org.springframework.expression.spel.ast

Class SpelNodeImpl

java.lang.Object

org.springframework.expression.spel.ast.SpelNodeImpl

All Implemented Interfaces:

Opcodes, SpelNode

Direct Known Subclasses:

Assign, BeanReference, CompoundExpression, ConstructorReference, Elvis, FunctionReference, Identifier, Indexer, InlineList, InlineMap, Literal, MethodReference, Operator, OperatorNot, Projection, PropertyOrFieldReference, QualifiedIdentifier, Selection, Ternary, TypeReference, VariableReference

public abstract class SpelNodeImpl
extends Object
implements SpelNode, Opcodes

The common supertype of all AST nodes in a parsed Spring Expression Language format expression.

Since:

3.0

Author:

Andy Clement

Field Summary

Fields

Modifier and Type	Field and Description
protected SpelNodeImpl[]	children
protected String	exitTypeDescriptor Indicates the type descriptor for the result of this expression node.
protected int	pos

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
SpelNodeImpl(int pos, SpelNodeImpl... operands)

Method Summary

Modifier and Type	Method and Description
void	generateCode(MethodVisitor mv, CodeFlow cf) Generate the bytecode for this node into the supplied visitor.
protected static void	generateCodeForArgument(MethodVisitor mv, CodeFlow cf, SpelNodeImpl argument, String paramDesc) Ask an argument to generate its bytecode and then follow it up with any boxing/unboxing/checkcasting to ensure it matches the expected parameter descriptor.
protected static void	generateCodeForArguments(MethodVisitor mv, CodeFlow cf, Member member, SpelNodeImpl[] arguments) Generate code that handles building the argument values for the specified method.
SpelNode	getChild(int index) Helper method that returns a SpelNode rather than an Antlr Tree node.
int	getChildCount()
int	getEndPosition()
String	getExitDescriptor()
Class<?>	getObjectClass(Object obj) Determine the class of the object passed in, unless it is already a class object.
int	getStartPosition()
TypedValue	getTypedValue(ExpressionState expressionState) Evaluate the expression node in the context of the supplied expression state and return the typed value.
Object	getValue(ExpressionState expressionState) Evaluate the expression node in the context of the supplied expression state and return the value.
protected <T> T	getValue(ExpressionState state, Class<T> desiredReturnType)
abstract TypedValue	getValueInternal(ExpressionState expressionState)
protected ValueRef	getValueRef(ExpressionState state)
boolean	isCompilable() Check whether a node can be compiled to bytecode.
boolean	isWritable(ExpressionState expressionState) Determine if this expression node will support a setValue() call.
protected boolean	nextChildIs(Class<?>... clazzes)
void	setValue(ExpressionState expressionState, Object newValue) Evaluate the expression to a node and then set the new value on that node.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.expression.spel.SpelNode

toStringAST

Field Detail

pos

protected int pos

children

protected SpelNodeImpl[] children

exitTypeDescriptor

@Nullable
protected volatile String exitTypeDescriptor

Indicates the type descriptor for the result of this expression node. This is set as soon as it is known. For a literal node it is known immediately. For a property access or method invocation it is known after one evaluation of that node.

The descriptor is like the bytecode form but is slightly easier to work with. It does not include the trailing semicolon (for non array reference types). Some examples: Ljava/lang/String, I, [I

Constructor Detail

SpelNodeImpl

public SpelNodeImpl(int pos,
                    SpelNodeImpl... operands)

Method Detail

nextChildIs

protected boolean nextChildIs(Class<?>... clazzes)

Returns:

true if the next child is one of the specified classes

getValue

@Nullable
public final Object getValue(ExpressionState expressionState)
                                throws EvaluationException

Description copied from interface: SpelNode

Evaluate the expression node in the context of the supplied expression state and return the value.

Specified by:

getValue in interface SpelNode

Parameters:

expressionState - the current expression state (includes the context)

Returns:

the value of this node evaluated against the specified state

Throws:

EvaluationException

getTypedValue

public final TypedValue getTypedValue(ExpressionState expressionState)
                               throws EvaluationException

Description copied from interface: SpelNode

Evaluate the expression node in the context of the supplied expression state and return the typed value.

Specified by:

getTypedValue in interface SpelNode

Parameters:

expressionState - the current expression state (includes the context)

Returns:

the type value of this node evaluated against the specified state

Throws:

EvaluationException

isWritable

public boolean isWritable(ExpressionState expressionState)
                   throws EvaluationException

Description copied from interface: SpelNode

Determine if this expression node will support a setValue() call.

Specified by:

isWritable in interface SpelNode

Parameters:

expressionState - the current expression state (includes the context)

Returns:

true if the expression node will allow setValue()

Throws:

EvaluationException - if something went wrong trying to determine if the node supports writing

setValue

public void setValue(ExpressionState expressionState,
                     @Nullable
                     Object newValue)
              throws EvaluationException

Description copied from interface: SpelNode

Evaluate the expression to a node and then set the new value on that node. For example, if the expression evaluates to a property reference, then the property will be set to the new value.

Specified by:

setValue in interface SpelNode

Parameters:

expressionState - the current expression state (includes the context)

newValue - the new value

Throws:

EvaluationException - if any problem occurs evaluating the expression or setting the new value

getChild

public SpelNode getChild(int index)

Description copied from interface: SpelNode

Helper method that returns a SpelNode rather than an Antlr Tree node.

Specified by:

getChild in interface SpelNode

Returns:

the child node cast to a SpelNode

getChildCount

public int getChildCount()

Specified by:

getChildCount in interface SpelNode

Returns:

the number of children under this node

getObjectClass

@Nullable
public Class<?> getObjectClass(@Nullable
                                         Object obj)

Description copied from interface: SpelNode

Determine the class of the object passed in, unless it is already a class object.

Specified by:

getObjectClass in interface SpelNode

Parameters:

obj - the object that the caller wants the class of

Returns:

the class of the object if it is not already a class object, or null if the object is null

getValue

@Nullable
protected final <T> T getValue(ExpressionState state,
                                         Class<T> desiredReturnType)
                                  throws EvaluationException

Throws:

EvaluationException

getStartPosition

public int getStartPosition()

Specified by:

getStartPosition in interface SpelNode

Returns:

the start position of this Ast node in the expression string

getEndPosition

public int getEndPosition()

Specified by:

getEndPosition in interface SpelNode

Returns:

the end position of this Ast node in the expression string

getValueRef

protected ValueRef getValueRef(ExpressionState state)
                        throws EvaluationException

Throws:

EvaluationException

isCompilable

public boolean isCompilable()

Check whether a node can be compiled to bytecode. The reasoning in each node may be different but will typically involve checking whether the exit type descriptor of the node is known and any relevant child nodes are compilable.

Returns:

true if this node can be compiled to bytecode

generateCode

public void generateCode(MethodVisitor mv,
                         CodeFlow cf)

Generate the bytecode for this node into the supplied visitor. Context info about the current expression being compiled is available in the codeflow object. For example it will include information about the type of the object currently on the stack.

Parameters:

mv - the ASM MethodVisitor into which code should be generated

cf - a context object with info about what is on the stack

getExitDescriptor

@Nullable
public String getExitDescriptor()

getValueInternal

public abstract TypedValue getValueInternal(ExpressionState expressionState)
                                     throws EvaluationException

Throws:

EvaluationException

generateCodeForArguments

protected static void generateCodeForArguments(MethodVisitor mv,
                                               CodeFlow cf,
                                               Member member,
                                               SpelNodeImpl[] arguments)

Generate code that handles building the argument values for the specified method. This method will take account of whether the invoked method is a varargs method and if it is then the argument values will be appropriately packaged into an array.

Parameters:

mv - the method visitor where code should be generated

cf - the current codeflow

member - the method or constructor for which arguments are being setup

arguments - the expression nodes for the expression supplied argument values

generateCodeForArgument

protected static void generateCodeForArgument(MethodVisitor mv,
                                              CodeFlow cf,
                                              SpelNodeImpl argument,
                                              String paramDesc)

Ask an argument to generate its bytecode and then follow it up with any boxing/unboxing/checkcasting to ensure it matches the expected parameter descriptor.