/////////////////////////////////////////////////////////////////////// // File: unichar.h // 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. // /////////////////////////////////////////////////////////////////////// #ifndef TESSERACT_CCUTIL_UNICHAR_H_ #define TESSERACT_CCUTIL_UNICHAR_H_ #include #include #include #include #include "platform.h" // Maximum number of characters that can be stored in a UNICHAR. Must be // at least 4. Must not exceed 31 without changing the coding of length. #define UNICHAR_LEN 30 // TODO(rays) Move these to the tesseract namespace. // A UNICHAR_ID is the unique id of a unichar. typedef int UNICHAR_ID; // A variable to indicate an invalid or uninitialized unichar id. static const int INVALID_UNICHAR_ID = -1; // A special unichar that corresponds to INVALID_UNICHAR_ID. static const char INVALID_UNICHAR[] = "__INVALID_UNICHAR__"; enum StrongScriptDirection { DIR_NEUTRAL = 0, // Text contains only neutral characters. DIR_LEFT_TO_RIGHT = 1, // Text contains no Right-to-Left characters. DIR_RIGHT_TO_LEFT = 2, // Text contains no Left-to-Right characters. DIR_MIX = 3, // Text contains a mixture of left-to-right // and right-to-left characters. }; namespace tesseract { typedef signed int char32; // The UNICHAR class holds a single classification result. This may be // a single Unicode character (stored as between 1 and 4 utf8 bytes) or // multiple Unicode characters representing the NFKC expansion of a ligature // such as fi, ffl etc. These are also stored as utf8. class UNICHAR { public: UNICHAR() { memset(chars, 0, UNICHAR_LEN); } // 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. UNICHAR(const char* utf8_str, int len); // Construct from a single UCS4 character. explicit UNICHAR(int unicode); // Default copy constructor and operator= are OK. // Get the first character as UCS-4. int first_uni() const; // Get the length of the UTF8 string. int utf8_len() const { int len = chars[UNICHAR_LEN - 1]; return len >=0 && len < UNICHAR_LEN ? len : UNICHAR_LEN; } // Get a UTF8 string, but NOT NULL terminated. const char* utf8() const { return chars; } // Get a terminated UTF8 string: Must delete[] it after use. char* utf8_str() const; // Get the number of bytes in the first character of the given utf8 string. static int utf8_step(const char* utf8_str); // A class to simplify iterating over and accessing elements of a UTF8 // string. Note that unlike the UNICHAR class, const_iterator does NOT COPY or // take ownership of the underlying byte array. It also does not permit // modification of the array (as the name suggests). // // Example: // for (UNICHAR::const_iterator it = UNICHAR::begin(str, str_len); // it != UNICHAR::end(str, len); // ++it) { // tprintf("UCS-4 symbol code = %d\n", *it); // char buf[5]; // int char_len = it.get_utf8(buf); buf[char_len] = '\0'; // tprintf("Char = %s\n", buf); // } class const_iterator { typedef const_iterator CI; public: // Step to the next UTF8 character. // If the current position is at an illegal UTF8 character, then print an // error message and step by one byte. If the current position is at a NULL // value, don't step past it. const_iterator& operator++(); // Return the UCS-4 value at the current position. // If the current position is at an illegal UTF8 value, return a single // space character. int operator*() const; // Store the UTF-8 encoding of the current codepoint into buf, which must be // at least 4 bytes long. Return the number of bytes written. // If the current position is at an illegal UTF8 value, writes a single // space character and returns 1. // Note that this method does not null-terminate the buffer. int get_utf8(char* buf) const; // Returns the number of bytes of the current codepoint. Returns 1 if the // current position is at an illegal UTF8 value. int utf8_len() const; // Returns true if the UTF-8 encoding at the current position is legal. bool is_legal() const; // Return the pointer into the string at the current position. const char* utf8_data() const { return it_; } // Iterator equality operators. friend bool operator==(const CI& lhs, const CI& rhs) { return lhs.it_ == rhs.it_; } friend bool operator!=(const CI& lhs, const CI& rhs) { return !(lhs == rhs); } private: friend class UNICHAR; explicit const_iterator(const char* it) : it_(it) {} const char* it_; // Pointer into the string. }; // Create a start/end iterator pointing to a string. Note that these methods // are static and do NOT create a copy or take ownership of the underlying // array. static const_iterator begin(const char* utf8_str, const int byte_length); static const_iterator end(const char* utf8_str, const int byte_length); // Converts a utf-8 string to a vector of unicodes. // Returns an empty vector if the input contains invalid UTF-8. static std::vector UTF8ToUTF32(const char* utf8_str); // Converts a vector of unicodes to a utf8 string. // Returns an empty string if the input contains an invalid unicode. static std::string UTF32ToUTF8(const std::vector& str32); private: // A UTF-8 representation of 1 or more Unicode characters. // The last element (chars[UNICHAR_LEN - 1]) is a length if // its value < UNICHAR_LEN, otherwise it is a genuine character. char chars[UNICHAR_LEN]; }; } // namespace tesseract #endif // TESSERACT_CCUTIL_UNICHAR_H_