1 files changed, 180 insertions, 6 deletions
diff --git a/layout/base/nsBidi.h b/layout/base/nsBidi.h
index c7c367092..731bc7116 100644
--- a/layout/base/nsBidi.h
+++ b/layout/base/nsBidi.h
@@ -7,10 +7,184 @@
 #ifndef nsBidi_h__
 #define nsBidi_h__
 
-#if ENABLE_INTL_API
-#include "nsBidi_ICU.h"
-#else
-#include "nsBidi_noICU.h"
-#endif
+#include "unicode/ubidi.h"
+#include "nsIFrame.h" // for nsBidiLevel/nsBidiDirection declarations
 
-#endif // _nsBidi_h_
+// nsBidi implemented as a simple wrapper around the bidi reordering engine
+// from ICU.
+// We could eliminate this and let callers use the ICU functions directly
+// once we no longer care about building without ICU available.
+
+class nsBidi
+{
+public:
+  /** @brief Default constructor.
+   *
+   * The nsBidi object is initially empty. It is assigned
+   * the Bidi properties of a paragraph by <code>SetPara()</code>.
+   */
+  explicit nsBidi();
+
+  /** @brief Destructor. */
+  virtual ~nsBidi();
+
+
+  /**
+   * Perform the Unicode Bidi algorithm.
+   *
+   * @param aText is a pointer to the single-paragraph text that the
+   *      Bidi algorithm will be performed on
+   *      (step (P1) of the algorithm is performed externally).
+   *      <strong>The text must be (at least) <code>aLength</code> long.</strong>
+   *
+   * @param aLength is the length of the text; if <code>aLength==-1</code> then
+   *      the text must be zero-terminated.
+   *
+   * @param aParaLevel specifies the default level for the paragraph;
+   *      it is typically 0 (LTR) or 1 (RTL).
+   *      If the function shall determine the paragraph level from the text,
+   *      then <code>aParaLevel</code> can be set to
+   *      either <code>NSBIDI_DEFAULT_LTR</code>
+   *      or <code>NSBIDI_DEFAULT_RTL</code>;
+   *      if there is no strongly typed character, then
+   *      the desired default is used (0 for LTR or 1 for RTL).
+   *      Any other value between 0 and <code>NSBIDI_MAX_EXPLICIT_LEVEL</code>
+   *      is also valid, with odd levels indicating RTL.
+   */
+  nsresult SetPara(const char16_t *aText, int32_t aLength,
+                   nsBidiLevel aParaLevel);
+
+  /**
+   * Get the directionality of the text.
+   *
+   * @param aDirection receives a <code>NSBIDI_XXX</code> value that indicates
+   *       if the entire text represented by this object is unidirectional,
+   *       and which direction, or if it is mixed-directional.
+   *
+   * @see nsBidiDirection
+   */
+  nsresult GetDirection(nsBidiDirection* aDirection);
+
+  /**
+   * Get the paragraph level of the text.
+   *
+   * @param aParaLevel receives a <code>NSBIDI_XXX</code> value indicating
+   *                   the paragraph level
+   *
+   * @see nsBidiLevel
+   */
+  nsresult GetParaLevel(nsBidiLevel* aParaLevel);
+
+  /**
+   * Get a logical run.
+   * This function returns information about a run and is used
+   * to retrieve runs in logical order.<p>
+   * This is especially useful for line-breaking on a paragraph.
+   *
+   * @param aLogicalStart is the first character of the run.
+   *
+   * @param aLogicalLimit will receive the limit of the run.
+   *      The l-value that you point to here may be the
+   *      same expression (variable) as the one for
+   *      <code>aLogicalStart</code>.
+   *      This pointer can be <code>nullptr</code> if this
+   *      value is not necessary.
+   *
+   * @param aLevel will receive the level of the run.
+   *      This pointer can be <code>nullptr</code> if this
+   *      value is not necessary.
+   */
+  nsresult GetLogicalRun(int32_t aLogicalStart, int32_t* aLogicalLimit,
+                         nsBidiLevel* aLevel);
+
+  /**
+   * Get the number of runs.
+   * This function may invoke the actual reordering on the
+   * <code>nsBidi</code> object, after <code>SetPara</code>
+   * may have resolved only the levels of the text. Therefore,
+   * <code>CountRuns</code> may have to allocate memory,
+   * and may fail doing so.
+   *
+   * @param aRunCount will receive the number of runs.
+   */
+  nsresult CountRuns(int32_t* aRunCount);
+
+  /**
+   * Get one run's logical start, length, and directionality,
+   * which can be 0 for LTR or 1 for RTL.
+   * In an RTL run, the character at the logical start is
+   * visually on the right of the displayed run.
+   * The length is the number of characters in the run.<p>
+   * <code>CountRuns</code> should be called
+   * before the runs are retrieved.
+   *
+   * @param aRunIndex is the number of the run in visual order, in the
+   *      range <code>[0..CountRuns-1]</code>.
+   *
+   * @param aLogicalStart is the first logical character index in the text.
+   *      The pointer may be <code>nullptr</code> if this index is not needed.
+   *
+   * @param aLength is the number of characters (at least one) in the run.
+   *      The pointer may be <code>nullptr</code> if this is not needed.
+   *
+   * @param aDirection will receive the directionality of the run,
+   *       <code>NSBIDI_LTR==0</code> or <code>NSBIDI_RTL==1</code>,
+   *       never <code>NSBIDI_MIXED</code>.
+   *
+   * @see CountRuns<p>
+   *
+   * Example:
+   * @code
+   *  int32_t i, count, logicalStart, visualIndex=0, length;
+   *  nsBidiDirection dir;
+   *  pBidi->CountRuns(&count);
+   *  for(i=0; i<count; ++i) {
+   *    pBidi->GetVisualRun(i, &logicalStart, &length, &dir);
+   *    if(NSBIDI_LTR==dir) {
+   *      do { // LTR
+   *        show_char(text[logicalStart++], visualIndex++);
+   *      } while(--length>0);
+   *    } else {
+   *      logicalStart+=length;  // logicalLimit
+   *      do { // RTL
+   *        show_char(text[--logicalStart], visualIndex++);
+   *      } while(--length>0);
+   *    }
+   *  }
+   * @endcode
+   *
+   * Note that in right-to-left runs, code like this places
+   * modifier letters before base characters and second surrogates
+   * before first ones.
+   */
+  nsresult GetVisualRun(int32_t aRunIndex, int32_t* aLogicalStart,
+                        int32_t* aLength, nsBidiDirection* aDirection);
+
+  /**
+   * This is a convenience function that does not use a nsBidi object.
+   * It is intended to be used for when an application has determined the levels
+   * of objects (character sequences) and just needs to have them reordered (L2).
+   * This is equivalent to using <code>GetVisualMap</code> on a
+   * <code>nsBidi</code> object.
+   *
+   * @param aLevels is an array with <code>aLength</code> levels that have been
+   *      determined by the application.
+   *
+   * @param aLength is the number of levels in the array, or, semantically,
+   *      the number of objects to be reordered.
+   *      It must be <code>aLength>0</code>.
+   *
+   * @param aIndexMap is a pointer to an array of <code>aLength</code>
+   *      indexes which will reflect the reordering of the characters.
+   *      The array does not need to be initialized.<p>
+   *      The index map will result in
+   *        <code>aIndexMap[aVisualIndex]==aLogicalIndex</code>.
+   */
+  static nsresult ReorderVisual(const nsBidiLevel* aLevels, int32_t aLength,
+                                int32_t* aIndexMap);
+
+protected:
+  UBiDi* mBiDi;
+};
+
+#endif // nsBidi_h__