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

Manages the class being generated by the compilation process.

Records intermediate compilation state as the bytecode is generated. Also includes various bytecode generation helper functions.

Since:

4.1

Author:

Andy Clement, Juergen Hoeller

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CodeFlow.ClinitAdder
static interface	CodeFlow.FieldAdder

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_MODULE, ACC_NATIVE, ACC_OPEN, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_STATIC_PHASE, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_TRANSITIVE, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASM4, ASM5, ASM6, 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, V1_9

Constructor Summary

Constructors

Constructor and Description
CodeFlow(String className, ClassWriter classWriter) Construct a new CodeFlow for the given class.

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 int	arrayCodeFor(String arraytype) Determine the appropriate T tag to use for the NEWARRAY bytecode.
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.
void	finish() Called after the main expression evaluation method has been generated, this method will callback any registered FieldAdders or ClinitAdders to add any extra information to the class representing the compiled expression.
String	getClassName()
static void	insertAnyNecessaryTypeConversionBytecodes(MethodVisitor mv, char targetDescriptor, String stackDescriptor) Insert any necessary numeric conversion bytecodes based upon what is on the stack and the desired target type.
static void	insertArrayStore(MethodVisitor mv, String arrayElementType) Produce appropriate bytecode to store a stack item in an array.
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	insertNewArrayCode(MethodVisitor mv, int size, String arraytype) Produce the correct bytecode to build an array.
static void	insertNumericUnboxOrPrimitiveTypeCoercion(MethodVisitor mv, String stackDescriptor, char targetDescriptor) For use in mathematical operators, handles converting from a (possibly boxed) number on the stack to a primitive numeric type.
static void	insertOptimalLoad(MethodVisitor mv, int value) Create the optimal instruction for loading a number on the stack.
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 void	insertUnboxNumberInsns(MethodVisitor mv, char targetDescriptor, String stackDescriptor) For numbers, use the appropriate method on the number to convert it to the primitive type requested.
static boolean	isBooleanCompatible(String descriptor)
static boolean	isIntegerForNumericOp(Number number) Determine whether the given number is to be considered as an integer for the purposes of a numeric operation at the bytecode level.
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.
static boolean	isReferenceTypeArray(String arraytype)
String	lastDescriptor() Return the descriptor for the item currently on top of the stack (in the current scope).
void	loadEvaluationContext(MethodVisitor mv) Push the bytecode to load the EvaluationContext (the second parameter passed to the compiled expression method).
void	loadTarget(MethodVisitor mv) Push the byte code to load the target (i.e.
int	nextFieldId()
int	nextFreeVariableId()
void	pushDescriptor(String descriptor) Record the descriptor for the most recently evaluated expression element.
void	registerNewClinit(CodeFlow.ClinitAdder clinitAdder) Register a ClinitAdder which will add code to the static initializer in the generated class to support the code produced by an ast nodes primary generateCode() method.
void	registerNewField(CodeFlow.FieldAdder fieldAdder) Register a FieldAdder which will add a new field to the generated class to support the code produced by an ast nodes primary generateCode() method.
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[]	toDescriptors(Class<?>[] types) Create an array of descriptors from an array of classes.
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(String className,
                ClassWriter classWriter)

Construct a new CodeFlow for the given class.

Parameters:

className - the name of the class

classWriter - the corresponding ASM ClassWriter

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

loadEvaluationContext

public void loadEvaluationContext(MethodVisitor mv)

Push the bytecode to load the EvaluationContext (the second parameter passed to the compiled expression method).

Parameters:

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

Since:

4.3.4

pushDescriptor

public void pushDescriptor(@Nullable
                           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

@Nullable
public String lastDescriptor()

Return 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

finish

public void finish()

Called after the main expression evaluation method has been generated, this method will callback any registered FieldAdders or ClinitAdders to add any extra information to the class representing the compiled expression.

registerNewField

public void registerNewField(CodeFlow.FieldAdder fieldAdder)

Register a FieldAdder which will add a new field to the generated class to support the code produced by an ast nodes primary generateCode() method.

registerNewClinit

public void registerNewClinit(CodeFlow.ClinitAdder clinitAdder)

Register a ClinitAdder which will add code to the static initializer in the generated class to support the code produced by an ast nodes primary generateCode() method.

nextFieldId

public int nextFieldId()

nextFreeVariableId

public int nextFreeVariableId()

getClassName

public String getClassName()

insertUnboxInsns

public static void insertUnboxInsns(MethodVisitor mv,
                                    char ch,
                                    @Nullable
                                    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

insertUnboxNumberInsns

public static void insertUnboxNumberInsns(MethodVisitor mv,
                                          char targetDescriptor,
                                          @Nullable
                                          String stackDescriptor)

For numbers, use the appropriate method on the number to convert it to the primitive type requested.

Parameters:

mv - the method visitor into which instructions should be inserted

targetDescriptor - the primitive type desired as output

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

insertAnyNecessaryTypeConversionBytecodes

public static void insertAnyNecessaryTypeConversionBytecodes(MethodVisitor mv,
                                                             char targetDescriptor,
                                                             String stackDescriptor)

Insert any necessary numeric conversion bytecodes based upon what is on the stack and the desired target type.

Parameters:

mv - the method visitor into which instructions should be placed

targetDescriptor - the (primitive) descriptor of the target type

stackDescriptor - the descriptor of the operand 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 method 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, followed by the descriptor for the return type, which is always "V". 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;)V")

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(@Nullable
                                            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(@Nullable
                                          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(@Nullable
                                  String descriptor)

Parameters:

descriptor - type descriptor

Returns:

true if the descriptor is for a primitive type

isPrimitiveArray

public static boolean isPrimitiveArray(@Nullable
                                       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(@Nullable
                                                                     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(@Nullable
                                                            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

isIntegerForNumericOp

public static boolean isIntegerForNumericOp(Number number)

Determine whether the given number is to be considered as an integer for the purposes of a numeric operation at the bytecode level.

Parameters:

number - the number to check

Returns:

true if it is an Integer, Short or Byte

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,
                                   @Nullable
                                   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,
                                        @Nullable
                                        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

toDescriptors

public static String[] toDescriptors(Class<?>[] types)

Create an array of descriptors from an array of classes.

Parameters:

types - the input array of classes

Returns:

an array of descriptors

insertOptimalLoad

public static void insertOptimalLoad(MethodVisitor mv,
                                     int value)

Create the optimal instruction for loading a number on the stack.

Parameters:

mv - where to insert the bytecode

value - the value to be loaded

insertArrayStore

public static void insertArrayStore(MethodVisitor mv,
                                    String arrayElementType)

Produce appropriate bytecode to store a stack item in an array. The instruction to use varies depending on whether the type is a primitive or reference type.

Parameters:

mv - where to insert the bytecode

arrayElementType - the type of the array elements

arrayCodeFor

public static int arrayCodeFor(String arraytype)

Determine the appropriate T tag to use for the NEWARRAY bytecode.

Parameters:

arraytype - the array primitive component type

Returns:

the T tag to use for NEWARRAY

isReferenceTypeArray

public static boolean isReferenceTypeArray(String arraytype)

Returns:

true if the supplied array type has a core component reference type

insertNewArrayCode

public static void insertNewArrayCode(MethodVisitor mv,
                                      int size,
                                      String arraytype)

Produce the correct bytecode to build an array. The opcode to use and the signature to pass along with the opcode can vary depending on the signature of the array type.

Parameters:

mv - the methodvisitor into which code should be inserted

size - the size of the array

arraytype - the type of the array

insertNumericUnboxOrPrimitiveTypeCoercion

public static void insertNumericUnboxOrPrimitiveTypeCoercion(MethodVisitor mv,
                                                             @Nullable
                                                             String stackDescriptor,
                                                             char targetDescriptor)

For use in mathematical operators, handles converting from a (possibly boxed) number on the stack to a primitive numeric type.

For example, from a Integer to a double, just need to call 'Number.doubleValue()' but from an int to a double, need to use the bytecode 'i2d'.

Parameters:

mv - the method visitor when instructions should be appended

stackDescriptor - a descriptor of the operand on the stack

targetDescriptor - a primitive type descriptor