mirror of https://github.com/djcb/mu.git
140 lines
3.3 KiB
C++
140 lines
3.3 KiB
C++
/*
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** Copyright (C) 2017 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
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**
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** This library is free software; you can redistribute it and/or
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** modify it under the terms of the GNU Lesser General Public License
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** as published by the Free Software Foundation; either version 2.1
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** of the License, or (at your option) any later version.
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**
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** This library is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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** Lesser General Public License for more details.
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**
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** You should have received a copy of the GNU Lesser General Public
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** License along with this library; if not, write to the Free
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** Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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** 02110-1301, USA.
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*/
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#ifndef __TOKENIZER_HH__
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#define __TOKENIZER_HH__
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#include <string>
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#include <vector>
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#include <deque>
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#include <ostream>
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#include <stdexcept>
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// A simple tokenizer, which turns a string into a deque of tokens
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//
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// It recognizes '(', ')', '*' 'and', 'or', 'xor', 'not'
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//
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// Note that even if we recognizes those at the lexical level, they might be demoted to mere strings
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// when we're creating the parse tree.
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//
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// Furthermore, we detect ranges ("a..b") and regexps (/../) at the parser level, since we need a
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// bit more context to resolve ambiguities.
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namespace Mu {
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// A token
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struct Token {
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enum class Type {
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Data, /**< e .g., banana or date:..456 */
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// Brackets
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Open, /**< ( */
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Close, /**< ) */
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// Unops
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Not, /**< logical not*/
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// Binops
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And, /**< logical and */
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Or, /**< logical not */
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Xor, /**< logical xor */
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Empty, /**< nothing */
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};
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size_t pos{}; /**< position in string */
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Type type{}; /**< token type */
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const std::string str{}; /**< data for this token */
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/**
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* operator==
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*
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* @param rhs right-hand side
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*
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* @return true if rhs is equal to this; false otherwise
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*/
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bool operator==(const Token& rhs) const
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{
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return pos == rhs.pos && type == rhs.type && str == rhs.str;
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}
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};
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/**
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* operator<<
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*
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* @param os an output stream
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* @param t a token type
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*
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* @return the updated output stream
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*/
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inline std::ostream&
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operator<<(std::ostream& os, Token::Type t)
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{
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switch (t) {
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case Token::Type::Data: os << "<data>"; break;
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case Token::Type::Open: os << "<open>"; break;
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case Token::Type::Close: os << "<close>"; break;
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case Token::Type::Not: os << "<not>"; break;
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case Token::Type::And: os << "<and>"; break;
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case Token::Type::Or: os << "<or>"; break;
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case Token::Type::Xor: os << "<xor>"; break;
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case Token::Type::Empty: os << "<empty>"; break;
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default: // can't happen, but pacify compiler
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throw std::runtime_error("<<bug>>");
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}
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return os;
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}
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/**
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* operator<<
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*
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* @param os an output stream
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* @param t a token
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*
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* @return the updated output stream
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*/
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inline std::ostream&
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operator<<(std::ostream& os, const Token& t)
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{
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os << t.pos << ": " << t.type;
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if (!t.str.empty())
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os << " [" << t.str << "]";
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return os;
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}
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/**
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* Tokenize a string into a vector of tokens. The tokenization always succeeds, ie., ignoring errors
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* such a missing end-".
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*
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* @param s a string
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*
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* @return a deque of tokens
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*/
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using Tokens = std::deque<Token>;
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Tokens tokenize(const std::string& s);
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} // namespace Mu
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#endif /* __TOKENIZER_HH__ */
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