forked from lix-project/lix
6526d1676b
Pos objects are somewhat wasteful as they duplicate the origin file name and input type for each object. on files that produce more than one Pos when parsed this a sizeable waste of memory (one pointer per Pos). the same goes for ptr<Pos> on 64 bit machines: parsing enough source to require 8 bytes to locate a position would need at least 8GB of input and 64GB of expression memory. it's not likely that we'll hit that any time soon, so we can use a uint32_t index to locate positions instead.
153 lines
3.3 KiB
C++
153 lines
3.3 KiB
C++
#pragma once
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#include "nixexpr.hh"
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#include "symbol-table.hh"
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#include <algorithm>
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#include <optional>
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namespace nix {
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class EvalState;
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struct Value;
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/* Map one attribute name to its value. */
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struct Attr
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{
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Symbol name;
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Value * value;
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PosIdx pos;
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Attr(Symbol name, Value * value, PosIdx pos = noPos)
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: name(name), value(value), pos(pos) { };
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Attr() { };
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bool operator < (const Attr & a) const
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{
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return name < a.name;
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}
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};
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/* Bindings contains all the attributes of an attribute set. It is defined
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by its size and its capacity, the capacity being the number of Attr
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elements allocated after this structure, while the size corresponds to
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the number of elements already inserted in this structure. */
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class Bindings
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{
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public:
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typedef uint32_t size_t;
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PosIdx pos;
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private:
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size_t size_, capacity_;
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Attr attrs[0];
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Bindings(size_t capacity) : size_(0), capacity_(capacity) { }
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Bindings(const Bindings & bindings) = delete;
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public:
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size_t size() const { return size_; }
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bool empty() const { return !size_; }
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typedef Attr * iterator;
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void push_back(const Attr & attr)
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{
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assert(size_ < capacity_);
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attrs[size_++] = attr;
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}
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iterator find(const Symbol & name)
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{
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Attr key(name, 0);
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iterator i = std::lower_bound(begin(), end(), key);
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if (i != end() && i->name == name) return i;
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return end();
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}
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Attr * get(const Symbol & name)
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{
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Attr key(name, 0);
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iterator i = std::lower_bound(begin(), end(), key);
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if (i != end() && i->name == name) return &*i;
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return nullptr;
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}
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iterator begin() { return &attrs[0]; }
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iterator end() { return &attrs[size_]; }
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Attr & operator[](size_t pos)
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{
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return attrs[pos];
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}
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void sort();
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size_t capacity() { return capacity_; }
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/* Returns the attributes in lexicographically sorted order. */
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std::vector<const Attr *> lexicographicOrder() const
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{
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std::vector<const Attr *> res;
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res.reserve(size_);
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for (size_t n = 0; n < size_; n++)
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res.emplace_back(&attrs[n]);
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std::sort(res.begin(), res.end(), [](const Attr * a, const Attr * b) {
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return (const std::string &) a->name < (const std::string &) b->name;
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});
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return res;
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}
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friend class EvalState;
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};
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/* A wrapper around Bindings that ensures that its always in sorted
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order at the end. The only way to consume a BindingsBuilder is to
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call finish(), which sorts the bindings. */
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class BindingsBuilder
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{
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Bindings * bindings;
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public:
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// needed by std::back_inserter
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using value_type = Attr;
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EvalState & state;
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BindingsBuilder(EvalState & state, Bindings * bindings)
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: bindings(bindings), state(state)
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{ }
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void insert(Symbol name, Value * value, PosIdx pos = noPos)
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{
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insert(Attr(name, value, pos));
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}
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void insert(const Attr & attr)
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{
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push_back(attr);
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}
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void push_back(const Attr & attr)
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{
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bindings->push_back(attr);
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}
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Value & alloc(const Symbol & name, PosIdx pos = noPos);
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Value & alloc(std::string_view name, PosIdx pos = noPos);
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Bindings * finish()
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{
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bindings->sort();
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return bindings;
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}
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Bindings * alreadySorted()
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{
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return bindings;
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}
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};
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}
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