tesseract/ccutil/unichar.cpp

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///////////////////////////////////////////////////////////////////////
// File: unichar.cpp
// Description: Unicode character/ligature class.
// Author: Ray Smith
// Created: Wed Jun 28 17:05:01 PDT 2006
//
// (C) Copyright 2006, Google Inc.
// 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 "unichar.h"
#include "errcode.h"
#include "genericvector.h"
#include "tprintf.h"
#define UNI_MAX_LEGAL_UTF32 0x0010FFFF
namespace tesseract {
// Construct from a utf8 string. If len<0 then the string is null terminated.
// If the string is too long to fit in the UNICHAR then it takes only what
// will fit. Checks for illegal input and stops at an illegal sequence.
// The resulting UNICHAR may be empty.
UNICHAR::UNICHAR(const char* utf8_str, int len) {
int total_len = 0;
int step = 0;
if (len < 0) {
for (len = 0; len < UNICHAR_LEN && utf8_str[len] != 0; ++len);
}
for (total_len = 0; total_len < len; total_len += step) {
step = utf8_step(utf8_str + total_len);
if (total_len + step > UNICHAR_LEN)
break; // Too long.
if (step == 0)
break; // Illegal first byte.
int i;
for (i = 1; i < step; ++i)
if ((utf8_str[total_len + i] & 0xc0) != 0x80)
break;
if (i < step)
break; // Illegal surrogate
}
memcpy(chars, utf8_str, total_len);
if (total_len < UNICHAR_LEN) {
chars[UNICHAR_LEN - 1] = total_len;
while (total_len < UNICHAR_LEN - 1)
chars[total_len++] = 0;
}
}
// Construct from a single UCS4 character. Illegal values are ignored,
// resulting in an empty UNICHAR.
UNICHAR::UNICHAR(int unicode) {
const int bytemask = 0xBF;
const int bytemark = 0x80;
if (unicode < 0x80) {
chars[UNICHAR_LEN - 1] = 1;
chars[2] = 0;
chars[1] = 0;
chars[0] = static_cast<char>(unicode);
} else if (unicode < 0x800) {
chars[UNICHAR_LEN - 1] = 2;
chars[2] = 0;
chars[1] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[0] = static_cast<char>(unicode | 0xc0);
} else if (unicode < 0x10000) {
chars[UNICHAR_LEN - 1] = 3;
chars[2] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[1] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[0] = static_cast<char>(unicode | 0xe0);
} else if (unicode <= UNI_MAX_LEGAL_UTF32) {
chars[UNICHAR_LEN - 1] = 4;
chars[3] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[2] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[1] = static_cast<char>((unicode | bytemark) & bytemask);
unicode >>= 6;
chars[0] = static_cast<char>(unicode | 0xf0);
} else {
memset(chars, 0, UNICHAR_LEN);
}
}
// Get the first character as UCS-4.
int UNICHAR::first_uni() const {
static const int utf8_offsets[5] = {
0, 0, 0x3080, 0xE2080, 0x3C82080
};
int uni = 0;
int len = utf8_step(chars);
const char* src = chars;
switch (len) {
default:
break;
case 4:
uni += static_cast<unsigned char>(*src++);
uni <<= 6;
case 3:
uni += static_cast<unsigned char>(*src++);
uni <<= 6;
case 2:
uni += static_cast<unsigned char>(*src++);
uni <<= 6;
case 1:
uni += static_cast<unsigned char>(*src++);
}
uni -= utf8_offsets[len];
return uni;
}
// Get a terminated UTF8 string: Must delete[] it after use.
char* UNICHAR::utf8_str() const {
int len = utf8_len();
char* str = new char[len + 1];
memcpy(str, chars, len);
str[len] = 0;
return str;
}
// Get the number of bytes in the first character of the given utf8 string.
int UNICHAR::utf8_step(const char* utf8_str) {
static const char utf8_bytes[256] = {
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, 4,4,4,4,4,4,4,4,0,0,0,0,0,0,0,0
};
return utf8_bytes[static_cast<unsigned char>(*utf8_str)];
}
UNICHAR::const_iterator& UNICHAR::const_iterator::operator++() {
ASSERT_HOST(it_ != NULL);
int step = utf8_step(it_);
if (step == 0) {
tprintf("ERROR: Illegal UTF8 encountered.\n");
for (int i = 0; i < 5 && it_[i] != '\0'; ++i) {
tprintf("Index %d char = 0x%x\n", i, it_[i]);
}
step = 1;
}
it_ += step;
return *this;
}
int UNICHAR::const_iterator::operator*() const {
ASSERT_HOST(it_ != NULL);
const int len = utf8_step(it_);
if (len == 0) {
tprintf("WARNING: Illegal UTF8 encountered\n");
return ' ';
}
UNICHAR uch(it_, len);
return uch.first_uni();
}
int UNICHAR::const_iterator::get_utf8(char* utf8_output) const {
ASSERT_HOST(it_ != NULL);
const int len = utf8_step(it_);
if (len == 0) {
tprintf("WARNING: Illegal UTF8 encountered\n");
utf8_output[0] = ' ';
return 1;
}
strncpy(utf8_output, it_, len);
return len;
}
int UNICHAR::const_iterator::utf8_len() const {
ASSERT_HOST(it_ != NULL);
const int len = utf8_step(it_);
if (len == 0) {
tprintf("WARNING: Illegal UTF8 encountered\n");
return 1;
}
return len;
}
bool UNICHAR::const_iterator::is_legal() const {
return utf8_step(it_) > 0;
}
UNICHAR::const_iterator UNICHAR::begin(const char* utf8_str, const int len) {
return UNICHAR::const_iterator(utf8_str);
}
UNICHAR::const_iterator UNICHAR::end(const char* utf8_str, const int len) {
return UNICHAR::const_iterator(utf8_str + len);
}
// Converts a utf-8 string to a vector of unicodes.
// Returns an empty vector if the input contains invalid UTF-8.
/* static */
std::vector<char32> UNICHAR::UTF8ToUTF32(const char* utf8_str) {
const int utf8_length = strlen(utf8_str);
std::vector<char32> unicodes;
unicodes.reserve(utf8_length);
const_iterator end_it(end(utf8_str, utf8_length));
for (const_iterator it(begin(utf8_str, utf8_length)); it != end_it; ++it) {
if (it.is_legal()) {
unicodes.push_back(*it);
} else {
unicodes.clear();
return unicodes;
}
}
return unicodes;
}
// Returns an empty string if the input contains an invalid unicode.
std::string UNICHAR::UTF32ToUTF8(const std::vector<char32>& str32) {
std::string utf8_str;
for (char32 ch : str32) {
UNICHAR uni_ch(ch);
int step;
if (uni_ch.utf8_len() > 0 && (step = utf8_step(uni_ch.utf8())) > 0) {
utf8_str.append(uni_ch.utf8(), step);
} else {
return "";
}
}
return utf8_str;
}
} // namespace tesseract