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// This file implements the underlying structure of Nix attribute sets.
#pragma once
#include <absl/container/btree_map.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){};
};
using AttributeMap = absl::btree_map<Symbol, Attr>;
class Bindings {
public:
using iterator = AttributeMap::iterator;
using const_iterator = AttributeMap::const_iterator;
// Allocate a new attribute set that is visible to the garbage
// collector.
static std::unique_ptr<Bindings> New(size_t capacity = 0);
// Create a new attribute set by merging two others. This is used to
// implement the `//` operator in Nix.
static std::unique_ptr<Bindings> Merge(const Bindings& lhs,
const Bindings& rhs);
// Return the number of contained elements.
size_t size() const;
// Is this attribute set empty?
bool empty();
// Insert, but do not replace, values in the attribute set.
void push_back(const Attr& attr);
// Are these two attribute sets deeply equal?
// Note: Does not special-case derivations. Use state.eqValues() to check
// attrsets that may be derivations.
bool Equal(const Bindings* other, EvalState& state) const;
// Look up a specific element of the attribute set.
iterator find(const Symbol& name);
iterator begin();
const_iterator cbegin() const;
iterator end();
const_iterator cend() const;
// oh no
friend class EvalState;
private:
AttributeMap attributes_;
};
} // namespace nix
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