feat(tvix): builtins.fromJSON: use nlohmann/json parser instead of custom parser
backported from upstream at f1fac0b5c3b75efab781949fdff2b67ffdda2cb3 Change-Id: I788e3a9b930351118a5f248b356c351afd7f5391 Reviewed-on: https://cl.tvl.fyi/c/depot/+/2138 Tested-by: BuildkiteCI Reviewed-by: tazjin <mail@tazj.in>
This commit is contained in:
Yorick van Pelt
glittershark
parent
de44fdf92a
commit
b595553f63
1 changed files with 120 additions and 159 deletions
279
third_party/nix/src/libexpr/json-to-value.cc
vendored
279
third_party/nix/src/libexpr/json-to-value.cc
vendored
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@ -1,185 +1,146 @@
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#include "libexpr/json-to-value.hh"
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#include <cstring>
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#include <nlohmann/json.hpp>
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#include <variant>
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#include <vector>
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#include "libexpr/value.hh"
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using json = nlohmann::json;
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namespace nix {
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static void skipWhitespace(const char*& s) {
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while (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r') {
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s++;
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}
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}
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// for more information, refer to
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// https://github.com/nlohmann/json/blob/master/include/nlohmann/detail/input/json_sax.hpp
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class JSONSax : nlohmann::json_sax<json> {
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class JSONState {
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protected:
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JSONState* parent;
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Value* v;
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static std::string parseJSONString(const char*& s) {
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std::string res;
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if (*s++ != '"') {
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throw JSONParseError("expected JSON string");
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}
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while (*s != '"') {
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if (*s == 0) {
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throw JSONParseError("got end-of-string in JSON string");
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public:
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virtual JSONState* resolve(EvalState&) {
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throw std::logic_error("tried to close toplevel json parser state");
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};
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explicit JSONState(JSONState* p) : parent(p), v(nullptr){};
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explicit JSONState(Value* v) : v(v){};
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JSONState(JSONState& p) = delete;
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Value& value(EvalState& state) {
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if (v == nullptr) v = state.allocValue();
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return *v;
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};
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virtual ~JSONState(){};
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virtual void add(){};
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};
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class JSONObjectState : public JSONState {
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using JSONState::JSONState;
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ValueMap attrs = ValueMap();
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virtual JSONState* resolve(EvalState& state) override {
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Value& v = parent->value(state);
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state.mkAttrs(v, attrs.size());
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for (auto& i : attrs) v.attrs->push_back(Attr(i.first, i.second));
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return parent;
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}
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if (*s == '\\') {
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s++;
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if (*s == '"') {
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res += '"';
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} else if (*s == '\\') {
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res += '\\';
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} else if (*s == '/') {
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res += '/';
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} else if (*s == '/') {
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res += '/';
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} else if (*s == 'b') {
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res += '\b';
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} else if (*s == 'f') {
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res += '\f';
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} else if (*s == 'n') {
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res += '\n';
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} else if (*s == 'r') {
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res += '\r';
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} else if (*s == 't') {
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res += '\t';
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} else if (*s == 'u') {
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throw JSONParseError(
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"\\u characters in JSON strings are currently not supported");
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} else {
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throw JSONParseError("invalid escaped character in JSON string");
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}
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s++;
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} else {
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res += *s++;
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virtual void add() override { v = nullptr; };
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public:
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void key(string_t& name, EvalState& state) {
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attrs[state.symbols.Create(name)] = &value(state);
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}
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}
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s++;
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return res;
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}
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};
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static void parseJSON(EvalState& state, const char*& s, Value& v) {
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skipWhitespace(s);
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if (*s == 0) {
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throw JSONParseError("expected JSON value");
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}
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if (*s == '[') {
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s++;
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NixList values;
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values.reserve(128);
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skipWhitespace(s);
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while (true) {
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if (values.empty() && *s == ']') {
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break;
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class JSONListState : public JSONState {
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std::vector<Value*> values;
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virtual JSONState* resolve(EvalState& state) override {
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Value& v = parent->value(state);
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state.mkList(v, values.size());
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for (size_t n = 0; n < values.size(); ++n) {
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(*v.list)[n] = values[n];
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}
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Value* v2 = state.allocValue();
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parseJSON(state, s, *v2);
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values.push_back(v2);
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skipWhitespace(s);
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if (*s == ']') {
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break;
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}
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if (*s != ',') {
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throw JSONParseError("expected ',' or ']' after JSON array element");
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}
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s++;
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}
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s++;
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state.mkList(v, values.size());
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for (size_t n = 0; n < values.size(); ++n) {
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(*v.list)[n] = values[n];
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}
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}
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else if (*s == '{') {
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s++;
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ValueMap attrs;
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while (true) {
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skipWhitespace(s);
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if (attrs.empty() && *s == '}') {
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break;
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}
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std::string name = parseJSONString(s);
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skipWhitespace(s);
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if (*s != ':') {
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throw JSONParseError("expected ':' in JSON object");
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}
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s++;
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Value* v2 = state.allocValue();
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parseJSON(state, s, *v2);
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attrs[state.symbols.Create(name)] = v2;
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skipWhitespace(s);
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if (*s == '}') {
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break;
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}
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if (*s != ',') {
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throw JSONParseError("expected ',' or '}' after JSON member");
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}
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s++;
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}
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state.mkAttrs(v, attrs.size());
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for (auto& i : attrs) {
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v.attrs->push_back(Attr(i.first, i.second));
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}
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s++;
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}
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else if (*s == '"') {
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mkString(v, parseJSONString(s));
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}
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else if ((isdigit(*s) != 0) || *s == '-' || *s == '.') {
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// Buffer into a std::string first, then use built-in C++ conversions
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std::string tmp_number;
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ValueType number_type = tInt;
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while ((isdigit(*s) != 0) || *s == '-' || *s == '.' || *s == 'e' ||
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*s == 'E') {
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if (*s == '.' || *s == 'e' || *s == 'E') {
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number_type = tFloat;
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}
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tmp_number += *s++;
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return parent;
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}
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try {
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if (number_type == tFloat) {
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mkFloat(v, stod(tmp_number));
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} else {
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mkInt(v, stol(tmp_number));
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}
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} catch (std::invalid_argument& e) {
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throw JSONParseError("invalid JSON number");
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} catch (std::out_of_range& e) {
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throw JSONParseError("out-of-range JSON number");
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void add() override {
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values.push_back(v);
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v = nullptr;
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};
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public:
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JSONListState(JSONState* p, std::size_t reserve) : JSONState(p) {
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values.reserve(reserve);
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}
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};
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EvalState& state;
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JSONState* rs;
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template <typename T, typename... Args>
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inline bool handle_value(T f, Args... args) {
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f(rs->value(state), args...);
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rs->add();
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return true;
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}
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else if (strncmp(s, "true", 4) == 0) {
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s += 4;
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mkBool(v, true);
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public:
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JSONSax(EvalState& state, Value& v) : state(state), rs(new JSONState(&v)){};
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~JSONSax() { delete rs; };
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bool null() { return handle_value(mkNull); }
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bool boolean(bool val) { return handle_value(mkBool, val); }
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bool number_integer(number_integer_t val) { return handle_value(mkInt, val); }
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bool number_unsigned(number_unsigned_t val) {
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return handle_value(mkInt, val);
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}
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else if (strncmp(s, "false", 5) == 0) {
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s += 5;
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mkBool(v, false);
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bool number_float(number_float_t val, const string_t& s) {
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return handle_value(mkFloat, val);
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}
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else if (strncmp(s, "null", 4) == 0) {
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s += 4;
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mkNull(v);
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bool string(string_t& val) {
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return handle_value<void(Value&, const char*)>(mkString, val.c_str());
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}
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else {
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throw JSONParseError("unrecognised JSON value");
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bool start_object(std::size_t len) {
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JSONState* old = rs;
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rs = new JSONObjectState(old);
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return true;
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}
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}
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bool key(string_t& name) {
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dynamic_cast<JSONObjectState*>(rs)->key(name, state);
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return true;
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}
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bool end_object() {
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JSONState* old = rs;
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rs = old->resolve(state);
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delete old;
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rs->add();
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return true;
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}
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bool end_array() { return end_object(); }
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bool start_array(size_t len) {
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JSONState* old = rs;
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rs = new JSONListState(
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old, len != std::numeric_limits<size_t>::max() ? len : 128);
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return true;
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}
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bool parse_error(std::size_t, const std::string&,
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const nlohmann::detail::exception& ex) {
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throw JSONParseError(ex.what());
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}
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};
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void parseJSON(EvalState& state, const std::string& s_, Value& v) {
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const char* s = s_.c_str();
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parseJSON(state, s, v);
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skipWhitespace(s);
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if (*s != 0) {
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throw JSONParseError(
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format("expected end-of-string while parsing JSON value: %1%") % s);
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}
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JSONSax parser(state, v);
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bool res = json::sax_parse(s_, &parser);
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if (!res) throw JSONParseError("Invalid JSON Value");
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}
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} // namespace nix
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