freemarker.template.expression
Class ExpressionUtils

java.lang.Object
  freemarker.template.expression.ExpressionUtils

public final class ExpressionUtils
extends java.lang.Object

Utility methods for evaluating expressions. These are used in various parts of the freemarker.template.expression package. They are also generally useful when dealing with TemplateModels directly, such as when retrieving parameters from a TemplateMethodModel2 parameter list.

Since:

1.7.5

Version:

$Id: ExpressionUtils.java 1101 2013-04-01 04:17:32Z run2000 $

Author:

Nicholas Cull

Nested Class Summary

static class

ExpressionUtils.ExpressionType Enumerates the types of results that an expression can generate.

Field Summary

static java.util.Set<ExpressionUtils.ExpressionType>	HASH The expression can be a Hash only.
static java.util.Set<ExpressionUtils.ExpressionType>	LIST The expression can be a List only.
static java.util.Set<ExpressionUtils.ExpressionType>	METHOD The expression can be a Method only.
static java.util.Set<ExpressionUtils.ExpressionType>	NUMBER The expression can be a Number only.
static java.util.Set<ExpressionUtils.ExpressionType>	STRING The expression can be a String only.
static java.util.Set<ExpressionUtils.ExpressionType>	STRING_OR_NUMBER The expression can be a String or a Number.
static java.util.Set<ExpressionUtils.ExpressionType>	VARIABLE The expression is a variable, so can return anything other than a constant.

Method Summary

static long	compareNumbers(TemplateModel leftModel, TemplateModel rightModel) Compares two numeric expressions.
static long	getAsNumber(TemplateModel model) Determines the given TemplateModel's long value.
static java.lang.String	getAsString(TemplateModel model) Determines the given TemplateModel's String value.
static java.lang.String	getAsStringOrEmpty(TemplateModel model) Determines the given TemplateModel's String value.
static boolean	isEqual(TemplateModel leftModel, TemplateModel rightModel) Determines whether both sides of an expression are equal.
static boolean	isTrue(TemplateModel model) Determines the "truth" of a given template model.

Methods inherited from class java.lang.Object

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

Field Detail

VARIABLE

public static final java.util.Set<ExpressionUtils.ExpressionType> VARIABLE

The expression is a variable, so can return anything other than a constant.

STRING_OR_NUMBER

public static final java.util.Set<ExpressionUtils.ExpressionType> STRING_OR_NUMBER

The expression can be a String or a Number.

STRING

public static final java.util.Set<ExpressionUtils.ExpressionType> STRING

The expression can be a String only.

NUMBER

public static final java.util.Set<ExpressionUtils.ExpressionType> NUMBER

The expression can be a Number only.

HASH

public static final java.util.Set<ExpressionUtils.ExpressionType> HASH

The expression can be a Hash only.

LIST

public static final java.util.Set<ExpressionUtils.ExpressionType> LIST

The expression can be a List only.

METHOD

public static final java.util.Set<ExpressionUtils.ExpressionType> METHOD

The expression can be a Method only.

Method Detail

isTrue

public static boolean isTrue(TemplateModel model)
                      throws TemplateModelException

Determines the "truth" of a given template model. This is determined as follows:

• If the template model is null, or is empty according to the TemplateModel.isEmpty() method, then it is false
• Otherwise, its true.

Parameters:

model - the TemplateModel to be tested, possibly null

Returns:

true if the model evaluates to true, otherwise false

Throws:

TemplateModelException - the truth of the template model could not be determined

getAsString

public static java.lang.String getAsString(TemplateModel model)
                                    throws TemplateModelException

Determines the given TemplateModel's String value. This is a simple case of getting the TemplateScalarModel.getAsString() value from the model, assuming it implements TemplateScalarModel. If it's a TemplateNumberModel, we return a base-10 encoding of the number value. If it's empty or null, return null.

Parameters:

model - the TemplateModel to get the String value from, possibly null

Returns:

the String value, or null if the model is empty

Throws:

TemplateModelException - the String value of the template model could not be determined

getAsStringOrEmpty

public static java.lang.String getAsStringOrEmpty(TemplateModel model)
                                           throws TemplateModelException

Determines the given TemplateModel's String value. This is a simple case of getting the TemplateScalarModel.getAsString() value from the model, assuming it implements TemplateScalarModel. If it's a TemplateNumberModel, we return a base-10 encoding of the number value. If it's empty or null, return the empty string.

Parameters:

model - the TemplateModel to get the String value from, possibly null

Returns:

the String value, or the empty String if the model is empty

Throws:

TemplateModelException - the String value of the template model could not be determined

Since:

1.9

getAsNumber

public static long getAsNumber(TemplateModel model)
                        throws TemplateModelException

Determines the given TemplateModel's long value. This is a simple case of getting the TemplateNumberModel.getAsNumber() value from the model, assuming it implements TemplateNumberModel. If it's empty or null, return 0.

Parameters:

model - the TemplateModel to get the long value from, possibly null

Throws:

TemplateModelException - the String value of the template model could not be determined

isEqual

public static boolean isEqual(TemplateModel leftModel,
                              TemplateModel rightModel)
                       throws TemplateModelException

Determines whether both sides of an expression are equal. Can deal with null values on either side of the test.

Parameters:

leftModel - the left-hand TemplateModel to be compared, possibly null

rightModel - the right-hand TemplateModel to be compared, possibly null

Returns:

true if the models are equal in value, otherwise false

Throws:

TemplateModelException - the template models could not be compared

compareNumbers

public static long compareNumbers(TemplateModel leftModel,
                                  TemplateModel rightModel)
                           throws TemplateModelException

Compares two numeric expressions. Can deal with null values on either side of the comparison.

Parameters:

leftModel - the left-hand TemplateModel to be compared, possibly null

rightModel - the right-hand TemplateModel to be compared, possibly null

Returns:

<0 if the left model is less than the right model, >0 if the left model is greater than the right model, or == 0 if the models are the same

Throws:

TemplateModelException - the template models could not be compared