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- /// Spart License (zlib/png)
- ///
- ///
- /// Copyright (c) 2003 Jonathan de Halleux
- ///
- /// This software is provided 'as-is', without any express or implied warranty.
- /// In no event will the authors be held liable for any damages arising from
- /// the use of this software.
- ///
- /// Permission is granted to anyone to use this software for any purpose,
- /// including commercial applications, and to alter it and redistribute it
- /// freely, subject to the following restrictions:
- ///
- /// 1. The origin of this software must not be misrepresented; you must not
- /// claim that you wrote the original software. If you use this software in a
- /// product, an acknowledgment in the product documentation would be
- /// appreciated but is not required.
- ///
- /// 2. Altered source versions must be plainly marked as such, and must not be
- /// misrepresented as being the original software.
- ///
- /// 3. This notice may not be removed or altered from any source distribution.
- ///
- /// Author: Jonathan de Halleuxnamespace Spart.Parsers.Composite
- namespace Spart.Parsers.Composite
- {
- using System;
- using Spart.Scanners;
- using Spart.Actions;
- using Spart.Parsers.NonTerminal;
- public class AlternativeParser : BinaryTerminalParser
- {
- public AlternativeParser(Parser first, Parser second)
- :base(first,second)
- {}
- public override ParserMatch ParseMain(IScanner scan)
- {
- // save scanner state
- long offset = scan.Offset;
- // apply the first parser
- ParserMatch m = FirstParser.Parse( scan );
- // if m1 successful, do m2
- if (m.Success)
- return m;
- // not found
- scan.Seek(offset);
- // apply the second parser
- m = SecondParser.Parse( scan );
- if (m.Success)
- return m;
- scan.Seek(offset);
- return scan.NoMatch;
- }
-
- public override Parser Clone()
- {
- return base.Clone();
- }
- }
- }
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