1 files changed, 102 insertions, 0 deletions
diff --git a/intl/unicharutil/util/is_combining_diacritic.py b/intl/unicharutil/util/is_combining_diacritic.py
new file mode 100644
index 0000000000..d8c3c4ba35
--- /dev/null
+++ b/intl/unicharutil/util/is_combining_diacritic.py
@@ -0,0 +1,102 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from unicodedata import combining
+
+UNICODE_LIMIT = 0x110000
+
+UNICODE_COMBINING_CLASS_NOT_REORDERED = 0
+UNICODE_COMBINING_CLASS_KANA_VOICING = 8
+UNICODE_COMBINING_CLASS_VIRAMA = 9
+
+
+# Keep this function in sync with IsCombiningDiacritic in nsUnicodeProperties.h.
+def is_combining_diacritic(char):
+    return combining(char) not in (
+        UNICODE_COMBINING_CLASS_NOT_REORDERED,
+        UNICODE_COMBINING_CLASS_KANA_VOICING,
+        UNICODE_COMBINING_CLASS_VIRAMA,
+        91,
+        129,
+        130,
+        132,
+    )
+
+
+# See gfxFontUtils.h for the SharedBitSet that we're creating a const instance of here.
+BLOCK_SIZE = 32
+BLOCK_SIZE_BITS = BLOCK_SIZE * 8
+
+
+def main(header):
+    blockIndex = []
+    blocks = []
+
+    # Figure out the contents of each 256-char block, and see if it is unique
+    # or can share an already-allocated block.
+    block = [0] * BLOCK_SIZE
+    byte = 0
+    bit = 0x01
+    for char in range(UNICODE_LIMIT):
+        if is_combining_diacritic(chr(char)):
+            block[byte] |= bit
+        bit <<= 1
+        if bit == 0x100:
+            bit = 0x01
+            byte += 1
+        if byte == BLOCK_SIZE:
+            found = False
+            for b in range(len(blocks)):
+                if block == blocks[b]:
+                    blockIndex.append(b)
+                    found = True
+                    break
+            if not found:
+                blockIndex.append(len(blocks))
+                blocks.append(block)
+            byte = 0
+            block = [0] * BLOCK_SIZE
+
+    # Strip trailing empty blocks from the index.
+    while blockIndex[len(blockIndex) - 1] == 0:
+        del blockIndex[len(blockIndex) - 1]
+
+    # Write the SharedBitSet as data in a C++ header file.
+    header.write("/* !GENERATED DATA -- DO NOT EDIT! */\n")
+    header.write("/* (see is_combining_diacritic.py) */\n")
+    header.write("\n")
+    header.write('#include "gfxFontUtils.h"\n')
+    header.write("\n")
+
+    header.write("typedef struct {\n")
+    header.write("  uint16_t mBlockIndexCount;\n")
+    header.write("  uint16_t mBlockCount;\n")
+    header.write("  uint16_t mBlockIndex[" + str(len(blockIndex)) + "];\n")
+    header.write("  uint8_t mBlockData[" + str(len(blocks) * BLOCK_SIZE) + "];\n")
+    header.write("} CombiningDiacriticsBitset_t;\n")
+    header.write("\n")
+
+    header.write(
+        "static const CombiningDiacriticsBitset_t COMBINING_DIACRITICS_BITSET_DATA = {\n"
+    )
+    header.write("  " + str(len(blockIndex)) + ",\n")
+    header.write("  " + str(len(blocks)) + ",\n")
+    header.write("  {\n")
+    for b in blockIndex:
+        header.write("    " + str(b) + ",\n")
+    header.write("  },\n")
+    header.write("  {\n")
+    for b in blocks:
+        header.write("    ")
+        for i in b:
+            header.write(str(i) + ",")
+        header.write("\n")
+    header.write("  },\n")
+    header.write("};\n")
+    header.write("\n")
+    header.write("static const SharedBitSet* sCombiningDiacriticsSet =\n")
+    header.write(
+        "    reinterpret_cast<const SharedBitSet*>(&COMBINING_DIACRITICS_BITSET_DATA);\n"
+    )
+    header.write("\n")