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#pragma once
///@file
#include <optional>
#include "types.hh"
#include "comparator.hh"
namespace nix {
/**
* A "search path" is a list of ways look for something, used with
* `builtins.findFile` and `< >` lookup expressions.
*/
struct SearchPath
{
/**
* A single element of a `SearchPath`.
*
* Each element is tried in succession when looking up a path. The first
* element to completely match wins.
*/
struct Elem;
/**
* The first part of a `SearchPath::Elem` pair.
*
* Called a "prefix" because it takes the form of a prefix of a file
* path (first `n` path components). When looking up a path, to use
* a `SearchPath::Elem`, its `Prefix` must match the path.
*/
struct Prefix;
/**
* The second part of a `SearchPath::Elem` pair.
*
* It is either a path or a URL (with certain restrictions / extra
* structure).
*
* If the prefix of the path we are looking up matches, we then
* check if the rest of the path points to something that exists
* within the directory denoted by this. If so, the
* `SearchPath::Elem` as a whole matches, and that *something* being
* pointed to by the rest of the path we are looking up is the
* result.
*/
struct Path;
/**
* The list of search path elements. Each one is checked for a path
* when looking up. (The actual lookup entry point is in `EvalState`
* not in this class.)
*/
std::list<SearchPath::Elem> elements;
/**
* Parse a string into a `SearchPath`
*/
static SearchPath parse(const Strings & rawElems);
};
struct SearchPath::Prefix
{
/**
* Underlying string
*
* @todo Should we normalize this when constructing a `SearchPath::Prefix`?
*/
std::string s;
GENERATE_CMP(SearchPath::Prefix, me->s);
/**
* If the path possibly matches this search path element, return the
* suffix that we should look for inside the resolved value of the
* element
* Note the double optionality in the name. While we might have a matching prefix, the suffix may not exist.
*/
std::optional<std::string_view> suffixIfPotentialMatch(std::string_view path) const;
};
struct SearchPath::Path
{
/**
* The location of a search path item, as a path or URL.
*
* @todo Maybe change this to `std::variant<SourcePath, URL>`.
*/
std::string s;
GENERATE_CMP(SearchPath::Path, me->s);
};
struct SearchPath::Elem
{
Prefix prefix;
Path path;
GENERATE_CMP(SearchPath::Elem, me->prefix, me->path);
/**
* Parse a string into a `SearchPath::Elem`
*/
static SearchPath::Elem parse(std::string_view rawElem);
};
}
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