ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change
on this file since 979df46 was
5a89a2b,
checked in by Aaron Moss <a3moss@…>, 5 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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Rev | Line | |
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[5a89a2b] | 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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