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// Copyright (C) 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "icing/util/i18n-utils.h"
#include <cctype>
#include <string_view>
#include "icing/text_classifier/lib3/utils/base/statusor.h"
#include "icing/absl_ports/canonical_errors.h"
#include "icing/absl_ports/str_cat.h"
#include "icing/util/logging.h"
#include "unicode/uchar.h"
#include "unicode/umachine.h"
#include "unicode/ustring.h"
#include "unicode/utf16.h"
#include "unicode/utf8.h"
#include "unicode/utypes.h"
namespace icing {
namespace lib {
namespace i18n_utils {
namespace {
// All ASCII punctuation that's also in a Unicode Punctuation category
// (https://www.fileformat.info/info/unicode/category/index.htm). The set of
// characters that are regarded as punctuation is not the same for std::ispunct
// and u_ispunct.
const std::string ascii_icu_punctuation = "!\"#%&'*,./:;?@\\_-([{}])";
} // namespace
libtextclassifier3::StatusOr<std::string> Utf16ToUtf8(
const std::u16string& utf16_string) {
std::string utf8_string;
// Allocates the maximum possible UTF8 string length:
// 3 UTF-8 bytes per UTF16 code unit, plus one for the terminating NUL.
//
// NOTE: we need to call resize() but not reserve() because values can't be
// set at positions after length().
utf8_string.resize(utf16_string.length() * 3 + 1);
int result_length = 0;
UErrorCode status = U_ZERO_ERROR;
u_strToUTF8(&utf8_string[0], utf8_string.length(), &result_length,
utf16_string.data(), utf16_string.length(), &status);
// Corrects the length
utf8_string.resize(result_length);
if (U_FAILURE(status)) {
return absl_ports::InternalError("Failed to convert UTF16 string to UTF8");
}
return utf8_string;
}
libtextclassifier3::StatusOr<std::u16string> Utf8ToUtf16(
std::string_view utf8_string) {
std::u16string utf16_result;
// The UTF16 string won't be longer than its UTF8 format
//
// NOTE: we need to call resize() but not reserve() because values can't be
// set at positions after length().
utf16_result.resize(utf8_string.length());
int result_length = 0;
UErrorCode status = U_ZERO_ERROR;
u_strFromUTF8(&utf16_result[0], utf16_result.length(), &result_length,
utf8_string.data(), utf8_string.length(), &status);
// Corrects the length
utf16_result.resize(result_length);
if (U_FAILURE(status)) {
return absl_ports::InternalError(absl_ports::StrCat(
"Failed to convert UTF8 string '", utf8_string, "' to UTF16"));
}
return utf16_result;
}
UChar32 GetUChar32At(const char* data, int length, int position) {
UChar32 uchar32;
U8_NEXT_OR_FFFD(data, position, length, uchar32);
return uchar32;
}
void SafeTruncateUtf8(std::string* str, int truncate_to_length) {
if (str == nullptr || truncate_to_length >= str->length()) {
return;
}
str->resize(SafeTruncateUtf8Length(str->c_str(), truncate_to_length));
}
int SafeTruncateUtf8Length(const char* str, int desired_length) {
while (desired_length > 0) {
if (IsLeadUtf8Byte(str[desired_length])) {
break;
}
--desired_length;
}
return desired_length;
}
bool IsAscii(char c) { return U8_IS_SINGLE((uint8_t)c); }
bool IsAscii(UChar32 c) { return U8_LENGTH(c) == 1; }
bool IsAlphaNumeric(UChar32 c) { return u_isalnum(c); }
int GetUtf8Length(UChar32 c) { return U8_LENGTH(c); }
int GetUtf16Length(UChar32 c) { return U16_LENGTH(c); }
bool IsLeadUtf8Byte(char c) { return IsAscii(c) || U8_IS_LEAD((uint8_t)c); }
bool IsPunctuationAt(std::string_view input, int position, int* char_len_out) {
if (IsAscii(input[position])) {
if (char_len_out != nullptr) {
*char_len_out = 1;
}
return ascii_icu_punctuation.find(input[position]) != std::string::npos;
}
UChar32 c = GetUChar32At(input.data(), input.length(), position);
if (char_len_out != nullptr) {
*char_len_out = U8_LENGTH(c);
}
return u_ispunct(c);
}
bool IsWhitespaceAt(std::string_view input, int position) {
if (IsAscii(input[position])) {
return std::isspace(input[position]);
}
UChar32 c = GetUChar32At(input.data(), input.length(), position);
return u_isUWhiteSpace(c);
}
bool IsAlphabeticAt(std::string_view input, int position) {
if (IsAscii(input[position])) {
return std::isalpha(input[position]);
}
UChar32 c = GetUChar32At(input.data(), input.length(), position);
return u_isUAlphabetic(c);
}
void AppendUchar32ToUtf8(std::string* utf8_string, UChar32 uchar) {
uint8_t utf8_buffer[4]; // U8_APPEND writes 0 to 4 bytes
int utf8_index = 0;
UBool has_error = false;
// utf8_index is advanced to the end of the contents if successful
U8_APPEND(utf8_buffer, utf8_index, sizeof(utf8_buffer), uchar, has_error);
if (has_error) {
ICING_LOG(WARNING) << "Error appending UChar32 to the UTF8 string.";
return;
}
utf8_string->append(reinterpret_cast<char*>(utf8_buffer), utf8_index);
}
} // namespace i18n_utils
} // namespace lib
} // namespace icing
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