tesseract/training/normstrngs.cpp

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/**********************************************************************
* File: normstrngs.cpp
* Description: Utilities to normalize and manipulate UTF-32 and
* UTF-8 strings.
* Author: Ranjith Unnikrishnan
* Created: Thu July 4 2013
*
* (C) Copyright 2013, 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 "normstrngs.h"
#include "icuerrorcode.h"
#include "unichar.h"
#include "unicode/normalizer2.h" // From libicu
#include "unicode/translit.h" // From libicu
#include "unicode/unorm2.h" // From libicu
namespace tesseract {
void UTF8ToUTF32(const char* utf8_str, GenericVector<char32>* str32) {
str32->clear();
str32->reserve(strlen(utf8_str));
int len = strlen(utf8_str);
int step = 0;
for (int ch = 0; ch < len; ch += step) {
step = UNICHAR::utf8_step(utf8_str + ch);
if (step > 0) {
UNICHAR uni_ch(utf8_str + ch, step);
(*str32) += uni_ch.first_uni();
}
}
}
void UTF32ToUTF8(const GenericVector<char32>& str32, STRING* utf8_str) {
utf8_str->ensure(str32.length());
utf8_str->assign("", 0);
for (int i = 0; i < str32.length(); ++i) {
UNICHAR uni_ch(str32[i]);
char *utf8 = uni_ch.utf8_str();
if (utf8 != nullptr) {
(*utf8_str) += utf8;
delete[] utf8;
}
}
}
bool is_hyphen_punc(const char32 ch) {
static const int kNumHyphenPuncUnicodes = 13;
static const char32 kHyphenPuncUnicodes[kNumHyphenPuncUnicodes] = {
'-',
0x2010, 0x2011, 0x2012, 0x2013, 0x2014, 0x2015, // hyphen..horizontal bar
0x207b, // superscript minus
0x208b, // subscript minus
0x2212, // minus sign
0xfe58, // small em dash
0xfe63, // small hyphen-minus
0xff0d, // fullwidth hyphen-minus
};
for (int i = 0; i < kNumHyphenPuncUnicodes; ++i) {
if (kHyphenPuncUnicodes[i] == ch)
return true;
}
return false;
}
bool is_single_quote(const char32 ch) {
static const int kNumSingleQuoteUnicodes = 8;
static const char32 kSingleQuoteUnicodes[kNumSingleQuoteUnicodes] = {
'\'',
'`',
0x2018, // left single quotation mark (English, others)
0x2019, // right single quotation mark (Danish, Finnish, Swedish, Norw.)
// We may have to introduce a comma set with 0x201a
0x201B, // single high-reveresed-9 quotation mark (PropList.txt)
0x2032, // prime
0x300C, // left corner bracket (East Asian languages)
0xFF07, // fullwidth apostrophe
};
for (int i = 0; i < kNumSingleQuoteUnicodes; ++i) {
if (kSingleQuoteUnicodes[i] == ch)
return true;
}
return false;
}
bool is_double_quote(const char32 ch) {
static const int kNumDoubleQuoteUnicodes = 8;
static const char32 kDoubleQuoteUnicodes[kNumDoubleQuoteUnicodes] = {
'"',
0x201C, // left double quotation mark (English, others)
0x201D, // right double quotation mark (Danish, Finnish, Swedish, Norw.)
0x201F, // double high-reversed-9 quotation mark (PropList.txt)
0x2033, // double prime
0x301D, // reversed double prime quotation mark (East Asian langs, horiz.)
0x301E, // close double prime (East Asian languages written horizontally)
0xFF02, // fullwidth quotation mark
};
for (int i = 0; i < kNumDoubleQuoteUnicodes; ++i) {
if (kDoubleQuoteUnicodes[i] == ch)
return true;
}
return false;
}
STRING NormalizeUTF8String(bool decompose, const char* str8) {
GenericVector<char32> str32, out_str32, norm_str;
UTF8ToUTF32(str8, &str32);
for (int i = 0; i < str32.length(); ++i) {
norm_str.clear();
NormalizeChar32(str32[i], decompose, &norm_str);
for (int j = 0; j < norm_str.length(); ++j) {
out_str32.push_back(norm_str[j]);
}
}
STRING out_str8;
UTF32ToUTF8(out_str32, &out_str8);
return out_str8;
}
void NormalizeChar32(char32 ch, bool decompose, GenericVector<char32>* str) {
IcuErrorCode error_code;
const icu::Normalizer2* nfkc = icu::Normalizer2::getInstance(
2017-01-26 08:20:19 +08:00
nullptr, "nfkc", decompose ? UNORM2_DECOMPOSE : UNORM2_COMPOSE,
error_code);
error_code.assertSuccess();
error_code.reset();
icu::UnicodeString uch_str(static_cast<UChar32>(ch));
icu::UnicodeString norm_str = nfkc->normalize(uch_str, error_code);
error_code.assertSuccess();
str->clear();
for (int i = 0; i < norm_str.length(); ++i) {
// If any spaces were added by NFKC, pretend normalization is a nop.
if (norm_str[i] == ' ') {
str->clear();
str->push_back(ch);
break;
} else {
str->push_back(OCRNormalize(static_cast<char32>(norm_str[i])));
}
}
}
// Apply just the OCR-specific normalizations and return the normalized char.
char32 OCRNormalize(char32 ch) {
if (is_hyphen_punc(ch))
return '-';
else if (is_single_quote(ch))
return '\'';
else if (is_double_quote(ch))
return '"';
return ch;
}
bool IsOCREquivalent(char32 ch1, char32 ch2) {
return OCRNormalize(ch1) == OCRNormalize(ch2);
}
bool IsValidCodepoint(const char32 ch) {
// In the range [0, 0xD800) or [0xE000, 0x10FFFF]
return (static_cast<uinT32>(ch) < 0xD800)
|| (ch >= 0xE000 && ch <= 0x10FFFF);
}
bool IsWhitespace(const char32 ch) {
ASSERT_HOST_MSG(IsValidCodepoint(ch),
"Invalid Unicode codepoint: 0x%x\n", ch);
return u_isUWhiteSpace(static_cast<UChar32>(ch));
}
bool IsUTF8Whitespace(const char* text) {
return SpanUTF8Whitespace(text) == strlen(text);
}
int SpanUTF8Whitespace(const char* text) {
int n_white = 0;
for (UNICHAR::const_iterator it = UNICHAR::begin(text, strlen(text));
it != UNICHAR::end(text, strlen(text));
++it) {
if (!IsWhitespace(*it)) break;
n_white += it.utf8_len();
}
return n_white;
}
int SpanUTF8NotWhitespace(const char* text) {
int n_notwhite = 0;
for (UNICHAR::const_iterator it = UNICHAR::begin(text, strlen(text));
it != UNICHAR::end(text, strlen(text));
++it) {
if (IsWhitespace(*it)) break;
n_notwhite += it.utf8_len();
}
return n_notwhite;
}
bool IsInterchangeValid(const char32 ch) {
return IsValidCodepoint(ch) &&
!(ch >= 0xFDD0 && ch <= 0xFDEF) && // Noncharacters.
!(ch >= 0xFFFE && ch <= 0xFFFF) &&
!(ch >= 0x1FFFE && ch <= 0x1FFFF) &&
!(ch >= 0x2FFFE && ch <= 0x2FFFF) &&
!(ch >= 0x3FFFE && ch <= 0x3FFFF) &&
!(ch >= 0x4FFFE && ch <= 0x4FFFF) &&
!(ch >= 0x5FFFE && ch <= 0x5FFFF) &&
!(ch >= 0x6FFFE && ch <= 0x6FFFF) &&
!(ch >= 0x7FFFE && ch <= 0x7FFFF) &&
!(ch >= 0x8FFFE && ch <= 0x8FFFF) &&
!(ch >= 0x9FFFE && ch <= 0x9FFFF) &&
!(ch >= 0xAFFFE && ch <= 0xAFFFF) &&
!(ch >= 0xBFFFE && ch <= 0xBFFFF) &&
!(ch >= 0xCFFFE && ch <= 0xCFFFF) &&
!(ch >= 0xDFFFE && ch <= 0xDFFFF) &&
!(ch >= 0xEFFFE && ch <= 0xEFFFF) &&
!(ch >= 0xFFFFE && ch <= 0xFFFFF) &&
!(ch >= 0x10FFFE && ch <= 0x10FFFF) &&
(!u_isISOControl(static_cast<UChar32>(ch)) ||
ch == '\n' || ch == '\f' || ch == '\t' || ch == '\r');
}
bool IsInterchangeValid7BitAscii(const char32 ch) {
return IsValidCodepoint(ch) &&
ch <= 128 &&
(!u_isISOControl(static_cast<UChar32>(ch)) ||
ch == '\n' || ch == '\f' || ch == '\t' || ch == '\r');
}
char32 FullwidthToHalfwidth(const char32 ch) {
// Return unchanged if not in the fullwidth-halfwidth Unicode block.
if (ch < 0xFF00 || ch > 0xFFEF || !IsValidCodepoint(ch)) {
if (ch != 0x3000) return ch;
}
// Special case for fullwidth left and right "white parentheses".
if (ch == 0xFF5F) return 0x2985;
if (ch == 0xFF60) return 0x2986;
// Construct a full-to-half width transliterator.
IcuErrorCode error_code;
icu::UnicodeString uch_str(static_cast<UChar32>(ch));
const icu::Transliterator* fulltohalf = icu::Transliterator::createInstance(
"Fullwidth-Halfwidth", UTRANS_FORWARD, error_code);
error_code.assertSuccess();
error_code.reset();
fulltohalf->transliterate(uch_str);
delete fulltohalf;
ASSERT_HOST(uch_str.length() != 0);
return uch_str[0];
}
} // namespace tesseract