com.google.gwt.i18n.shared

Class BidiFormatter

java.lang.Object

com.google.gwt.i18n.shared.BidiFormatter

public static class BidiFormatter
extends Object

Utility class for formatting text for display in a potentially opposite-direction context without garbling. The direction of the context is set at formatter creation and the direction of the text can be either estimated or passed in when known. Provides the following functionality:

1. BiDi Wrapping: When text in one language is mixed into a document in another, opposite-direction language, e.g. when an English business name is embedded in a Hebrew web page, both the inserted string and the text following it may be displayed incorrectly unless the inserted string is explicitly separated from the surrounding text in a "wrapper" that declares its direction at the start and then resets it back at the end. This wrapping can be done in HTML mark-up (e.g. a 'span dir=rtl' tag) or - only in contexts where mark-up cannot be used - in Unicode BiDi formatting codes (LRE|RLE and PDF). Optionally, the mark-up can be inserted even when the direction is the same, in order to keep the DOM structure more stable. Providing such wrapping services is the basic purpose of the BiDi formatter.

2. Direction estimation: How does one know whether a string about to be inserted into surrounding text has the same direction? Well, in many cases, one knows that this must be the case when writing the code doing the insertion, e.g. when a localized message is inserted into a localized page. In such cases there is no need to involve the BiDi formatter at all. In some other cases, it need not be the same as the context, but is either constant (e.g. urls are always LTR) or otherwise known. In the remaining cases, e.g. when the string is user-entered or comes from a database, the language of the string (and thus its direction) is not known a priori, and must be estimated at run-time. The BiDi formatter can do this automatically.

3. Escaping: When wrapping plain text - i.e. text that is not already HTML or HTML-escaped - in HTML mark-up, the text must first be HTML-escaped to prevent XSS attacks and other nasty business. This of course is always true, but the escaping can not be done after the string has already been wrapped in mark-up, so the BiDi formatter also serves as a last chance and includes escaping services.

Thus, in a single call, the formatter will escape the input string as specified, determine its direction, and wrap it as necessary. It is then up to the caller to insert the return value in the output.

See Also:

Serialized Form

Method Summary

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString