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ICU-23004 add sample code to file docs

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Markus Scherer 2025-03-24 14:34:14 -07:00
parent fbf6c6d7e0
commit 7920b32004
1 changed files with 105 additions and 0 deletions
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105
icu4c/source/common/unicode/utfiterator.h
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@ -98,6 +98,111 @@ namespace header {}
/**
* \file
* \brief C++ header-only API: C++ iterators over Unicode strings (=UTF-8/16/32 if well-formed).
*
* Sample code:
* \code
* #include <string_view>
* #include <iostream>
* #include "unicode/utypes.h"
* #include "unicode/utfiterator.h"
*
* using U_HEADER_ONLY_NAMESPACE::utfIterator;
* using U_HEADER_ONLY_NAMESPACE::utfStringCodePoints;
* using U_HEADER_ONLY_NAMESPACE::unsafeUTFIterator;
* using U_HEADER_ONLY_NAMESPACE::unsafeUTFStringCodePoints;
*
* int32_t rangeLoop16(std::u16string_view s) {
* // We are just adding up the code points for minimal-code demonstration purposes.
* int32_t sum = 0;
* for (auto units : utfStringCodePoints<UChar32, UTF_BEHAVIOR_NEGATIVE>(s)) {
* sum += units.codePoint(); // < 0 if ill-formed
* }
* return sum;
* }
*
* int32_t loopIterPlusPlus16(std::u16string_view s) {
* auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
* int32_t sum = 0;
* for (auto iter = range.begin(), limit = range.end(); iter != limit;) {
* sum += (*iter++).codePoint(); // U+FFFD if ill-formed
* }
* return sum;
* }
*
* int32_t backwardLoop16(std::u16string_view s) {
* auto range = utfStringCodePoints<UChar32, UTF_BEHAVIOR_SURROGATE>(s);
* int32_t sum = 0;
* for (auto start = range.begin(), iter = range.end(); start != iter;) {
* sum += (*--iter).codePoint(); // surrogate code point if unpaired / ill-formed
* }
* return sum;
* }
*
* int32_t reverseLoop8(std::string_view s) {
* auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
* int32_t sum = 0;
* for (auto iter = range.rbegin(), limit = range.rend(); iter != limit; ++iter) {
* sum += iter->codePoint(); // U+FFFD if ill-formed
* }
* return sum;
* }
*
* int32_t countCodePoints16(std::u16string_view s) {
* auto range = utfStringCodePoints<UChar32, UTF_BEHAVIOR_SURROGATE>(s);
* return std::distance(range.begin(), range.end());
* }
*
* int32_t unsafeRangeLoop16(std::u16string_view s) {
* int32_t sum = 0;
* for (auto units : unsafeUTFStringCodePoints<UChar32>(s)) {
* sum += units.codePoint();
* }
* return sum;
* }
*
* int32_t unsafeReverseLoop8(std::string_view s) {
* auto range = unsafeUTFStringCodePoints<UChar32>(s);
* int32_t sum = 0;
* for (auto iter = range.rbegin(), limit = range.rend(); iter != limit; ++iter) {
* sum += iter->codePoint();
* }
* return sum;
* }
*
* char32_t firstCodePointOrFFFD16(std::u16string_view s) {
* if (s.empty()) { return 0xfffd; }
* auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
* return range.begin()->codePoint();
* }
*
* std::string_view firstSequence8(std::string_view s) {
* if (s.empty()) { return {}; }
* auto range = utfStringCodePoints<char32_t, UTF_BEHAVIOR_FFFD>(s);
* auto units = *(range.begin());
* if (units.wellFormed()) {
* return units.stringView();
* } else {
* return {};
* }
* }
*
* template<typename InputStream> // some istream or streambuf
* std::u32string cpFromInput(InputStream &in) {
* // This is a single-pass input_iterator.
* std::istreambuf_iterator bufIter(in);
* std::istreambuf_iterator<typename InputStream::char_type> bufLimit;
* auto iter = utfIterator<char32_t, UTF_BEHAVIOR_FFFD>(bufIter);
* auto limit = utfIterator<char32_t, UTF_BEHAVIOR_FFFD>(bufLimit);
* std::u32string s32;
* for (; iter != limit; ++iter) {
* s32.push_back(iter->codePoint());
* }
* return s32;
* }
*
* std::u32string cpFromStdin() { return cpFromInput(std::cin); }
* std::u32string cpFromWideStdin() { return cpFromInput(std::wcin); }
* \endcode
*/
#ifndef U_HIDE_DRAFT_API