Package freemarker.core

Class TruncateBuiltinAlgorithm

java.lang.Object

freemarker.core.TruncateBuiltinAlgorithm

Direct Known Subclasses:

DefaultTruncateBuiltinAlgorithm

public abstract class TruncateBuiltinAlgorithm
extends Object

Used for implementing the "truncate" family of built-ins. There are several variations of the "truncate" built-ins, each has a corresponding method here. See truncateM(String, int, TemplateModel, Integer, Environment) as the starting point.

New methods may be added in later versions, whoever they won't be abstract for backward compatibility.

Since:

2.3.29

See Also:

Configurable.setTruncateBuiltinAlgorithm(TruncateBuiltinAlgorithm)

Constructor Summary

Constructors

Constructor	Description
TruncateBuiltinAlgorithm()

Method Summary

Modifier and Type	Method	Description
abstract TemplateScalarModel	truncate(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate(...) in templates.
abstract TemplateScalarModel	truncateC(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_c_m(...) in templates.
abstract TemplateModel	truncateCM(String s, int maxLength, TemplateModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_c_m(...) in templates.
abstract TemplateModel	truncateM(String s, int maxLength, TemplateModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_m(...) in templates.
abstract TemplateScalarModel	truncateW(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_w(...) in templates.
abstract TemplateModel	truncateWM(String s, int maxLength, TemplateModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_w_m(...) in templates.

Methods inherited from class java.lang.Object

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

Constructor Details

TruncateBuiltinAlgorithm

public TruncateBuiltinAlgorithm()

Method Details

truncateM

public abstract TemplateModel truncateM(String s,
 int maxLength,
 TemplateModel terminator,
 Integer terminatorLength,
 Environment env)
                                 throws TemplateException

Corresponds to ?truncate_m(...) in templates. This method decides automatically if it will truncate at word boundary (see truncateWM(java.lang.String, int, freemarker.template.TemplateModel, java.lang.Integer, freemarker.core.Environment)) or at character boundary (see truncateCM(java.lang.String, int, freemarker.template.TemplateModel, java.lang.Integer, freemarker.core.Environment)). While it depends on the implementation, the idea is that it should truncate at word boundary, unless that gives a too short string, in which case it falls back to truncation at character duration.

The terminator and the return value can be TemplateMarkupOutputModel (FTL markup output type), not just String (FTL string type), hence the "m" in the name.

Parameters:

s - The input string whose length need to be limited. The caller (the FreeMarker core normally) is expected to guarantee that this won't be null.

maxLength - The maximum length of the returned string, although the algorithm need not guarantee this strictly. For example, if this is less than the length of the terminator string, then most algorithms should still return the terminator string. Or, some sophisticated algorithm may counts in letters differently depending on their visual width. The goal is usually to prevent unusually long string values to ruin visual layout, while showing clearly to the user that the end of the string was cut off. If the input string is not longer than the maximum length, then it should be returned as is. The caller (the FreeMarker core normally) is expected to guarantee that this will be at least 0.

terminator - The string or markup to show at the end of the returned string if the string was actually truncated. This can be null, in which case the default terminator of the algorithm will be used. It can be an FTL string (a TemplateScalarModel) of any length (including 0), or a TemplateMarkupOutputModel (typically HTML markup). If it's TemplateMarkupOutputModel, then the result is TemplateMarkupOutputModel of the same output format as well, otherwise it can remain TemplateScalarModel. Note that the length of the terminator counts into the result length that shouldn't be exceed (maxLength) (or at least the algorithm should make an effort to avoid that).

terminatorLength - The assumed length of the terminator. If this is null (and typically it is), then the method decides the length of the terminator. If this is not null, then the method must pretend that the terminator length is this. This can be used to specify the visual length of a terminator explicitly, which can't always be decided well programmatically.

env - The runtime environment from which this algorithm was called. The caller (the FreeMarker core normally) is expected to guarantee that this won't be null.

Returns:

The truncated text, which is either a TemplateScalarModel (FTL string), or a TemplateMarkupOutputModel.

Throws:

TemplateException - If anything goes wrong during truncating. It's unlikely that an implementation will need this though.

truncate

public abstract TemplateScalarModel truncate(String s,
 int maxLength,
 TemplateScalarModel terminator,
 Integer terminatorLength,
 Environment env)
                                      throws TemplateException

Corresponds to ?truncate(...) in templates. Similar to truncateM(String, int, TemplateModel, Integer, Environment), but only allows an FTL string as terminator, and thence the return value is always an FTL string as well (not TemplateMarkupOutputModel).

Throws:

TemplateException

truncateW

public abstract TemplateScalarModel truncateW(String s,
 int maxLength,
 TemplateScalarModel terminator,
 Integer terminatorLength,
 Environment env)
                                       throws TemplateException

Corresponds to ?truncate_w(...) in templates. Same as truncateWM(String, int, TemplateModel, Integer, Environment), but only allows an FTL string as terminator, and thence the return value is always an FTL string as well (not TemplateMarkupOutputModel).

Throws:

TemplateException

truncateWM

public abstract TemplateModel truncateWM(String s,
 int maxLength,
 TemplateModel terminator,
 Integer terminatorLength,
 Environment env)
                                  throws TemplateException

Corresponds to ?truncate_w_m(...) in templates. Similar to truncateM(String, int, TemplateModel, Integer, Environment), but the truncation should happen at word boundary (hence the "w"). That is, the truncation isn't allowed to truncate a word. What counts as a word, is up to the implementation, but at least in DefaultTruncateBuiltinAlgorithm words are the sections that are separated by whitespace (so punctuation doesn't separate words).

Throws:

TemplateException

truncateC

public abstract TemplateScalarModel truncateC(String s,
 int maxLength,
 TemplateScalarModel terminator,
 Integer terminatorLength,
 Environment env)
                                       throws TemplateException

Corresponds to ?truncate_c_m(...) in templates. Same as truncateCM(String, int, TemplateModel, Integer, Environment), but only allows an FTL string as terminator, and thence the return value is always an FTL string as well (not markup).

Throws:

TemplateException

truncateCM

public abstract TemplateModel truncateCM(String s,
 int maxLength,
 TemplateModel terminator,
 Integer terminatorLength,
 Environment env)
                                  throws TemplateException

Corresponds to ?truncate_c_m(...) in templates. Similar to truncateM(String, int, TemplateModel, Integer, Environment), but the truncation should not prefer truncating at word boundaries over the closer approximation of the desired maxLength. Hence, we say that it truncates at character boundary (hence the "c").

Throws:

TemplateException