[libc] utf8 to 32 CharacterConverter

libc/src/__support/wchar/character_converter.cpp

@@ -22,13 +22,64 @@ bool CharacterConverter::isComplete() {
   return state->bytes_processed == state->total_bytes;
 }
 
-int CharacterConverter::push(char8_t utf8_byte) {}
-
-int CharacterConverter::push(char32_t utf32) {}
-
-utf_ret<char8_t> CharacterConverter::pop_utf8() {}
+int CharacterConverter::push(char8_t utf8_byte) {
+  // Checking the first byte if first push
+  if (state->bytes_processed == 0 && state->total_bytes == 0) {
+    // 1 byte total
+    if ((utf8_byte & 128) == 0) {
+      state->total_bytes = 1;
+      state->bytes_processed = 1;
+      state->partial = static_cast<char32_t>(utf8_byte);
+      return 0;
+    }
+    // 2 bytes total
+    else if ((utf8_byte & 0xE0) == 0xC0) {
+      state->total_bytes = 2;
+      state->bytes_processed = 1;
+      utf8_byte &= 0x1F;
+      state->partial = static_cast<char32_t>(utf8_byte);
+      return 0;
+    }
+    // 3 bytes total
+    else if ((utf8_byte & 0xF0) == 0xE0) {
+      state->total_bytes = 3;
+      state->bytes_processed = 1;
+      utf8_byte &= 0x0F;
+      state->partial = static_cast<char32_t>(utf8_byte);
+      return 0;
+    }
+    // 4 bytes total
+    else if ((utf8_byte & 0xF8) == 0xF0) {
+      state->total_bytes = 4;
+      state->bytes_processed = 1;
+      utf8_byte &= 0x07;
+      state->partial = static_cast<char32_t>(utf8_byte);
+      return 0;
+    }
+    // Invalid
+    else {
+      state->bytes_processed++;
+      return -1;
+    }
+  }
+  // Any subsequent push
+  if ((utf8_byte & 0xC0) == 0x80) {
+    state->partial = state->partial << 6;
+    char32_t byte = utf8_byte & 0x3F;
+    state->partial |= byte;
+    state->bytes_processed++;
+    return 0;
+  }
+  state->bytes_processed++;
+  return -1;
+}
 
-utf_ret<char32_t> CharacterConverter::pop_utf32() {}
+utf_ret<char32_t> CharacterConverter::pop_utf32() {
+  utf_ret<char32_t> utf32;
+  utf32.error = 0;
+  utf32.out = state->partial;
+  return utf32;
+}
 
 } // namespace internal
 } // namespace LIBC_NAMESPACE_DECL

libc/test/src/__support/CMakeLists.txt

@@ -275,3 +275,8 @@ add_subdirectory(fixed_point)
 add_subdirectory(HashTable)
 add_subdirectory(time)
 add_subdirectory(threads)
+# Requires access to uchar header which is not on MacOS
+# Cannot currently build this on MacOS in overlay mode
+if(NOT(LIBC_TARGET_OS_IS_DARWIN))
+  add_subdirectory(wchar)
+endif()

libc/test/src/__support/wchar/CMakeLists.txt

@@ -0,0 +1,11 @@
+add_custom_target(libc-support-wchar-tests)
+
+add_libc_test(
+  utf8_to_32_test 
+  SUITE
+    libc-support-tests
+  SRCS
+    utf8_to_32_test.cpp 
+  DEPENDS
+    libc.src.__support.wchar.character_converter
+)

libc/test/src/__support/wchar/utf8_to_32_test.cpp

@@ -0,0 +1,125 @@
+//===-- Unittests for character_converter utf8->3 -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/wchar/character_converter.h"
+#include "src/__support/wchar/mbstate.h"
+#include "src/__support/wchar/utf_ret.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, OneByte) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  char ch = 'A';
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  int err = char_conv.push(static_cast<char8_t>(ch));
+  LIBC_NAMESPACE::internal::utf_ret<char32_t> wch = char_conv.pop_utf32();
+
+  EXPECT_EQ(err, 0);
+  EXPECT_EQ(wch.error, 0);
+  EXPECT_EQ(static_cast<int>(wch.out), 65);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, TwoBytes) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char *ch = "Ž"; // hex 0xC2, 0x8E
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  char_conv.push(static_cast<char8_t>(ch[0]));
+  char_conv.push(static_cast<char8_t>(ch[1]));
+  LIBC_NAMESPACE::internal::utf_ret<char32_t> wch = char_conv.pop_utf32();
+
+  ASSERT_EQ(wch.error, 0);
+  ASSERT_EQ(static_cast<int>(wch.out), 142);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, ThreeBytes) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char *ch = "∑"; // hex 0xE2, 0x88, 0x91
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  char_conv.push(static_cast<char8_t>(ch[0]));
+  char_conv.push(static_cast<char8_t>(ch[1]));
+  char_conv.push(static_cast<char8_t>(ch[2]));
+  LIBC_NAMESPACE::internal::utf_ret<char32_t> wch = char_conv.pop_utf32();
+
+  ASSERT_EQ(wch.error, 0);
+  ASSERT_EQ(static_cast<int>(wch.out), 8721);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, FourBytes) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char *ch = "🤡"; // hex 0xF0, 0x9F, 0xA4, 0xA1
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  char_conv.push(static_cast<char8_t>(ch[0]));
+  char_conv.push(static_cast<char8_t>(ch[1]));
+  char_conv.push(static_cast<char8_t>(ch[2]));
+  char_conv.push(static_cast<char8_t>(ch[3]));
+  LIBC_NAMESPACE::internal::utf_ret<char32_t> wch = char_conv.pop_utf32();
+
+  ASSERT_EQ(wch.error, 0);
+  ASSERT_EQ(static_cast<int>(wch.out), 129313);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, InvalidByte) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char ch = static_cast<char>(0x80); // invalid starting bit sequence
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  int err = char_conv.push(static_cast<char8_t>(ch));
+
+  ASSERT_EQ(err, -1);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, InvalidMultiByte) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char ch[4] = {static_cast<char>(0x80), static_cast<char>(0x00),
+                      static_cast<char>(0x00),
+                      static_cast<char>(0x00)}; // All bytes are invalid
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  int err = char_conv.push(static_cast<char8_t>(ch[0]));
+  ASSERT_EQ(err, -1);
+  err = char_conv.push(static_cast<char8_t>(ch[1]));
+  ASSERT_EQ(err, -1);
+  err = char_conv.push(static_cast<char8_t>(ch[2]));
+  ASSERT_EQ(err, -1);
+  err = char_conv.push(static_cast<char8_t>(ch[3]));
+  ASSERT_EQ(err, -1);
+}
+
+TEST(LlvmLibcCharacterConverterUTF8To32Test, InvalidMiddleByte) {
+  LIBC_NAMESPACE::internal::mbstate state;
+  state.bytes_processed = 0;
+  state.total_bytes = 0;
+  const char ch[4] = {static_cast<char>(0xF1), static_cast<char>(0xC0),
+                      static_cast<char>(0x80),
+                      static_cast<char>(0x80)}; // invalid second byte
+
+  LIBC_NAMESPACE::internal::CharacterConverter char_conv(&state);
+  int err = char_conv.push(static_cast<char8_t>(ch[0]));
+  ASSERT_EQ(err, 0);
+  err = char_conv.push(static_cast<char8_t>(ch[1]));
+  ASSERT_EQ(err, -1);
+  err = char_conv.push(static_cast<char8_t>(ch[2]));
+  ASSERT_EQ(err, 0);
+  err = char_conv.push(static_cast<char8_t>(ch[3]));
+  ASSERT_EQ(err, 0);
+}