org.objectweb.asm.tree.analysis

Interface Interpreter

public interface Interpreter

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 {@link Analyzer} to work with various semantic interpreters, without needing to duplicate the code to simulate the transfer of values.

Author: Eric Bruneton

Method Summary
ValuebinaryOperation(AbstractInsnNode insn, Value value1, Value value2)
Interprets a bytecode instruction with two arguments.
ValuecopyOperation(AbstractInsnNode insn, Value value)
Interprets a bytecode instruction that moves a value on the stack or to or from local variables.
Valuemerge(Value v, Value w)
Merges two values.
ValuenaryOperation(AbstractInsnNode insn, List values)
Interprets a bytecode instruction with a variable number of arguments.
ValuenewOperation(AbstractInsnNode insn)
Interprets a bytecode instruction without arguments.
ValuenewValue(Type type)
Creates a new value that represents the given type.
ValueternaryOperation(AbstractInsnNode insn, Value value1, Value value2, Value value3)
Interprets a bytecode instruction with three arguments.
ValueunaryOperation(AbstractInsnNode insn, Value value)
Interprets a bytecode instruction with a single argument.

Method Detail

binaryOperation

public Value binaryOperation(AbstractInsnNode insn, Value value1, Value value2)
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 occured during the interpretation.

copyOperation

public Value copyOperation(AbstractInsnNode insn, Value value)
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 occured during the interpretation.

merge

public Value merge(Value v, Value w)
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: v a value. w another value.

Returns: the merged value. If the merged value is equal to v, this method must return v.

naryOperation

public Value naryOperation(AbstractInsnNode insn, List values)
Interprets a bytecode instruction with a variable number of arguments. This method is called for the following opcodes: INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC, INVOKEINTERFACE, MULTIANEWARRAY

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 occured during the interpretation.

newOperation

public Value newOperation(AbstractInsnNode insn)
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 occured during the interpretation.

newValue

public Value 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.

ternaryOperation

public Value ternaryOperation(AbstractInsnNode insn, Value value1, Value value2, Value value3)
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 occured during the interpretation.

unaryOperation

public Value unaryOperation(AbstractInsnNode insn, Value value)
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 occured during the interpretation.