// Copyright (c) 2005, Google Inc. // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // // Author: Sanjay Ghemawat // // Regular-expression based scanner for parsing an input stream. // // Example 1: parse a sequence of "var = number" entries from input: // // Scanner scanner(input); // string var; // int number; // scanner.SetSkipExpression("\\s+"); // Skip any white space we encounter // while (scanner.Consume("(\\w+) = (\\d+)", &var, &number)) { // ...; // } #ifndef _PCRE_SCANNER_H #define _PCRE_SCANNER_H #include <assert.h> #include <string> #include <vector> #include <pcrecpp.h> #include <pcre_stringpiece.h> namespace pcrecpp { class PCRECPP_EXP_DEFN Scanner { public: Scanner(); explicit Scanner(const std::string& input); ~Scanner(); // Return current line number. The returned line-number is // one-based. I.e. it returns 1 + the number of consumed newlines. // // Note: this method may be slow. It may take time proportional to // the size of the input. int LineNumber() const; // Return the byte-offset that the scanner is looking in the // input data; int Offset() const; // Return true iff the start of the remaining input matches "re" bool LookingAt(const RE& re) const; // Return true iff all of the following are true // a. the start of the remaining input matches "re", // b. if any arguments are supplied, matched sub-patterns can be // parsed and stored into the arguments. // If it returns true, it skips over the matched input and any // following input that matches the "skip" regular expression. bool Consume(const RE& re, const Arg& arg0 = RE::no_arg, const Arg& arg1 = RE::no_arg, const Arg& arg2 = RE::no_arg // TODO: Allow more arguments? ); // Set the "skip" regular expression. If after consuming some data, // a prefix of the input matches this RE, it is automatically // skipped. For example, a programming language scanner would use // a skip RE that matches white space and comments. // // scanner.SetSkipExpression("\\s+|//.*|/[*](.|\n)*?[*]/"); // // Skipping repeats as long as it succeeds. We used to let people do // this by writing "(...)*" in the regular expression, but that added // up to lots of recursive calls within the pcre library, so now we // control repetition explicitly via the function call API. // // You can pass NULL for "re" if you do not want any data to be skipped. void Skip(const char* re); // DEPRECATED; does *not* repeat void SetSkipExpression(const char* re); // Temporarily pause "skip"ing. This // Skip("Foo"); code ; DisableSkip(); code; EnableSkip() // is similar to // Skip("Foo"); code ; Skip(NULL); code ; Skip("Foo"); // but avoids creating/deleting new RE objects. void DisableSkip(); // Reenable previously paused skipping. Any prefix of the input // that matches the skip pattern is immediately dropped. void EnableSkip(); /***** Special wrappers around SetSkip() for some common idioms *****/ // Arranges to skip whitespace, C comments, C++ comments. // The overall RE is a disjunction of the following REs: // \\s whitespace // //.*\n C++ comment // /[*](.|\n)*?[*]/ C comment (x*? means minimal repetitions of x) // We get repetition via the semantics of SetSkipExpression, not by using * void SkipCXXComments() { SetSkipExpression("\\s|//.*\n|/[*](?:\n|.)*?[*]/"); } void set_save_comments(bool comments) { save_comments_ = comments; } bool save_comments() { return save_comments_; } // Append to vector ranges the comments found in the // byte range [start,end] (inclusive) of the input data. // Only comments that were extracted entirely within that // range are returned: no range splitting of atomically-extracted // comments is performed. void GetComments(int start, int end, std::vector<StringPiece> *ranges); // Append to vector ranges the comments added // since the last time this was called. This // functionality is provided for efficiency when // interleaving scanning with parsing. void GetNextComments(std::vector<StringPiece> *ranges); private: std::string data_; // All the input data StringPiece input_; // Unprocessed input RE* skip_; // If non-NULL, RE for skipping input bool should_skip_; // If true, use skip_ bool skip_repeat_; // If true, repeat skip_ as long as it works bool save_comments_; // If true, aggregate the skip expression // the skipped comments // TODO: later consider requiring that the StringPieces be added // in order by their start position std::vector<StringPiece> *comments_; // the offset into comments_ that has been returned by GetNextComments int comments_offset_; // helper function to consume *skip_ and honour // save_comments_ void ConsumeSkip(); }; } // namespace pcrecpp #endif /* _PCRE_SCANNER_H */