# UTF8-CPP: UTF-8 with C++ in a Portable Way
-[The Sourceforge project page](https://sourceforge.net/projects/utfcpp)
-
-<div id="toc">
-
-## Table of Contents
-
-* [Introduction](#introduction)
-* [Examples of Use](#examples)
- * [Introductionary Sample](#introsample)
- * [Checking if a file contains valid UTF-8 text](#validfile)
- * [Ensure that a string contains valid UTF-8 text](#fixinvalid)
-* [Reference](#reference)
- * [Functions From utf8 Namespace](#funutf8)
- * [Types From utf8 Namespace](#typesutf8)
- * [Functions From utf8::unchecked Namespace](#fununchecked)
- * [Types From utf8::unchecked Namespace](#typesunchecked)
-* [Points of Interest](#points)
-* [Links](#links)
-
-</div>
## Introduction
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:
-<pre><span class="preprocessor">#include <fstream></span>
-<span class="preprocessor">#include <iostream></span>
-<span class="preprocessor">#include <string></span>
-<span class="preprocessor">#include <vector></span>
-<span class="preprocessor">#include "utf8.h"</span>
-<span class="keyword">using namespace</span> std;
-<span class="keyword">int</span> main(<span class="keyword">int</span> argc, <span class="keyword">char</span>** argv)
+```
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+#include "utf8.h"
+using namespace std;
+int main(int argc, char** argv)
{
- <span class="keyword">if</span> (argc != <span class="literal">2</span>) {
- cout << <span class="literal">"\nUsage: docsample filename\n"</span>;
- <span class="keyword">return</span> <span class="literal">0</span>;
+ if (argc != 2) {
+ cout << "\nUsage: docsample filename\n";
+ return 0;
}
- <span class="keyword">const char</span>* test_file_path = argv[1];
- <span class="comment">// Open the test file (contains UTF-8 encoded text)</span>
+ const char* test_file_path = argv[1];
+ // Open the test file (contains UTF-8 encoded text)
ifstream fs8(test_file_path);
- <span class="keyword">if</span> (!fs8.is_open()) {
- cout << <span class="literal">"Could not open "</span> << test_file_path << endl;
- <span class="keyword">return</span> <span class="literal">0</span>;
+ if (!fs8.is_open()) {
+ cout << "Could not open " << test_file_path << endl;
+ return 0;
}
- <span class="keyword">unsigned</span> line_count = <span class="literal">1</span>;
+ unsigned line_count = 1;
string line;
- <span class="comment">// Play with all the lines in the file</span>
- <span class="keyword">while</span> (getline(fs8, line)) {
- <span class="comment">// check for invalid utf-8 (for a simple yes/no check, there is also utf8::is_valid function)</span>
+ // 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());
- <span class="keyword">if</span> (end_it != line.end()) {
- cout << <span class="literal">"Invalid UTF-8 encoding detected at line "</span> << line_count << <span class="literal">"\n"</span>;
- cout << <span class="literal">"This part is fine: "</span> << string(line.begin(), end_it) << <span class="literal">"\n"</span>;
+ 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";
}
- <span class="comment">// Get the line length (at least for the valid part)</span>
- <span class="keyword">int</span> length = utf8::distance(line.begin(), end_it);
- cout << <span class="literal">"Length of line "</span> << line_count << <span class="literal">" is "</span> << length << <span class="literal">"\n"</span>;
+ // 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";
- <span class="comment">// Convert it to utf-16</span>
+ // Convert it to utf-16
vector<unsigned short> utf16line;
utf8::utf8to16(line.begin(), end_it, back_inserter(utf16line));
- <span class="comment">// And back to utf-8</span>
+ // And back to utf-8
string utf8line;
utf8::utf16to8(utf16line.begin(), utf16line.end(), back_inserter(utf8line));
- <span class="comment">// Confirm that the conversion went OK:</span>
- <span class="keyword">if</span> (utf8line != string(line.begin(), end_it))
- cout << <span class="literal">"Error in UTF-16 conversion at line: "</span> << line_count << <span class="literal">"\n"</span>;
+ // 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++;
}
- <span class="keyword">return</span> <span class="literal">0</span>;
+ return 0;
}
-</pre>
+```
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`.
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:
-<pre>
-<span class="keyword">bool</span> valid_utf8_file(i<span class="keyword">const char</span>* file_name)
+```
+bool valid_utf8_file(const char* file_name)
{
ifstream ifs(file_name);
- <span class="keyword">if</span> (!ifs)
- <span class="keyword">return false</span>; <span class="comment">// even better, throw here</span>
+ if (!ifs)
+ return false; // even better, throw here
- istreambuf_iterator<<span class="keyword">char</span>> it(ifs.rdbuf());
- istreambuf_iterator<<span class="keyword">char</span>> eos;
+ istreambuf_iterator<char> it(ifs.rdbuf());
+ istreambuf_iterator<char> eos;
- <span class="keyword">return</span> utf8::is_valid(it, eos);
+ return utf8::is_valid(it, eos);
}
-</pre>
+```
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:
-<pre> utf8::utf8to16(it, eos, back_inserter(u16string));
-</pre>
+```
+ 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:
-<pre><span class="keyword">void</span> fix_utf8_string(std::string& str)
+```
+void fix_utf8_string(std::string& str)
{
std::string temp;
utf8::replace_invalid(str.begin(), str.end(), back_inserter(temp));
str = temp;
}
-</pre>
+```
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.
Encodes a 32 bit code point as a UTF-8 sequence of octets and appends the sequence to a UTF-8 string.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
octet_iterator append(uint32_t cp, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: an iterator pointing to the place after the newly appended sequence.
+`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:
-<pre><span class="keyword">unsigned char</span> u[<span class="literal">5</span>] = {<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>};
-<span class="keyword">unsigned char</span>* end = append(<span class="literal">0x0448</span>, u);
-assert (u[<span class="literal">0</span>] == <span class="literal">0xd1</span> && u[<span class="literal">1</span>] == <span class="literal">0x88</span> && u[<span class="literal">2</span>] == <span class="literal">0</span> && u[<span class="literal">3</span>] == <span class="literal">0</span> && u[<span class="literal">4</span>] == <span class="literal">0</span>);
-</pre>
+```
+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.
Given the iterator to the beginning of the UTF-8 sequence, it returns the code point and moves the iterator to the next position.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t next(octet_iterator& it, octet_iterator end);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the processed UTF-8 code point.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars;
-<span class="keyword">int</span> cp = next(w, twochars + <span class="literal">6</span>);
-assert (cp == <span class="literal">0x65e5</span>);
-assert (w == twochars + <span class="literal">3</span>);
-</pre>
+```
+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.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t peek_next(octet_iterator it, octet_iterator end);
+```
-</pre>
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the processed UTF-8 code point.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars;
-<span class="keyword">int</span> cp = peek_next(w, twochars + <span class="literal">6</span>);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = peek_next(w, twochars + 6);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
In case of an invalid UTF-8 seqence, a `utf8::invalid_utf8` exception is thrown.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t prior(octet_iterator& it, octet_iterator start);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the previous code point.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">unsigned char</span>* w = twochars + <span class="literal">3</span>;
-<span class="keyword">int</span> cp = prior (w, twochars);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+unsigned char* w = twochars + 3;
+int cp = prior (w, twochars);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
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.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t previous(octet_iterator& it, octet_iterator pass_start);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the previous code point.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">unsigned char</span>* w = twochars + <span class="literal">3</span>;
-<span class="keyword">int</span> cp = previous (w, twochars - <span class="literal">1</span>);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+unsigned char* w = twochars + 3;
+int cp = previous (w, twochars - 1);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
+
`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.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, typename distance_type>
-<span class="keyword">void</span> advance (octet_iterator& it, distance_type n, octet_iterator end);
-
-</pre>
+```
+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.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">unsigned char</span>* w = twochars;
-advance (w, <span class="literal">2</span>, twochars + <span class="literal">6</span>);
-assert (w == twochars + <span class="literal">5</span>);
-</pre>
+```
+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.
Given the iterators to two UTF-8 encoded code points in a seqence, returns the number of code points between them.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">typename</span> std::iterator_traits<octet_iterator>::difference_type distance (octet_iterator first, octet_iterator last);
-
-</pre>
+```
+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.
- <span class="return_value">Return value</span> the distance between the iterators, in code points.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-size_t dist = utf8::distance(twochars, twochars + <span class="literal">5</span>);
-assert (dist == <span class="literal">2</span>);
-</pre>
+```
+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.
Converts a UTF-16 encoded string to UTF-8.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> u16bit_iterator, <span class="keyword">typename</span> octet_iterator>
+```
+template <typename u16bit_iterator, typename octet_iterator>
octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-8 string.
+`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:
-<pre><span class="keyword">unsigned short</span> utf16string[] = {<span class="literal">0x41</span>, <span class="literal">0x0448</span>, <span class="literal">0x65e5</span>, <span class="literal">0xd834</span>, <span class="literal">0xdd1e</span>};
-vector<<span class="keyword">unsigned char</span>> utf8result;
-utf16to8(utf16string, utf16string + <span class="literal">5</span>, back_inserter(utf8result));
-assert (utf8result.size() == <span class="literal">10</span>);
-</pre>
+```
+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.
Converts an UTF-8 encoded string to UTF-16
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> u16bit_iterator, typename octet_iterator>
+```
+template <typename u16bit_iterator, typename octet_iterator>
u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-16 string.
+`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:
-<pre><span class="keyword">char</span> utf8_with_surrogates[] = <span class="literal">"\xe6\x97\xa5\xd1\x88\xf0\x9d\x84\x9e"</span>;
-vector <<span class="keyword">unsigned short</span>> utf16result;
-utf8to16(utf8_with_surrogates, utf8_with_surrogates + <span class="literal">9</span>, back_inserter(utf16result));
-assert (utf16result.size() == <span class="literal">4</span>);
-assert (utf16result[<span class="literal">2</span>] == <span class="literal">0xd834</span>);
-assert (utf16result[<span class="literal">3</span>] == <span class="literal">0xdd1e</span>);
-</pre>
+```
+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.
Converts a UTF-32 encoded string to UTF-8.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, typename u32bit_iterator>
+```
+template <typename octet_iterator, typename u32bit_iterator>
octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-8 string.
+`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:
-<pre><span class="keyword">int</span> utf32string[] = {<span class="literal">0x448</span>, <span class="literal">0x65E5</span>, <span class="literal">0x10346</span>, <span class="literal">0</span>};
-vector<<span class="keyword">unsigned char</span>> utf8result;
-utf32to8(utf32string, utf32string + <span class="literal">3</span>, back_inserter(utf8result));
-assert (utf8result.size() == <span class="literal">9</span>);
-</pre>
+```
+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.
Converts a UTF-8 encoded string to UTF-32.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, <span class="keyword">typename</span> u32bit_iterator>
+```
+template <typename octet_iterator, typename u32bit_iterator>
u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-32 string.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-vector<<span class="keyword">int</span>> utf32result;
-utf8to32(twochars, twochars + <span class="literal">5</span>, back_inserter(utf32result));
-assert (utf32result.size() == <span class="literal">2</span>);
-</pre>
+```
+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.
Detects an invalid sequence within a UTF-8 string.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
octet_iterator find_invalid(octet_iterator start, octet_iterator end);
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: an iterator pointing to the first invalid octet in the UTF-8 string. In case none were found, equals `end`.
+`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:
-<pre><span class="keyword">char</span> utf_invalid[] = <span class="literal">"\xe6\x97\xa5\xd1\x88\xfa"</span>;
-<span class="keyword">char</span>* invalid = find_invalid(utf_invalid, utf_invalid + <span class="literal">6</span>);
-assert (invalid == utf_invalid + <span class="literal">5</span>);
-</pre>
+```
+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.
Checks whether a sequence of octets is a valid UTF-8 string.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">bool</span> is_valid(octet_iterator start, octet_iterator end);
-
-</pre>
+```
+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.
- <span class="return_value">Return value</span>: `true` if the sequence is a valid UTF-8 string; `false` if not.
+`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:
-<pre><span class="keyword">char</span> utf_invalid[] = <span class="literal">"\xe6\x97\xa5\xd1\x88\xfa"</span>;
-<span class="keyword">bool</span> bvalid = is_valid(utf_invalid, utf_invalid + <span class="literal">6</span>);
+```
+char utf_invalid[] = "\xe6\x97\xa5\xd1\x88\xfa";
+bool bvalid = is_valid(utf_invalid, utf_invalid + 6);
assert (bvalid == false);
-</pre>
+```
`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.
Replaces all invalid UTF-8 sequences within a string with a replacement marker.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, <span class="keyword">typename</span> output_iterator>
+```
+template <typename octet_iterator, typename output_iterator>
output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, uint32_t replacement);
-<span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, <span class="keyword">typename</span> output_iterator>
+template <typename octet_iterator, typename output_iterator>
output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out);
-
-</pre>
+```
`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`
- <span class="return_value">Return value</span>: An iterator pointing to the place after the UTF-8 string with replaced invalid sequences.
+`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:
-<pre><span class="keyword">char</span> invalid_sequence[] = <span class="literal">"a\x80\xe0\xa0\xc0\xaf\xed\xa0\x80z"</span>;
-vector<<span class="keyword">char</span>> replace_invalid_result;
-replace_invalid (invalid_sequence, invalid_sequence + sizeof(invalid_sequence), back_inserter(replace_invalid_result), <span class="literal">'?'</span>);
+```
+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);
-<span class="keyword">char</span>* fixed_invalid_sequence = <span class="literal">"a????z"</span>;
+char* fixed_invalid_sequence = "a????z";
assert (std::equal(replace_invalid_result.begin(), replace_invalid_result.end(), fixed_invalid_sequence));
-</pre>
+```
`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.
Checks whether an octet sequence starts with a UTF-8 byte order mark (BOM)
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">bool</span> starts_with_bom (octet_iterator it, octet_iterator end);
-</pre>
+```
+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
- <span class="return_value">Return value</span>: `true` if the sequence starts with a UTF-8 byte order mark; `false` if not.
+`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:
-<pre><span class="keyword">unsigned char</span> byte_order_mark[] = {<span class="literal">0xef</span>, <span class="literal">0xbb</span>, <span class="literal">0xbf</span>};
-<span class="keyword">bool</span> bbom = starts_with_bom(byte_order_mark, byte_order_mark + <span class="keyword">sizeof</span>(byte_order_mark));
-assert (bbom == <span class="literal">true</span>);
-</pre>
+```
+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.
Checks whether a sequence of three octets is a UTF-8 byte order mark (BOM)
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">bool</span> is_bom (octet_iterator it); <span class="comment"> // Deprecated</span>
-</pre>
+```
+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
- <span class="return_value">Return value</span>: `true` if the sequence is UTF-8 byte order mark; `false` if not.
+`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:
-<pre><span class="keyword">unsigned char</span> byte_order_mark[] = {<span class="literal">0xef</span>, <span class="literal">0xbb</span>, <span class="literal">0xbf</span>};
-<span class="keyword">bool</span> bbom = is_bom(byte_order_mark);
-assert (bbom == <span class="literal">true</span>);
-</pre>
+```
+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.
Base class for the exceptions thrown by UTF CPP library functions.
-<pre><span class="keyword">class</span> exception : <span class="keyword">public</span> std::exception {};
-</pre>
+```
+class exception : public std::exception {};
+```
Example of use:
-<pre><span class="keyword">try</span> {
+```
+try {
code_that_uses_utf_cpp_library();
}
-<span class="keyword">catch</span>(<span class="keyword">const</span> utf8::exception& utfcpp_ex) {
+catch(const utf8::exception& utfcpp_ex) {
cerr << utfcpp_ex.what();
}
-</pre>
+```
#### utf8::invalid_code_point
Thrown by UTF8 CPP functions such as `advance` and `next` if an UTF-8 sequence represents and invalid code point.
-<pre><span class="keyword">class</span> invalid_code_point : <span class="keyword">public</span> exception {
-<span class="keyword">public</span>:
- uint32_t code_point() <span class="keyword">const</span>;
+```
+class invalid_code_point : public exception {
+public:
+ uint32_t code_point() const;
};
-
-</pre>
+```
Member function `code_point()` can be used to determine the invalid code point that caused the exception to be thrown.
Thrown by UTF8 CPP functions such as `next` and `prior` if an invalid UTF-8 sequence is detected during decoding.
-<pre><span class="keyword">class</span> invalid_utf8 : <span class="keyword">public</span> exception {
-<span class="keyword">public</span>:
- uint8_t utf8_octet() <span class="keyword">const</span>;
+```
+class invalid_utf8 : public exception {
+public:
+ uint8_t utf8_octet() const;
};
-</pre>
+```
Member function `utf8_octet()` can be used to determine the beginning of the byte sequence that caused the exception to be thrown.
Thrown by UTF8 CPP function `utf16to8` if an invalid UTF-16 sequence is detected during decoding.
-<pre><span class="keyword">class</span> invalid_utf16 : <span class="keyword">public</span> exception {
-<span class="keyword">public</span>:
- uint16_t utf16_word() <span class="keyword">const</span>;
+```
+class invalid_utf16 : public exception {
+public:
+ uint16_t utf16_word() const;
};
-</pre>
+```
Member function `utf16_word()` can be used to determine the UTF-16 code unit that caused the exception to be thrown.
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.
-<pre><span class="keyword">class</span> not_enough_room : <span class="keyword">public</span> exception {};
-</pre>
+```
+class not_enough_room : public exception {};
+```
#### utf8::iterator
Adapts the underlying octet iterator to iterate over the sequence of code points, rather than raw octets.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">class</span> iterator;
-</pre>
+```
+template <typename octet_iterator>
+class iterator;
+```
##### Member functions
-<dl>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-</dl>
+`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:
-<pre><span class="keyword">char</span>* threechars = <span class="literal">"\xf0\x90\x8d\x86\xe6\x97\xa5\xd1\x88"</span>;
-utf8::iterator<<span class="keyword">char</span>*> it(threechars, threechars, threechars + <span class="literal">9</span>);
-utf8::iterator<<span class="keyword">char</span>*> it2 = it;
+```
+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 == <span class="literal">0x10346</span>);
-assert (*(++it) == <span class="literal">0x65e5</span>);
-assert ((*it++) == <span class="literal">0x65e5</span>);
-assert (*it == <span class="literal">0x0448</span>);
+assert (*it == 0x10346);
+assert (*(++it) == 0x65e5);
+assert ((*it++) == 0x65e5);
+assert (*it == 0x0448);
assert (it != it2);
-utf8::iterator<<span class="keyword">char</span>*> endit (threechars + <span class="literal">9</span>, threechars, threechars + <span class="literal">9</span>);
+utf8::iterator<char*> endit (threechars + 9, threechars, threechars + 9);
assert (++it == endit);
-assert (*(--it) == <span class="literal">0x0448</span>);
-assert ((*it--) == <span class="literal">0x0448</span>);
-assert (*it == <span class="literal">0x65e5</span>);
-assert (--it == utf8::iterator<<span class="keyword">char</span>*>(threechars, threechars, threechars + <span class="literal">9</span>));
-assert (*it == <span class="literal">0x10346</span>);
-</pre>
+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.:
-<pre>std::string s = <span class="literal">"example"</span>;
+```
+std::string s = "example";
utf8::iterator i (s.begin(), s.begin(), s.end());
-</pre>
+```
### Functions From utf8::unchecked Namespace
Encodes a 32 bit code point as a UTF-8 sequence of octets and appends the sequence to a UTF-8 string.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
octet_iterator append(uint32_t cp, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the newly appended 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:
-<pre><span class="keyword">unsigned char</span> u[<span class="literal">5</span>] = {<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>,<span class="literal">0</span>};
-<span class="keyword">unsigned char</span>* end = unchecked::append(<span class="literal">0x0448</span>, u);
-assert (u[<span class="literal">0</span>] == <span class="literal">0xd1</span> && u[<span class="literal">1</span>] == <span class="literal">0x88</span> && u[<span class="literal">2</span>] == <span class="literal">0</span> && u[<span class="literal">3</span>] == <span class="literal">0</span> && u[<span class="literal">4</span>] == <span class="literal">0</span>);
-</pre>
+```
+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.
Given the iterator to the beginning of a UTF-8 sequence, it returns the code point and moves the iterator to the next position.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t next(octet_iterator& it);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the processed UTF-8 code point.
+ Return value: the 32 bit representation of the processed UTF-8 code point.
Example of use:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars;
-<span class="keyword">int</span> cp = unchecked::next(w);
-assert (cp == <span class="literal">0x65e5</span>);
-assert (w == twochars + <span class="literal">3</span>);
-</pre>
+```
+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.
Given the iterator to the beginning of a UTF-8 sequence, it returns the code point.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t peek_next(octet_iterator it);
-
-</pre>
+```
`it`: an iterator pointing to the beginning of an UTF-8 encoded code point.
- <span class="return_value">Return value</span>: the 32 bit representation of the processed UTF-8 code point.
+Return value: the 32 bit representation of the processed UTF-8 code point.
Example of use:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars;
-<span class="keyword">int</span> cp = unchecked::peek_next(w);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars;
+int cp = unchecked::peek_next(w);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
This is a faster but less safe version of `utf8::peek_next`. It does not check for validity of the supplied UTF-8 sequence.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t prior(octet_iterator& it);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the previous code point.
+ Return value: the 32 bit representation of the previous code point.
Example of use:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars + <span class="literal">3</span>;
-<span class="keyword">int</span> cp = unchecked::prior (w);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars + 3;
+int cp = unchecked::prior (w);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
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.
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.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
+```
+template <typename octet_iterator>
uint32_t previous(octet_iterator& it);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: the 32 bit representation of the previous code point.
+Return value: the 32 bit representation of the previous code point.
Example of use:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars + <span class="literal">3</span>;
-<span class="keyword">int</span> cp = unchecked::previous (w);
-assert (cp == <span class="literal">0x65e5</span>);
+```
+char* twochars = "\xe6\x97\xa5\xd1\x88";
+char* w = twochars + 3;
+int cp = unchecked::previous (w);
+assert (cp == 0x65e5);
assert (w == twochars);
-</pre>
+```
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`
Advances an iterator by the specified number of code points within an UTF-8 sequence.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, typename distance_type>
-<span class="keyword">void</span> advance (octet_iterator& it, distance_type n);
-
-</pre>
+```
+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.
+`n`: a positive integer that shows how many code points we want to advance.
Example of use:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-<span class="keyword">char</span>* w = twochars;
-unchecked::advance (w, <span class="literal">2</span>);
-assert (w == twochars + <span class="literal">5</span>);
-</pre>
+```
+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.
Given the iterators to two UTF-8 encoded code points in a seqence, returns the number of code points between them.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">typename</span> std::iterator_traits<octet_iterator>::difference_type distance (octet_iterator first, octet_iterator last);
-</pre>
+```
+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.
- <span class="return_value">Return value</span> the distance between the iterators, in code points.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-size_t dist = utf8::unchecked::distance(twochars, twochars + <span class="literal">5</span>);
-assert (dist == <span class="literal">2</span>);
-</pre>
+```
+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.
Converts a UTF-16 encoded string to UTF-8.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> u16bit_iterator, <span class="keyword">typename</span> octet_iterator>
+```
+template <typename u16bit_iterator, typename octet_iterator>
octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-8 string.
+`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:
-<pre><span class="keyword">unsigned short</span> utf16string[] = {<span class="literal">0x41</span>, <span class="literal">0x0448</span>, <span class="literal">0x65e5</span>, <span class="literal">0xd834</span>, <span class="literal">0xdd1e</span>};
-vector<<span class="keyword">unsigned char</span>> utf8result;
-unchecked::utf16to8(utf16string, utf16string + <span class="literal">5</span>, back_inserter(utf8result));
-assert (utf8result.size() == <span class="literal">10</span>);
-</pre>
+```
+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.
Converts an UTF-8 encoded string to UTF-16
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> u16bit_iterator, typename octet_iterator>
+```
+template <typename u16bit_iterator, typename octet_iterator>
u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-16 string.
+`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:
-<pre><span class="keyword">char</span> utf8_with_surrogates[] = <span class="literal">"\xe6\x97\xa5\xd1\x88\xf0\x9d\x84\x9e"</span>;
-vector <<span class="keyword">unsigned short</span>> utf16result;
-unchecked::utf8to16(utf8_with_surrogates, utf8_with_surrogates + <span class="literal">9</span>, back_inserter(utf16result));
-assert (utf16result.size() == <span class="literal">4</span>);
-assert (utf16result[<span class="literal">2</span>] == <span class="literal">0xd834</span>);
-assert (utf16result[<span class="literal">3</span>] == <span class="literal">0xdd1e</span>);
-</pre>
+```
+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.
Converts a UTF-32 encoded string to UTF-8.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, <span class="keyword">typename</span> u32bit_iterator>
+```
+template <typename octet_iterator, typename u32bit_iterator>
octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-8 string.
+`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:
-<pre><span class="keyword">int</span> utf32string[] = {<span class="literal">0x448</span>, <span class="literal">0x65e5</span>, <span class="literal">0x10346</span>, <span class="literal">0</span>};
-vector<<span class="keyword">unsigned char</span>> utf8result;
-utf32to8(utf32string, utf32string + <span class="literal">3</span>, back_inserter(utf8result));
-assert (utf8result.size() == <span class="literal">9</span>);
-</pre>
+```
+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.
Converts a UTF-8 encoded string to UTF-32.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator, typename u32bit_iterator>
+```
+template <typename octet_iterator, typename u32bit_iterator>
u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result);
-
-</pre>
+```
`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.
- <span class="return_value">Return value</span>: An iterator pointing to the place after the appended UTF-32 string.
+`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:
-<pre><span class="keyword">char</span>* twochars = <span class="literal">"\xe6\x97\xa5\xd1\x88"</span>;
-vector<<span class="keyword">int</span>> utf32result;
-unchecked::utf8to32(twochars, twochars + <span class="literal">5</span>, back_inserter(utf32result));
-assert (utf32result.size() == <span class="literal">2</span>);
-</pre>
+```
+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.
Adapts the underlying octet iterator to iterate over the sequence of code points, rather than raw octets.
-<pre><span class="keyword">template</span> <<span class="keyword">typename</span> octet_iterator>
-<span class="keyword">class</span> iterator;
-</pre>
+```
+template <typename octet_iterator>
+class iterator;
+```
##### Member functions
-<dl>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-<dt>
-
-<dd>
-
-</dl>
+`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:
-<pre><span class="keyword">char</span>* threechars = <span class="literal">"\xf0\x90\x8d\x86\xe6\x97\xa5\xd1\x88"</span>;
-utf8::unchecked::iterator<<span class="keyword">char</span>*> un_it(threechars);
-utf8::unchecked::iterator<<span class="keyword">char</span>*> un_it2 = un_it;
+```
+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 == <span class="literal">0x10346</span>);
-assert (*(++un_it) == <span class="literal">0x65e5</span>);
-assert ((*un_it++) == <span class="literal">0x65e5</span>);
-assert (*un_it == <span class="literal">0x0448</span>);
+assert (*un_it == 0x10346);
+assert (*(++un_it) == 0x65e5);
+assert ((*un_it++) == 0x65e5);
+assert (*un_it == 0x0448);
assert (un_it != un_it2);
-utf8::::unchecked::iterator<<span class="keyword">char</span>*> un_endit (threechars + <span class="literal">9</span>);
+utf8::::unchecked::iterator<char*> un_endit (threechars + 9);
assert (++un_it == un_endit);
-assert (*(--un_it) == <span class="literal">0x0448</span>);
-assert ((*un_it--) == <span class="literal">0x0448</span>);
-assert (*un_it == <span class="literal">0x65e5</span>);
-assert (--un_it == utf8::unchecked::iterator<<span class="keyword">char</span>*>(threechars));
-assert (*un_it == <span class="literal">0x10346</span>);
-</pre>
+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.
projects / icinga2 / commitdiff