Package org.springframework.expression.spel.ast

Class MethodReference

java.lang.Object

org.springframework.expression.spel.ast.SpelNodeImpl

org.springframework.expression.spel.ast.MethodReference

All Implemented Interfaces:

Opcodes, SpelNode

public class MethodReference
extends SpelNodeImpl

Expression language AST node that represents a method reference (i.e., a method invocation other than a simple property reference).

Null-safe Invocation

Null-safe invocation is supported via the '?.' operator. For example, 'counter?.incrementBy(1)' will evaluate to null if counter is null and will otherwise evaluate to the value returned from the invocation of counter.incrementBy(1). As of Spring Framework 7.0, null-safe invocation also applies when invoking a method on an Optional target. For example, if counter is of type Optional<Counter>, the expression 'counter?.incrementBy(1)' will evaluate to null if counter is null or empty and will otherwise evaluate the value returned from the invocation of counter.get().incrementBy(1).

Since:

3.0

Author:

Andy Clement, Juergen Hoeller, Sam Brannen

Field Summary

Fields inherited from class org.springframework.expression.spel.ast.SpelNodeImpl

children, exitTypeDescriptor

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_RECORD, 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, ASM10_EXPERIMENTAL, ASM4, ASM5, ASM6, ASM7, ASM8, ASM9, 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, SOURCE_DEPRECATED, SOURCE_MASK, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V_PREVIEW, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V10, V11, V12, V13, V14, V15, V16, V17, V18, V19, V20, V21, V22, V23, V24, V9

Constructor Summary

Constructors

Constructor	Description
MethodReference(boolean nullSafe, String methodName, int startPos, int endPos, SpelNodeImpl... arguments)

Method Summary

Modifier and Type	Method	Description
void	generateCode(MethodVisitor mv, CodeFlow cf)	Generate the bytecode for this node into the supplied MethodVisitor.
final String	getName()	Get the name of the referenced method.
TypedValue	getValueInternal(ExpressionState state)
protected ValueRef	getValueRef(ExpressionState state)
boolean	isCompilable()	A method reference is compilable if it has been resolved to a reflectively accessible method and the child nodes (arguments to the method) are also compilable.
final boolean	isNullSafe()	Does this node represent a null-safe method reference?
String	toStringAST()	Return the string form of this AST node.

Methods inherited from class org.springframework.expression.spel.ast.SpelNodeImpl

generateCodeForArgument, generateCodeForArguments, generateCodeForArguments, getChild, getChildCount, getEndPosition, getExitDescriptor, getObjectClass, getStartPosition, getTypedValue, getValue, getValue, isWritable, nextChildIs, setValue, setValueInternal

Methods inherited from class java.lang.Object

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

Constructor Details

MethodReference

public MethodReference(boolean nullSafe,
 String methodName,
 int startPos,
 int endPos,
 SpelNodeImpl... arguments)

Method Details

isNullSafe

public final boolean isNullSafe()

Does this node represent a null-safe method reference?

Overrides:

isNullSafe in class SpelNodeImpl

Returns:

true if this node is the target of a null-safe operation

Since:

6.0.13

getName

public final String getName()

Get the name of the referenced method.

getValueRef

protected ValueRef getValueRef(ExpressionState state)
                        throws EvaluationException

Overrides:

getValueRef in class SpelNodeImpl

Throws:

EvaluationException

getValueInternal

public TypedValue getValueInternal(ExpressionState state)
                            throws EvaluationException

Specified by:

getValueInternal in class SpelNodeImpl

Throws:

EvaluationException

toStringAST

public String toStringAST()

Description copied from interface: SpelNode

Return the string form of this AST node.

Returns:

the string form

isCompilable

public boolean isCompilable()

A method reference is compilable if it has been resolved to a reflectively accessible method and the child nodes (arguments to the method) are also compilable.

Returns:

true if this node can be compiled to bytecode

See Also:

• SpelNode.generateCode(MethodVisitor, CodeFlow)

generateCode

public void generateCode(MethodVisitor mv,
 CodeFlow cf)

Description copied from interface: SpelNode

Generate the bytecode for this node into the supplied MethodVisitor.

Context information about the current expression being compiled is available in the supplied CodeFlow object — for example, information about the type of the object currently on the stack.

This method will not be invoked unless SpelNode.isCompilable() returns true.

The default implementation throws an IllegalStateException since SpelNode.isCompilable() returns false by default.

If you override this method, you must also override SpelNode.isCompilable().

Parameters:

mv - the ASM MethodVisitor into which code should be generated

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

See Also:

• SpelNode.isCompilable()