diff options
Diffstat (limited to 'third_party')
| -rw-r--r-- | third_party/nix/src/libexpr/json-to-value.cc | 267 |
1 files changed, 114 insertions, 153 deletions
diff --git a/third_party/nix/src/libexpr/json-to-value.cc b/third_party/nix/src/libexpr/json-to-value.cc index 5f8352dde63b..562b9174f62d 100644 --- a/third_party/nix/src/libexpr/json-to-value.cc +++ b/third_party/nix/src/libexpr/json-to-value.cc @@ -1,185 +1,146 @@ #include "libexpr/json-to-value.hh" -#include <cstring> +#include <nlohmann/json.hpp> +#include <variant> +#include <vector> + +#include "libexpr/value.hh" + +using json = nlohmann::json; namespace nix { -static void skipWhitespace(const char*& s) { - while (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r') { - s++; - } -} +// for more information, refer to +// https://github.com/nlohmann/json/blob/master/include/nlohmann/detail/input/json_sax.hpp +class JSONSax : nlohmann::json_sax<json> { + class JSONState { + protected: + JSONState* parent; + Value* v; + + public: + virtual JSONState* resolve(EvalState&) { + throw std::logic_error("tried to close toplevel json parser state"); + }; + explicit JSONState(JSONState* p) : parent(p), v(nullptr){}; + explicit JSONState(Value* v) : v(v){}; + JSONState(JSONState& p) = delete; + Value& value(EvalState& state) { + if (v == nullptr) v = state.allocValue(); + return *v; + }; + virtual ~JSONState(){}; + virtual void add(){}; + }; + + class JSONObjectState : public JSONState { + using JSONState::JSONState; + ValueMap attrs = ValueMap(); + virtual JSONState* resolve(EvalState& state) override { + Value& v = parent->value(state); + state.mkAttrs(v, attrs.size()); + for (auto& i : attrs) v.attrs->push_back(Attr(i.first, i.second)); + return parent; + } + virtual void add() override { v = nullptr; }; -static std::string parseJSONString(const char*& s) { - std::string res; - if (*s++ != '"') { - throw JSONParseError("expected JSON string"); - } - while (*s != '"') { - if (*s == 0) { - throw JSONParseError("got end-of-string in JSON string"); + public: + void key(string_t& name, EvalState& state) { + attrs[state.symbols.Create(name)] = &value(state); } - if (*s == '\\') { - s++; - if (*s == '"') { - res += '"'; - } else if (*s == '\\') { - res += '\\'; - } else if (*s == '/') { - res += '/'; - } else if (*s == '/') { - res += '/'; - } else if (*s == 'b') { - res += '\b'; - } else if (*s == 'f') { - res += '\f'; - } else if (*s == 'n') { - res += '\n'; - } else if (*s == 'r') { - res += '\r'; - } else if (*s == 't') { - res += '\t'; - } else if (*s == 'u') { - throw JSONParseError( - "\\u characters in JSON strings are currently not supported"); - } else { - throw JSONParseError("invalid escaped character in JSON string"); + }; + + class JSONListState : public JSONState { + std::vector<Value*> values; + virtual JSONState* resolve(EvalState& state) override { + Value& v = parent->value(state); + state.mkList(v, values.size()); + for (size_t n = 0; n < values.size(); ++n) { + (*v.list)[n] = values[n]; } - s++; - } else { - res += *s++; + return parent; } - } - s++; - return res; -} - -static void parseJSON(EvalState& state, const char*& s, Value& v) { - skipWhitespace(s); - if (*s == 0) { - throw JSONParseError("expected JSON value"); - } + void add() override { + values.push_back(v); + v = nullptr; + }; - if (*s == '[') { - s++; - NixList values; - values.reserve(128); - skipWhitespace(s); - while (true) { - if (values.empty() && *s == ']') { - break; - } - Value* v2 = state.allocValue(); - parseJSON(state, s, *v2); - values.push_back(v2); - skipWhitespace(s); - if (*s == ']') { - break; - } - if (*s != ',') { - throw JSONParseError("expected ',' or ']' after JSON array element"); - } - s++; - } - s++; - state.mkList(v, values.size()); - for (size_t n = 0; n < values.size(); ++n) { - (*v.list)[n] = values[n]; + public: + JSONListState(JSONState* p, std::size_t reserve) : JSONState(p) { + values.reserve(reserve); } - } + }; - else if (*s == '{') { - s++; - ValueMap attrs; - while (true) { - skipWhitespace(s); - if (attrs.empty() && *s == '}') { - break; - } - std::string name = parseJSONString(s); - skipWhitespace(s); - if (*s != ':') { - throw JSONParseError("expected ':' in JSON object"); - } - s++; - Value* v2 = state.allocValue(); - parseJSON(state, s, *v2); - attrs[state.symbols.Create(name)] = v2; - skipWhitespace(s); - if (*s == '}') { - break; - } - if (*s != ',') { - throw JSONParseError("expected ',' or '}' after JSON member"); - } - s++; - } - state.mkAttrs(v, attrs.size()); - for (auto& i : attrs) { - v.attrs->push_back(Attr(i.first, i.second)); - } - s++; + EvalState& state; + JSONState* rs; + + template <typename T, typename... Args> + inline bool handle_value(T f, Args... args) { + f(rs->value(state), args...); + rs->add(); + return true; } - else if (*s == '"') { - mkString(v, parseJSONString(s)); + public: + JSONSax(EvalState& state, Value& v) : state(state), rs(new JSONState(&v)){}; + ~JSONSax() { delete rs; }; + + bool null() { return handle_value(mkNull); } + + bool boolean(bool val) { return handle_value(mkBool, val); } + + bool number_integer(number_integer_t val) { return handle_value(mkInt, val); } + + bool number_unsigned(number_unsigned_t val) { + return handle_value(mkInt, val); } - else if ((isdigit(*s) != 0) || *s == '-' || *s == '.') { - // Buffer into a std::string first, then use built-in C++ conversions - std::string tmp_number; - ValueType number_type = tInt; + bool number_float(number_float_t val, const string_t& s) { + return handle_value(mkFloat, val); + } - while ((isdigit(*s) != 0) || *s == '-' || *s == '.' || *s == 'e' || - *s == 'E') { - if (*s == '.' || *s == 'e' || *s == 'E') { - number_type = tFloat; - } - tmp_number += *s++; - } + bool string(string_t& val) { + return handle_value<void(Value&, const char*)>(mkString, val.c_str()); + } - try { - if (number_type == tFloat) { - mkFloat(v, stod(tmp_number)); - } else { - mkInt(v, stol(tmp_number)); - } - } catch (std::invalid_argument& e) { - throw JSONParseError("invalid JSON number"); - } catch (std::out_of_range& e) { - throw JSONParseError("out-of-range JSON number"); - } + bool start_object(std::size_t len) { + JSONState* old = rs; + rs = new JSONObjectState(old); + return true; } - else if (strncmp(s, "true", 4) == 0) { - s += 4; - mkBool(v, true); + bool key(string_t& name) { + dynamic_cast<JSONObjectState*>(rs)->key(name, state); + return true; } - else if (strncmp(s, "false", 5) == 0) { - s += 5; - mkBool(v, false); + bool end_object() { + JSONState* old = rs; + rs = old->resolve(state); + delete old; + rs->add(); + return true; } - else if (strncmp(s, "null", 4) == 0) { - s += 4; - mkNull(v); + bool end_array() { return end_object(); } + + bool start_array(size_t len) { + JSONState* old = rs; + rs = new JSONListState( + old, len != std::numeric_limits<size_t>::max() ? len : 128); + return true; } - else { - throw JSONParseError("unrecognised JSON value"); + bool parse_error(std::size_t, const std::string&, + const nlohmann::detail::exception& ex) { + throw JSONParseError(ex.what()); } -} +}; void parseJSON(EvalState& state, const std::string& s_, Value& v) { - const char* s = s_.c_str(); - parseJSON(state, s, v); - skipWhitespace(s); - if (*s != 0) { - throw JSONParseError( - format("expected end-of-string while parsing JSON value: %1%") % s); - } + JSONSax parser(state, v); + bool res = json::sax_parse(s_, &parser); + if (!res) throw JSONParseError("Invalid JSON Value"); } - } // namespace nix |