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// This file implements the underlying structure of Nix attribute sets.
#pragma once
#include <absl/container/btree_map.h>
#include <gc/gc_allocator.h>
#include "libexpr/nixexpr.hh"
#include "libexpr/symbol-table.hh"
#include "libutil/types.hh"
namespace nix { // TODO(tazjin): ::expr
class EvalState;
struct Value;
/* Map one attribute name to its value. */
struct Attr {
Symbol name;
Value* value; // TODO(tazjin): Who owns this?
Pos* pos; // TODO(tazjin): Who owns this?
Attr(Symbol name, Value* value, Pos* pos = &noPos)
: name(name), value(value), pos(pos){};
Attr() : pos(&noPos){};
bool operator<(const Attr& other) const { return name < other.name; }
};
// TODO: remove this, it only exists briefly while I get rid of the
// current Attr struct
inline bool operator==(const Attr& lhs, const Attr& rhs) {
return lhs.name == rhs.name;
}
// Convenience alias for the backing map, with the garbage-collecting
// allocator explicitly specified.
using AttributeMap =
absl::btree_map<Symbol, Attr, std::less<Symbol>,
gc_allocator<std::pair<const Symbol, Attr>>>;
class Bindings {
public:
typedef AttributeMap::iterator iterator;
// Allocate a new attribute set that is visible to the garbage
// collector.
static Bindings* NewGC();
// Return the number of contained elements.
size_t size();
// Is this attribute set empty?
bool empty();
// Insert, but do not replace, values in the attribute set.
void push_back(const Attr& attr);
// Insert a value, or replace an existing one.
void insert_or_assign(const Attr& attr);
// Look up a specific element of the attribute set.
iterator find(const Symbol& name);
// TODO
iterator begin();
iterator end();
// Merge values from other into the current attribute
void merge(const Bindings& other);
// ???
[[deprecated]] size_t capacity();
// oh no
// Attr& operator[](size_t pos); // { return attrs[pos]; }
// TODO: can callers just iterate?
[[deprecated]] std::vector<const Attr*> lexicographicOrder();
// oh no
friend class EvalState;
private:
AttributeMap attributes_;
};
} // namespace nix
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