Package freemarker.core

Class DefaultTruncateBuiltinAlgorithm

java.lang.Object

freemarker.core.TruncateBuiltinAlgorithm

freemarker.core.DefaultTruncateBuiltinAlgorithm

public class DefaultTruncateBuiltinAlgorithm
extends TruncateBuiltinAlgorithm

The default TruncateBuiltinAlgorithm implementation; see Configurable.setTruncateBuiltinAlgorithm(TruncateBuiltinAlgorithm). To know the properties of this TruncateBuiltinAlgorithm implementation, see the constructor. You can find more explanation and examples in the documentation of the truncate built-in in the FreeMarker Manual.

Since:

2.3.29

Field Summary

Fields

Modifier and Type	Field	Description
static DefaultTruncateBuiltinAlgorithm	ASCII_INSTANCE	Instance that uses "[...]" as the defaultTerminator constructor argument, and thus is safe to use for all output charsets.
static double	DEFAULT_WORD_BOUNDARY_MIN_LENGTH	The value used in the constructor of ASCII_INSTANCE and UNICODE_INSTANCE as the wordBoundaryMinLength argument.
static String	STANDARD_ASCII_TERMINATOR	Used by ASCII_INSTANCE as the terminator.
static TemplateHTMLOutputModel	STANDARD_M_TERMINATOR	Used by ASCII_INSTANCE and UNICODE_INSTANCE as the markup terminator; HTML <span class='truncateTerminator'>[&#8230;]</span>, where &#8230; is the ellipsis (…) character.
static String	STANDARD_UNICODE_TERMINATOR	Used by UNICODE_INSTANCE as the terminator.
static DefaultTruncateBuiltinAlgorithm	UNICODE_INSTANCE	Instance that uses "[…]" as the defaultTerminator constructor argument, which contains ellipsis character ("…", U+2026), and thus only works with UTF-8, and the cp125x charsets (like cp1250), and with some other rarely used ones.

Constructor Summary

Constructors

Constructor	Description
DefaultTruncateBuiltinAlgorithm(String defaultTerminator, boolean addSpaceAtWordBoundary)	Creates an instance with string (plain text) terminator.
DefaultTruncateBuiltinAlgorithm(String defaultTerminator, TemplateMarkupOutputModel<?> defaultMTerminator, boolean addSpaceAtWordBoundary)	Creates an instance with a string (plain text) terminator and a markup terminator.
DefaultTruncateBuiltinAlgorithm(String defaultTerminator, Integer defaultTerminatorLength, Boolean defaultTerminatorRemovesDots, TemplateMarkupOutputModel<?> defaultMTerminator, Integer defaultMTerminatorLength, Boolean defaultMTerminatorRemovesDots, boolean addSpaceAtWordBoundary, Double wordBoundaryMinLength)	Creates an instance with markup terminator.

Method Summary

Modifier and Type	Method	Description
boolean	getAddSpaceAtWordBoundary()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
TemplateMarkupOutputModel<?>	getDefaultMTerminator()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
Integer	getDefaultMTerminatorLength()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
boolean	getDefaultMTerminatorRemovesDots()
String	getDefaultTerminator()
int	getDefaultTerminatorLength()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
boolean	getDefaultTerminatorRemovesDots()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
protected int	getMTerminatorLength(TemplateMarkupOutputModel<?> mTerminator)	Returns the (estimated) length of the argument terminator.
protected boolean	getMTerminatorRemovesDots(TemplateMarkupOutputModel terminator)	Same as getTerminatorRemovesDots(String), but invoked for a markup terminator.
protected boolean	getTerminatorRemovesDots(String terminator)	Tells if the dots touched by the terminator text should be removed.
double	getWordBoundaryMinLength()	See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.
TemplateScalarModel	truncate(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate(...) in templates.
TemplateScalarModel	truncateC(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_c_m(...) in templates.
TemplateModel	truncateCM(String s, int maxLength, TemplateModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_c_m(...) in templates.
TemplateModel	truncateM(String s, int maxLength, TemplateModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_m(...) in templates.
TemplateScalarModel	truncateW(String s, int maxLength, TemplateScalarModel terminator, Integer terminatorLength, Environment env)	Corresponds to ?truncate_w(...) in templates.
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

Field Details

STANDARD_ASCII_TERMINATOR

public static final String STANDARD_ASCII_TERMINATOR

Used by ASCII_INSTANCE as the terminator.

See Also:

Constant Field Values

STANDARD_UNICODE_TERMINATOR

public static final String STANDARD_UNICODE_TERMINATOR

Used by UNICODE_INSTANCE as the terminator.

See Also:

Constant Field Values

STANDARD_M_TERMINATOR

public static final TemplateHTMLOutputModel STANDARD_M_TERMINATOR

Used by ASCII_INSTANCE and UNICODE_INSTANCE as the markup terminator; HTML <span class='truncateTerminator'>[&#8230;]</span>, where … is the ellipsis (…) character. Note that while the ellipsis character is not in US-ASCII, this still works safely regardless of output charset, as … itself only contains US-ASCII characters.

DEFAULT_WORD_BOUNDARY_MIN_LENGTH

public static final double DEFAULT_WORD_BOUNDARY_MIN_LENGTH

The value used in the constructor of ASCII_INSTANCE and UNICODE_INSTANCE as the wordBoundaryMinLength argument.

See Also:

Constant Field Values

ASCII_INSTANCE

public static final DefaultTruncateBuiltinAlgorithm ASCII_INSTANCE

Instance that uses "[...]" as the defaultTerminator constructor argument, and thus is safe to use for all output charsets. Because of that, this is the default of Configurable.setTruncateBuiltinAlgorithm(TruncateBuiltinAlgorithm). The defaultMTerminator (markup terminator) is STANDARD_M_TERMINATOR, and the wordBoundaryMinLength is DEFAULT_WORD_BOUNDARY_MIN_LENGTH, and addSpaceAtWordBoundary is true.

UNICODE_INSTANCE

public static final DefaultTruncateBuiltinAlgorithm UNICODE_INSTANCE

Instance that uses "[…]" as the defaultTerminator constructor argument, which contains ellipsis character ("…", U+2026), and thus only works with UTF-8, and the cp125x charsets (like cp1250), and with some other rarely used ones. It does not work (becomes to a question mark) with ISO-8859-x charsets (like ISO-8859-1), which are probably the most often used charsets after UTF-8.

The defaultMTerminator (markup terminator) is STANDARD_M_TERMINATOR, and the wordBoundaryMinLength is DEFAULT_WORD_BOUNDARY_MIN_LENGTH, and addSpaceAtWordBoundary is true.

Constructor Details

DefaultTruncateBuiltinAlgorithm

public DefaultTruncateBuiltinAlgorithm(String defaultTerminator,
 TemplateMarkupOutputModel<?> defaultMTerminator,
 boolean addSpaceAtWordBoundary)

Creates an instance with a string (plain text) terminator and a markup terminator. See parameters in DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double); the missing parameters will be null.

DefaultTruncateBuiltinAlgorithm

public DefaultTruncateBuiltinAlgorithm(String defaultTerminator,
 boolean addSpaceAtWordBoundary)

Creates an instance with string (plain text) terminator. See parameters in DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double); the missing parameters will be null.

DefaultTruncateBuiltinAlgorithm

public DefaultTruncateBuiltinAlgorithm(String defaultTerminator,
 Integer defaultTerminatorLength,
 Boolean defaultTerminatorRemovesDots,
 TemplateMarkupOutputModel<?> defaultMTerminator,
 Integer defaultMTerminatorLength,
 Boolean defaultMTerminatorRemovesDots,
 boolean addSpaceAtWordBoundary,
 Double wordBoundaryMinLength)

Creates an instance with markup terminator.

Parameters:

defaultTerminator - The terminator to use if the invocation (like s?truncate(20)) doesn't specify it. The terminator is the text appended after a truncated string, to indicate that it was truncated. Typically, it's "[...]" or "...", or the same with UNICODE ellipsis character.

defaultTerminatorLength - The assumed length of defaultTerminator, or null if the assumed length is simply defaultTerminator.length().

defaultTerminatorRemovesDots - Whether dots and ellipsis characters that the defaultTerminator touches should be removed. If null, this will be auto-detected based on if defaultTerminator starts with dot or ellipsis. The goal is to avoid outcomes where we have more dots next to each other than there are in the terminator.

defaultMTerminator - Similar to defaultTerminator, but is markup instead of plain text. This can be null, in which case defaultTerminator will be used even if ?truncate_m or similar built-in is called.

defaultMTerminatorLength - The assumed length of the terminator, or null if the assumed length will be getMTerminatorLength(TemplateMarkupOutputModel). Note that if you have HTML tags, or entity references in the defaultMTerminator, then the visual length differs from the string length, and getMTerminatorLength(TemplateMarkupOutputModel) accounts for these complications to an extent, but it for example it won't know what CSS does, or if the nested content of some HTML elements are not displayed.

defaultMTerminatorRemovesDots - Similar to defaultTerminatorRemovesDots, but for defaultMTerminator. If null, and defaultMTerminator is HTML/XML/XHTML, then it will be examined of the first character of the terminator that's outside a HTML/XML tag or comment is dot or ellipsis (after resolving numerical character references). For other kind of markup it defaults to true, to be on the safe side.

addSpaceAtWordBoundary - , Whether to add a space before the terminator if the truncation happens directly after the end of a word. For example, when "too long sentence" is truncated, it will be a like "too long [...]" instead of "too long[...]". When the truncation happens inside a word, this has no effect, i.e., it will be always like "too long se[...]" (no space before the terminator). Note that only whitespace is considered to be a word separator, not punctuation, so if this is true, you get results like "Some sentence. [...]".

wordBoundaryMinLength - Used when truncate(java.lang.String, int, freemarker.template.TemplateScalarModel, java.lang.Integer, freemarker.core.Environment) or truncateM(java.lang.String, int, freemarker.template.TemplateModel, java.lang.Integer, freemarker.core.Environment) has to decide between word boundary truncation, and character boundary truncation; it's the minimum length, given as proportion of maxLength, that word boundary truncation has to produce. If the resulting length is less, we do character boundary truncation instead. For example, if maxLength is 30, and this parameter is 0.85, then: 30 * 0.85 = 25.5, rounded up that's 26, so the resulting length must be at least 26. The result of character boundary truncation will always be accepted, even if it's still too short. If this parameter is null, then DEFAULT_WORD_BOUNDARY_MIN_LENGTH will be used. If this parameter is 0, then truncation always happens at word boundary. If this parameter is 1.0, then truncation doesn't prefer word boundaries over other places.

Method Details

truncate

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate(...) in templates. Similar to TruncateBuiltinAlgorithm.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).

Specified by:

truncate in class TruncateBuiltinAlgorithm

Throws:

TemplateException

truncateW

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate_w(...) in templates. Same as TruncateBuiltinAlgorithm.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).

Specified by:

truncateW in class TruncateBuiltinAlgorithm

Throws:

TemplateException

truncateC

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate_c_m(...) in templates. Same as TruncateBuiltinAlgorithm.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).

Specified by:

truncateC in class TruncateBuiltinAlgorithm

Throws:

TemplateException

truncateM

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate_m(...) in templates. This method decides automatically if it will truncate at word boundary (see TruncateBuiltinAlgorithm.truncateWM(java.lang.String, int, freemarker.template.TemplateModel, java.lang.Integer, freemarker.core.Environment)) or at character boundary (see TruncateBuiltinAlgorithm.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.

Specified by:

truncateM in class TruncateBuiltinAlgorithm

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.

truncateWM

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate_w_m(...) in templates. Similar to TruncateBuiltinAlgorithm.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).

Specified by:

truncateWM in class TruncateBuiltinAlgorithm

Throws:

TemplateException

truncateCM

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

Description copied from class: TruncateBuiltinAlgorithm

Corresponds to ?truncate_c_m(...) in templates. Similar to TruncateBuiltinAlgorithm.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").

Specified by:

truncateCM in class TruncateBuiltinAlgorithm

Throws:

TemplateException

getDefaultTerminator

public String getDefaultTerminator()

getDefaultTerminatorLength

public int getDefaultTerminatorLength()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getDefaultTerminatorRemovesDots

public boolean getDefaultTerminatorRemovesDots()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getDefaultMTerminator

public TemplateMarkupOutputModel<?> getDefaultMTerminator()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getDefaultMTerminatorLength

public Integer getDefaultMTerminatorLength()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getDefaultMTerminatorRemovesDots

public boolean getDefaultMTerminatorRemovesDots()

getWordBoundaryMinLength

public double getWordBoundaryMinLength()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getAddSpaceAtWordBoundary

public boolean getAddSpaceAtWordBoundary()

See similarly named parameter of DefaultTruncateBuiltinAlgorithm(String, Integer, Boolean, TemplateMarkupOutputModel, Integer, Boolean, boolean, Double) the construction}.

getMTerminatorLength

protected int getMTerminatorLength(TemplateMarkupOutputModel<?> mTerminator)
                            throws TemplateModelException

Returns the (estimated) length of the argument terminator. It should only count characters that are visible for the user (like in the web browser).

In the implementation in DefaultTruncateBuiltinAlgorithm, if the markup is HTML/XML/XHTML, then this counts the characters outside tags and comments, and inside CDATA sections (ignoring the CDATA section delimiters). Furthermore, then it counts character and entity references as having length of 1. If the markup is not HTML/XML/XHTML (or subclasses of those MarkupOutputFormat-s) then it doesn't know how to measure it, and simply returns 3.

Throws:

TemplateModelException

getTerminatorRemovesDots

protected boolean getTerminatorRemovesDots(String terminator)
                                    throws TemplateModelException

Tells if the dots touched by the terminator text should be removed.

The implementation in DefaultTruncateBuiltinAlgorithm return true if the terminator starts with dot (or ellipsis).

Parameters:

terminator - A TemplateScalarModel or TemplateMarkupOutputModel. Not null.

Throws:

TemplateModelException

getMTerminatorRemovesDots

protected boolean getMTerminatorRemovesDots(TemplateMarkupOutputModel terminator)
                                     throws TemplateModelException

Same as getTerminatorRemovesDots(String), but invoked for a markup terminator.

The implementation in DefaultTruncateBuiltinAlgorithm will skip HTML/XML tags and comments, and resolves relevant character references to find out if the first character is dot or ellipsis. But it only does this for HTML/XMl/XHTML (or subclasses of those MarkupOutputFormat-s), otherwise it always returns true to be on the safe side.

Throws:

TemplateModelException