From db81b925d776103326128bf629cbdda576a223e7 Mon Sep 17 00:00:00 2001 From: sanine Date: Sat, 16 Apr 2022 11:55:09 -0500 Subject: move 3rd-party librarys into libs/ and add built-in honeysuckle --- libs/assimp/contrib/utf8cpp/doc/utf8cpp.html | 1789 ++++++++++++++++++++++++++ 1 file changed, 1789 insertions(+) create mode 100644 libs/assimp/contrib/utf8cpp/doc/utf8cpp.html (limited to 'libs/assimp/contrib/utf8cpp/doc/utf8cpp.html') diff --git a/libs/assimp/contrib/utf8cpp/doc/utf8cpp.html b/libs/assimp/contrib/utf8cpp/doc/utf8cpp.html new file mode 100644 index 0000000..6f2aacb --- /dev/null +++ b/libs/assimp/contrib/utf8cpp/doc/utf8cpp.html @@ -0,0 +1,1789 @@ + + + + + + + + + UTF8-CPP: UTF-8 with C++ in a Portable Way + + + + +

+ UTF8-CPP: UTF-8 with C++ in a Portable Way +

+ The Sourceforge project page +

+ Table of Contents +

+ Introduction +
+ Examples of Use +
- + Introductionary Sample +
- + Checking if a file contains valid UTF-8 text +
- + Ensure that a string contains valid UTF-8 text +
+
+ Reference +
- + Functions From utf8 Namespace +
- + Types From utf8 Namespace +
- + Functions From utf8::unchecked Namespace +
- + Types From utf8::unchecked Namespace +
+
+ Points of Interest +
+ Links +

+ Introduction +

+ Many C++ developers miss an easy and portable way of handling Unicode encoded + strings. The original C++ Standard (known as C++98 or C++03) is Unicode agnostic. + C++11 provides some support for Unicode on core language and library level: + u8, u, and U character and string literals, char16_t and char32_t character types, + u16string and u32string library classes, and codecvt support for conversions + between Unicode encoding forms. + In the meantime, developers use third party libraries like ICU, OS specific capabilities, or simply + roll out their own solutions. +

+ In order to easily handle UTF-8 encoded Unicode strings, I came up with a small + generic library. For anybody used to work with STL algorithms and iterators, it should be + easy and natural to use. The code is freely available for any purpose - check out + the license at the beginning of the utf8.h file. If you run into + bugs or performance issues, please let me know and I'll do my best to address them. +

+ The purpose of this article is not to offer an introduction to Unicode in general, + and UTF-8 in particular. If you are not familiar with Unicode, be sure to check out + Unicode Home Page or some other source of + information for Unicode. Also, it is not my aim to advocate the use of UTF-8 + encoded strings in C++ programs; if you want to handle UTF-8 encoded strings from + C++, I am sure you have good reasons for it. +

+ Examples of use +

+ Introductionary Sample +

+ To illustrate the use of the library, let's start with a small but complete program + that opens a file containing UTF-8 encoded text, reads it line by line, checks each line + for invalid UTF-8 byte sequences, and converts it to UTF-16 encoding and back to UTF-8: +

+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+#include "utf8.h"
+using namespace std;
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        cout << "\nUsage: docsample filename\n";
+        return 0;
+    }
+
+    const char* test_file_path = argv[1];
+    // Open the test file (contains UTF-8 encoded text)
+    ifstream fs8(test_file_path);
+    if (!fs8.is_open()) {
+    cout << "Could not open " << test_file_path << endl;
+    return 0;
+    }
+
+    unsigned line_count = 1;
+    string line;
+    // Play with all the lines in the file
+    while (getline(fs8, line)) {
+       // check for invalid utf-8 (for a simple yes/no check, there is also utf8::is_valid function)
+        string::iterator end_it = utf8::find_invalid(line.begin(), line.end());
+        if (end_it != line.end()) {
+            cout << "Invalid UTF-8 encoding detected at line " << line_count << "\n";
+            cout << "This part is fine: " << string(line.begin(), end_it) << "\n";
+        }
+
+        // Get the line length (at least for the valid part)
+        int length = utf8::distance(line.begin(), end_it);
+        cout << "Length of line " << line_count << " is " << length <<  "\n";
+
+        // Convert it to utf-16
+        vector<unsigned short> utf16line;
+        utf8::utf8to16(line.begin(), end_it, back_inserter(utf16line));
+
+        // And back to utf-8
+        string utf8line; 
+        utf8::utf16to8(utf16line.begin(), utf16line.end(), back_inserter(utf8line));
+
+        // Confirm that the conversion went OK:
+        if (utf8line != string(line.begin(), end_it))
+            cout << "Error in UTF-16 conversion at line: " << line_count << "\n";        
+
+        line_count++;
+    }
+    return 0;
+}
+

+ In the previous code sample, for each line we performed + a detection of invalid UTF-8 sequences with find_invalid; the number + of characters (more precisely - the number of Unicode code points, including the end + of line and even BOM if there is one) in each line was + determined with a use of utf8::distance; finally, we have converted + each line to UTF-16 encoding with utf8to16 and back to UTF-8 with + utf16to8. +

Checking if a file contains valid UTF-8 text

+Here is a function that checks whether the content of a file is valid UTF-8 encoded text without +reading the content into the memory: +

    
+bool valid_utf8_file(iconst char* file_name)
+{
+    ifstream ifs(file_name);
+    if (!ifs)
+        return false; // even better, throw here
+
+    istreambuf_iterator<char> it(ifs.rdbuf());
+    istreambuf_iterator<char> eos;
+
+    return utf8::is_valid(it, eos);
+}
+

+Because the function utf8::is_valid() works with input iterators, we were able +to pass an istreambuf_iterator to it and read the content of the file directly +without loading it to the memory first.

+Note that other functions that take input iterator arguments can be used in a similar way. For +instance, to read the content of a UTF-8 encoded text file and convert the text to UTF-16, just +do something like: +

+    utf8::utf8to16(it, eos, back_inserter(u16string));
+

Ensure that a string contains valid UTF-8 text

+If we have some text that "probably" contains UTF-8 encoded text and we want to +replace any invalid UTF-8 sequence with a replacement character, something like +the following function may be used: +

+void fix_utf8_string(std::string& str)
+{
+    std::string temp;
+    utf8::replace_invalid(str.begin(), str.end(), back_inserter(temp));
+    str = temp;
+}
+

The function will replace any invalid UTF-8 sequence with a Unicode replacement character. +There is an overloaded function that enables the caller to supply their own replacement character. +

+ Reference +

+ Functions From utf8 Namespace +

+ utf8::append +

+ Available in version 1.0 and later. +

+ Encodes a 32 bit code point as a UTF-8 sequence of octets and appends the sequence + to a UTF-8 string. +

+template <typename octet_iterator>
+octet_iterator append(uint32_t cp, octet_iterator result);
+   
+

+ octet_iterator: an output iterator.
+ cp: a 32 bit integer representing a code point to append to the + sequence.
+ result: an output iterator to the place in the sequence where to + append the code point.
+ Return value: an iterator pointing to the place + after the newly appended sequence. +

+ Example of use: +

+unsigned char u[5] = {0,0,0,0,0};
+unsigned char* end = append(0x0448, u);
+assert (u[0] == 0xd1 && u[1] == 0x88 && u[2] == 0 && u[3] == 0 && u[4] == 0);
+

+ Note that append does not allocate any memory - it is the burden of + the caller to make sure there is enough memory allocated for the operation. To make + things more interesting, append can add anywhere between 1 and 4 + octets to the sequence. In practice, you would most often want to use + std::back_inserter to ensure that the necessary memory is allocated. +

+ In case of an invalid code point, a utf8::invalid_code_point exception + is thrown. +

+ utf8::next +

+ Available in version 1.0 and later. +

+ Given the iterator to the beginning of the UTF-8 sequence, it returns the code + point and moves the iterator to the next position. +

+template <typename octet_iterator> 
+uint32_t next(octet_iterator& it, octet_iterator end);
+   
+

+ octet_iterator: an input iterator.
+ it: a reference to an iterator pointing to the beginning of an UTF-8 + encoded code point. After the function returns, it is incremented to point to the + beginning of the next code point.
+ end: end of the UTF-8 sequence to be processed. If it + gets equal to end during the extraction of a code point, an + utf8::not_enough_room exception is thrown.
+ Return value: the 32 bit representation of the + processed UTF-8 code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = next(w, twochars + 6);
+assert (cp == 0x65e5);
+assert (w == twochars + 3);
+

+ This function is typically used to iterate through a UTF-8 encoded string. +

+ In case of an invalid UTF-8 seqence, a utf8::invalid_utf8 exception is + thrown. +

+ utf8::peek_next +

+ Available in version 2.1 and later. +

+ Given the iterator to the beginning of the UTF-8 sequence, it returns the code + point for the following sequence without changing the value of the iterator. +

+template <typename octet_iterator> 
+uint32_t peek_next(octet_iterator it, octet_iterator end);
+   
+

+ octet_iterator: an input iterator.
+ it: an iterator pointing to the beginning of an UTF-8 + encoded code point.
+ end: end of the UTF-8 sequence to be processed. If it + gets equal to end during the extraction of a code point, an + utf8::not_enough_room exception is thrown.
+ Return value: the 32 bit representation of the + processed UTF-8 code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = peek_next(w, twochars + 6);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ In case of an invalid UTF-8 seqence, a utf8::invalid_utf8 exception is + thrown. +

+ utf8::prior +

+ Available in version 1.02 and later. +

+ Given a reference to an iterator pointing to an octet in a UTF-8 sequence, it + decreases the iterator until it hits the beginning of the previous UTF-8 encoded + code point and returns the 32 bits representation of the code point. +

+template <typename octet_iterator> 
+uint32_t prior(octet_iterator& it, octet_iterator start);
+   
+

+ octet_iterator: a bidirectional iterator.
+ it: a reference pointing to an octet within a UTF-8 encoded string. + After the function returns, it is decremented to point to the beginning of the + previous code point.
+ start: an iterator to the beginning of the sequence where the search + for the beginning of a code point is performed. It is a + safety measure to prevent passing the beginning of the string in the search for a + UTF-8 lead octet.
+ Return value: the 32 bit representation of the + previous code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+unsigned char* w = twochars + 3;
+int cp = prior (w, twochars);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ This function has two purposes: one is two iterate backwards through a UTF-8 + encoded string. Note that it is usually a better idea to iterate forward instead, + since utf8::next is faster. The second purpose is to find a beginning + of a UTF-8 sequence if we have a random position within a string. Note that in that + case utf8::prior may not detect an invalid UTF-8 sequence in some scenarios: + for instance if there are superfluous trail octets, it will just skip them. +

+ it will typically point to the beginning of + a code point, and start will point to the + beginning of the string to ensure we don't go backwards too far. it is + decreased until it points to a lead UTF-8 octet, and then the UTF-8 sequence + beginning with that octet is decoded to a 32 bit representation and returned. +

+ In case start is reached before a UTF-8 lead octet is hit, or if an + invalid UTF-8 sequence is started by the lead octet, an invalid_utf8 + exception is thrown. +

In case start equals it, a not_enough_room + exception is thrown. +

+ utf8::previous +

+ Deprecated in version 1.02 and later. +

+ Given a reference to an iterator pointing to an octet in a UTF-8 seqence, it + decreases the iterator until it hits the beginning of the previous UTF-8 encoded + code point and returns the 32 bits representation of the code point. +

+template <typename octet_iterator> 
+uint32_t previous(octet_iterator& it, octet_iterator pass_start);
+   
+

+ octet_iterator: a random access iterator.
+ it: a reference pointing to an octet within a UTF-8 encoded string. + After the function returns, it is decremented to point to the beginning of the + previous code point.
+ pass_start: an iterator to the point in the sequence where the search + for the beginning of a code point is aborted if no result was reached. It is a + safety measure to prevent passing the beginning of the string in the search for a + UTF-8 lead octet.
+ Return value: the 32 bit representation of the + previous code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+unsigned char* w = twochars + 3;
+int cp = previous (w, twochars - 1);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ utf8::previous is deprecated, and utf8::prior should + be used instead, although the existing code can continue using this function. + The problem is the parameter pass_start that points to the position + just before the beginning of the sequence. Standard containers don't have the + concept of "pass start" and the function can not be used with their iterators. +

+ it will typically point to the beginning of + a code point, and pass_start will point to the octet just before the + beginning of the string to ensure we don't go backwards too far. it is + decreased until it points to a lead UTF-8 octet, and then the UTF-8 sequence + beginning with that octet is decoded to a 32 bit representation and returned. +

+ In case pass_start is reached before a UTF-8 lead octet is hit, or if an + invalid UTF-8 sequence is started by the lead octet, an invalid_utf8 + exception is thrown +

+ utf8::advance +

+ Available in version 1.0 and later. +

+ Advances an iterator by the specified number of code points within an UTF-8 + sequence. +

+template <typename octet_iterator, typename distance_type> 
+void advance (octet_iterator& it, distance_type n, octet_iterator end);
+   
+

+ octet_iterator: an input iterator.
+ distance_type: an integral type convertible to octet_iterator's difference type.
+ it: a reference to an iterator pointing to the beginning of an UTF-8 + encoded code point. After the function returns, it is incremented to point to the + nth following code point.
+ n: a positive integer that shows how many code points we want to + advance.
+ end: end of the UTF-8 sequence to be processed. If it + gets equal to end during the extraction of a code point, an + utf8::not_enough_room exception is thrown.
+

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+unsigned char* w = twochars;
+advance (w, 2, twochars + 6);
+assert (w == twochars + 5);
+

+ This function works only "forward". In case of a negative n, there is + no effect. +

+ In case of an invalid code point, a utf8::invalid_code_point exception + is thrown. +

+ utf8::distance +

+ Available in version 1.0 and later. +

+ Given the iterators to two UTF-8 encoded code points in a seqence, returns the + number of code points between them. +

+template <typename octet_iterator> 
+typename std::iterator_traits<octet_iterator>::difference_type distance (octet_iterator first, octet_iterator last);
+   
+

+ octet_iterator: an input iterator.
+ first: an iterator to a beginning of a UTF-8 encoded code point.
+ last: an iterator to a "post-end" of the last UTF-8 encoded code + point in the sequence we are trying to determine the length. It can be the + beginning of a new code point, or not.
+ Return value the distance between the iterators, + in code points. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+size_t dist = utf8::distance(twochars, twochars + 5);
+assert (dist == 2);
+

+ This function is used to find the length (in code points) of a UTF-8 encoded + string. The reason it is called distance, rather than, say, + length is mainly because developers are used that length is an + O(1) function. Computing the length of an UTF-8 string is a linear operation, and + it looked better to model it after std::distance algorithm. +

+ In case of an invalid UTF-8 seqence, a utf8::invalid_utf8 exception is + thrown. If last does not point to the past-of-end of a UTF-8 seqence, + a utf8::not_enough_room exception is thrown. +

+ utf8::utf16to8 +

+ Available in version 1.0 and later. +

+ Converts a UTF-16 encoded string to UTF-8. +

+template <typename u16bit_iterator, typename octet_iterator>
+octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result);
+   
+

+ u16bit_iterator: an input iterator.
+ octet_iterator: an output iterator.
+ start: an iterator pointing to the beginning of the UTF-16 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-16 encoded + string to convert.
+ result: an output iterator to the place in the UTF-8 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-8 string. +

+ Example of use: +

+unsigned short utf16string[] = {0x41, 0x0448, 0x65e5, 0xd834, 0xdd1e};
+vector<unsigned char> utf8result;
+utf16to8(utf16string, utf16string + 5, back_inserter(utf8result));
+assert (utf8result.size() == 10);    
+

+ In case of invalid UTF-16 sequence, a utf8::invalid_utf16 exception is + thrown. +

+ utf8::utf8to16 +

+ Available in version 1.0 and later. +

+ Converts an UTF-8 encoded string to UTF-16 +

+template <typename u16bit_iterator, typename octet_iterator>
+u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result);
+   
+

+ octet_iterator: an input iterator.
+ u16bit_iterator: an output iterator.
+ start: an iterator pointing to the beginning of the UTF-8 encoded + string to convert. < br /> end: an iterator pointing to + pass-the-end of the UTF-8 encoded string to convert.
+ result: an output iterator to the place in the UTF-16 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-16 string. +

+ Example of use: +

+char utf8_with_surrogates[] = "\xe6\x97\xa5\xd1\x88\xf0\x9d\x84\x9e";
+vector <unsigned short> utf16result;
+utf8to16(utf8_with_surrogates, utf8_with_surrogates + 9, back_inserter(utf16result));
+assert (utf16result.size() == 4);
+assert (utf16result[2] == 0xd834);
+assert (utf16result[3] == 0xdd1e);
+

+ In case of an invalid UTF-8 seqence, a utf8::invalid_utf8 exception is + thrown. If end does not point to the past-of-end of a UTF-8 seqence, a + utf8::not_enough_room exception is thrown. +

+ utf8::utf32to8 +

+ Available in version 1.0 and later. +

+ Converts a UTF-32 encoded string to UTF-8. +

+template <typename octet_iterator, typename u32bit_iterator>
+octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result);
+   
+

+ octet_iterator: an output iterator.
+ u32bit_iterator: an input iterator.
+ start: an iterator pointing to the beginning of the UTF-32 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-32 encoded + string to convert.
+ result: an output iterator to the place in the UTF-8 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-8 string. +

+ Example of use: +

+int utf32string[] = {0x448, 0x65E5, 0x10346, 0};
+vector<unsigned char> utf8result;
+utf32to8(utf32string, utf32string + 3, back_inserter(utf8result));
+assert (utf8result.size() == 9);
+

+ In case of invalid UTF-32 string, a utf8::invalid_code_point exception + is thrown. +

+ utf8::utf8to32 +

+ Available in version 1.0 and later. +

+ Converts a UTF-8 encoded string to UTF-32. +

+template <typename octet_iterator, typename u32bit_iterator>
+u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result);
+   
+

+ octet_iterator: an input iterator.
+ u32bit_iterator: an output iterator.
+ start: an iterator pointing to the beginning of the UTF-8 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-8 encoded string + to convert.
+ result: an output iterator to the place in the UTF-32 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-32 string. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+vector<int> utf32result;
+utf8to32(twochars, twochars + 5, back_inserter(utf32result));
+assert (utf32result.size() == 2);
+

+ In case of an invalid UTF-8 seqence, a utf8::invalid_utf8 exception is + thrown. If end does not point to the past-of-end of a UTF-8 seqence, a + utf8::not_enough_room exception is thrown. +

+ utf8::find_invalid +

+ Available in version 1.0 and later. +

+ Detects an invalid sequence within a UTF-8 string. +

+template <typename octet_iterator> 
+octet_iterator find_invalid(octet_iterator start, octet_iterator end);
+

+ octet_iterator: an input iterator.
+ start: an iterator pointing to the beginning of the UTF-8 string to + test for validity.
+ end: an iterator pointing to pass-the-end of the UTF-8 string to test + for validity.
+ Return value: an iterator pointing to the first + invalid octet in the UTF-8 string. In case none were found, equals + end. +

+ Example of use: +

+char utf_invalid[] = "\xe6\x97\xa5\xd1\x88\xfa";
+char* invalid = find_invalid(utf_invalid, utf_invalid + 6);
+assert (invalid == utf_invalid + 5);
+

+ This function is typically used to make sure a UTF-8 string is valid before + processing it with other functions. It is especially important to call it if before + doing any of the unchecked operations on it. +

+ utf8::is_valid +

+ Available in version 1.0 and later. +

+ Checks whether a sequence of octets is a valid UTF-8 string. +

+template <typename octet_iterator> 
+bool is_valid(octet_iterator start, octet_iterator end);
+   
+

+ octet_iterator: an input iterator.
+ start: an iterator pointing to the beginning of the UTF-8 string to + test for validity.
+ end: an iterator pointing to pass-the-end of the UTF-8 string to test + for validity.
+ Return value: true if the sequence + is a valid UTF-8 string; false if not. +

+ Example of use: +

+char utf_invalid[] = "\xe6\x97\xa5\xd1\x88\xfa";
+bool bvalid = is_valid(utf_invalid, utf_invalid + 6);
+assert (bvalid == false);
+

+ is_valid is a shorthand for find_invalid(start, end) == + end;. You may want to use it to make sure that a byte seqence is a valid + UTF-8 string without the need to know where it fails if it is not valid. +

+ utf8::replace_invalid +

+ Available in version 2.0 and later. +

+ Replaces all invalid UTF-8 sequences within a string with a replacement marker. +

+template <typename octet_iterator, typename output_iterator>
+output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, uint32_t replacement);
+template <typename octet_iterator, typename output_iterator>
+output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out);
+   
+

+ octet_iterator: an input iterator.
+ output_iterator: an output iterator.
+ start: an iterator pointing to the beginning of the UTF-8 string to + look for invalid UTF-8 sequences.
+ end: an iterator pointing to pass-the-end of the UTF-8 string to look + for invalid UTF-8 sequences.
+ out: An output iterator to the range where the result of replacement + is stored.
+ replacement: A Unicode code point for the replacement marker. The + version without this parameter assumes the value 0xfffd
+ Return value: An iterator pointing to the place + after the UTF-8 string with replaced invalid sequences. +

+ Example of use: +

+char invalid_sequence[] = "a\x80\xe0\xa0\xc0\xaf\xed\xa0\x80z";
+vector<char> replace_invalid_result;
+replace_invalid (invalid_sequence, invalid_sequence + sizeof(invalid_sequence), back_inserter(replace_invalid_result), '?');
+bvalid = is_valid(replace_invalid_result.begin(), replace_invalid_result.end());
+assert (bvalid);
+char* fixed_invalid_sequence = "a????z";
+assert (std::equal(replace_invalid_result.begin(), replace_invalid_result.end(), fixed_invalid_sequence));
+

+ replace_invalid does not perform in-place replacement of invalid + sequences. Rather, it produces a copy of the original string with the invalid + sequences replaced with a replacement marker. Therefore, out must not + be in the [start, end] range. +

+ If end does not point to the past-of-end of a UTF-8 sequence, a + utf8::not_enough_room exception is thrown. +

+ utf8::starts_with_bom +

+ Available in version 2.3 and later. Relaces deprecated is_bom() function. +

+ Checks whether an octet sequence starts with a UTF-8 byte order mark (BOM) +

+template <typename octet_iterator> 
+bool starts_with_bom (octet_iterator it, octet_iterator end);
+

+ octet_iterator: an input iterator.
+ it: beginning of the octet sequence to check
+ end: pass-end of the sequence to check
+ Return value: true if the sequence + starts with a UTF-8 byte order mark; false if not. +

+ Example of use: +

+unsigned char byte_order_mark[] = {0xef, 0xbb, 0xbf};
+bool bbom = starts_with_bom(byte_order_mark, byte_order_mark + sizeof(byte_order_mark));
+assert (bbom == true);
+

+ The typical use of this function is to check the first three bytes of a file. If + they form the UTF-8 BOM, we want to skip them before processing the actual UTF-8 + encoded text. +

+ utf8::is_bom +

+ Available in version 1.0 and later. Deprecated in version 2.3. starts_with_bom() should be used + instead. +

+ Checks whether a sequence of three octets is a UTF-8 byte order mark (BOM) +

+template <typename octet_iterator> 
+bool is_bom (octet_iterator it);  // Deprecated
+

+ octet_iterator: an input iterator.
+ it: beginning of the 3-octet sequence to check
+ Return value: true if the sequence + is UTF-8 byte order mark; false if not. +

+ Example of use: +

+unsigned char byte_order_mark[] = {0xef, 0xbb, 0xbf};
+bool bbom = is_bom(byte_order_mark);
+assert (bbom == true);
+

+ The typical use of this function is to check the first three bytes of a file. If + they form the UTF-8 BOM, we want to skip them before processing the actual UTF-8 + encoded text. +

+ If a sequence is + shorter than three bytes, an invalid iterator will be dereferenced. Therefore, this function is deprecated + in favor of starts_with_bom()that takes the end of sequence as an argument. +

+ Types From utf8 Namespace +

utf8::exception +

+ Available in version 2.3 and later. +

+ Base class for the exceptions thrown by UTF CPP library functions. +

+class exception : public std::exception {};
+

+ Example of use: +

+try {
+  code_that_uses_utf_cpp_library();
+}
+catch(const utf8::exception& utfcpp_ex) {
+  cerr << utfcpp_ex.what();
+}
+

+ +

utf8::invalid_code_point +

+ Available in version 1.0 and later. +

+ Thrown by UTF8 CPP functions such as advance and next if an UTF-8 sequence represents and invalid code point. +

+ +

+class invalid_code_point : public exception {
+public: 
+    uint32_t code_point() const;
+};
+
+

+ Member function code_point() can be used to determine the invalid code point that + caused the exception to be thrown. +

utf8::invalid_utf8 +

+ Available in version 1.0 and later. +

+ Thrown by UTF8 CPP functions such as next and prior if an invalid UTF-8 sequence + is detected during decoding. +

+ +

+class invalid_utf8 : public exception {
+public: 
+    uint8_t utf8_octet() const;
+};
+

+ +

+ Member function utf8_octet() can be used to determine the beginning of the byte + sequence that caused the exception to be thrown. +

+ +

utf8::invalid_utf16 +

+ Available in version 1.0 and later. +

+ Thrown by UTF8 CPP function utf16to8 if an invalid UTF-16 sequence + is detected during decoding. +

+ +

+class invalid_utf16 : public exception {
+public: 
+    uint16_t utf16_word() const;
+};
+

+ +

+ Member function utf16_word() can be used to determine the UTF-16 code unit + that caused the exception to be thrown. +

utf8::not_enough_room +

+ Available in version 1.0 and later. +

+ Thrown by UTF8 CPP functions such as next if the end of the decoded UTF-8 sequence + was reached before the code point was decoded. +

+ +

+class not_enough_room : public exception {};
+

+ utf8::iterator +

+ Available in version 2.0 and later. +

+ Adapts the underlying octet iterator to iterate over the sequence of code points, + rather than raw octets. +

+template <typename octet_iterator>
+class iterator;
+

+ +

Member functions

iterator();: the deafult constructor; the underlying octet_iterator is + constructed with its default constructor. +
explicit iterator (const octet_iterator& octet_it, + const octet_iterator& range_start, + const octet_iterator& range_end);: a constructor + that initializes the underlying octet_iterator with octet_it + and sets the range in which the iterator is considered valid. +
octet_iterator base () const;: returns the + underlying octet_iterator. +
uint32_t operator * () const;: decodes the utf-8 sequence + the underlying octet_iterator is pointing to and returns the code point. +
bool operator == (const iterator& rhs) + const;: returns true + if the two underlaying iterators are equal. +
bool operator != (const iterator& rhs) + const;: returns true + if the two underlaying iterators are not equal. +
iterator& operator ++ ();: the prefix increment - moves + the iterator to the next UTF-8 encoded code point. +
iterator operator ++ (int);: + the postfix increment - moves the iterator to the next UTF-8 encoded code point and returns the current one. +
iterator& operator -- ();: the prefix decrement - moves + the iterator to the previous UTF-8 encoded code point. +
iterator operator -- (int);: + the postfix decrement - moves the iterator to the previous UTF-8 encoded code point and returns the current one. +

+ Example of use: +

+char* threechars = "\xf0\x90\x8d\x86\xe6\x97\xa5\xd1\x88";
+utf8::iterator<char*> it(threechars, threechars, threechars + 9);
+utf8::iterator<char*> it2 = it;
+assert (it2 == it);
+assert (*it == 0x10346);
+assert (*(++it) == 0x65e5);
+assert ((*it++) == 0x65e5);
+assert (*it == 0x0448);
+assert (it != it2);
+utf8::iterator<char*> endit (threechars + 9, threechars, threechars + 9);  
+assert (++it == endit);
+assert (*(--it) == 0x0448);
+assert ((*it--) == 0x0448);
+assert (*it == 0x65e5);
+assert (--it == utf8::iterator<char*>(threechars, threechars, threechars + 9));
+assert (*it == 0x10346);
+

+ The purpose of utf8::iterator adapter is to enable easy iteration as well as the use of STL + algorithms with UTF-8 encoded strings. Increment and decrement operators are implemented in terms of + utf8::next() and utf8::prior() functions. +

+ Note that utf8::iterator adapter is a checked iterator. It operates on the range specified in + the constructor; any attempt to go out of that range will result in an exception. Even the comparison operators + require both iterator object to be constructed against the same range - otherwise an exception is thrown. Typically, + the range will be determined by sequence container functions begin and end, i.e.: +

+std::string s = "example";
+utf8::iterator i (s.begin(), s.begin(), s.end());
+

+ Functions From utf8::unchecked Namespace +

+ utf8::unchecked::append +

+ Available in version 1.0 and later. +

+ Encodes a 32 bit code point as a UTF-8 sequence of octets and appends the sequence + to a UTF-8 string. +

+template <typename octet_iterator>
+octet_iterator append(uint32_t cp, octet_iterator result);
+   
+

+ cp: A 32 bit integer representing a code point to append to the + sequence.
+ result: An output iterator to the place in the sequence where to + append the code point.
+ Return value: An iterator pointing to the place + after the newly appended sequence. +

+ Example of use: +

+unsigned char u[5] = {0,0,0,0,0};
+unsigned char* end = unchecked::append(0x0448, u);
+assert (u[0] == 0xd1 && u[1] == 0x88 && u[2] == 0 && u[3] == 0 && u[4] == 0);
+

+ This is a faster but less safe version of utf8::append. It does not + check for validity of the supplied code point, and may produce an invalid UTF-8 + sequence. +

+ utf8::unchecked::next +

+ Available in version 1.0 and later. +

+ Given the iterator to the beginning of a UTF-8 sequence, it returns the code point + and moves the iterator to the next position. +

+template <typename octet_iterator>
+uint32_t next(octet_iterator& it);
+   
+

+ it: a reference to an iterator pointing to the beginning of an UTF-8 + encoded code point. After the function returns, it is incremented to point to the + beginning of the next code point.
+ Return value: the 32 bit representation of the + processed UTF-8 code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = unchecked::next(w);
+assert (cp == 0x65e5);
+assert (w == twochars + 3);
+

+ This is a faster but less safe version of utf8::next. It does not + check for validity of the supplied UTF-8 sequence. +

+ utf8::unchecked::peek_next +

+ Available in version 2.1 and later. +

+ Given the iterator to the beginning of a UTF-8 sequence, it returns the code point. +

+template <typename octet_iterator>
+uint32_t peek_next(octet_iterator it);
+   
+

+ it: an iterator pointing to the beginning of an UTF-8 + encoded code point.
+ Return value: the 32 bit representation of the + processed UTF-8 code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = unchecked::peek_next(w);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ This is a faster but less safe version of utf8::peek_next. It does not + check for validity of the supplied UTF-8 sequence. +

+ utf8::unchecked::prior +

+ Available in version 1.02 and later. +

+template <typename octet_iterator>
+uint32_t prior(octet_iterator& it);
+   
+

+ it: a reference pointing to an octet within a UTF-8 encoded string. + After the function returns, it is decremented to point to the beginning of the + previous code point.
+ Return value: the 32 bit representation of the + previous code point. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars + 3;
+int cp = unchecked::prior (w);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ This is a faster but less safe version of utf8::prior. It does not + check for validity of the supplied UTF-8 sequence and offers no boundary checking. +

+ utf8::unchecked::previous (deprecated, see utf8::unchecked::prior) +

+ Deprecated in version 1.02 and later. +

+template <typename octet_iterator>
+uint32_t previous(octet_iterator& it);
+   
+

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars + 3;
+int cp = unchecked::previous (w);
+assert (cp == 0x65e5);
+assert (w == twochars);
+

+ The reason this function is deprecated is just the consistency with the "checked" + versions, where prior should be used instead of previous. + In fact, unchecked::previous behaves exactly the same as + unchecked::prior +

+ This is a faster but less safe version of utf8::previous. It does not + check for validity of the supplied UTF-8 sequence and offers no boundary checking. +

+ utf8::unchecked::advance +

+ Available in version 1.0 and later. +

+ Advances an iterator by the specified number of code points within an UTF-8 + sequence. +

+template <typename octet_iterator, typename distance_type>
+void advance (octet_iterator& it, distance_type n);
+   
+

+ it: a reference to an iterator pointing to the beginning of an UTF-8 + encoded code point. After the function returns, it is incremented to point to the + nth following code point.
+ n: a positive integer that shows how many code points we want to + advance.
+

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+unchecked::advance (w, 2);
+assert (w == twochars + 5);
+

+ This function works only "forward". In case of a negative n, there is + no effect. +

+ This is a faster but less safe version of utf8::advance. It does not + check for validity of the supplied UTF-8 sequence and offers no boundary checking. +

+ utf8::unchecked::distance +

+ Available in version 1.0 and later. +

+ Given the iterators to two UTF-8 encoded code points in a seqence, returns the + number of code points between them. +

+template <typename octet_iterator>
+typename std::iterator_traits<octet_iterator>::difference_type distance (octet_iterator first, octet_iterator last);
+

+ first: an iterator to a beginning of a UTF-8 encoded code point.
+ last: an iterator to a "post-end" of the last UTF-8 encoded code + point in the sequence we are trying to determine the length. It can be the + beginning of a new code point, or not.
+ Return value the distance between the iterators, + in code points. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+size_t dist = utf8::unchecked::distance(twochars, twochars + 5);
+assert (dist == 2);
+

+ This is a faster but less safe version of utf8::distance. It does not + check for validity of the supplied UTF-8 sequence. +

+ utf8::unchecked::utf16to8 +

+ Available in version 1.0 and later. +

+ Converts a UTF-16 encoded string to UTF-8. +

+template <typename u16bit_iterator, typename octet_iterator>
+octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result);
+   
+

+ start: an iterator pointing to the beginning of the UTF-16 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-16 encoded + string to convert.
+ result: an output iterator to the place in the UTF-8 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-8 string. +

+ Example of use: +

+unsigned short utf16string[] = {0x41, 0x0448, 0x65e5, 0xd834, 0xdd1e};
+vector<unsigned char> utf8result;
+unchecked::utf16to8(utf16string, utf16string + 5, back_inserter(utf8result));
+assert (utf8result.size() == 10);    
+

+ This is a faster but less safe version of utf8::utf16to8. It does not + check for validity of the supplied UTF-16 sequence. +

+ utf8::unchecked::utf8to16 +

+ Available in version 1.0 and later. +

+ Converts an UTF-8 encoded string to UTF-16 +

+template <typename u16bit_iterator, typename octet_iterator>
+u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result);
+   
+

+ start: an iterator pointing to the beginning of the UTF-8 encoded + string to convert. < br /> end: an iterator pointing to + pass-the-end of the UTF-8 encoded string to convert.
+ result: an output iterator to the place in the UTF-16 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-16 string. +

+ Example of use: +

+char utf8_with_surrogates[] = "\xe6\x97\xa5\xd1\x88\xf0\x9d\x84\x9e";
+vector <unsigned short> utf16result;
+unchecked::utf8to16(utf8_with_surrogates, utf8_with_surrogates + 9, back_inserter(utf16result));
+assert (utf16result.size() == 4);
+assert (utf16result[2] == 0xd834);
+assert (utf16result[3] == 0xdd1e);
+

+ This is a faster but less safe version of utf8::utf8to16. It does not + check for validity of the supplied UTF-8 sequence. +

+ utf8::unchecked::utf32to8 +

+ Available in version 1.0 and later. +

+ Converts a UTF-32 encoded string to UTF-8. +

+template <typename octet_iterator, typename u32bit_iterator>
+octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result);
+   
+

+ start: an iterator pointing to the beginning of the UTF-32 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-32 encoded + string to convert.
+ result: an output iterator to the place in the UTF-8 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-8 string. +

+ Example of use: +

+int utf32string[] = {0x448, 0x65e5, 0x10346, 0};
+vector<unsigned char> utf8result;
+utf32to8(utf32string, utf32string + 3, back_inserter(utf8result));
+assert (utf8result.size() == 9);
+

+ This is a faster but less safe version of utf8::utf32to8. It does not + check for validity of the supplied UTF-32 sequence. +

+ utf8::unchecked::utf8to32 +

+ Available in version 1.0 and later. +

+ Converts a UTF-8 encoded string to UTF-32. +

+template <typename octet_iterator, typename u32bit_iterator>
+u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result);
+   
+

+ start: an iterator pointing to the beginning of the UTF-8 encoded + string to convert.
+ end: an iterator pointing to pass-the-end of the UTF-8 encoded string + to convert.
+ result: an output iterator to the place in the UTF-32 string where to + append the result of conversion.
+ Return value: An iterator pointing to the place + after the appended UTF-32 string. +

+ Example of use: +

+char* twochars = "\xe6\x97\xa5\xd1\x88";
+vector<int> utf32result;
+unchecked::utf8to32(twochars, twochars + 5, back_inserter(utf32result));
+assert (utf32result.size() == 2);
+

+ This is a faster but less safe version of utf8::utf8to32. It does not + check for validity of the supplied UTF-8 sequence. +

+ Types From utf8::unchecked Namespace +

+ utf8::iterator +

+ Available in version 2.0 and later. +

+ Adapts the underlying octet iterator to iterate over the sequence of code points, + rather than raw octets. +

+template <typename octet_iterator>
+class iterator;
+

+ +

Member functions

iterator();: the deafult constructor; the underlying octet_iterator is + constructed with its default constructor. +
explicit iterator (const octet_iterator& octet_it); +: a constructor + that initializes the underlying octet_iterator with octet_it +
octet_iterator base () const;: returns the + underlying octet_iterator. +
uint32_t operator * () const;: decodes the utf-8 sequence + the underlying octet_iterator is pointing to and returns the code point. +
bool operator == (const iterator& rhs) + const;: returns true + if the two underlaying iterators are equal. +
bool operator != (const iterator& rhs) + const;: returns true + if the two underlaying iterators are not equal. +
iterator& operator ++ ();: the prefix increment - moves + the iterator to the next UTF-8 encoded code point. +
iterator operator ++ (int);: + the postfix increment - moves the iterator to the next UTF-8 encoded code point and returns the current one. +
iterator& operator -- ();: the prefix decrement - moves + the iterator to the previous UTF-8 encoded code point. +
iterator operator -- (int);: + the postfix decrement - moves the iterator to the previous UTF-8 encoded code point and returns the current one. +

+ Example of use: +

+char* threechars = "\xf0\x90\x8d\x86\xe6\x97\xa5\xd1\x88";
+utf8::unchecked::iterator<char*> un_it(threechars);
+utf8::unchecked::iterator<char*> un_it2 = un_it;
+assert (un_it2 == un_it);
+assert (*un_it == 0x10346);
+assert (*(++un_it) == 0x65e5);
+assert ((*un_it++) == 0x65e5);
+assert (*un_it == 0x0448);
+assert (un_it != un_it2);
+utf8::::unchecked::iterator<char*> un_endit (threechars + 9);  
+assert (++un_it == un_endit);
+assert (*(--un_it) == 0x0448);
+assert ((*un_it--) == 0x0448);
+assert (*un_it == 0x65e5);
+assert (--un_it == utf8::unchecked::iterator<char*>(threechars));
+assert (*un_it == 0x10346);
+

+ This is an unchecked version of utf8::iterator. It is faster in many cases, but offers + no validity or range checks. +

+ Points of interest +

+ Design goals and decisions +

+ The library was designed to be: +

+ Generic: for better or worse, there are many C++ string classes out there, and + the library should work with as many of them as possible. +
+ Portable: the library should be portable both accross different platforms and + compilers. The only non-portable code is a small section that declares unsigned + integers of different sizes: three typedefs. They can be changed by the users of + the library if they don't match their platform. The default setting should work + for Windows (both 32 and 64 bit), and most 32 bit and 64 bit Unix derivatives. +
+ Lightweight: follow the "pay only for what you use" guideline. +
+ Unintrusive: avoid forcing any particular design or even programming style on the + user. This is a library, not a framework. +

+ Alternatives +

+ In case you want to look into other means of working with UTF-8 strings from C++, + here is the list of solutions I am aware of: +

+ ICU Library. It is very powerful, + complete, feature-rich, mature, and widely used. Also big, intrusive, + non-generic, and doesn't play well with the Standard Library. I definitelly + recommend looking at ICU even if you don't plan to use it. +
+ C++11 language and library features. Still far from complete, and not widely + supported by compiler vendors. +
+ Glib::ustring. + A class specifically made to work with UTF-8 strings, and also feel like + std::string. If you prefer to have yet another string class in your + code, it may be worth a look. Be aware of the licensing issues, though. +
+ Platform dependent solutions: Windows and POSIX have functions to convert strings + from one encoding to another. That is only a subset of what my library offers, + but if that is all you need it may be good enough. +

+ Links +

+ The Unicode Consortium. +
+ ICU Library. +
+ UTF-8 at Wikipedia +
+ UTF-8 and Unicode FAQ for + Unix/Linux +

+ + -- cgit v1.2.1