265 lines
8.8 KiB
C++
265 lines
8.8 KiB
C++
#include "command.hh"
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#include "store-api.hh"
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#include "progress-bar.hh"
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#include "fs-accessor.hh"
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#include "shared.hh"
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#include <queue>
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using namespace nix;
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static std::string hilite(const std::string & s, size_t pos, size_t len,
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const std::string & colour = ANSI_RED)
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{
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return
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std::string(s, 0, pos)
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+ colour
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+ std::string(s, pos, len)
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+ ANSI_NORMAL
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+ std::string(s, pos + len);
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}
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static std::string filterPrintable(const std::string & s)
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{
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std::string res;
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for (char c : s)
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res += isprint(c) ? c : '.';
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return res;
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}
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struct CmdWhyDepends : SourceExprCommand
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{
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std::string _package, _dependency;
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bool all = false;
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CmdWhyDepends()
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{
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expectArg("package", &_package);
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expectArg("dependency", &_dependency);
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mkFlag()
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.longName("all")
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.shortName('a')
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.description("show all edges in the dependency graph leading from 'package' to 'dependency', rather than just a shortest path")
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.set(&all, true);
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}
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std::string description() override
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{
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return "show why a package has another package in its closure";
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}
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Examples examples() override
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{
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return {
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Example{
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"To show one path through the dependency graph leading from Hello to Glibc:",
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"nix why-depends nixpkgs.hello nixpkgs.glibc"
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},
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Example{
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"To show all files and paths in the dependency graph leading from Thunderbird to libX11:",
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"nix why-depends --all nixpkgs.thunderbird nixpkgs.xorg.libX11"
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},
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Example{
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"To show why Glibc depends on itself:",
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"nix why-depends nixpkgs.glibc nixpkgs.glibc"
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},
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};
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}
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void run(ref<Store> store) override
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{
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auto package = parseInstallable(*this, store, _package, false);
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auto packagePath = toStorePath(store, Build, package);
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auto dependency = parseInstallable(*this, store, _dependency, false);
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auto dependencyPath = toStorePath(store, NoBuild, dependency);
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auto dependencyPathHash = storePathToHash(store->printStorePath(dependencyPath));
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StorePathSet closure;
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store->computeFSClosure({packagePath}, closure, false, false);
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if (!closure.count(dependencyPath)) {
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printError("'%s' does not depend on '%s'", package->what(), dependency->what());
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return;
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}
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stopProgressBar(); // FIXME
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auto accessor = store->getFSAccessor();
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auto const inf = std::numeric_limits<size_t>::max();
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struct Node
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{
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StorePath path;
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StorePathSet refs;
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StorePathSet rrefs;
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size_t dist = inf;
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Node * prev = nullptr;
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bool queued = false;
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bool visited = false;
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};
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std::map<StorePath, Node> graph;
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for (auto & path : closure)
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graph.emplace(path.clone(), Node{path.clone(), cloneStorePathSet(store->queryPathInfo(path)->references)});
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// Transpose the graph.
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for (auto & node : graph)
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for (auto & ref : node.second.refs)
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graph.find(ref)->second.rrefs.insert(node.first.clone());
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/* Run Dijkstra's shortest path algorithm to get the distance
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of every path in the closure to 'dependency'. */
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graph[dependencyPath.clone()].dist = 0;
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std::priority_queue<Node *> queue;
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queue.push(&graph.at(dependencyPath));
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while (!queue.empty()) {
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auto & node = *queue.top();
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queue.pop();
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for (auto & rref : node.rrefs) {
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auto & node2 = graph.at(rref);
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auto dist = node.dist + 1;
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if (dist < node2.dist) {
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node2.dist = dist;
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node2.prev = &node;
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if (!node2.queued) {
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node2.queued = true;
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queue.push(&node2);
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}
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}
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}
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}
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/* Print the subgraph of nodes that have 'dependency' in their
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closure (i.e., that have a non-infinite distance to
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'dependency'). Print every edge on a path between `package`
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and `dependency`. */
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std::function<void(Node &, const string &, const string &)> printNode;
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const string treeConn = "╠═══";
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const string treeLast = "╚═══";
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const string treeLine = "║ ";
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const string treeNull = " ";
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struct BailOut { };
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printNode = [&](Node & node, const string & firstPad, const string & tailPad) {
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auto pathS = store->printStorePath(node.path);
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assert(node.dist != inf);
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std::cout << fmt("%s%s%s%s" ANSI_NORMAL "\n",
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firstPad,
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node.visited ? "\e[38;5;244m" : "",
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firstPad != "" ? "=> " : "",
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pathS);
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if (node.path == dependencyPath && !all
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&& packagePath != dependencyPath)
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throw BailOut();
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if (node.visited) return;
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node.visited = true;
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/* Sort the references by distance to `dependency` to
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ensure that the shortest path is printed first. */
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std::multimap<size_t, Node *> refs;
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std::set<std::string> hashes;
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for (auto & ref : node.refs) {
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if (ref == node.path && packagePath != dependencyPath) continue;
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auto & node2 = graph.at(ref);
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if (node2.dist == inf) continue;
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refs.emplace(node2.dist, &node2);
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hashes.insert(storePathToHash(store->printStorePath(node2.path)));
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}
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/* For each reference, find the files and symlinks that
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contain the reference. */
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std::map<std::string, Strings> hits;
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std::function<void(const Path &)> visitPath;
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visitPath = [&](const Path & p) {
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auto st = accessor->stat(p);
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auto p2 = p == pathS ? "/" : std::string(p, pathS.size() + 1);
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auto getColour = [&](const std::string & hash) {
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return hash == dependencyPathHash ? ANSI_GREEN : ANSI_BLUE;
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};
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if (st.type == FSAccessor::Type::tDirectory) {
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auto names = accessor->readDirectory(p);
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for (auto & name : names)
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visitPath(p + "/" + name);
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}
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else if (st.type == FSAccessor::Type::tRegular) {
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auto contents = accessor->readFile(p);
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for (auto & hash : hashes) {
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auto pos = contents.find(hash);
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if (pos != std::string::npos) {
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size_t margin = 32;
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auto pos2 = pos >= margin ? pos - margin : 0;
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hits[hash].emplace_back(fmt("%s: …%s…\n",
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p2,
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hilite(filterPrintable(
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std::string(contents, pos2, pos - pos2 + hash.size() + margin)),
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pos - pos2, storePathHashLen,
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getColour(hash))));
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}
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}
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}
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else if (st.type == FSAccessor::Type::tSymlink) {
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auto target = accessor->readLink(p);
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for (auto & hash : hashes) {
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auto pos = target.find(hash);
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if (pos != std::string::npos)
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hits[hash].emplace_back(fmt("%s -> %s\n", p2,
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hilite(target, pos, storePathHashLen, getColour(hash))));
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}
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}
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};
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// FIXME: should use scanForReferences().
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visitPath(pathS);
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RunPager pager;
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for (auto & ref : refs) {
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auto hash = storePathToHash(store->printStorePath(ref.second->path));
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bool last = all ? ref == *refs.rbegin() : true;
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for (auto & hit : hits[hash]) {
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bool first = hit == *hits[hash].begin();
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std::cout << tailPad
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<< (first ? (last ? treeLast : treeConn) : (last ? treeNull : treeLine))
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<< hit;
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if (!all) break;
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}
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printNode(*ref.second,
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tailPad + (last ? treeNull : treeLine),
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tailPad + (last ? treeNull : treeLine));
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}
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};
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try {
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printNode(graph.at(packagePath), "", "");
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} catch (BailOut & ) { }
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}
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};
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static auto r1 = registerCommand<CmdWhyDepends>("why-depends");
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