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

Field Summary

static int	EXPRESSION_TYPE_HASH The expression can return type Hash.
static int	EXPRESSION_TYPE_LIST The expression can return type List.
static int	EXPRESSION_TYPE_METHOD The expression can return type Method.
static int	EXPRESSION_TYPE_NUMBER The expression can return type Number.
static int	EXPRESSION_TYPE_STRING The expression can return type String.
static int	EXPRESSION_TYPE_TRANSFORM The expression can return type Transform.
static int	EXPRESSION_TYPE_VARIABLE The expression is a variable, so can return anything.

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

EXPRESSION_TYPE_STRING

public static final int EXPRESSION_TYPE_STRING

The expression can return type String.

See Also:

Constant Field Values

EXPRESSION_TYPE_NUMBER

public static final int EXPRESSION_TYPE_NUMBER

The expression can return type Number.

See Also:

Constant Field Values

EXPRESSION_TYPE_LIST

public static final int EXPRESSION_TYPE_LIST

The expression can return type List.

See Also:

Constant Field Values

EXPRESSION_TYPE_HASH

public static final int EXPRESSION_TYPE_HASH

The expression can return type Hash.

See Also:

Constant Field Values

EXPRESSION_TYPE_TRANSFORM

public static final int EXPRESSION_TYPE_TRANSFORM

The expression can return type Transform.

See Also:

Constant Field Values

EXPRESSION_TYPE_METHOD

public static final int EXPRESSION_TYPE_METHOD

The expression can return type Method.

See Also:

Constant Field Values

EXPRESSION_TYPE_VARIABLE

public static final int EXPRESSION_TYPE_VARIABLE

The expression is a variable, so can return anything.

See Also:

Constant Field Values

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