Bug 1431025 - Use encoding_rs::mem::is_utf16_bidi() as the implementation of HasRTLChars(). r=jfkthame

MozReview-Commit-ID: KnaI7wIndVf

--HG--
extra : rebase_source : 6a00c8fc140c1cf070e8fa668e7e099f98621820

dom/base/nsGenericDOMDataNode.cpp

@@ -349,7 +349,7 @@ nsGenericDOMDataNode::SetTextInternal(uint32_t aOffset, uint32_t aCount,
     if (aLength) {
       to.Append(aBuffer, aLength);
       if (!bidi && (!document || !document->GetBidiEnabled())) {
-        bidi = HasRTLChars(aBuffer, aLength);
+        bidi = HasRTLChars(MakeSpan(aBuffer, aLength));
       }
     }
     if (endOffset != textLength) {

dom/base/nsTextFragment.cpp

@@ -508,7 +508,7 @@ void
 nsTextFragment::UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength)
 {
   if (mState.mIs2b && !mState.mIsBidi) {
-    if (HasRTLChars(aBuffer, aLength)) {
+    if (HasRTLChars(MakeSpan(aBuffer, aLength))) {
       mState.mIsBidi = true;
     }
   }

intl/encoding_glue/src/lib.rs

@@ -583,3 +583,10 @@ fn checked_min(one: Option<usize>, other: Option<usize>) -> Option<usize> {
         other
     }
 }
+
+// Bindings for encoding_rs::mem. These may move to a separate crate in the future.
+
+#[no_mangle]
+pub unsafe extern "C" fn encoding_mem_is_utf16_bidi(buffer: *const u16, len: usize) -> bool {
+    encoding_rs::mem::is_utf16_bidi(::std::slice::from_raw_parts(buffer, len))
+}

intl/unicharutil/util/nsBidiUtils.cpp

@@ -85,21 +85,3 @@ nsresult HandleNumbers(char16_t* aBuffer, uint32_t aSize, uint32_t aNumFlag)
   }
   return NS_OK;
 }
-
-bool HasRTLChars(const char16_t* aText, uint32_t aLength)
-{
-  // This is used to determine whether a string has right-to-left characters
-  // that mean it will require bidi processing.
-  const char16_t* cp = aText;
-  const char16_t* end = cp + aLength;
-  while (cp < end) {
-    char16_t ch = *cp++;
-    if (ch < mozilla::kMinRTLChar) {
-      continue;
-    }
-    if (UTF16_CODE_UNIT_IS_BIDI(ch) || IsBidiControlRTL(ch)) {
-      return true;
-    }
-  }
-  return false;
-}

intl/unicharutil/util/nsBidiUtils.h

@@ -8,6 +8,14 @@
 
 #include "nsString.h"
 
+extern "C" {
+
+bool
+encoding_mem_is_utf16_bidi(char16_t const* buffer,
+                           size_t len);
+
+}
+
    /**
     *  Read ftp://ftp.unicode.org/Public/UNIDATA/ReadMe-Latest.txt
     *  section BIDIRECTIONAL PROPERTIES
@@ -125,12 +133,12 @@ typedef enum nsCharType nsCharType;
 #define PDI_CHAR 0x2069
 
 #define ALM_CHAR 0x061C
-   inline bool IsBidiControl(uint32_t aChar) {
-     return ((LRE_CHAR <= aChar && aChar <= RLO_CHAR) ||
-             (LRI_CHAR <= aChar && aChar <= PDI_CHAR) ||
-             (aChar == ALM_CHAR) ||
-             (aChar & 0xfffffe) == LRM_CHAR);
-   }
+  inline bool IsBidiControl(uint32_t aChar) {
+    return ((LRE_CHAR <= aChar && aChar <= RLO_CHAR) ||
+            (LRI_CHAR <= aChar && aChar <= PDI_CHAR) ||
+            (aChar == ALM_CHAR) ||
+            (aChar & 0xfffffe) == LRM_CHAR);
+  }
 
   /**
    * Give a UTF-32 codepoint
@@ -138,26 +146,23 @@ typedef enum nsCharType nsCharType;
    * in RTL directionality and therefore needs to trigger bidi resolution;
    * return false otherwise.
    */
-   inline bool IsBidiControlRTL(uint32_t aChar) {
-     return aChar == RLM_CHAR ||
-            aChar == RLE_CHAR ||
-            aChar == RLO_CHAR ||
-            aChar == RLI_CHAR ||
-            aChar == ALM_CHAR;
-   }
+  inline bool IsBidiControlRTL(uint32_t aChar) {
+    return aChar == RLM_CHAR ||
+           aChar == RLE_CHAR ||
+           aChar == RLO_CHAR ||
+           aChar == RLI_CHAR ||
+           aChar == ALM_CHAR;
+  }
 
   /**
-   * Give a 16-bit (UTF-16) text buffer and length
+   * Give a 16-bit (UTF-16) text buffer
    * @return true if the string contains right-to-left characters
    */
-   bool HasRTLChars(const char16_t* aText, uint32_t aLength);
-
-  /**
-   * Convenience function to call the above on an nsAString.
-   */
-   inline bool HasRTLChars(const nsAString& aString) {
-     return HasRTLChars(aString.BeginReading(), aString.Length());
-   }
+  inline bool HasRTLChars(mozilla::Span<const char16_t> aBuffer) {
+    // Span ensures we never pass a nullptr to Rust--even if the
+    // length of the buffer is zero.
+    return encoding_mem_is_utf16_bidi(aBuffer.Elements(), aBuffer.Length());
+  }
 
 // These values are shared with Preferences dialog
 //  ------------------

layout/base/nsBidiPresUtils.cpp

@@ -1333,7 +1333,7 @@ nsBidiPresUtils::ChildListMayRequireBidi(nsIFrame*    aFirstChild,
         if (content != *aCurrContent) {
           *aCurrContent = content;
           const nsTextFragment* txt = content->GetText();
-          if (txt->Is2b() && HasRTLChars(txt->Get2b(), txt->GetLength())) {
+          if (txt->Is2b() && HasRTLChars(MakeSpan(txt->Get2b(), txt->GetLength()))) {
             return true;
           }
         }