com.google.gwt.i18n.shared

## Class BidiFormatter

- java.lang.Object
- - com.google.gwt.i18n.shared.BidiFormatterBase
  - - com.google.gwt.i18n.shared.BidiFormatter

-     public class BidiFormatter
      extends BidiFormatterBase

  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.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `(package private) static class` | `BidiFormatter.Factory`

    - ### Nested classes/interfaces inherited from class com.google.gwt.i18n.shared.BidiFormatterBase

      `BidiFormatterBase.Format`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `java.lang.String` | `dirAttr(java.lang.String str)` Like `dirAttr(String, boolean)`, but assumes `isHtml` is false.
    `java.lang.String` | `dirAttr(java.lang.String str, boolean isHtml)` Returns "dir=ltr" or "dir=rtl", depending on `str`'s estimated direction, if it is not the same as the context direction.
    `java.lang.String` | `endEdge()` Returns "left" for RTL context direction.
    `static BidiFormatter` | `getInstance(boolean rtlContext)` Factory for creating an instance of BidiFormatter given the context direction.
    `static BidiFormatter` | `getInstance(boolean rtlContext, boolean alwaysSpan)` Factory for creating an instance of BidiFormatter given the context direction and the desired span wrapping behavior (see below).
    `static BidiFormatter` | `getInstance(HasDirection.Direction contextDir)` Factory for creating an instance of BidiFormatter given the context direction.
    `static BidiFormatter` | `getInstance(HasDirection.Direction contextDir, boolean alwaysSpan)` Factory for creating an instance of BidiFormatter given the context direction and the desired span wrapping behavior (see below).
    `static BidiFormatter` | `getInstanceForCurrentLocale()` Factory for creating an instance of BidiFormatter whose context direction matches the current locale's direction.
    `static BidiFormatter` | `getInstanceForCurrentLocale(boolean alwaysSpan)` Factory for creating an instance of BidiFormatter whose context direction matches the current locale's direction, and given the desired span wrapping behavior (see below).
    `java.lang.String` | `knownDirAttr(HasDirection.Direction dir)` Returns "dir=ltr" or "dir=rtl", depending on the given direction, if it is not the same as the context direction.
    `java.lang.String` | `mark()` Returns the Unicode BiDi mark matching the context direction (LRM for LTR context direction, RLM for RTL context direction), or the empty string for default / unknown context direction.
    `java.lang.String` | `markAfter(java.lang.String str)` Like `markAfter(String, boolean)`, but assumes `isHtml` is false.
    `java.lang.String` | `markAfter(java.lang.String str, boolean isHtml)` Returns a Unicode BiDi mark matching the context direction (LRM or RLM) if either the direction or the exit direction of `str` is opposite to the context direction.
    `java.lang.String` | `spanWrap(java.lang.String str)` Like `spanWrap(String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
    `java.lang.String` | `spanWrap(java.lang.String str, boolean isHtml)` Like `spanWrap(String, boolean, boolean)`, but assumes `dirReset` is true.
    `java.lang.String` | `spanWrap(java.lang.String str, boolean isHtml, boolean dirReset)` Formats a string of unknown direction for use in HTML output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.
    `java.lang.String` | `spanWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str)` Like `spanWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
    `java.lang.String` | `spanWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str, boolean isHtml)` Like `spanWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `dirReset` is true.
    `java.lang.String` | `spanWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str, boolean isHtml, boolean dirReset)` Formats a string of given direction for use in HTML output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.
    `java.lang.String` | `startEdge()` Returns "right" for RTL context direction.
    `java.lang.String` | `unicodeWrap(java.lang.String str)` Like `unicodeWrap(String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
    `java.lang.String` | `unicodeWrap(java.lang.String str, boolean isHtml)` Like `unicodeWrap(String, boolean, boolean)`, but assumes `dirReset` is true.
    `java.lang.String` | `unicodeWrap(java.lang.String str, boolean isHtml, boolean dirReset)` Formats a string of unknown direction for use in plain-text output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.
    `java.lang.String` | `unicodeWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str)` Like `unicodeWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
    `java.lang.String` | `unicodeWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str, boolean isHtml)` Like `unicodeWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `dirReset` is true.
    `java.lang.String` | `unicodeWrapWithKnownDir(HasDirection.Direction dir, java.lang.String str, boolean isHtml, boolean dirReset)` Formats a string of given direction for use in plain-text output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.

    - ### Methods inherited from class com.google.gwt.i18n.shared.BidiFormatterBase

      `dirAttrBase, endEdgeBase, estimateDirection, estimateDirection, getAlwaysSpan, getContextDir, isRtlContext, knownDirAttrBase, markAfterBase, markBase, spanWrapBase, spanWrapWithKnownDirBase, startEdgeBase, unicodeWrapBase, unicodeWrapWithKnownDirBase`

    - ### Methods inherited from class java.lang.Object

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

- - ### Method Detail

    - #### getInstance

          public static BidiFormatter getInstance(boolean rtlContext)

      Factory for creating an instance of BidiFormatter given the context direction. The default behavior of `spanWrap(java.lang.String)` and its variations is set to avoid span wrapping unless it's necessary ('dir' attribute needs to be set).
      Parameters:
        `rtlContext` - Whether the context direction is RTL. In one simple use case, the context direction would simply be the locale direction, which can be retrieved using `LocaleInfo.getCurrentLocale().isRTL()`

    - #### getInstance

          public static BidiFormatter getInstance(boolean rtlContext,
                                  boolean alwaysSpan)

      Factory for creating an instance of BidiFormatter given the context direction and the desired span wrapping behavior (see below).
      Parameters:
        `rtlContext` - Whether the context direction is RTL. See an example of a simple use case at `getInstance(boolean)`
        `alwaysSpan` - Whether `spanWrap(java.lang.String)` (and its variations) should always use a 'span' tag, even when the input direction is neutral or matches the context, so that the DOM structure of the output does not depend on the combination of directions

    - #### getInstance

          public static BidiFormatter getInstance(HasDirection.Direction contextDir)

      Factory for creating an instance of BidiFormatter given the context direction. The default behavior of `spanWrap(java.lang.String)` and its variations is set to avoid span wrapping unless it's necessary ('dir' attribute needs to be set).
      Parameters:
        `contextDir` - The context direction. See an example of a simple use case at `getInstance(boolean)`. Note: Direction.DEFAULT indicates unknown context direction. Try not to use it, since it is impossible to reset the direction back to the context when it is unknown

    - #### getInstance

          public static BidiFormatter getInstance(HasDirection.Direction contextDir,
                                  boolean alwaysSpan)

      Factory for creating an instance of BidiFormatter given the context direction and the desired span wrapping behavior (see below).
      Parameters:
        `contextDir` - The context direction. See an example of a simple use case at `getInstance(boolean)`. Note: Direction.DEFAULT indicates unknown context direction. Try not to use it, since it is impossible to reset the direction back to the context when it is unknown
        `alwaysSpan` - Whether `spanWrap(java.lang.String)` (and its variations) should always use a 'span' tag, even when the input direction is neutral or matches the context, so that the DOM structure of the output does not depend on the combination of directions

    - #### getInstanceForCurrentLocale

          public static BidiFormatter getInstanceForCurrentLocale()

      Factory for creating an instance of BidiFormatter whose context direction matches the current locale's direction. The default behavior of `spanWrap(java.lang.String)` and its variations is set to avoid span wrapping unless it's necessary ('dir' attribute needs to be set).

    - #### getInstanceForCurrentLocale

          public static BidiFormatter getInstanceForCurrentLocale(boolean alwaysSpan)

      Factory for creating an instance of BidiFormatter whose context direction matches the current locale's direction, and given the desired span wrapping behavior (see below).
      Parameters:
        `alwaysSpan` - Whether `spanWrap(java.lang.String)` (and its variations) should always use a 'span' tag, even when the input direction is neutral or matches the context, so that the DOM structure of the output does not depend on the combination of directions

    - #### dirAttr

          public java.lang.String dirAttr(java.lang.String str)

      Like `dirAttr(String, boolean)`, but assumes `isHtml` is false.
      Parameters:
        `str` - String whose direction is to be estimated
      Returns:
        "dir=rtl" for RTL text in non-RTL context; "dir=ltr" for LTR text in non-LTR context; else, the empty string.

    - #### dirAttr

          public java.lang.String dirAttr(java.lang.String str,
                                 boolean isHtml)

      Returns "dir=ltr" or "dir=rtl", depending on `str`'s estimated direction, if it is not the same as the context direction. Otherwise, returns the empty string.
      Parameters:
        `str` - String whose direction is to be estimated
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        "dir=rtl" for RTL text in non-RTL context; "dir=ltr" for LTR text in non-LTR context; else, the empty string.

    - #### endEdge

          public java.lang.String endEdge()

      Returns "left" for RTL context direction. Otherwise (LTR or default / unknown context direction) returns "right".

    - #### knownDirAttr

          public java.lang.String knownDirAttr(HasDirection.Direction dir)

      Returns "dir=ltr" or "dir=rtl", depending on the given direction, if it is not the same as the context direction. Otherwise, returns the empty string.
      Parameters:
        `dir` - Given direction
      Returns:
        "dir=rtl" for RTL text in non-RTL context; "dir=ltr" for LTR text in non-LTR context; else, the empty string.

    - #### mark

          public java.lang.String mark()

      Returns the Unicode BiDi mark matching the context direction (LRM for LTR context direction, RLM for RTL context direction), or the empty string for default / unknown context direction.

    - #### markAfter

          public java.lang.String markAfter(java.lang.String str)

      Like `markAfter(String, boolean)`, but assumes `isHtml` is false.
      Parameters:
        `str` - String after which the mark may need to appear
      Returns:
        LRM for RTL text in LTR context; RLM for LTR text in RTL context; else, the empty string.

    - #### markAfter

          public java.lang.String markAfter(java.lang.String str,
                                   boolean isHtml)

      Returns a Unicode BiDi mark matching the context direction (LRM or RLM) if either the direction or the exit direction of `str` is opposite to the context direction. Otherwise returns the empty string.
      Parameters:
        `str` - String after which the mark may need to appear
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        LRM for RTL text in LTR context; RLM for LTR text in RTL context; else, the empty string.

    - #### spanWrap

          public java.lang.String spanWrap(java.lang.String str)

      Like `spanWrap(String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
      Parameters:
        `str` - The input string
      Returns:
        Input string after applying the above processing.

    - #### spanWrap

          public java.lang.String spanWrap(java.lang.String str,
                                  boolean isHtml)

      Like `spanWrap(String, boolean, boolean)`, but assumes `dirReset` is true.
      Parameters:
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        Input string after applying the above processing.

    - #### spanWrap

          public java.lang.String spanWrap(java.lang.String str,
                                  boolean isHtml,
                                  boolean dirReset)

      Formats a string of unknown direction for use in HTML output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.

      The algorithm: estimates the direction of input argument `str`. In case its direction doesn't match the context direction, wraps it with a 'span' tag and adds a "dir" attribute (either 'dir=rtl' or 'dir=ltr').

      If `setAlwaysSpan(true)` was used, the input is always wrapped with 'span', skipping just the dir attribute when it's not needed.

      If `dirReset`, and if the overall direction or the exit direction of `str` are opposite to the context direction, a trailing unicode BiDi mark matching the context direction is appended (LRM or RLM).

      If !`isHtml`, HTML-escapes `str` regardless of wrapping.

      Parameters:
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
        `dirReset` - Whether to append a trailing unicode bidi mark matching the context direction, when needed, to prevent the possible garbling of whatever may follow `str`
      Returns:
        Input string after applying the above processing.

    - #### spanWrapWithKnownDir

          public java.lang.String spanWrapWithKnownDir(HasDirection.Direction dir,
                                              java.lang.String str)

      Like `spanWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
      Returns:
        Input string after applying the above processing.

    - #### spanWrapWithKnownDir

          public java.lang.String spanWrapWithKnownDir(HasDirection.Direction dir,
                                              java.lang.String str,
                                              boolean isHtml)

      Like `spanWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `dirReset` is true.
      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        Input string after applying the above processing.

    - #### spanWrapWithKnownDir

          public java.lang.String spanWrapWithKnownDir(HasDirection.Direction dir,
                                              java.lang.String str,
                                              boolean isHtml,
                                              boolean dirReset)

      Formats a string of given direction for use in HTML output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it.

      The algorithm: estimates the direction of input argument `str`. In case its direction doesn't match the context direction, wraps it with a 'span' tag and adds a "dir" attribute (either 'dir=rtl' or 'dir=ltr').

      If `setAlwaysSpan(true)` was used, the input is always wrapped with 'span', skipping just the dir attribute when it's not needed.

      If `dirReset`, and if the overall direction or the exit direction of `str` are opposite to the context direction, a trailing unicode BiDi mark matching the context direction is appended (LRM or RLM).

      If !`isHtml`, HTML-escapes `str` regardless of wrapping.

      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
        `dirReset` - Whether to append a trailing unicode bidi mark matching the context direction, when needed, to prevent the possible garbling of whatever may follow `str`
      Returns:
        Input string after applying the above processing.

    - #### startEdge

          public java.lang.String startEdge()

      Returns "right" for RTL context direction. Otherwise (LTR or default / unknown context direction) returns "left".

    - #### unicodeWrap

          public java.lang.String unicodeWrap(java.lang.String str)

      Like `unicodeWrap(String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
      Parameters:
        `str` - The input string
      Returns:
        Input string after applying the above processing.

    - #### unicodeWrap

          public java.lang.String unicodeWrap(java.lang.String str,
                                     boolean isHtml)

      Like `unicodeWrap(String, boolean, boolean)`, but assumes `dirReset` is true.
      Parameters:
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        Input string after applying the above processing.

    - #### unicodeWrap

          public java.lang.String unicodeWrap(java.lang.String str,
                                     boolean isHtml,
                                     boolean dirReset)

      Formats a string of unknown direction for use in plain-text output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it. As opposed to `spanWrap(java.lang.String)`, this makes use of Unicode BiDi formatting characters. In HTML, its *only* valid use is inside of elements that do not allow mark-up, e.g. an 'option' tag.

      The algorithm: estimates the direction of input argument `str`. In case it doesn't match the context direction, wraps it with Unicode BiDi formatting characters: RLE+`str`+PDF for RTL text, or LRE+ `str`+PDF for LTR text.

      If `opt_dirReset`, and if the overall direction or the exit direction of `str` are opposite to the context direction, a trailing unicode BiDi mark matching the context direction is appended (LRM or RLM).

      Does *not* do HTML-escaping regardless of the value of `isHtml`.

      Parameters:
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
        `dirReset` - Whether to append a trailing unicode bidi mark matching the context direction, when needed, to prevent the possible garbling of whatever may follow `str`
      Returns:
        Input string after applying the above processing.

    - #### unicodeWrapWithKnownDir

          public java.lang.String unicodeWrapWithKnownDir(HasDirection.Direction dir,
                                                 java.lang.String str)

      Like `unicodeWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `isHtml` is false and `dirReset` is true.
      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
      Returns:
        Input string after applying the above processing.

    - #### unicodeWrapWithKnownDir

          public java.lang.String unicodeWrapWithKnownDir(HasDirection.Direction dir,
                                                 java.lang.String str,
                                                 boolean isHtml)

      Like `unicodeWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, String, boolean, boolean)`, but assumes `dirReset` is true.
      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
      Returns:
        Input string after applying the above processing.

    - #### unicodeWrapWithKnownDir

          public java.lang.String unicodeWrapWithKnownDir(HasDirection.Direction dir,
                                                 java.lang.String str,
                                                 boolean isHtml,
                                                 boolean dirReset)

      Formats a string of given direction for use in plain-text output of the context direction, so an opposite-direction string is neither garbled nor garbles what follows it. As opposed to `spanWrapWithKnownDir(com.google.gwt.i18n.client.HasDirection.Direction, java.lang.String)`, this makes use of unicode BiDi formatting characters. In HTML, its *only* valid use is inside of elements that do not allow mark-up, e.g. an 'option' tag.

      The algorithm: estimates the direction of input argument `str`. In case it doesn't match the context direction, wraps it with Unicode BiDi formatting characters: RLE+`str`+PDF for RTL text, or LRE+ `str`+PDF for LTR text.

      If `opt_dirReset`, and if the overall direction or the exit direction of `str` are opposite to the context direction, a trailing unicode BiDi mark matching the context direction is appended (LRM or RLM).

      Does *not* do HTML-escaping regardless of the value of `isHtml`.

      Parameters:
        `dir` - `str`'s direction
        `str` - The input string
        `isHtml` - Whether `str` is HTML / HTML-escaped
        `dirReset` - Whether to append a trailing unicode bidi mark matching the context direction, when needed, to prevent the possible garbling of whatever may follow `str`
      Returns:
        Input string after applying the above processing.