diff options
Diffstat (limited to 'pcre_scanner.h')
| -rw-r--r-- | pcre_scanner.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/pcre_scanner.h b/pcre_scanner.h new file mode 100644 index 0000000..5617e45 --- /dev/null +++ b/pcre_scanner.h @@ -0,0 +1,172 @@ +// 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 */ |