ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change
on this file since db62eef was
5a89a2b,
checked in by Aaron Moss <a3moss@…>, 6 years ago
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Add interned_string code to proposals
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Property mode set to
100644
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File size:
1.6 KB
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1 | #pragma once |
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2 | |
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3 | // Copyright (c) 2015 University of Waterloo |
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4 | // |
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5 | // The contents of this file are covered under the licence agreement in |
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6 | // the file "LICENCE" distributed with this repository. |
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7 | |
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8 | #include <functional> |
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9 | #include <string> |
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10 | #include <unordered_set> |
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11 | #include <utility> |
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12 | |
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13 | /// Keeps canonical copies of a std::string for quicker comparisons |
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14 | class interned_string { |
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15 | /// Shared map of canonical string representations |
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16 | static std::unordered_set< std::string > canonical; |
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17 | |
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18 | /// Canonical representation of empty string |
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19 | static const std::string* empty_string() { |
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20 | static const std::string* mt = [](){ |
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21 | return &*canonical.emplace( "" ).first; |
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22 | }(); |
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23 | return mt; |
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24 | } |
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25 | |
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26 | /// Canonicalize string |
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27 | template<typename S> |
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28 | static const std::string* intern( S&& s ) { |
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29 | return &*canonical.emplace( std::forward<S>(s) ).first; |
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30 | } |
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31 | |
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32 | /// Pointer to stored string |
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33 | const std::string* s; |
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34 | |
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35 | public: |
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36 | interned_string() : s{empty_string()} {} |
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37 | interned_string(const char* cs) : s{intern(cs)} {} |
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38 | interned_string(const std::string& ss) : s{intern(ss)} {} |
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39 | |
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40 | operator const std::string& () const { return *s; } |
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41 | |
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42 | bool operator== (const interned_string& o) const { return s == o.s; } |
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43 | bool operator!= (const interned_string& o) const { return s != o.s; } |
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44 | bool operator< (const interned_string& o) const { return *s < *o.s; } |
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45 | }; |
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46 | |
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47 | inline std::ostream& operator<< (std::ostream& out, const interned_string& s) { |
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48 | return out << (const std::string&)s; |
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49 | } |
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50 | |
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51 | namespace std { |
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52 | template<> struct hash<interned_string> { |
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53 | std::size_t operator() (const interned_string& s) const { |
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54 | return std::hash<const std::string*>{}( &(const std::string&)s ); |
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55 | } |
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56 | }; |
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57 | } |
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