249 lines
9.1 KiB
Nix
249 lines
9.1 KiB
Nix
# Compatibility function to allow flakes to be used by
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# non-flake-enabled Nix versions. Given a source tree containing a
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# 'flake.nix' and 'flake.lock' file, it fetches the flake inputs and
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# calls the flake's 'outputs' function. It then returns an attrset
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# containing 'defaultNix' (to be used in 'default.nix'), 'shellNix'
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# (to be used in 'shell.nix').
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{ src, system ? builtins.currentSystem or "unknown-system" }:
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let
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lockFilePath = src + "/flake.lock";
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lockFile = builtins.fromJSON (builtins.readFile lockFilePath);
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# Using custom fetchurl function here so that we can specify outputHashMode.
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# The hash we get from the lock file is using recursive ingestion even though
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# it’s not unpacked. So builtins.fetchurl and import <nix/fetchurl.nix> are
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# insufficient.
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fetchurl = { url, sha256 }:
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derivation {
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builder = "builtin:fetchurl";
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name = "source";
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inherit url;
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outputHash = sha256;
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outputHashAlgo = "sha256";
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outputHashMode = "recursive";
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executable = false;
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unpack = false;
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system = "builtin";
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# No need to double the amount of network traffic
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preferLocalBuild = true;
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impureEnvVars = [
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# We borrow these environment variables from the caller to allow
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# easy proxy configuration. This is impure, but a fixed-output
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# derivation like fetchurl is allowed to do so since its result is
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# by definition pure.
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"http_proxy" "https_proxy" "ftp_proxy" "all_proxy" "no_proxy"
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];
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# To make "nix-prefetch-url" work.
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urls = [ url ];
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};
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fetchTree =
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info:
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if info.type == "github" then
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{ outPath =
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fetchTarball
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({ url = "https://api.${info.host or "github.com"}/repos/${info.owner}/${info.repo}/tarball/${info.rev}"; }
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// (if info ? narHash then { sha256 = info.narHash; } else {})
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);
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rev = info.rev;
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shortRev = builtins.substring 0 7 info.rev;
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lastModified = info.lastModified;
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lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
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narHash = info.narHash;
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}
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else if info.type == "git" then
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{ outPath =
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builtins.fetchGit
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({ url = info.url; }
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// (if info ? rev then { inherit (info) rev; } else {})
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// (if info ? ref then { inherit (info) ref; } else {})
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// (if info ? submodules then { inherit (info) submodules; } else {})
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);
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lastModified = info.lastModified;
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lastModifiedDate = formatSecondsSinceEpoch info.lastModified;
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narHash = info.narHash;
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} // (if info ? rev then {
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rev = info.rev;
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shortRev = builtins.substring 0 7 info.rev;
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} else {
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})
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else if info.type == "path" then
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{ outPath = builtins.path { path = info.path; };
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narHash = info.narHash;
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}
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else if info.type == "tarball" then
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{ outPath =
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if builtins.substring 0 7 info.url == "http://" || builtins.substring 0 8 info.url == "https://" then
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fetchTarball
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({ inherit (info) url; }
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// (if info ? narHash then { sha256 = info.narHash; } else {})
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)
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else throw "can't support url scheme of flake input with url '${info.url}'";
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narHash = info.narHash;
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}
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else if info.type == "gitlab" then
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{ inherit (info) rev narHash lastModified;
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outPath =
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fetchTarball
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({ url = "https://${info.host or "gitlab.com"}/api/v4/projects/${info.owner}%2F${info.repo}/repository/archive.tar.gz?sha=${info.rev}"; }
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// (if info ? narHash then { sha256 = info.narHash; } else {})
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);
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shortRev = builtins.substring 0 7 info.rev;
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}
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else if info.type == "file" then
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{ outPath =
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if builtins.substring 0 7 info.url == "http://" || builtins.substring 0 8 info.url == "https://" then
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fetchurl
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({ inherit (info) url; }
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// (if info ? narHash then { sha256 = info.narHash; } else {}))
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else if builtins.substring 0 7 info.url == "file://" then
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builtins.path { path = builtins.substring 7 (-1) info.url; }
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else throw "can't support url scheme of flake input with url '${info.url}'";
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narHash = info.narHash;
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}
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else
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# FIXME: add Mercurial input
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throw "flake input has unsupported input type '${info.type}'";
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callFlake4 = flakeSrc: locks:
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let
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flake = import (flakeSrc + "/flake.nix");
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inputs = builtins.mapAttrs (n: v:
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if v.flake or true
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then callFlake4 (fetchTree (v.locked // v.info)) v.inputs
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else fetchTree (v.locked // v.info)) locks;
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outputs = flakeSrc // (flake.outputs (inputs // {self = outputs;}));
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in
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assert flake.edition == 201909;
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outputs;
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callLocklessFlake = flakeSrc:
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let
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flake = import (flakeSrc + "/flake.nix");
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outputs = flakeSrc // (flake.outputs ({ self = outputs; }));
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in outputs;
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rootSrc = let
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# Try to clean the source tree by using fetchGit, if this source
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# tree is a valid git repository.
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tryFetchGit = src:
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if isGit && !isShallow
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then
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let res = builtins.fetchGit src;
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in if res.rev == "0000000000000000000000000000000000000000" then removeAttrs res ["rev" "shortRev"] else res
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else { outPath = src; };
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# NB git worktrees have a file for .git, so we don't check the type of .git
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isGit = builtins.pathExists (src + "/.git");
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isShallow = builtins.pathExists (src + "/.git/shallow");
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in
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{ lastModified = 0; lastModifiedDate = formatSecondsSinceEpoch 0; }
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// (if src ? outPath then src else tryFetchGit src);
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# Format number of seconds in the Unix epoch as %Y%m%d%H%M%S.
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formatSecondsSinceEpoch = t:
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let
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rem = x: y: x - x / y * y;
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days = t / 86400;
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secondsInDay = rem t 86400;
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hours = secondsInDay / 3600;
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minutes = (rem secondsInDay 3600) / 60;
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seconds = rem t 60;
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# Courtesy of https://stackoverflow.com/a/32158604.
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z = days + 719468;
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era = (if z >= 0 then z else z - 146096) / 146097;
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doe = z - era * 146097;
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yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
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y = yoe + era * 400;
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doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
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mp = (5 * doy + 2) / 153;
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d = doy - (153 * mp + 2) / 5 + 1;
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m = mp + (if mp < 10 then 3 else -9);
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y' = y + (if m <= 2 then 1 else 0);
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pad = s: if builtins.stringLength s < 2 then "0" + s else s;
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in "${toString y'}${pad (toString m)}${pad (toString d)}${pad (toString hours)}${pad (toString minutes)}${pad (toString seconds)}";
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allNodes =
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builtins.mapAttrs
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(key: node:
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let
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sourceInfo =
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if key == lockFile.root
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then rootSrc
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else fetchTree (node.info or {} // removeAttrs node.locked ["dir"]);
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subdir = if key == lockFile.root then "" else node.locked.dir or "";
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flake = import (sourceInfo + (if subdir != "" then "/" else "") + subdir + "/flake.nix");
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inputs = builtins.mapAttrs
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(inputName: inputSpec: allNodes.${resolveInput inputSpec})
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(node.inputs or {});
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# Resolve a input spec into a node name. An input spec is
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# either a node name, or a 'follows' path from the root
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# node.
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resolveInput = inputSpec:
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if builtins.isList inputSpec
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then getInputByPath lockFile.root inputSpec
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else inputSpec;
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# Follow an input path (e.g. ["dwarffs" "nixpkgs"]) from the
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# root node, returning the final node.
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getInputByPath = nodeName: path:
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if path == []
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then nodeName
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else
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getInputByPath
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# Since this could be a 'follows' input, call resolveInput.
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(resolveInput lockFile.nodes.${nodeName}.inputs.${builtins.head path})
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(builtins.tail path);
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outputs = flake.outputs (inputs // { self = result; });
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result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
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in
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if node.flake or true then
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assert builtins.isFunction flake.outputs;
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result
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else
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sourceInfo
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)
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lockFile.nodes;
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result =
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if !(builtins.pathExists lockFilePath)
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then callLocklessFlake rootSrc
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else if lockFile.version == 4
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then callFlake4 rootSrc (lockFile.inputs)
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else if lockFile.version >= 5 && lockFile.version <= 7
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then allNodes.${lockFile.root}
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else throw "lock file '${lockFilePath}' has unsupported version ${toString lockFile.version}";
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in
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rec {
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defaultNix =
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result
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// (if result ? defaultPackage.${system} then { default = result.defaultPackage.${system}; } else {})
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// (if result ? packages.${system}.default then { default = result.packages.${system}.default; } else {});
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shellNix =
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defaultNix
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// (if result ? devShell.${system} then { default = result.devShell.${system}; } else {})
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// (if result ? devShells.${system}.default then { default = result.devShells.${system}.default; } else {});
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}
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