be518e73ae
- Better types - Own header / C++ file pair - Test factored out methods - Pass parsed thing around more than strings Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
109 lines
2.7 KiB
C++
109 lines
2.7 KiB
C++
#pragma once
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///@file
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#include <optional>
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#include "types.hh"
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#include "comparator.hh"
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namespace nix {
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/**
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* A "search path" is a list of ways look for something, used with
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* `builtins.findFile` and `< >` lookup expressions.
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*/
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struct SearchPath
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{
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/**
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* A single element of a `SearchPath`.
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*
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* Each element is tried in succession when looking up a path. The first
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* element to completely match wins.
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*/
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struct Elem;
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/**
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* The first part of a `SearchPath::Elem` pair.
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*
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* Called a "prefix" because it takes the form of a prefix of a file
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* path (first `n` path components). When looking up a path, to use
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* a `SearchPath::Elem`, its `Prefix` must match the path.
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*/
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struct Prefix;
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/**
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* The second part of a `SearchPath::Elem` pair.
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*
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* It is either a path or a URL (with certain restrictions / extra
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* structure).
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*
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* If the prefix of the path we are looking up matches, we then
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* check if the rest of the path points to something that exists
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* within the directory denoted by this. If so, the
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* `SearchPath::Elem` as a whole matches, and that *something* being
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* pointed to by the rest of the path we are looking up is the
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* result.
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*/
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struct Path;
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/**
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* The list of search path elements. Each one is checked for a path
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* when looking up. (The actual lookup entry point is in `EvalState`
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* not in this class.)
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*/
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std::list<SearchPath::Elem> elements;
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/**
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* Parse a string into a `SearchPath`
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*/
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static SearchPath parse(const Strings & rawElems);
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};
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struct SearchPath::Prefix
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{
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/**
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* Underlying string
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*
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* @todo Should we normalize this when constructing a `SearchPath::Prefix`?
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*/
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std::string s;
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GENERATE_CMP(SearchPath::Prefix, me->s);
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/**
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* If the path possibly matches this search path element, return the
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* suffix that we should look for inside the resolved value of the
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* element
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* Note the double optionality in the name. While we might have a matching prefix, the suffix may not exist.
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*/
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std::optional<std::string_view> suffixIfPotentialMatch(std::string_view path) const;
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};
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struct SearchPath::Path
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{
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/**
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* The location of a search path item, as a path or URL.
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*
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* @todo Maybe change this to `std::variant<SourcePath, URL>`.
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*/
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std::string s;
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GENERATE_CMP(SearchPath::Path, me->s);
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};
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struct SearchPath::Elem
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{
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Prefix prefix;
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Path path;
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GENERATE_CMP(SearchPath::Elem, me->prefix, me->path);
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/**
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* Parse a string into a `SearchPath::Elem`
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*/
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static SearchPath::Elem parse(std::string_view rawElem);
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};
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}
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