pcre_scanner.h
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	// 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 */

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