org.springframework.expression.spel.ast
Class SpelNodeImpl

java.lang.Object
  org.springframework.expression.spel.ast.SpelNodeImpl

All Implemented Interfaces:

SpelNode

Direct Known Subclasses:

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

public abstract class SpelNodeImpl
extends Object
implements SpelNode

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

Since:

3.0

Author:

Andy Clement

Field Summary

protected SpelNodeImpl[]	children
protected int	pos

Constructor Summary

SpelNodeImpl(int pos, SpelNodeImpl... operands)

Method Summary

SpelNode	getChild(int index) Helper method that returns a SpelNode rather than an Antlr Tree node.
int	getChildCount()
int	getEndPosition()
Class<?>	getObjectClass(Object obj) Determine the class of the object passed in, unless it is already a class object.
protected SpelNodeImpl	getPreviousChild()
int	getStartPosition()
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)
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.
abstract String	toStringAST()

Methods inherited from class java.lang.Object

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

Field Detail

pos

protected int pos

children

protected SpelNodeImpl[] children

Constructor Detail

SpelNodeImpl

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

Method Detail

getPreviousChild

protected SpelNodeImpl getPreviousChild()

nextChildIs

protected boolean nextChildIs(Class... clazzes)

Returns:

true if the next child is one of the specified classes

getValue

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

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,
                     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

public Class<?> getObjectClass(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

Returns:

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

getValue

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

Throws:

EvaluationException

getValueInternal

public abstract TypedValue getValueInternal(ExpressionState expressionState)
                                     throws EvaluationException

Throws:

EvaluationException

toStringAST

public abstract String toStringAST()

Specified by:

toStringAST in interface SpelNode

Returns:

the string form of this AST node

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