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#include "command.hh"
#include "common-args.hh"
#include "print-options.hh"
#include "shared.hh"
#include "store-api.hh"
#include "eval.hh"
#include "eval-inline.hh"
#include "value-to-json.hh"
#include <nlohmann/json.hpp>
using namespace nix;
struct CmdEval : MixJSON, InstallableCommand, MixReadOnlyOption
{
bool raw = false;
std::optional<std::string> apply;
std::optional<Path> writeTo;
CmdEval() : InstallableCommand()
{
addFlag({
.longName = "raw",
.description = "Print strings without quotes or escaping.",
.handler = {&raw, true},
});
addFlag({
.longName = "apply",
.description = "Apply the function *expr* to each argument.",
.labels = {"expr"},
.handler = {&apply},
});
addFlag({
.longName = "write-to",
.description = "Write a string or attrset of strings to *path*.",
.labels = {"path"},
.handler = {&writeTo},
});
}
std::string description() override
{
return "evaluate a Nix expression";
}
std::string doc() override
{
return
#include "eval.md"
;
}
Category category() override { return catSecondary; }
void run(ref<Store> store, ref<Installable> installable) override
{
if (raw && json)
throw UsageError("--raw and --json are mutually exclusive");
auto const installableValue = InstallableValue::require(installable);
auto state = getEvalState();
auto [v, pos] = installableValue->toValue(*state);
NixStringContext context;
if (apply) {
auto vApply = state->allocValue();
state->eval(state->parseExprFromString(*apply, state->rootPath(CanonPath::fromCwd())), *vApply);
auto vRes = state->allocValue();
state->callFunction(*vApply, *v, *vRes, noPos);
v = vRes;
}
if (writeTo) {
logger->pause();
if (pathExists(*writeTo))
throw Error("path '%s' already exists", *writeTo);
std::function<void(Value & v, const PosIdx pos, const Path & path)> recurse;
recurse = [&](Value & v, const PosIdx pos, const Path & path)
{
state->forceValue(v, pos);
if (v.type() == nString)
// FIXME: disallow strings with contexts?
writeFile(path, v.string.s);
else if (v.type() == nAttrs) {
if (mkdir(path.c_str(), 0777) == -1)
throw SysError("creating directory '%s'", path);
for (auto & attr : *v.attrs) {
std::string_view name = state->symbols[attr.name];
try {
if (name == "." || name == "..")
throw Error("invalid file name '%s'", name);
recurse(*attr.value, attr.pos, concatStrings(path, "/", name));
} catch (Error & e) {
e.addTrace(
state->positions[attr.pos],
HintFmt("while evaluating the attribute '%s'", name));
throw;
}
}
}
else
state->error<TypeError>("value at '%s' is not a string or an attribute set", state->positions[pos]).debugThrow();
};
recurse(*v, pos, *writeTo);
}
else if (raw) {
logger->pause();
writeFull(STDOUT_FILENO, *state->coerceToString(noPos, *v, context, "while generating the eval command output"));
}
else if (json) {
logger->cout("%s", printValueAsJSON(*state, true, *v, pos, context, false));
}
else {
logger->cout(
"%s",
ValuePrinter(
*state,
*v,
PrintOptions {
.force = true,
.derivationPaths = true,
.errors = ErrorPrintBehavior::ThrowTopLevel,
}
)
);
}
}
};
static auto rCmdEval = registerCommand<CmdEval>("eval");
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