Class ExpressionState

java.lang.Object

org.springframework.expression.spel.ExpressionState

public class ExpressionState
extends Object

ExpressionState is for maintaining per-expression-evaluation state: any changes to it are not seen by other expressions, but it gives a place to hold local variables and for component expressions in a compound expression to communicate state. This is in contrast to the EvaluationContext, which is shared amongst expression evaluations, and any changes to it will be seen by other expressions or any code that chooses to ask questions of the context.

It also acts as a place to define common utility routines that the various AST nodes might need.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller, Sam Brannen

Constructor Summary

Constructors

Constructor	Description
ExpressionState(EvaluationContext context)
ExpressionState(EvaluationContext context, SpelParserConfiguration configuration)
ExpressionState(EvaluationContext context, TypedValue rootObject)
ExpressionState(EvaluationContext context, TypedValue rootObject, SpelParserConfiguration configuration)

Method Summary

Modifier and Type	Method	Description
TypedValue	assignVariable(String name, Supplier<TypedValue> valueSupplier)	Assign the value created by the specified Supplier to a named variable within the evaluation context.
Object	convertValue(Object value, TypeDescriptor targetTypeDescriptor)
@Nullable Object	convertValue(TypedValue value, TypeDescriptor targetTypeDescriptor)
void	enterScope()	Enter a new scope with a new root context object and a new local variable scope.
void	exitScope()
Class<?>	findType(String type)
TypedValue	getActiveContextObject()	The active context object is what unqualified references to properties/etc are resolved against.
SpelParserConfiguration	getConfiguration()
EvaluationContext	getEvaluationContext()
List<PropertyAccessor>	getPropertyAccessors()
TypedValue	getRootContextObject()
TypedValue	getScopeRootContextObject()
TypeComparator	getTypeComparator()
TypeConverter	getTypeConverter()
TypedValue	lookupVariable(String name)	Look up a named global variable in the evaluation context.
TypedValue	operate(Operation op, @Nullable Object left, @Nullable Object right)
void	popActiveContextObject()
void	pushActiveContextObject(TypedValue obj)
void	setVariable(String name, @Nullable Object value)	Set a named variable in the evaluation context to a specified value.

Methods inherited from class java.lang.Object

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

Constructor Details

ExpressionState

public ExpressionState(EvaluationContext context)

ExpressionState

public ExpressionState(EvaluationContext context,
 SpelParserConfiguration configuration)

ExpressionState

public ExpressionState(EvaluationContext context,
 TypedValue rootObject)

ExpressionState

public ExpressionState(EvaluationContext context,
 TypedValue rootObject,
 SpelParserConfiguration configuration)

Method Details

getActiveContextObject

public TypedValue getActiveContextObject()

The active context object is what unqualified references to properties/etc are resolved against.

pushActiveContextObject

public void pushActiveContextObject(TypedValue obj)

popActiveContextObject

public void popActiveContextObject()

getRootContextObject

public TypedValue getRootContextObject()

getScopeRootContextObject

public TypedValue getScopeRootContextObject()

assignVariable

public TypedValue assignVariable(String name,
 Supplier<TypedValue> valueSupplier)

Assign the value created by the specified Supplier to a named variable within the evaluation context.

In contrast to setVariable(String, Object), this method should only be invoked to support assignment within an expression.

Parameters:

name - the name of the variable to assign

valueSupplier - the supplier of the value to be assigned to the variable

Returns:

a TypedValue wrapping the assigned value

Since:

5.2.24

See Also:

• EvaluationContext.assignVariable(String, Supplier)

setVariable

public void setVariable(String name,
 @Nullable Object value)

Set a named variable in the evaluation context to a specified value.

In contrast to assignVariable(String, Supplier), this method should only be invoked programmatically.

Parameters:

name - the name of the variable to set

value - the value to be placed in the variable

See Also:

• EvaluationContext.setVariable(String, Object)

lookupVariable

public TypedValue lookupVariable(String name)

Look up a named global variable in the evaluation context.

Parameters:

name - the name of the variable to look up

Returns:

a TypedValue containing the value of the variable, or TypedValue.NULL if the variable does not exist

See Also:

• assignVariable(String, Supplier)
• setVariable(String, Object)

getTypeComparator

public TypeComparator getTypeComparator()

findType

public Class<?> findType(String type)
                  throws EvaluationException

Throws:

EvaluationException

getTypeConverter

public TypeConverter getTypeConverter()

convertValue

public Object convertValue(Object value,
 TypeDescriptor targetTypeDescriptor)
                    throws EvaluationException

Throws:

EvaluationException

convertValue

public @Nullable Object convertValue(TypedValue value,
 TypeDescriptor targetTypeDescriptor)
                              throws EvaluationException

Throws:

EvaluationException

enterScope

public void enterScope()

Enter a new scope with a new root context object and a new local variable scope.

exitScope

public void exitScope()

operate

public TypedValue operate(Operation op,
 @Nullable Object left,
 @Nullable Object right)
                   throws EvaluationException

Throws:

EvaluationException

getPropertyAccessors

public List<PropertyAccessor> getPropertyAccessors()

getEvaluationContext

public EvaluationContext getEvaluationContext()

getConfiguration

public SpelParserConfiguration getConfiguration()