ba81e871b2
Given flake:
```nix
{ description = "nix json error provenance";
inputs = {};
outputs = { self }: {
jsonFunction = _: "function";
json = builtins.toJSON (_: "function");
};
}
```
- Before:
```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON
```
- After:
```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON
at /nix/store/b7imf1c2j4jnkg3ys7fsfbj02s5j0i4f-source/testflake/flake.nix:4:5:
3| outputs = { self }: {
4| jsonFunction = _: "function";
| ^
5| json = builtins.toJSON (_: "function");
```
125 lines
3.6 KiB
C++
125 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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