Package net.sf.jett.expression

Class Expression

java.lang.Object

net.sf.jett.expression.Expression

public class Expression
extends java.lang.Object

An Expression object represents a JEXL Expression that can be evaluated given a Map of bean names to values. Many Expressions may be created in a cell. Here in JETT, Expressions are built from the text found in between "${" and "}".

Author:

Randy Gettman

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	BEGIN_EXPR	Determines the start of a JEXL expression.
static java.lang.String	END_EXPR	Determines the end of a JEXL expression.
static java.lang.String	NEGATIVE_LOOKBEHIND_BACKSLASH	This pattern makes sure that there is no backslash in front of an expression that is due to be replaced with the result of its evaluation.

Constructor Summary

Constructors

Constructor	Description
Expression(java.lang.String expression)	Create an Expression.

Method Summary

Modifier and Type	Method	Description
static void	clearExpressionToCollNamesMap()	Clear the Map that is used to cache the fact that a certain collection name may be present in expression text.
java.lang.Object	evaluate(ExpressionFactory factory, java.util.Map<java.lang.String,java.lang.Object> beans)	Evaluate this Expression using the given Map of beans as a context.
static java.lang.Object	evaluateString(java.lang.String value, ExpressionFactory factory, java.util.Map<java.lang.String,java.lang.Object> beans)	Find any Expressions embedded in the given string, evaluate them, and replace the expressions with the resulting values.
static java.lang.Object	evaluateString(org.apache.poi.ss.usermodel.RichTextString richTextString, org.apache.poi.ss.usermodel.CreationHelper helper, ExpressionFactory factory, java.util.Map<java.lang.String,java.lang.Object> beans)	Find any Expressions embedded in the given string, evaluate them, and replace the expressions with the resulting values.
static java.util.List<java.lang.String>	getImplicitCollectionExpr(java.lang.String value, java.util.Map<java.lang.String,java.lang.Object> beans, WorkbookContext context)	Determines whether a string representing an Expression represents implicit Collections access, which would result in an implicit collections processing loop.
java.lang.String	getValueIndicatingImplicitCollection(java.util.Map<java.lang.String,java.lang.Object> beans, WorkbookContext context)	Determines whether this represents implicit Collections access, which would result in an implicit collections processing loop.

Methods inherited from class java.lang.Object

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

Field Detail

NEGATIVE_LOOKBEHIND_BACKSLASH

public static final java.lang.String NEGATIVE_LOOKBEHIND_BACKSLASH

This pattern makes sure that there is no backslash in front of an expression that is due to be replaced with the result of its evaluation.

Since:

0.8.0

See Also:

Constant Field Values

BEGIN_EXPR

public static final java.lang.String BEGIN_EXPR

Determines the start of a JEXL expression.

See Also:

Constant Field Values

END_EXPR

public static final java.lang.String END_EXPR

Determines the end of a JEXL expression.

See Also:

Constant Field Values

Constructor Detail

Expression

public Expression(java.lang.String expression)

Create an Expression.

Parameters:

expression - The expression in String form.

Method Detail

evaluate

public java.lang.Object evaluate(ExpressionFactory factory,
                                 java.util.Map<java.lang.String,java.lang.Object> beans)

Evaluate this Expression using the given Map of beans as a context.

Parameters:

factory - An ExpressionFactory.

beans - A Map mapping strings to objects.

Returns:

The result of the evaluation.

getValueIndicatingImplicitCollection

public java.lang.String getValueIndicatingImplicitCollection(java.util.Map<java.lang.String,java.lang.Object> beans,
                                                             WorkbookContext context)

Determines whether this represents implicit Collections access, which would result in an implicit collections processing loop. If so, then it returns the substring representing the Collection, else it returns null.

This method uses JEXL internal parser logic.

Parameters:

beans - A Map mapping strings to objects.

context - A WorkbookContext. Don't return a collection expression whose collection property name is found in the List of such names maintained by this WorkbookContext..

Returns:

The string representing the Collection, or null if it doesn't represent implicit Collections access.

clearExpressionToCollNamesMap

public static void clearExpressionToCollNamesMap()

Clear the Map that is used to cache the fact that a certain collection name may be present in expression text. Call this method when a new beans Map is being used, which would render the cache useless. Such a situation arises when supplying multiple bean maps to the transform method on ExcelTransformer, and we are moving to a new Sheet, or if either transform method on ExcelTransformer is called more than once.

getImplicitCollectionExpr

public static java.util.List<java.lang.String> getImplicitCollectionExpr(java.lang.String value,
                                                                         java.util.Map<java.lang.String,java.lang.Object> beans,
                                                                         WorkbookContext context)

Determines whether a string representing an Expression represents implicit Collections access, which would result in an implicit collections processing loop. If so, then it returns the substring representing the Collection, else it returns null.

Parameters:

value - The string possibly representing an Expression.

beans - A Map mapping strings to objects.

context - A WorkbookContext, which supplies a List of collection names to ignore and the ExpressionFactory. Don't return a collection expression whose collection property name is found in this List.

Returns:

A List of strings representing the Collections found, possibly empty if it doesn't represent implicit Collections access.

evaluateString

public static java.lang.Object evaluateString(org.apache.poi.ss.usermodel.RichTextString richTextString,
                                              org.apache.poi.ss.usermodel.CreationHelper helper,
                                              ExpressionFactory factory,
                                              java.util.Map<java.lang.String,java.lang.Object> beans)

Find any Expressions embedded in the given string, evaluate them, and replace the expressions with the resulting values. If the entire string consists of one Expression, then the returned value may be any Object.

Parameters:

richTextString - The rich text string, with possibly embedded expressions.

helper - A CreationHelper that can create the proper RichTextString.

factory - An ExpressionFactory.

beans - A Map mapping strings to objects.

Returns:

A new string, with any embedded expressions replaced with the expression string values.

evaluateString

public static java.lang.Object evaluateString(java.lang.String value,
                                              ExpressionFactory factory,
                                              java.util.Map<java.lang.String,java.lang.Object> beans)

Find any Expressions embedded in the given string, evaluate them, and replace the expressions with the resulting values. If the entire string consists of one Expression, then the returned value may be any Object.

Parameters:

value - The string, with possibly embedded expressions.

factory - An ExpressionFactory.

beans - A Map mapping strings to objects.

Returns:

A new string, with any embedded expressions replaced with the expression string values.