forked from lix-project/lix
bbe97dff8b
Most functions now take a StorePath argument rather than a Path (which is just an alias for std::string). The StorePath constructor ensures that the path is syntactically correct (i.e. it looks like <store-dir>/<base32-hash>-<name>). Similarly, functions like buildPaths() now take a StorePathWithOutputs, rather than abusing Path by adding a '!<outputs>' suffix. Note that the StorePath type is implemented in Rust. This involves some hackery to allow Rust values to be used directly in C++, via a helper type whose destructor calls the Rust type's drop() function. The main issue is the dynamic nature of C++ move semantics: after we have moved a Rust value, we should not call the drop function on the original value. So when we move a value, we set the original value to bitwise zero, and the destructor only calls drop() if the value is not bitwise zero. This should be sufficient for most types. Also lots of minor cleanups to the C++ API to make it more modern (e.g. using std::optional and std::string_view in some places).
93 lines
1.7 KiB
C++
93 lines
1.7 KiB
C++
#pragma once
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#include <map>
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#include <unordered_set>
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#include "types.hh"
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namespace nix {
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/* Symbol table used by the parser and evaluator to represent and look
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up identifiers and attributes efficiently. SymbolTable::create()
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converts a string into a symbol. Symbols have the property that
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they can be compared efficiently (using a pointer equality test),
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because the symbol table stores only one copy of each string. */
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class Symbol
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{
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private:
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const string * s; // pointer into SymbolTable
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Symbol(const string * s) : s(s) { };
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friend class SymbolTable;
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public:
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Symbol() : s(0) { };
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bool operator == (const Symbol & s2) const
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{
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return s == s2.s;
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}
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bool operator != (const Symbol & s2) const
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{
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return s != s2.s;
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}
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bool operator < (const Symbol & s2) const
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{
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return s < s2.s;
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}
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operator const std::string & () const
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{
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return *s;
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}
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operator const std::string_view () const
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{
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return *s;
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}
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bool set() const
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{
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return s;
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}
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bool empty() const
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{
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return s->empty();
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}
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friend std::ostream & operator << (std::ostream & str, const Symbol & sym);
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};
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class SymbolTable
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{
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private:
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typedef std::unordered_set<string> Symbols;
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Symbols symbols;
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public:
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Symbol create(const string & s)
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{
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std::pair<Symbols::iterator, bool> res = symbols.insert(s);
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return Symbol(&*res.first);
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}
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size_t size() const
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{
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return symbols.size();
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}
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size_t totalSize() const;
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template<typename T>
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void dump(T callback)
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{
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for (auto & s : symbols)
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callback(s);
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}
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};
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}
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