first argument of the instruction to be interpreted.
value1
,
V
the second argument of the instruction to be interpreted.
value2
,
V
the third argument of the instruction to be interpreted.
value3
)

Interprets a bytecode instruction with three arguments.

public abstract V

Returns:

the result of the interpretation of the given instruction.
unaryOperation
(AbstractInsnNode
the bytecode instruction to be interpreted.
insn
,
V
the argument of the instruction to be interpreted.
value
)

Interprets a bytecode instruction with a single argument.

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

Field Detail

apiback to summary
protected final int api

The ASM API version supported by this interpreter. The value of this field must be one of the ASMx values in Opcodes.

Constructor Detail

Interpreterback to summary
protected Interpreter(final int api)

Constructs a new Interpreter.

Parameters
api:int

the ASM API version supported by this interpreter. Must be one of the ASMx values in Opcodes.

Method Detail

binaryOperationback to summary
public abstract V binaryOperation(AbstractInsnNode insn, V value1, V value2) throws AnalyzerException

Interprets a bytecode instruction with two arguments. This method is called for the following opcodes:

IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, ISHL, LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE, PUTFIELD

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

value1:V

the first argument of the instruction to be interpreted.

value2:V

the second argument of the instruction to be interpreted.

Returns:V

the result of the interpretation of the given instruction.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
copyOperationback to summary
public abstract V copyOperation(AbstractInsnNode insn, V value) throws AnalyzerException

Interprets a bytecode instruction that moves a value on the stack or to or from local variables. This method is called for the following opcodes:

ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE, ASTORE, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

value:V

the value that must be moved by the instruction.

Returns:V

the result of the interpretation of the given instruction. The returned value must be equal to the given value.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
mergeback to summary
public abstract V merge(V value1, V value2)

Merges two values. The merge operation must return a value that represents both values (for instance, if the two values are two types, the merged value must be a common super type of the two types. If the two values are integer intervals, the merged value must be an interval that contains the previous ones. Likewise for other types of values).

Parameters
value1:V

a value.

value2:V

another value.

Returns:V

the merged value. If the merged value is equal to value1, this method must return value1.

naryOperationback to summary
public abstract V naryOperation(AbstractInsnNode insn, List<? extends V> values) throws AnalyzerException

Interprets a bytecode instruction with a variable number of arguments. This method is called for the following opcodes:

INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC, INVOKEINTERFACE, MULTIANEWARRAY and INVOKEDYNAMIC

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

values:List<? extends V>

the arguments of the instruction to be interpreted.

Returns:V

the result of the interpretation of the given instruction.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
newEmptyValueback to summary
public V newEmptyValue(final int local)

Creates a new uninitialized value for a local variable. This method is called to initialize the value of a local that does not correspond to a method parameter, and to reset one half of a size-2 value when the other half is assigned a size-1 value.

By default, calls newValue(null).

Parameters
local:int

the local variable index.

Returns:V

a value representing an uninitialized value. The size of the returned value must be equal to 1.

newExceptionValueback to summary
public V newExceptionValue(final TryCatchBlockNode tryCatchBlockNode, final Frame<V> handlerFrame, final Type exceptionType)

Creates a new value that represents the given exception type. This method is called to initialize the exception value on the call stack at the entry of an exception handler.

By default, calls newValue(exceptionType).

Parameters
tryCatchBlockNode:TryCatchBlockNode

the exception handler.

handlerFrame:Frame<V>

the exception handler frame.

exceptionType:Type

the exception type handled by this handler.

Returns:V

a value that represents the given exceptionType. The size of the returned value must be equal to 1.

newOperationback to summary
public abstract V newOperation(AbstractInsnNode insn) throws AnalyzerException

Interprets a bytecode instruction without arguments. This method is called for the following opcodes:

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, BIPUSH, SIPUSH, LDC, JSR, GETSTATIC, NEW

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

Returns:V

the result of the interpretation of the given instruction.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
newParameterValueback to summary
public V newParameterValue(final boolean isInstanceMethod, final int local, final Type type)

Creates a new value that represents the given parameter type. This method is called to initialize the value of a local corresponding to a method parameter in a frame.

By default, calls newValue(type).

Parameters
isInstanceMethod:boolean

true if the method is non-static.

local:int

the local variable index.

type:Type

a primitive or reference type.

Returns:V

a value that represents the given type. The size of the returned value must be equal to the size of the given type.

newReturnTypeValueback to summary
public V newReturnTypeValue(final Type type)

Creates a new value that represents the given return type. This method is called to initialize the return type value of a frame.

By default, calls newValue(type).

Parameters
type:Type

a primitive or reference type.

Returns:V

a value that represents the given type. The size of the returned value must be equal to the size of the given type.

newValueback to summary
public abstract V newValue(Type type)

Creates a new value that represents the given type.

Called for method parameters (including this), exception handler variable and with null type for variables reserved by long and double types.

An interpreter may choose to implement one or more of Interpreter#newReturnTypeValue(Type), Interpreter#newParameterValue(boolean, int, Type), Interpreter#newEmptyValue(int), Interpreter#newExceptionValue(TryCatchBlockNode, Frame, Type) to distinguish different types of new value.

Parameters
type:Type

a primitive or reference type, or null to represent an uninitialized value.

Returns:V

a value that represents the given type. The size of the returned value must be equal to the size of the given type.

returnOperationback to summary
public abstract void returnOperation(AbstractInsnNode insn, V value, V expected) throws AnalyzerException

Interprets a bytecode return instruction. This method is called for the following opcodes:

IRETURN, LRETURN, FRETURN, DRETURN, ARETURN

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

value:V

the argument of the instruction to be interpreted.

expected:V

the expected return type of the analyzed method.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
ternaryOperationback to summary
public abstract V ternaryOperation(AbstractInsnNode insn, V value1, V value2, V value3) throws AnalyzerException

Interprets a bytecode instruction with three arguments. This method is called for the following opcodes:

IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

value1:V

the first argument of the instruction to be interpreted.

value2:V

the second argument of the instruction to be interpreted.

value3:V

the third argument of the instruction to be interpreted.

Returns:V

the result of the interpretation of the given instruction.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.
unaryOperationback to summary
public abstract V unaryOperation(AbstractInsnNode insn, V value) throws AnalyzerException

Interprets a bytecode instruction with a single argument. This method is called for the following opcodes:

INEG, LNEG, FNEG, DNEG, IINC, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C, I2S, IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, TABLESWITCH, LOOKUPSWITCH, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, PUTSTATIC, GETFIELD, NEWARRAY, ANEWARRAY, ARRAYLENGTH, ATHROW, CHECKCAST, INSTANCEOF, MONITORENTER, MONITOREXIT, IFNULL, IFNONNULL

Parameters
insn:AbstractInsnNode

the bytecode instruction to be interpreted.

value:V

the argument of the instruction to be interpreted.

Returns:V

the result of the interpretation of the given instruction.

Exceptions
AnalyzerException:
if an error occurred during the interpretation.