org.springframework.expression.spel

Class CodeFlow

java.lang.Object

org.springframework.expression.spel.CodeFlow

All Implemented Interfaces:

Opcodes

public class CodeFlow
extends Object
implements Opcodes

Records intermediate compilation state as the bytecode is generated for a parsed expression. Also contains bytecode generation helper functions.

Since:

4.1

Author:

Andy Clement

Field Summary

Fields inherited from interface org.springframework.asm.Opcodes

AALOAD, AASTORE, ACC_ABSTRACT, ACC_ANNOTATION, ACC_BRIDGE, ACC_DEPRECATED, ACC_ENUM, ACC_FINAL, ACC_INTERFACE, ACC_MANDATED, ACC_NATIVE, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASM4, ASM5, ASTORE, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DMUL, DNEG, DOUBLE, DREM, DRETURN, DSTORE, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F_APPEND, F_CHOP, F_FULL, F_NEW, F_SAME, F_SAME1, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAT, FMUL, FNEG, FREM, FRETURN, FSTORE, FSUB, GETFIELD, GETSTATIC, GOTO, H_GETFIELD, H_GETSTATIC, H_INVOKEINTERFACE, H_INVOKESPECIAL, H_INVOKESTATIC, H_INVOKEVIRTUAL, H_NEWINVOKESPECIAL, H_PUTFIELD, H_PUTSTATIC, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, IMUL, INEG, INSTANCEOF, INTEGER, INVOKEDYNAMIC, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISUB, IUSHR, IXOR, JSR, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDIV, LLOAD, LMUL, LNEG, LONG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, NULL, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8

Constructor Summary

Constructors

Constructor and Description
CodeFlow()

Method Summary

Modifier and Type	Method and Description
static boolean	areBoxingCompatible(String desc1, String desc2) Determine if boxing/unboxing can get from one type to the other.
static String	createSignatureDescriptor(Constructor<?> ctor) Create the JVM signature descriptor for a constructor.
static String	createSignatureDescriptor(Method method) Create the JVM signature descriptor for a method.
void	enterCompilationScope() Enter a new compilation scope, usually due to nested expression evaluation.
void	exitCompilationScope() Exit a compilation scope, usually after a nested expression has been evaluated.
static void	insertBoxIfNecessary(MethodVisitor mv, char ch) Determine the appropriate boxing instruction for a specific type (if it needs boxing) and insert the instruction into the supplied visitor.
static void	insertBoxIfNecessary(MethodVisitor mv, String descriptor) Determine the appropriate boxing instruction for a specific type (if it needs boxing) and insert the instruction into the supplied visitor.
static void	insertCheckCast(MethodVisitor mv, String descriptor) Insert the appropriate CHECKCAST instruction for the supplied descriptor.
static void	insertUnboxInsns(MethodVisitor mv, char ch, String stackDescriptor) Insert any necessary cast and value call to convert from a boxed type to a primitive value
static boolean	isBooleanCompatible(String descriptor)
static boolean	isPrimitive(String descriptor)
static boolean	isPrimitiveArray(String descriptor)
static boolean	isPrimitiveOrUnboxableSupportedNumber(String descriptor) Determine if the supplied descriptor is for a supported number.
static boolean	isPrimitiveOrUnboxableSupportedNumberOrBoolean(String descriptor) Determine if the supplied descriptor is for a supported number type or boolean.
String	lastDescriptor()
void	loadTarget(MethodVisitor mv) Push the byte code to load the target (i.e.
void	pushDescriptor(String descriptor) Record the descriptor for the most recently evaluated expression element.
static String	toDescriptor(Class<?> type) Deduce the descriptor for a type.
static String	toDescriptorFromObject(Object value) Determine the descriptor for an object instance (or null).
static String	toJVMDescriptor(Class<?> clazz) Determine the JVM descriptor for a specified class.
static String[]	toParamDescriptors(Constructor<?> ctor) Create an array of descriptors representing the parameter types for the supplied constructor.
static String[]	toParamDescriptors(Method method) Create an array of descriptors representing the parameter types for the supplied method.
static char	toPrimitiveTargetDesc(String descriptor)
void	unboxBooleanIfNecessary(MethodVisitor mv) If the codeflow shows the last expression evaluated to java.lang.Boolean then insert the necessary instructions to unbox that to a boolean primitive.

Methods inherited from class java.lang.Object

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

Constructor Detail

CodeFlow

public CodeFlow()

Method Detail

loadTarget

public void loadTarget(MethodVisitor mv)

Push the byte code to load the target (i.e. what was passed as the first argument to CompiledExpression.getValue(target, context))

Parameters:

mv - the visitor into which the load instruction should be inserted

pushDescriptor

public void pushDescriptor(String descriptor)

Record the descriptor for the most recently evaluated expression element.

Parameters:

descriptor - type descriptor for most recently evaluated element

enterCompilationScope

public void enterCompilationScope()

Enter a new compilation scope, usually due to nested expression evaluation. For example when the arguments for a method invocation expression are being evaluated, each argument will be evaluated in a new scope.

exitCompilationScope

public void exitCompilationScope()

Exit a compilation scope, usually after a nested expression has been evaluated. For example after an argument for a method invocation has been evaluated this method returns us to the previous (outer) scope.

lastDescriptor

public String lastDescriptor()

Returns:

the descriptor for the item currently on top of the stack (in the current scope)

unboxBooleanIfNecessary

public void unboxBooleanIfNecessary(MethodVisitor mv)

If the codeflow shows the last expression evaluated to java.lang.Boolean then insert the necessary instructions to unbox that to a boolean primitive.

Parameters:

mv - the visitor into which new instructions should be inserted

insertUnboxInsns

public static void insertUnboxInsns(MethodVisitor mv,
                                    char ch,
                                    String stackDescriptor)

Insert any necessary cast and value call to convert from a boxed type to a primitive value

Parameters:

mv - the method visitor into which instructions should be inserted

ch - the primitive type desired as output

stackDescriptor - the descriptor of the type on top of the stack

createSignatureDescriptor

public static String createSignatureDescriptor(Method method)

Create the JVM signature descriptor for a method. This consists of the descriptors for the constructor parameters surrounded with parentheses, followed by the descriptor for the return type. Note the descriptors here are JVM descriptors, unlike the other descriptor forms the compiler is using which do not include the trailing semicolon.

Parameters:

method - the method

Returns:

a String signature descriptor (e.g. "(ILjava/lang/String;)V")

createSignatureDescriptor

public static String createSignatureDescriptor(Constructor<?> ctor)

Create the JVM signature descriptor for a constructor. This consists of the descriptors for the constructor parameters surrounded with parentheses. Note the descriptors here are JVM descriptors, unlike the other descriptor forms the compiler is using which do not include the trailing semicolon.

Parameters:

ctor - the constructor

Returns:

a String signature descriptor (e.g. "(ILjava/lang/String;)")

toJVMDescriptor

public static String toJVMDescriptor(Class<?> clazz)

Determine the JVM descriptor for a specified class. Unlike the other descriptors used in the compilation process, this is the one the JVM wants, so this one includes any necessary trailing semicolon (e.g. Ljava/lang/String; rather than Ljava/lang/String)

Parameters:

clazz - a class

Returns:

the JVM descriptor for the class

toDescriptorFromObject

public static String toDescriptorFromObject(Object value)

Determine the descriptor for an object instance (or null).

Parameters:

value - an object (possibly null)

Returns:

the type descriptor for the object (descriptor is "Ljava/lang/Object" for null value)

isBooleanCompatible

public static boolean isBooleanCompatible(String descriptor)

Parameters:

descriptor - type descriptor

Returns:

true if the descriptor is for a boolean primitive or boolean reference type

isPrimitive

public static boolean isPrimitive(String descriptor)

Parameters:

descriptor - type descriptor

Returns:

true if the descriptor is for a primitive type

isPrimitiveArray

public static boolean isPrimitiveArray(String descriptor)

Parameters:

descriptor - the descriptor for a possible primitive array

Returns:

true if the descriptor is for a primitive array (e.g. "[[I")

areBoxingCompatible

public static boolean areBoxingCompatible(String desc1,
                                          String desc2)

Determine if boxing/unboxing can get from one type to the other. Assumes at least one of the types is in boxed form (i.e. single char descriptor).

Returns:

true if it is possible to get (via boxing) from one descriptor to the other

isPrimitiveOrUnboxableSupportedNumberOrBoolean

public static boolean isPrimitiveOrUnboxableSupportedNumberOrBoolean(String descriptor)

Determine if the supplied descriptor is for a supported number type or boolean. The compilation process only (currently) supports certain number types. These are double, float, long and int.

Parameters:

descriptor - the descriptor for a type

Returns:

true if the descriptor is for a supported numeric type or boolean

isPrimitiveOrUnboxableSupportedNumber

public static boolean isPrimitiveOrUnboxableSupportedNumber(String descriptor)

Determine if the supplied descriptor is for a supported number. The compilation process only (currently) supports certain number types. These are double, float, long and int.

Parameters:

descriptor - the descriptor for a type

Returns:

true if the descriptor is for a supported numeric type

toPrimitiveTargetDesc

public static char toPrimitiveTargetDesc(String descriptor)

Parameters:

descriptor - a descriptor for a type that should have a primitive representation

Returns:

the single character descriptor for a primitive input descriptor

insertCheckCast

public static void insertCheckCast(MethodVisitor mv,
                                   String descriptor)

Insert the appropriate CHECKCAST instruction for the supplied descriptor.

Parameters:

mv - the target visitor into which the instruction should be inserted

descriptor - the descriptor of the type to cast to

insertBoxIfNecessary

public static void insertBoxIfNecessary(MethodVisitor mv,
                                        String descriptor)

Determine the appropriate boxing instruction for a specific type (if it needs boxing) and insert the instruction into the supplied visitor.

Parameters:

mv - the target visitor for the new instructions

descriptor - the descriptor of a type that may or may not need boxing

insertBoxIfNecessary

public static void insertBoxIfNecessary(MethodVisitor mv,
                                        char ch)

Determine the appropriate boxing instruction for a specific type (if it needs boxing) and insert the instruction into the supplied visitor.

Parameters:

mv - the target visitor for the new instructions

ch - the descriptor of the type that might need boxing

toDescriptor

public static String toDescriptor(Class<?> type)

Deduce the descriptor for a type. Descriptors are like JVM type names but missing the trailing ';' so for Object the descriptor is "Ljava/lang/Object" for int it is "I".

Parameters:

type - the type (may be primitive) for which to determine the descriptor

Returns:

the descriptor

toParamDescriptors

public static String[] toParamDescriptors(Method method)

Create an array of descriptors representing the parameter types for the supplied method. Returns a zero sized array if there are no parameters.

Parameters:

method - a Method

Returns:

a String array of descriptors, one entry for each method parameter

toParamDescriptors

public static String[] toParamDescriptors(Constructor<?> ctor)

Create an array of descriptors representing the parameter types for the supplied constructor. Returns a zero sized array if there are no parameters.

Parameters:

ctor - a Constructor

Returns:

a String array of descriptors, one entry for each constructor parameter