forked from lix-project/lix
d439dceb3b
we'll retain the old coerceToString interface that returns a string, but callers that don't need the returned value to outlive the Value it came from can save copies by using the new interface instead. for values that weren't stringy we'll pass a new buffer argument that'll be used for storage and shouldn't be inspected.
126 lines
3.6 KiB
C++
126 lines
3.6 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 "eval-inline.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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std::optional<std::string> apply;
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std::optional<Path> writeTo;
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CmdEval()
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{
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addFlag({
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.longName = "raw",
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.description = "Print strings without quotes or escaping.",
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.handler = {&raw, true},
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});
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addFlag({
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.longName = "apply",
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.description = "Apply the function *expr* to each argument.",
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.labels = {"expr"},
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.handler = {&apply},
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});
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addFlag({
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.longName = "write-to",
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.description = "Write a string or attrset of strings to *path*.",
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.labels = {"path"},
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.handler = {&writeTo},
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});
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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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std::string doc() override
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{
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return
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#include "eval.md"
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;
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}
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Category category() override { return catSecondary; }
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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, pos] = installable->toValue(*state);
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PathSet context;
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if (apply) {
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auto vApply = state->allocValue();
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state->eval(state->parseExprFromString(*apply, absPath(".")), *vApply);
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auto vRes = state->allocValue();
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state->callFunction(*vApply, *v, *vRes, noPos);
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v = vRes;
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}
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if (writeTo) {
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stopProgressBar();
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if (pathExists(*writeTo))
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throw Error("path '%s' already exists", *writeTo);
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std::function<void(Value & v, const Pos & pos, const Path & path)> recurse;
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recurse = [&](Value & v, const Pos & pos, const Path & path)
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{
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state->forceValue(v);
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if (v.type() == nString)
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// FIXME: disallow strings with contexts?
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writeFile(path, v.string.s);
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else if (v.type() == nAttrs) {
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if (mkdir(path.c_str(), 0777) == -1)
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throw SysError("creating directory '%s'", path);
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for (auto & attr : *v.attrs)
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try {
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if (attr.name == "." || attr.name == "..")
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throw Error("invalid file name '%s'", attr.name);
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recurse(*attr.value, *attr.pos, path + "/" + std::string(attr.name));
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} catch (Error & e) {
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e.addTrace(*attr.pos, hintfmt("while evaluating the attribute '%s'", attr.name));
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throw;
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}
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}
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else
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throw TypeError("value at '%s' is not a string or an attribute set", pos);
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};
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recurse(*v, pos, *writeTo);
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}
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else if (raw) {
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stopProgressBar();
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std::cout << *state->coerceToString(noPos, *v, context);
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}
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else if (json) {
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JSONPlaceholder jsonOut(std::cout);
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printValueAsJSON(*state, true, *v, pos, jsonOut, context);
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}
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else {
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state->forceValueDeep(*v);
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logger->cout("%s", *v);
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}
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}
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};
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static auto rCmdEval = registerCommand<CmdEval>("eval");
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