Provides methods to process bidirectional text with a specific structure.
Provides access to registered structured text handlers.
There are various types of structured text. Each type should be handled by a specific type handler. A number of standard type handlers are supplied with this package.
Bidirectional text offers interesting challenges to presentation systems. For plain text, the Unicode Bidirectional Algorithm (UBA) 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.
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.
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.
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.
In this package, text without directional formatting characters is called lean text while the text with added directional formatting characters is called full text.
For each of these types, an identifier is defined in StructuredTextTypeHandlerFactory :These identifiers can be used as argument in some methods of StructuredTextProcessor to specify the type of handler to apply.
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:
When their needs go beyond the conditions above, users can use classes in the org.eclipse.equinox.bidi.advanced package.
Developers who want to develop new handlers to support types of structured text not currently supported can use components of the package org.eclipse.equinox.bidi.custom. 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.
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.
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:
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