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// Copyright (c) 2008 by Dr. Colin Hirsch // Please see license.txt for license. // Include the only public header file for the PEGTL. #include <pegtl.hh> namespace example { using namespace pegtl; // This example defines a rule for quoted strings with C-style backslash-escapes // that is compatible with UTF-8 input, i.e. the quoted string can contain UTF-8 // without ever truncating a multi-byte character. // The rule 'escaped' matches a backslash-escaped character; the use of ifmust<> // ensures that every backlash is followed by one of the appropriate characters. struct escaped : ifmust< one< '\\' >, one< '\\', '"', '\'', 'a', 'f', 'n', 'r', 't', 'v' > > {}; // A regular character is anything that is not an ASCII control character. This // also matches any byte of a unicode character with multi-byte encoding in UTF-8. struct regular : not_range< 0, 31 > {}; // This is simple, a character in the quoted string is either an escaped character // or a regular character. Note that the order of the two rules is important; with // sor< regular, escaped >, a backslash would always match rule 'regular', and rule // 'escaped' would never fire, so backslash would loose its special meaning. struct character : sor< escaped, regular > {}; // A quoted string starts with a quote, and then contains characters until another // quote is encountered. Escaped quotes can be embedded, they will be matched by // rule 'escaped'. A seq<> could be used instead of the ifmust<>, however usually // a grammar will have only one rule that will match a string starting with a quote, // and in this case the ifmust<> will produce a better error message (because an // input that starts with a quote, but does not contain the corresponding closing // quote, will produce an error in rule 'quoted', rather than wherever any sor<> // backtracking in the grammar might lead to). struct quoted : ifmust< one< '"' >, until< one< '"' >, character > > {}; // Note that rule 'quoted' will work fine with UTF-8 in the sense that the quoted // string can contain any UTF-8 character, however no validation of multi-byte // encoded characters is performed. Support for UTF-8 will likely be extended // in the future.... } // example int main( int argc, char ** argv ) { for ( int i = 1; i < argc; ++i ) { pegtl::basic_parse_string< example::quoted >( argv[ i ] ); } return 0; }

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