bundles/org.eclipse.equinox.bidi/src/org/eclipse/equinox/bidi/package.html - equinox/rt.equinox.bundles - Git at Google

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 <body bgcolor="white">

 This package provides classes for processing bidirectional
 text with a special structure to ensure its proper presentation.
 <p>
 There are various types of structured text. Each type should
 be handled by a specific <i>type handler</i>. A number of
 standard type handlers are supplied with this package.

 <h2>Introduction to Structured Text</h2>
 <p>
 Bidirectional text offers interesting challenges to presentation systems.
 For plain text, the Unicode Bidirectional Algorithm
 (<a href="http://www.unicode.org/reports/tr9/">UBA</a>)
 generally specifies satisfactorily how to reorder bidirectional text for
 display. This algorithm is implemented in many presentation and operating
 systems, like Java/Swing, Windows, Linux.
 </p><p>
 However, all bidirectional text is not necessarily plain text. There
 are also instances of text structured to follow a given syntax, which
 should be reflected in the display order. The general algorithm, which
 has no awareness of these special cases, often gives incorrect results
 when displaying such structured text.
 </p><p>
 The general idea in handling structured text in this package is to add
 directional formatting characters at proper locations in the text to
 supplement the standard algorithm, so that the final result is correctly
 displayed using the UBA.
 </p><p>
 A class which handles structured text is thus essentially a
 transformation engine which receives text without directional formatting
 characters as input and produces as output the same text with added
 directional formatting characters, hopefully in the minimum quantity
 which is sufficient to ensure correct display, considering the type of
 structured text involved.
 </p><p>
 In this package, text without directional formatting characters is
 called <b><i>lean</i></b> text while the text with added directional
 formatting characters is called <b><i>full</i></b> text.
 </p><p>
 The class
 <a href="StructuredTextProcessor.html"><b>StructuredTextProcessor</b></a>
 is the main tool for processing structured text.  It facilitates
 handling several types of structured text, each type being handled
 by a specific
 <a href="./custom/StructuredTextTypeHandler.html">
 <b><i>type handler</i></b></a> :</p>
 <ul>
   <li>comma delimited list</li>
   <li>e-mail address</li>
   <li>directory and file path</li>
   <li>Java code</li>
   <li>regular expression</li>
   <li>SQL statements</li>
   <li>compound name (xxx_yy_zzzz)</li>
   <li>URL</li>
   <li>Xpath</li>
 </ul>
 <p>
 For each of these types, an identifier is defined in
  <a href="StructuredTextTypeHandlerFactory.html">
 <b><i>StructuredTextTypeHandlerFactory</i></b></a> :</p>
 <p>
 These identifiers can be used as argument in some methods of
 <b>StructuredTextProcessor</b> to specify the type of handler to apply.
 </p><p>
 The classes included in this package are intended for users who
 need to process structured text in the most straightforward
 manner, when the following conditions are satisfied:
 <ul>
   <li>There exists an appropriate handler for the type of the
       structured text.</li>
   <li>There is no need to specify non-default conditions related
       to the <a href="advanced/StructuredTextEnvironment.html">
       environment</a>.</li>
   <li>The only operations needed are to transform <i>lean</i> text
       into <i>full</i> text or vice versa.</li>
   <li>There is no interdependence between the processing of a
       given string and the processing of preceding or
       succeeding strings.</li>
 </ul>
 <p>
 When their needs go beyond the conditions above,
 users can use classes in the
 <a href="advanced/package-summary.html">
 org.eclipse.equinox.bidi.advanced</a>}package.
 </p><p>
 Developers who want to develop new handlers to support types of
 structured text not currently supported can use components
 of the package <a href="custom/package-summary.html">
 org.eclipse.equinox.bidi.custom</a>.
 The source code of packages org.eclipse.equinox.bidi.* can serve as example of
 how to develop processors for currently unsupported types of structured text.
 </p><p>
 However, users wishing to process the currently supported types of structured
 text typically don't need to deal with the org.eclipse.equinox.bidi.custom
 package.
 </p>

 <h2>Abbreviations used in the documentation of this package</h2>

 <dl>
 <dt><b>UBA</b><dd>Unicode Bidirectional Algorithm

 <dt><b>Bidi</b><dd>Bidirectional

 <dt><b>GUI</b><dd>Graphical User Interface

 <dt><b>UI</b><dd>User Interface

 <dt><b>LTR</b><dd>Left to Right

 <dt><b>RTL</b><dd>Right to Left

 <dt><b>LRM</b><dd>Left-to-Right Mark

 <dt><b>RLM</b><dd>Right-to-Left Mark

 <dt><b>LRE</b><dd>Left-to-Right Embedding

 <dt><b>RLE</b><dd>Right-to-Left Embedding

 <dt><b>PDF</b><dd>Pop Directional Formatting
 </dl>

 <p>&nbsp;</p>

 <h2>Known Limitations</h2>

 <p>The proposed solution is making extensive usage of LRM, RLM, LRE, RLE
 and PDF directional controls which are invisible but affect the way bidi
 text is displayed. The following related key points merit special
 attention:</p>

 <ul>
 <li>Implementations of the UBA on various platforms (e.g., Windows and
 Linux) are very similar but nevertheless have known differences. Those
 differences are minor and will not have a visible effect in most cases.
 However there might be cases in which the same bidi text on two
 platforms will look different. These differences will surface in Java
 applications when they use the platform visual components for their UI
 (e.g., AWT, SWT).</li>

 <li>It is assumed that the presentation engine supports LRE, RLE and
 PDF directional formatting characters.</li>

 <li>Because some presentation engines are not strictly conformant to the
 UBA, the implementation of structured text in this package adds LRM
 or RLM characters in association with LRE, RLE or PDF in cases where
 this would not be needed if the presentation engine was fully conformant
 to the UBA. Such added marks will not have harmful effects on
 conformant presentation engines and will help less conformant engines to
 achieve the desired presentation.</li>
 </ul>

 </body>
 </html>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
	<html>
	<body bgcolor="white">

	This package provides classes for processing bidirectional
	text with a special structure to ensure its proper presentation.
	<p>
	There are various types of structured text. Each type should
	be handled by a specific <i>type handler</i>. A number of
	standard type handlers are supplied with this package.

	<h2>Introduction to Structured Text</h2>
	<p>
	Bidirectional text offers interesting challenges to presentation systems.
	For plain text, the Unicode Bidirectional Algorithm
	(<a href="http://www.unicode.org/reports/tr9/">UBA</a>)
	generally specifies satisfactorily how to reorder bidirectional text for
	display. This algorithm is implemented in many presentation and operating
	systems, like Java/Swing, Windows, Linux.
	</p><p>
	However, all bidirectional text is not necessarily plain text. There
	are also instances of text structured to follow a given syntax, which
	should be reflected in the display order. The general algorithm, which
	has no awareness of these special cases, often gives incorrect results
	when displaying such structured text.
	</p><p>
	The general idea in handling structured text in this package is to add
	directional formatting characters at proper locations in the text to
	supplement the standard algorithm, so that the final result is correctly
	displayed using the UBA.
	</p><p>
	A class which handles structured text is thus essentially a
	transformation engine which receives text without directional formatting
	characters as input and produces as output the same text with added
	directional formatting characters, hopefully in the minimum quantity
	which is sufficient to ensure correct display, considering the type of
	structured text involved.
	</p><p>
	In this package, text without directional formatting characters is
	called <b><i>lean</i></b> text while the text with added directional
	formatting characters is called <b><i>full</i></b> text.
	</p><p>
	The class
	<a href="StructuredTextProcessor.html"><b>StructuredTextProcessor</b></a>
	is the main tool for processing structured text. It facilitates
	handling several types of structured text, each type being handled
	by a specific
	<a href="./custom/StructuredTextTypeHandler.html">
	<b><i>type handler</i></b></a> :</p>
	<ul>
	<li>comma delimited list</li>
	<li>e-mail address</li>
	<li>directory and file path</li>
	<li>Java code</li>
	<li>regular expression</li>
	<li>SQL statements</li>
	<li>compound name (xxx_yy_zzzz)</li>
	<li>URL</li>
	<li>Xpath</li>
	</ul>
	<p>
	For each of these types, an identifier is defined in
	<a href="StructuredTextTypeHandlerFactory.html">
	<b><i>StructuredTextTypeHandlerFactory</i></b></a> :</p>
	<p>
	These identifiers can be used as argument in some methods of
	<b>StructuredTextProcessor</b> to specify the type of handler to apply.
	</p><p>
	The classes included in this package are intended for users who
	need to process structured text in the most straightforward
	manner, when the following conditions are satisfied:
	<ul>
	<li>There exists an appropriate handler for the type of the
	structured text.</li>
	<li>There is no need to specify non-default conditions related
	to the <a href="advanced/StructuredTextEnvironment.html">
	environment</a>.</li>
	<li>The only operations needed are to transform <i>lean</i> text
	into <i>full</i> text or vice versa.</li>
	<li>There is no interdependence between the processing of a
	given string and the processing of preceding or
	succeeding strings.</li>
	</ul>
	<p>
	When their needs go beyond the conditions above,
	users can use classes in the
	<a href="advanced/package-summary.html">
	org.eclipse.equinox.bidi.advanced</a>}package.
	</p><p>
	Developers who want to develop new handlers to support types of
	structured text not currently supported can use components
	of the package <a href="custom/package-summary.html">
	org.eclipse.equinox.bidi.custom</a>.
	The source code of packages org.eclipse.equinox.bidi.* can serve as example of
	how to develop processors for currently unsupported types of structured text.
	</p><p>
	However, users wishing to process the currently supported types of structured
	text typically don't need to deal with the org.eclipse.equinox.bidi.custom
	package.
	</p>

	<h2>Abbreviations used in the documentation of this package</h2>

	<dl>
	<dt><b>UBA</b><dd>Unicode Bidirectional Algorithm

	<dt><b>Bidi</b><dd>Bidirectional

	<dt><b>GUI</b><dd>Graphical User Interface

	<dt><b>UI</b><dd>User Interface

	<dt><b>LTR</b><dd>Left to Right

	<dt><b>RTL</b><dd>Right to Left

	<dt><b>LRM</b><dd>Left-to-Right Mark

	<dt><b>RLM</b><dd>Right-to-Left Mark

	<dt><b>LRE</b><dd>Left-to-Right Embedding

	<dt><b>RLE</b><dd>Right-to-Left Embedding

	<dt><b>PDF</b><dd>Pop Directional Formatting
	</dl>

	<p> </p>

	<h2>Known Limitations</h2>

	<p>The proposed solution is making extensive usage of LRM, RLM, LRE, RLE
	and PDF directional controls which are invisible but affect the way bidi
	text is displayed. The following related key points merit special
	attention:</p>

	<ul>
	<li>Implementations of the UBA on various platforms (e.g., Windows and
	Linux) are very similar but nevertheless have known differences. Those
	differences are minor and will not have a visible effect in most cases.
	However there might be cases in which the same bidi text on two
	platforms will look different. These differences will surface in Java
	applications when they use the platform visual components for their UI
	(e.g., AWT, SWT).</li>

	<li>It is assumed that the presentation engine supports LRE, RLE and
	PDF directional formatting characters.</li>

	<li>Because some presentation engines are not strictly conformant to the
	UBA, the implementation of structured text in this package adds LRM
	or RLM characters in association with LRE, RLE or PDF in cases where
	this would not be needed if the presentation engine was fully conformant
	to the UBA. Such added marks will not have harmful effects on
	conformant presentation engines and will help less conformant engines to
	achieve the desired presentation.</li>
	</ul>

	</body>
	</html>