forked from lix-project/lix
72 lines
1.8 KiB
C++
72 lines
1.8 KiB
C++
#include "command.hh"
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#include "common-args.hh"
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#include "shared.hh"
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#include "store-api.hh"
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#include "eval.hh"
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#include "json.hh"
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#include "value-to-json.hh"
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#include "progress-bar.hh"
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using namespace nix;
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struct CmdEval : MixJSON, InstallableCommand
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{
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bool raw = false;
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CmdEval()
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{
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mkFlag(0, "raw", "print strings unquoted", &raw);
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}
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std::string description() override
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{
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return "evaluate a Nix expression";
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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 evaluate a Nix expression given on the command line:",
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"nix eval --expr '1 + 2'"
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},
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Example{
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"To evaluate a Nix expression from a file or URI:",
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"nix eval -f channel:nixos-17.09 hello.name"
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},
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Example{
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"To get the current version of Nixpkgs:",
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"nix eval --raw nixpkgs.lib.version"
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},
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Example{
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"To print the store path of the Hello package:",
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"nix eval --raw nixpkgs.hello"
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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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if (raw && json)
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throw UsageError("--raw and --json are mutually exclusive");
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auto state = getEvalState();
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auto v = installable->toValue(*state).first;
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PathSet context;
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if (raw) {
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stopProgressBar();
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std::cout << state->coerceToString(noPos, *v, context);
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} else if (json) {
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JSONPlaceholder jsonOut(std::cout);
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printValueAsJSON(*state, true, *v, jsonOut, context);
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} else {
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state->forceValueDeep(*v);
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logger->stdout("%s", *v);
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}
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}
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};
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static auto r1 = registerCommand<CmdEval>("eval");
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