TreeValueExpression (Camunda BPM Javadocs 7.13.18-ee)

java.lang.Object
- org.camunda.bpm.engine.impl.javax.el.Expression
- - org.camunda.bpm.engine.impl.javax.el.ValueExpression
  - - org.camunda.bpm.engine.impl.juel.TreeValueExpression

All Implemented Interfaces:

Serializable
```
public final class TreeValueExpression
extends ValueExpression
```
A value expression is ready to be evaluated (by calling either getType(ELContext), getValue(ELContext), isReadOnly(ELContext) or setValue(ELContext, Object). Instances of this class are usually created using an ExpressionFactoryImpl.

Author:

Christoph Beck

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description
`TreeValueExpression(TreeStore store, FunctionMapper functions, VariableMapper variables, TypeConverter converter, String expr, Class<?> type)` Create a new value expression.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`dump(PrintWriter writer)` Print the parse tree.
`boolean`	`equals(Object obj)` Expressions are compared using the concept of a structural id: variable and function names are anonymized such that two expressions with same tree structure will also have the same structural id and vice versa.
`Class<?>`	`getExpectedType()` Returns the type the result of the expression will be coerced to after evaluation.
`String`	`getExpressionString()` Returns the original String used to create this Expression, unmodified.
`Class<?>`	`getType(ELContext context)` Evaluates the expression as an lvalue and answers the result type.
`Object`	`getValue(ELContext context)` Evaluates the expression as an rvalue and answers the result.
`ValueReference`	`getValueReference(ELContext context)` Returns a `ValueReference` for this expression instance.
`int`	`hashCode()` Returns the hash code for this Expression.
`boolean`	`isDeferred()` Answer `true` if this is a deferred expression (containing sub-expressions starting with `#{`)
`boolean`	`isLeftValue()` Answer `true` if this could be used as an lvalue.
`boolean`	`isLiteralText()` Returns whether this expression was created from only literal text.
`boolean`	`isReadOnly(ELContext context)` Evaluates the expression as an lvalue and determines if `setValue(ELContext, Object)` will always fail.
`void`	`setValue(ELContext context, Object value)` Evaluates the expression as an lvalue and assigns the given value.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - TreeValueExpression
```
public TreeValueExpression(TreeStore store,
                           FunctionMapper functions,
                           VariableMapper variables,
                           TypeConverter converter,
                           String expr,
                           Class<?> type)
```
    Create a new value expression.
    
    Parameters:
    
    store - used to get the parse tree from.
    
    functions - the function mapper used to bind functions
    
    variables - the variable mapper used to bind variables
    
    expr - the expression string
    
    type - the expected type (may be null)
- Method Detail
  - getExpectedType
```
public Class<?> getExpectedType()
```
    Description copied from class: ValueExpression
    
    Returns the type the result of the expression will be coerced to after evaluation.
    
    Specified by:
    
    getExpectedType in class ValueExpression
    
    Returns:
    
    the expectedType passed to the ExpressionFactory.createValueExpression method that created this ValueExpression.
  - getExpressionString
```
public String getExpressionString()
```
    Description copied from class: Expression
    
    Returns the original String used to create this Expression, unmodified. This is used for debugging purposes but also for the purposes of comparison (e.g. to ensure the expression in a configuration file has not changed). This method does not provide sufficient information to re-create an expression. Two different expressions can have exactly the same expression string but different function mappings. Serialization should be used to save and restore the state of an Expression.
    
    Specified by:
    
    getExpressionString in class Expression
    
    Returns:
    
    The original expression String.
  - getType
```
public Class<?> getType(ELContext context)
                 throws ELException
```
    Evaluates the expression as an lvalue and answers the result type.
    
    Specified by:
    
    getType in class ValueExpression
    
    Parameters:
    
    context - used to resolve properties (base.property and base[property]) and to determine the result from the last base/property pair
    
    Returns:
    
    lvalue evaluation type or null for rvalue expressions
    
    Throws:
    
    ELException - if evaluation fails (e.g. property not found, type conversion failed, ...)
  - getValue
```
public Object getValue(ELContext context)
                throws ELException
```
    Evaluates the expression as an rvalue and answers the result.
    
    Specified by:
    
    getValue in class ValueExpression
    
    Parameters:
    
    context - used to resolve properties (base.property and base[property]) and to determine the result from the last base/property pair
    
    Returns:
    
    rvalue evaluation result
    
    Throws:
    
    ELException - if evaluation fails (e.g. property not found, type conversion failed, ...)
  - isReadOnly
```
public boolean isReadOnly(ELContext context)
                   throws ELException
```
    Evaluates the expression as an lvalue and determines if setValue(ELContext, Object) will always fail.
    
    Specified by:
    
    isReadOnly in class ValueExpression
    
    Parameters:
    
    context - used to resolve properties (base.property and base[property]) and to determine the result from the last base/property pair
    
    Returns:
    
    true if setValue(ELContext, Object) always fails.
    
    Throws:
    
    ELException - if evaluation fails (e.g. property not found, type conversion failed, ...)
  - setValue
```
public void setValue(ELContext context,
                     Object value)
              throws ELException
```
    Evaluates the expression as an lvalue and assigns the given value.
    
    Specified by:
    
    setValue in class ValueExpression
    
    Parameters:
    
    context - used to resolve properties (base.property and base[property]) and to perform the assignment to the last base/property pair
    
    value - The new value to be set.
    
    Throws:
    
    ELException - if evaluation fails (e.g. property not found, type conversion failed, assignment failed...)
  - isLiteralText
```
public boolean isLiteralText()
```
    Description copied from class: Expression
    
    Returns whether this expression was created from only literal text. This method must return true if and only if the expression string this expression was created from contained no unescaped EL delimeters (${...} or #{...}).
    
    Specified by:
    
    isLiteralText in class Expression
    
    Returns:
    
    true if this is a literal text expression
  - getValueReference
```
public ValueReference getValueReference(ELContext context)
```
    Description copied from class: ValueExpression
    
    Returns a ValueReference for this expression instance.
    
    Overrides:
    
    getValueReference in class ValueExpression
    
    Parameters:
    
    context - the context of this evaluation
    
    Returns:
    
    the ValueReference for this ValueExpression, or null if this ValueExpression is not a reference to a base (null or non-null) and a property. If the base is null, and the property is a EL variable, return the ValueReference for the ValueExpression associated with this EL variable.
  - isLeftValue
```
public boolean isLeftValue()
```
    Answer true if this could be used as an lvalue. This is the case for eval expressions consisting of a simple identifier or a nonliteral prefix, followed by a sequence of property operators (. or [])
  - isDeferred
```
public boolean isDeferred()
```
    Answer true if this is a deferred expression (containing sub-expressions starting with #{)
  - equals
```
public boolean equals(Object obj)
```
    Expressions are compared using the concept of a structural id: variable and function names are anonymized such that two expressions with same tree structure will also have the same structural id and vice versa. Two value expressions are equal if
    1. their structural id's are equal
    2. their bindings are equal
    3. their expected types are equal
    Specified by:
    
    equals in class Expression
    
    Parameters:
    
    obj - the Object to test for equality.
    
    Returns:
    
    true if obj equals this Expression; false otherwise.
  - hashCode
```
public int hashCode()
```
    Description copied from class: Expression
    
    Returns the hash code for this Expression. See the note in the Expression.equals(Object) method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. Implementations must take special note and implement hashCode correctly.
    
    Specified by:
    
    hashCode in class Expression
    
    Returns:
    
    The hash code for this Expression.
    
    See Also:
    
    Expression.equals(Object), Hashtable, Object.hashCode()
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - dump
```
public void dump(PrintWriter writer)
```
    Print the parse tree.
    
    Parameters:
    
    writer -

Class TreeValueExpression

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TreeValueExpression

Method Detail

getExpectedType

getExpressionString

getType

getValue

isReadOnly

setValue

isLiteralText

getValueReference

isLeftValue

isDeferred

equals

hashCode

toString

dump