An action is executed when the respective expression is found. Sregex expr = (+_w) > _s > +_w Įxample 9.4 returns true for boost::xpressive::regex_match() and writes Boost to standard output. A notation like “ \w?” becomes !_w with Boost.Xpressive because the exclamation mark must be prefixed.īoost.Xpressive supports actions that can be linked to expressions – something Boost.Regex doesn’t support. Since the question mark isn’t a valid operator in C++, Boost.Xpressive replaces it with the exclamation mark. For example, the question mark is a meta character in regular expressions to express that a preceding item is optional. The plus sign is an unary operator, which in C++ must be put in front of an object.īoost.Xpressive emulates the rules of regular expressions as much as they can be emulated in C++. While the syntax of regular expressions expects that quantifiers are put behind character groups – like with “ \w+” – the plus sign must be put in front of _w. To express that at least one alphanumeric character should be found, _w is prefixed with a plus sign. Boost.Xpressive provides the operator operator>, which is used in Example 9.3. Otherwise, the result wouldn’t be valid C++ code. While “ \w” and “ \s” can be written one after another in a string, objects like _w and _s must be concatenated with an operator. For example, the object _w is similar to “ \w”. The library provides objects for character groups. Both examples search for at least one alphanumeric character followed by one space followed by at least one alphanumeric character.īoost.Xpressive makes it possible to write regular expressions with C++ code. It is exactly the same regular expression. Compare this with Example 9.2, where the regular expression is applied to a string of type const char*. Because s is based on std::string in Example 9.1, the type of the regular expression must be boost::xpressive::sregex. The type of the regular expression in Boost.Xpressive depends on the type of the string being searched. However, there is a fundamental difference between Boost.Xpressive and Boost.Regex. You can see this in Example 9.1, which uses the function boost::xpressive::regex_match(), and which looks similar to Example 8.1. boost::xpressive::regex_match() compares strings, boost::xpressive::regex_search() searches in strings, and boost::xpressive::regex_replace() replaces characters in strings. Std::cout << std::boolalpha << regex_match(s, expr) << '\n' īoost.Xpressive basically provides the same functions as Boost.Regex, except they are defined in the namespace of Boost.Xpressive. Send us feedback about these examples.Sregex expr = sregex::compile("\\w+\\s\\w+") These examples are programmatically compiled from various online sources to illustrate current usage of the word 'expressive.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Manohla Dargis, New York Times, 15 June 2023 See More Manuel Mendoza, Dallas News, 15 June 2023 Together with Scarlett Johansson, Schwartzman fills out the film’s expressive center with humor and perfect timing. Ben Croll, Variety, 14 June 2023 It’s always been this avenue that encompasses the athletic side of me and then the drama and expressive storytelling. Armond White, National Review, 23 June 2023 Taking inspiration from mother nature, who thoughtfully designed the real life critters to be intensely physically expressive, Renner gave his mallard characters wide and expressive eyes, with undulating brows that act as punctuation marks, rising and falling to underscore each line and emotion. Tarot Astrologers, Chicago Tribune, 24 June 2023 Hipgnosis epitomized how the packaging of music on long-playing vinyl discs created a new expressive form. Dale Arden Chong, ELLE, 28 June 2023 Taurus April 20-May 20 A negative voice in your head could derail your more expressive urges. Kiara Alfonseca, ABC News, 30 June 2023 This shopper, the designer explains, is expressive and bold-and also on the move. Jeremy Eichler,, 7 July 2023 The Supreme Court ruled on Friday in favor of an evangelical Christian website designer in a case involving whether businesses can refuse to do services that involve expressive speech because of First Amendment free speech rights. Recent Examples on the Web Enter Email Sign Up True to form, A Far Cry’s performances drew strength from its alchemical wedding of typically opposing forces: pinpoint ensemble precision and intense expressive commitment.
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