Ichthyostega
cf91f167dd
Seems like a pragmatic choice, which simplifies most syntax definitions significantly. In exceptional cases, it is still possible to enforce a situation with `\b` or `\B`
97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
/*
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REGEX.hpp - helpers for working with regular expressions
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Copyright (C)
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2022, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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*/
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/** @file regex.hpp
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** Convenience wrappers and helpers for dealing with regular expressions.
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*/
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#ifndef LIB_REGEX_H
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#define LIB_REGEX_H
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#include "lib/iter-adapter.hpp"
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#include <regex>
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#include <string>
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#include <optional>
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namespace util {
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using std::regex;
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using std::smatch;
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using std::string;
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using std::string_view;
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/** wrapped regex iterator to allow usage in foreach loops */
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struct RegexSearchIter
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: std::sregex_iterator
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{
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RegexSearchIter() = default;
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RegexSearchIter (string const& toParse, regex const& regex)
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: std::sregex_iterator{toParse.begin(), toParse.end(), regex}
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{ }
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RegexSearchIter (string_view toParse, regex const& regex)
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: std::sregex_iterator{string::const_iterator{toParse.begin()}
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,string::const_iterator{toParse.end()}, regex}
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{ }
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operator bool() const { return isValid(); }
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bool isValid () const { return (*this)->ready() and not (*this)->empty(); }
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bool empty () const { return not isValid(); }
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LIFT_PARENT_INCREMENT_OPERATOR (std::sregex_iterator);
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ENABLE_USE_IN_STD_RANGE_FOR_LOOPS (RegexSearchIter);
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};
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/**
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* Helper algorithm to perform a search but require the match to start
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* at the beginning of the string or sequence, while accepting trailing content.
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* @param toParse a string, string-view or something that can be converted to string.
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* @return a std::optional with the match result (`std::smatch`).
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*/
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template<typename STR>
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std::optional<smatch>
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matchAtStart (STR&& toParse, regex const& regex)
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{
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auto search = RegexSearchIter{std::forward<STR> (toParse), regex};
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if (search and 0 == search->position(0))
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return *search;
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else
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return std::nullopt;
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}
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/** @return number of leading whitespace characters */
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template<typename STR>
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size_t
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leadingWhitespace (STR&& toParse)
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{
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static const regex LEADING_WHITESPACE{"^\\s*", regex::optimize};
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auto search = RegexSearchIter{std::forward<STR> (toParse), LEADING_WHITESPACE};
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return search? search->length() : 0;
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}
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}// namespace util
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namespace lib {
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using std::regex;
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using std::smatch;
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using std::string;
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}// namespace lib
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#endif/*LIB_REGEX_H*/
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