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https://github.com/NixOS/nix
synced 2025-06-25 02:21:16 +02:00
c6a89c1a16
While preparing PRs like #9753, I've had to change error messages in dozens of code paths. It would be nice if instead of EvalError("expected 'boolean' but found '%1%'", showType(v)) we could write TypeError(v, "boolean") or similar. Then, changing the error message could be a mechanical refactor with the compiler pointing out places the constructor needs to be changed, rather than the error-prone process of grepping through the codebase. Structured errors would also help prevent the "same" error from having multiple slightly different messages, and could be a first step towards error codes / an error index. This PR reworks the exception infrastructure in `libexpr` to support exception types with different constructor signatures than `BaseError`. Actually refactoring the exceptions to use structured data will come in a future PR (this one is big enough already, as it has to touch every exception in `libexpr`). The core design is in `eval-error.hh`. Generally, errors like this: state.error("'%s' is not a string", getAttrPathStr()) .debugThrow<TypeError>() are transformed like this: state.error<TypeError>("'%s' is not a string", getAttrPathStr()) .debugThrow() The type annotation has moved from `ErrorBuilder::debugThrow` to `EvalState::error`.
110 lines
3.3 KiB
C++
110 lines
3.3 KiB
C++
#include "primops.hh"
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#include "eval-inline.hh"
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#include "../../toml11/toml.hpp"
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#include <sstream>
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namespace nix {
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static void prim_fromTOML(EvalState & state, const PosIdx pos, Value * * args, Value & val)
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{
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auto toml = state.forceStringNoCtx(*args[0], pos, "while evaluating the argument passed to builtins.fromTOML");
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std::istringstream tomlStream(std::string{toml});
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std::function<void(Value &, toml::value)> visit;
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visit = [&](Value & v, toml::value t) {
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switch(t.type())
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{
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case toml::value_t::table:
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{
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auto table = toml::get<toml::table>(t);
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size_t size = 0;
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for (auto & i : table) { (void) i; size++; }
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auto attrs = state.buildBindings(size);
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for(auto & elem : table)
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visit(attrs.alloc(elem.first), elem.second);
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v.mkAttrs(attrs);
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}
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break;;
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case toml::value_t::array:
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{
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auto array = toml::get<std::vector<toml::value>>(t);
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size_t size = array.size();
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state.mkList(v, size);
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for (size_t i = 0; i < size; ++i)
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visit(*(v.listElems()[i] = state.allocValue()), array[i]);
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}
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break;;
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case toml::value_t::boolean:
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v.mkBool(toml::get<bool>(t));
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break;;
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case toml::value_t::integer:
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v.mkInt(toml::get<int64_t>(t));
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break;;
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case toml::value_t::floating:
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v.mkFloat(toml::get<NixFloat>(t));
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break;;
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case toml::value_t::string:
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v.mkString(toml::get<std::string>(t));
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break;;
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case toml::value_t::local_datetime:
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case toml::value_t::offset_datetime:
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case toml::value_t::local_date:
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case toml::value_t::local_time:
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{
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if (experimentalFeatureSettings.isEnabled(Xp::ParseTomlTimestamps)) {
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auto attrs = state.buildBindings(2);
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attrs.alloc("_type").mkString("timestamp");
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std::ostringstream s;
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s << t;
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attrs.alloc("value").mkString(s.str());
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v.mkAttrs(attrs);
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} else {
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throw std::runtime_error("Dates and times are not supported");
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}
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}
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break;;
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case toml::value_t::empty:
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v.mkNull();
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break;;
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}
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};
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try {
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visit(val, toml::parse(tomlStream, "fromTOML" /* the "filename" */));
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} catch (std::exception & e) { // TODO: toml::syntax_error
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state.error<EvalError>("while parsing TOML: %s", e.what()).atPos(pos).debugThrow();
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}
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}
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static RegisterPrimOp primop_fromTOML({
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.name = "fromTOML",
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.args = {"e"},
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.doc = R"(
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Convert a TOML string to a Nix value. For example,
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```nix
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builtins.fromTOML ''
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x=1
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s="a"
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[table]
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y=2
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''
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```
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returns the value `{ s = "a"; table = { y = 2; }; x = 1; }`.
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)",
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.fun = prim_fromTOML
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});
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}
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