Package org.springframework.expression.spel.ast

Class Elvis

java.lang.Object

org.springframework.expression.spel.ast.SpelNodeImpl

org.springframework.expression.spel.ast.Elvis

All Implemented Interfaces:

Opcodes, SpelNode

public class Elvis
extends SpelNodeImpl

Represents the Elvis operator ?:. For an expression a?:b if a is neither null nor an empty String, the value of the expression is a. If a is null or the empty String, then the value of the expression is b.

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
Elvis(int startPos, int endPos, SpelNodeImpl... args)

Method Summary

Modifier and Type	Method	Description
void	generateCode(MethodVisitor mv, CodeFlow cf)	Generate the bytecode for this node into the supplied MethodVisitor.
TypedValue	getValueInternal(ExpressionState state)	Evaluate the condition and if neither null nor an empty String, return it.
boolean	isCompilable()	Determine if this node can be compiled to bytecode.
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, getValueRef, isNullSafe, isWritable, nextChildIs, setValue, setValueInternal

Methods inherited from class java.lang.Object

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

Constructor Details

Elvis

public Elvis(int startPos,
 int endPos,
 SpelNodeImpl... args)

Method Details

getValueInternal

public TypedValue getValueInternal(ExpressionState state)
                            throws EvaluationException

Evaluate the condition and if neither null nor an empty String, return it. If it is null or an empty String, return the other value.

Specified by:

getValueInternal in class SpelNodeImpl

Parameters:

state - the expression state

Throws:

EvaluationException - if the condition does not evaluate correctly to a boolean or there is a problem executing the chosen alternative

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()

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()