mirror of
https://github.com/GothenburgBitFactory/taskwarrior.git
synced 2025-07-07 20:06:36 +02:00
125 lines
3.2 KiB
C++
125 lines
3.2 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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// taskwarrior - a command line task list manager.
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//
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// Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
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// All rights reserved.
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//
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// This program is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free Software
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// Foundation; either version 2 of the License, or (at your option) any later
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// version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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// details.
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//
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// You should have received a copy of the GNU General Public License along with
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// this program; if not, write to the
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//
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// Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor,
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// Boston, MA
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// 02110-1301
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// USA
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//
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////////////////////////////////////////////////////////////////////////////////
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#include "Lisp.h"
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////////////////////////////////////////////////////////////////////////////////
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Lisp::Lisp ()
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{
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}
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////////////////////////////////////////////////////////////////////////////////
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Lisp::~Lisp ()
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{
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}
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////////////////////////////////////////////////////////////////////////////////
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Tree* Lisp::parse (const std::string& input)
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{
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Tree* root = new Tree ("root");
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if (root)
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{
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Nibbler n (input);
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parseNode (root, n);
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}
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return root;
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}
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////////////////////////////////////////////////////////////////////////////////
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// Grammar
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// node ::= '(' list ')'
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// list ::= item [[space item] ...]
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// item ::= word | node
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void Lisp::parseNode (Tree* parent, Nibbler& n)
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{
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// Work on a stack-based copy, to allow backtracking.
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Nibbler attempt (n);
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if (attempt.skip ('('))
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{
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Tree* b = new Tree ("");
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parent->addBranch (b);
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parseList (b, attempt);
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if (attempt.skip (')'))
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{
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n = attempt;
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return;
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}
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}
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throw std::string ("Error: malformed node");
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}
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////////////////////////////////////////////////////////////////////////////////
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void Lisp::parseList (Tree* parent, Nibbler& n)
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{
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// Work on a stack-based copy, to allow backtracking.
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Nibbler attempt (n);
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parseItem (parent, attempt);
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while (attempt.skip (' '))
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parseItem (parent, attempt);
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n = attempt;
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}
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////////////////////////////////////////////////////////////////////////////////
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void Lisp::parseItem (Tree* parent, Nibbler& n)
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{
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// Work on a stack-based copy, to allow backtracking.
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Nibbler attempt (n);
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if (attempt.next () == '(')
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parseNode (parent, attempt);
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else
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parseWord (parent, attempt);
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n = attempt;
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return;
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}
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////////////////////////////////////////////////////////////////////////////////
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// A word is any group of non-whitespace followed by a space or ')'.
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void Lisp::parseWord (Tree* parent, Nibbler& n)
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{
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// Work on a stack-based copy, to allow backtracking.
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Nibbler attempt (n);
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std::string word;
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if (attempt.getUntilOneOf (" )", word))
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{
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parent->tag (word);
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n = attempt;
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return;
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}
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throw std::string ("Error: failed to parse word");
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}
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////////////////////////////////////////////////////////////////////////////////
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