Package org.springframework.expression.spel.ast

Class PropertyOrFieldReference

java.lang.Object

org.springframework.expression.spel.ast.SpelNodeImpl

org.springframework.expression.spel.ast.PropertyOrFieldReference

All Implemented Interfaces:

Opcodes, SpelNode

public class PropertyOrFieldReference
extends SpelNodeImpl

Represents a simple public property or field reference.

Null-safe Navigation

Null-safe navigation is supported via the '?.' operator. For example, 'user?.name' will evaluate to null if user is null and will otherwise evaluate to the name of the user. As of Spring Framework 7.0, null-safe navigation also applies when accessing a property or field on an Optional target. For example, if user is of type Optional<User>, the expression 'user?.name' will evaluate to null if user is null or empty and will otherwise evaluate to the name of the user, effectively user.get().getName() or user.get().name.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller, Clark Duplichien, 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
PropertyOrFieldReference(boolean nullSafe, String propertyOrFieldName, int startPos, int endPos)

Method Summary

Modifier and Type	Method	Description
void	generateCode(MethodVisitor mv, CodeFlow cf)	Generate the bytecode for this node into the supplied MethodVisitor.
String	getName()	Get the name of the referenced property or field.
TypedValue	getValueInternal(ExpressionState state)
ValueRef	getValueRef(ExpressionState state)
boolean	isCompilable()	Determine if this node can be compiled to bytecode.
boolean	isNullSafe()	Does this node represent a null-safe property or field reference?
boolean	isWritable(ExpressionState state)	Determine if this expression node will support a setValue() call.
boolean	isWritableProperty(String name, TypedValue contextObject, EvaluationContext evalContext)
TypedValue	setValueInternal(ExpressionState state, Supplier<TypedValue> valueSupplier)	Evaluate the expression to a node and then set the new value created by the specified Supplier on that node.
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, nextChildIs, setValue

Methods inherited from class java.lang.Object

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

Constructor Details

PropertyOrFieldReference

public PropertyOrFieldReference(boolean nullSafe,
 String propertyOrFieldName,
 int startPos,
 int endPos)

Method Details

isNullSafe

public boolean isNullSafe()

Does this node represent a null-safe property or field reference?

Overrides:

isNullSafe in class SpelNodeImpl

Returns:

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

getName

public String getName()

Get the name of the referenced property or field.

getValueRef

public 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

setValueInternal

public TypedValue setValueInternal(ExpressionState state,
 Supplier<TypedValue> valueSupplier)
                            throws EvaluationException

Description copied from class: SpelNodeImpl

Evaluate the expression to a node and then set the new value created by the specified Supplier on that node.

For example, if the expression evaluates to a property reference, then the property will be set to the new value.

Favor this method over SpelNodeImpl.setValue(ExpressionState, Object) when the value should be lazily computed.

By default, this method throws a SpelEvaluationException, effectively disabling this feature. Subclasses may override this method to provide an actual implementation.

Overrides:

setValueInternal in class SpelNodeImpl

Parameters:

state - the current expression state (includes the context)

valueSupplier - a supplier of the new value

Throws:

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

isWritable

public boolean isWritable(ExpressionState state)
                   throws EvaluationException

Description copied from interface: SpelNode

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

Specified by:

isWritable in interface SpelNode

Overrides:

isWritable in class SpelNodeImpl

Parameters:

state - 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

toStringAST

public String toStringAST()

Description copied from interface: SpelNode

Return the string form of this AST node.

Returns:

the string form

isWritableProperty

public boolean isWritableProperty(String name,
 TypedValue contextObject,
 EvaluationContext evalContext)
                           throws EvaluationException

Throws:

EvaluationException

isCompilable

public boolean isCompilable()

Description copied from interface: SpelNode

Determine if this 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.

The default implementation returns false.

If you override this method, you must also override SpelNode.generateCode(MethodVisitor, CodeFlow).

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()