Package scala.tools.asm.tree.analysis

Class Interpreter<V extends Value>

java.lang.Object

scala.tools.asm.tree.analysis.Interpreter<V>

Type Parameters:

V - type of the Value used for the analysis.

Direct Known Subclasses:

BasicInterpreter, SourceInterpreter

public abstract class Interpreter<V extends Value>
extends java.lang.Object

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.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	api	The ASM API version supported by this interpreter.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Interpreter(int api)	Constructs a new Interpreter.

Method Summary

Modifier and Type	Method	Description
abstract V	binaryOperation(AbstractInsnNode insn, V value1, V value2)	Interprets a bytecode instruction with two arguments.
abstract V	copyOperation(AbstractInsnNode insn, V value)	Interprets a bytecode instruction that moves a value on the stack or to or from local variables.
abstract V	merge(V value1, V value2)	Merges two values.
abstract V	naryOperation(AbstractInsnNode insn, java.util.List<? extends V> values)	Interprets a bytecode instruction with a variable number of arguments.
V	newEmptyNonParameterLocalValue(int local)	Called by the analyzer when initializing a non-parameter local in a frame.
V	newEmptyValueAfterSize2Local(int local)	Called by the analyzer and the interpreter.
V	newEmptyValueForPreviousSize2Local(int local)	Called by the interpreter.
V	newExceptionValue(TryCatchBlockNode tryCatchBlockNode, Frame handlerFrame, Type exceptionType)	Called by the analyzer when initializing the exception value on the call stack at the entry of an exception handler.
abstract V	newOperation(AbstractInsnNode insn)	Interprets a bytecode instruction without arguments.
V	newParameterValue(boolean isInstanceMethod, int local, Type type)	Called by the analyzer when initializing the value of a parameter in a frame.
V	newReturnTypeValue(Type type)	Called by the analyzer for initializing the return type value of a frame.
abstract V	newValue(Type type)	Creates a new value that represents the given type.
abstract void	returnOperation(AbstractInsnNode insn, V value, V expected)	Interprets a bytecode return instruction.
abstract V	ternaryOperation(AbstractInsnNode insn, V value1, V value2, V value3)	Interprets a bytecode instruction with three arguments.
abstract V	unaryOperation(AbstractInsnNode insn, V value)	Interprets a bytecode instruction with a single argument.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

api

protected final int api

The ASM API version supported by this interpreter. The value of this field must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7_EXPERIMENTAL.

Constructor Detail

Interpreter

protected Interpreter(int api)

Constructs a new Interpreter.

Parameters:

api - the ASM API version supported by this interpreter. Must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7_EXPERIMENTAL.

Method Detail

newValue

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.

Parameters:

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

Returns:

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

newOperation

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 - the bytecode instruction to be interpreted.

Returns:

the result of the interpretation of the given instruction.

Throws:

AnalyzerException - if an error occurred during the interpretation.

newReturnTypeValue

public V newReturnTypeValue(Type type)

Called by the analyzer for initializing the return type value of a frame.

newParameterValue

public V newParameterValue(boolean isInstanceMethod,
                           int local,
                           Type type)

Called by the analyzer when initializing the value of a parameter in a frame.

newEmptyNonParameterLocalValue

public V newEmptyNonParameterLocalValue(int local)

Called by the analyzer when initializing a non-parameter local in a frame. This method has to return a size-1 value representing an empty slot.

newEmptyValueAfterSize2Local

public V newEmptyValueAfterSize2Local(int local)

Called by the analyzer and the interpreter. When initializing or setting the value of a size-2 local, the value of the subsequent slot is reset using this method. This method has to return a size-1 value representing an empty slot.

newEmptyValueForPreviousSize2Local

public V newEmptyValueForPreviousSize2Local(int local)

Called by the interpreter. When setting the value of a local variable, the interpreter checks whether the current value stored at the preceding index is of size-2. In this case, the preceding size-2 value is no longer valid and reset using this method. This method has to return a size-1 value representing an empty slot.

newExceptionValue

public V newExceptionValue(TryCatchBlockNode tryCatchBlockNode,
                           Frame handlerFrame,
                           Type exceptionType)

Called by the analyzer when initializing the exception value on the call stack at the entry of an exception handler.

copyOperation

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 - the bytecode instruction to be interpreted.

value - the value that must be moved by the instruction.

Returns:

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

Throws:

AnalyzerException - if an error occurred during the interpretation.

unaryOperation

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 - the bytecode instruction to be interpreted.

value - the argument of the instruction to be interpreted.

Returns:

the result of the interpretation of the given instruction.

Throws:

AnalyzerException - if an error occurred during the interpretation.

binaryOperation

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 - the bytecode instruction to be interpreted.

value1 - the first argument of the instruction to be interpreted.

value2 - the second argument of the instruction to be interpreted.

Returns:

the result of the interpretation of the given instruction.

Throws:

AnalyzerException - if an error occurred during the interpretation.

ternaryOperation

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 - the bytecode instruction to be interpreted.

value1 - the first argument of the instruction to be interpreted.

value2 - the second argument of the instruction to be interpreted.

value3 - the third argument of the instruction to be interpreted.

Returns:

the result of the interpretation of the given instruction.

Throws:

AnalyzerException - if an error occurred during the interpretation.

naryOperation

public abstract V naryOperation(AbstractInsnNode insn,
                                java.util.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 - the bytecode instruction to be interpreted.

values - the arguments of the instruction to be interpreted.

Returns:

the result of the interpretation of the given instruction.

Throws:

AnalyzerException - if an error occurred during the interpretation.

returnOperation

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 - the bytecode instruction to be interpreted.

value - the argument of the instruction to be interpreted.

expected - the expected return type of the analyzed method.

Throws:

AnalyzerException - if an error occurred during the interpretation.

merge

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 - a value.

value2 - another value.

Returns:

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