Working!

.github/workflows/aarch64.yml

@@ -1,4 +1,4 @@
-name: Ubuntu ppc64le (GCC 11)
+name: Ubuntu aarch64 (GCC 13)
 
 on:
   push:

benchmark/distinct_user_id/yyjson.h

@@ -44,7 +44,10 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<uint64_t> &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(distinct_user_id, yyjson)->UseManualTime();
@@ -52,11 +55,15 @@ BENCHMARK_TEMPLATE(distinct_user_id, yyjson)->UseManualTime();
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<uint64_t> &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(distinct_user_id, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace distinct_user_id
 
 #endif // SIMDJSON_COMPETITION_YYJSON

benchmark/find_tweet/yyjson.h

@@ -36,18 +36,26 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, uint64_t find_id, std::string_view &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), find_id, result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, find_id, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(find_tweet, yyjson)->UseManualTime();
+
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, uint64_t find_id, std::string_view &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), find_id, result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, find_id, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(find_tweet, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace find_tweet
 
 #endif // SIMDJSON_COMPETITION_YYJSON

benchmark/json2msgpack/yyjson.h

@@ -100,6 +100,7 @@ struct yyjson : yyjson2msgpack {
            std::string_view &result) {
     yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
     result = to_msgpack(doc, reinterpret_cast<uint8_t*>(buffer));
+    yyjson_doc_free(doc);
     return true;
   }
 };
@@ -113,6 +114,7 @@ struct yyjson_insitu : yyjson2msgpack {
     yyjson_doc *doc =
         yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
     result = to_msgpack(doc, reinterpret_cast<uint8_t*>(buffer));
+    yyjson_doc_free(doc);
     return true;
   }
 };
@@ -120,4 +122,4 @@ BENCHMARK_TEMPLATE(json2msgpack, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
 } // namespace json2msgpack
 
-#endif // SIMDJSON_COMPETITION_YYJSON
+#endif // SIMDJSON_COMPETITION_YYJSON

benchmark/kostya/yyjson.h

@@ -49,18 +49,26 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<point> &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(kostya, yyjson)->UseManualTime();
+
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<point> &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(kostya, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace kostya
 
 #endif // SIMDJSON_COMPETITION_YYJSON

benchmark/large_random/yyjson.h

@@ -47,18 +47,26 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<point> &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(large_random, yyjson)->UseManualTime();
+
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<point> &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(large_random, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace large_random
 
 #endif // SIMDJSON_COMPETITION_YYJSON

benchmark/partial_tweets/yyjson.h

@@ -62,19 +62,26 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<tweet<std::string_view>> &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(partial_tweets, yyjson)->UseManualTime();
+
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, std::vector<tweet<std::string_view>> &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(partial_tweets, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace partial_tweets
 
 #endif // SIMDJSON_COMPETITION_YYJSON
-

benchmark/top_tweet/yyjson.h

@@ -51,18 +51,26 @@ struct yyjson_base {
 
 struct yyjson : yyjson_base {
   bool run(simdjson::padded_string &json, int64_t max_retweet_count, top_tweet_result<StringType> &result) {
-    return yyjson_base::run(yyjson_read(json.data(), json.size(), 0), max_retweet_count, result);
+    yyjson_doc *doc = yyjson_read(json.data(), json.size(), 0);
+    bool b = yyjson_base::run(doc, max_retweet_count, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(top_tweet, yyjson)->UseManualTime();
+
 #if SIMDJSON_COMPETITION_ONDEMAND_INSITU
 struct yyjson_insitu : yyjson_base {
   bool run(simdjson::padded_string &json, int64_t max_retweet_count, top_tweet_result<StringType> &result) {
-    return yyjson_base::run(yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0), max_retweet_count, result);
+    yyjson_doc *doc = yyjson_read_opts(json.data(), json.size(), YYJSON_READ_INSITU, 0, 0);
+    bool b = yyjson_base::run(doc, max_retweet_count, result);
+    yyjson_doc_free(doc);
+    return b;
   }
 };
 BENCHMARK_TEMPLATE(top_tweet, yyjson_insitu)->UseManualTime();
 #endif // SIMDJSON_COMPETITION_ONDEMAND_INSITU
+
 } // namespace top_tweet
 
 #endif // SIMDJSON_COMPETITION_YYJSON

doc/basics.md

@@ -452,7 +452,7 @@ support for users who avoid exceptions. See [the simdjson error handling documen
 * **Field Access:** To get the value of the "foo" field in an object, use `object["foo"]`. This will
   scan through the object looking for the field with the matching string, doing a character-by-character
   comparison. It may generate the error `simdjson::NO_SUCH_FIELD` if there is no such key in the object, it may throw an exception (see [Error handling](#error-handling)). For efficiency reason, you should avoid looking up the same field repeatedly: e.g., do
-  not do `object["foo"]` followed by `object["foo"]` with the same `object` instance. Generally, you should not mix and match iterating through an object (`for(auto field : object) {...}`) and key accesses (`object["foo"]`): if you need to iterate through an object after a key access, you need to call `reset()` on the object. Whenever you call `reset()`, you need to keep in mind that though you can iterate over the array repeatedly, values should be consumedonly once (e.g., repeatedly calling `unescaped_key()` on the same  key is forbidden). Keep in mind that On-Demand does not buffer or save the result of the parsing: if you repeatedly access `object["foo"]`, then it must repeatedly seek the key and parse the content. The library does not provide a distinct function to check if a key is present, instead we recommend you attempt to access the key: e.g., by doing `ondemand::value val{}; if (!object["foo"].get(val)) {...}`, you have that `val` contains the requested value inside the if clause.  It is your responsibility as a user to temporarily keep a reference to the value (`auto v = object["foo"]`), or to consume the content and store it in your own data structures. If you consume an
+  not do `object["foo"]` followed by `object["foo"]` with the same `object` instance. Generally, you should not mix and match iterating through an object (`for(auto field : object) {...}`) and key accesses (`object["foo"]`): if you need to iterate through an object after a key access, you need to call `reset()` on the object. Whenever you call `reset()`, you need to keep in mind that though you can iterate over the array repeatedly, values should be consumed only once (e.g., repeatedly calling `unescaped_key()` on the same  key is forbidden). Keep in mind that On-Demand does not buffer or save the result of the parsing: if you repeatedly access `object["foo"]`, then it must repeatedly seek the key and parse the content. The library does not provide a distinct function to check if a key is present, instead we recommend you attempt to access the key: e.g., by doing `ondemand::value val{}; if (!object["foo"].get(val)) {...}`, you have that `val` contains the requested value inside the if clause.  It is your responsibility as a user to temporarily keep a reference to the value (`auto v = object["foo"]`), or to consume the content and store it in your own data structures. If you consume an
   object twice: `std::string_view(object["foo"]` followed by `std::string_view(object["foo"]` then your code
   is in error. Furthermore, you can only consume one field at a time, on the same object. The
   value instance you get from  `content["bids"]` becomes invalid when you call `content["asks"]`.

include/simdjson/constevalutil.h

@@ -53,6 +53,7 @@ consteval std::string consteval_to_quoted_escaped(std::string_view input) {
 #if SIMDJSON_SUPPORTS_CONCEPTS
 template <std::size_t N>
 struct fixed_string {
+    constexpr fixed_string() : data{} {}  // Default constructor for buffers
     constexpr fixed_string(const char (&str)[N])  {
         for (std::size_t i = 0; i < N; ++i) {
             data[i] = str[i];

include/simdjson/generic/ondemand/amalgamated.h

@@ -52,3 +52,7 @@
 #include "simdjson/generic/ondemand/json_string_builder-inl.h"
 #include "simdjson/generic/ondemand/json_builder.h"
 
+// Compile-time JSON parsing (C++26 P2996 reflection)
+#include "simdjson/generic/ondemand/compile_time_json.h"
+#include "simdjson/generic/ondemand/compile_time_json-inl.h"
+

include/simdjson/generic/ondemand/compile_time_json-inl.h

@@ -0,0 +1,98 @@
+/**
+ * @file compile_time_json-inl.h
+ * @brief Implementation details for compile-time JSON parsing
+ *
+ * This file contains inline implementations and helper utilities for compile-time
+ * JSON parsing. Currently, the main implementation is self-contained in the header.
+ */
+
+#ifndef SIMDJSON_GENERIC_COMPILE_TIME_JSON_INL_H
+
+#ifndef SIMDJSON_CONDITIONAL_INCLUDE
+#define SIMDJSON_GENERIC_COMPILE_TIME_JSON_INL_H
+#include "simdjson/generic/ondemand/compile_time_json.h"
+#endif // SIMDJSON_CONDITIONAL_INCLUDE
+
+#if SIMDJSON_STATIC_REFLECTION
+
+#include <meta>
+#include <array>
+#include <string_view>
+#include <cstdint>
+
+namespace simdjson {
+namespace SIMDJSON_IMPLEMENTATION {
+namespace compile_time {
+
+/**
+ * @brief Optimized constexpr string to integer conversion
+ *
+ * This can be used for more efficient integer parsing in the future.
+ * Currently, we parse all numbers as doubles for simplicity.
+ */
+constexpr int64_t parse_int_fast(std::string_view str) {
+    int64_t result = 0;
+    bool negative = false;
+    std::size_t i = 0;
+
+    if (i < str.size() && str[i] == '-') {
+        negative = true;
+        ++i;
+    }
+
+    while (i < str.size() && str[i] >= '0' && str[i] <= '9') {
+        result = result * 10 + (str[i] - '0');
+        ++i;
+    }
+
+    return negative ? -result : result;
+}
+
+/**
+ * @brief Unescape JSON string at compile-time
+ *
+ * Currently, strings are returned as views into the original JSON.
+ * This function can be used in the future for proper escape handling.
+ */
+template<std::size_t MaxLen = 1024>
+constexpr auto unescape_json_string(std::string_view escaped) {
+    std::array<char, MaxLen> result{};
+    std::size_t out_pos = 0;
+    std::size_t i = 0;
+
+    while (i < escaped.size() && out_pos < MaxLen) {
+        if (escaped[i] == '\\' && i + 1 < escaped.size()) {
+            ++i;
+            switch (escaped[i]) {
+                case '"':  result[out_pos++] = '"'; break;
+                case '\\': result[out_pos++] = '\\'; break;
+                case '/':  result[out_pos++] = '/'; break;
+                case 'b':  result[out_pos++] = '\b'; break;
+                case 'f':  result[out_pos++] = '\f'; break;
+                case 'n':  result[out_pos++] = '\n'; break;
+                case 'r':  result[out_pos++] = '\r'; break;
+                case 't':  result[out_pos++] = '\t'; break;
+                case 'u':
+                    // Unicode escape - would need proper implementation
+                    // For now, skip the escape sequence
+                    i += 4; // Skip 4 hex digits
+                    break;
+                default:
+                    result[out_pos++] = escaped[i];
+            }
+            ++i;
+        } else {
+            result[out_pos++] = escaped[i];
+            ++i;
+        }
+    }
+
+    return std::pair{result, out_pos};
+}
+
+} // namespace compile_time
+} // namespace SIMDJSON_IMPLEMENTATION
+} // namespace simdjson
+
+#endif // SIMDJSON_STATIC_REFLECTION
+#endif // SIMDJSON_GENERIC_COMPILE_TIME_JSON_INL_H

include/simdjson/generic/ondemand/compile_time_json.h

@@ -0,0 +1,464 @@
+/**
+ * @file compile_time_json.h
+ * @brief Compile-time JSON parsing using C++26 reflection with std::meta::substitute()
+ *
+ * Based on the godbolt example: https://godbolt.org/z/Kn5b46T8j
+ * Uses the Outer<Ms...>::Inner + substitute() pattern for recursive type generation.
+ */
+
+#ifndef SIMDJSON_GENERIC_COMPILE_TIME_JSON_H
+
+#ifndef SIMDJSON_CONDITIONAL_INCLUDE
+#define SIMDJSON_GENERIC_COMPILE_TIME_JSON_H
+#include "simdjson/generic/ondemand/base.h"
+#endif // SIMDJSON_CONDITIONAL_INCLUDE
+
+#if SIMDJSON_STATIC_REFLECTION
+
+#include <meta>
+#include <string_view>
+#include <array>
+#include <vector>
+#include <cstdint>
+#include <string>
+#include <algorithm>
+
+namespace simdjson {
+namespace SIMDJSON_IMPLEMENTATION {
+namespace compile_time {
+
+/**
+ * @brief Helper struct for substitute() pattern
+ * The consteval block can use define_aggregate because it's in a template context
+ */
+template <std::meta::info ...Ms>
+struct Outer {
+    struct Inner;
+    consteval {
+        std::meta::define_aggregate(^^Inner, {Ms...});
+    }
+};
+
+/**
+ * @brief Type alias for the generated struct
+ */
+template <std::meta::info ...Ms>
+using Cls = Outer<Ms...>::Inner;
+
+/**
+ * @brief Variable template for constructing instances with values
+ */
+template <typename T, auto ... Vs>
+constexpr auto construct_from = T{Vs...};
+
+// Forward declaration
+consteval std::meta::info parse_json_impl(std::string_view json);
+
+/**
+ * @brief Parse JSON array and return std::meta::info for the generated array
+ */
+consteval std::meta::info parse_json_array_impl(std::string_view json) {
+    auto cursor = json.begin();
+    auto end = json.end();
+
+    auto is_whitespace = [](char c) {
+        return c == ' ' || c == '\n' || c == '\t' || c == '\r';
+    };
+
+    auto skip_whitespace = [&]() -> void {
+        while (cursor != end && is_whitespace(*cursor)) cursor++;
+    };
+
+    auto expect_consume = [&](char c) -> void {
+        skip_whitespace();
+        if (cursor == end || *(cursor++) != c) throw "unexpected character";
+    };
+
+    auto parse_value = [&](std::string &out) -> void {
+        skip_whitespace();
+
+        bool quoted = false;
+        unsigned depth = 0;
+        while (true) {
+            if (cursor == end) throw "unexpected end of stream";
+            if (is_whitespace(*cursor) && !quoted && depth == 0)
+                break;
+
+            if (depth == 0 && (*cursor == ',' || *cursor == ']'))
+                break;
+            out += *(cursor++);
+
+            if (out.back() == '{')
+                ++depth;
+            else if (out.back() == '}')
+                --depth;
+            else if (out.back() == '[')
+                ++depth;
+            else if (out.back() == ']')
+                --depth;
+            else if (out.back() == '"') {
+                if (quoted && depth == 0)
+                    break;
+                quoted = true;
+            }
+        }
+    };
+
+    skip_whitespace();
+    expect_consume('[');
+
+    std::vector<std::meta::info> values = {^^void};
+    std::meta::info element_type = ^^void;
+    bool first = true;
+
+    using std::meta::reflect_constant, std::meta::reflect_constant_string;
+
+    skip_whitespace();
+    if (cursor != end && *cursor == ']') {
+        expect_consume(']');
+        // Empty array - use int as placeholder type since void doesn't work
+        auto array_type = std::meta::substitute(^^std::array, {^^int, reflect_constant(0uz)});
+        values[0] = array_type;
+        return std::meta::substitute(^^construct_from, values);
+    }
+
+    while (cursor != end && *cursor != ']') {
+        std::string value;
+        parse_value(value);
+
+        if (value.empty()) throw "expected value";
+
+        if (value[0] == '"') {
+            if (value.back() != '"') throw "expected end of string";
+            std::string_view contents(&value[1], value.size() - 2);
+
+            if (first) element_type = ^^char const*;
+            values.push_back(reflect_constant_string(contents));
+        } else if (value == "true") {
+            if (first) element_type = ^^bool;
+            values.push_back(reflect_constant(true));
+        } else if (value == "false") {
+            if (first) element_type = ^^bool;
+            values.push_back(reflect_constant(false));
+        } else if (value == "null") {
+            if (first) element_type = ^^std::nullptr_t;
+            values.push_back(reflect_constant(nullptr));
+        } else if ((value[0] >= '0' && value[0] <= '9') || value[0] == '-') {
+            // Try to parse as integer first
+            bool is_int = true;
+            for (char c : value) {
+                if (c == '.' || c == 'e' || c == 'E') {
+                    is_int = false;
+                    break;
+                }
+            }
+
+            if (is_int) {
+                int contents = [](std::string_view in) {
+                    int out = 0;
+                    bool negative = false;
+                    std::size_t i = 0;
+                    if (in[0] == '-') {
+                        negative = true;
+                        i = 1;
+                    }
+                    for (; i < in.size(); ++i) {
+                        out = out * 10 + (in[i] - '0');
+                    }
+                    return negative ? -out : out;
+                }(value);
+
+                if (first) element_type = ^^int;
+                values.push_back(reflect_constant(contents));
+            } else {
+                // Parse as double
+                double contents = [](std::string_view in) {
+                    double result = 0.0;
+                    double sign = 1.0;
+                    std::size_t i = 0;
+
+                    if (in[0] == '-') {
+                        sign = -1.0;
+                        i = 1;
+                    }
+
+                    while (i < in.size() && in[i] >= '0' && in[i] <= '9') {
+                        result = result * 10.0 + (in[i] - '0');
+                        ++i;
+                    }
+
+                    if (i < in.size() && in[i] == '.') {
+                        ++i;
+                        double fraction = 0.0;
+                        double divisor = 1.0;
+                        while (i < in.size() && in[i] >= '0' && in[i] <= '9') {
+                            fraction = fraction * 10.0 + (in[i] - '0');
+                            divisor *= 10.0;
+                            ++i;
+                        }
+                        result += fraction / divisor;
+                    }
+
+                    return result * sign;
+                }(value);
+
+                if (first) element_type = ^^double;
+                values.push_back(reflect_constant(contents));
+            }
+        } else if (value[0] == '{') {
+            // Nested object in array
+            std::meta::info parsed = parse_json_impl(value);
+            if (first) element_type = std::meta::type_of(parsed);
+            values.push_back(parsed);
+        } else if (value[0] == '[') {
+            // Nested array
+            std::meta::info parsed = parse_json_array_impl(value);
+            if (first) element_type = std::meta::type_of(parsed);
+            values.push_back(parsed);
+        }
+
+        first = false;
+
+        skip_whitespace();
+        if (cursor != end && *cursor == ',')
+            ++cursor;
+    }
+
+    if (cursor == end) throw "unexpected end";
+    expect_consume(']');
+
+    // Create std::array<ElementType, Count> type
+    std::size_t count = values.size() - 1; // -1 because first element is ^^void placeholder
+    auto array_type = std::meta::substitute(^^std::array, {element_type, reflect_constant(count)});
+
+    // Create array instance with values
+    values[0] = array_type;
+    return std::meta::substitute(^^construct_from, values);
+}
+
+/**
+ * @brief Parse JSON and return std::meta::info for the generated type + instance
+ */
+consteval std::meta::info parse_json_impl(std::string_view json) {
+    auto cursor = json.begin();
+    auto end = json.end();
+
+    auto is_whitespace = [](char c) {
+        return c == ' ' || c == '\n' || c == '\t' || c == '\r';
+    };
+
+    auto skip_whitespace = [&]() -> void {
+        while (cursor != end && is_whitespace(*cursor)) cursor++;
+    };
+
+    auto expect_consume = [&](char c) -> void {
+        skip_whitespace();
+        if (cursor == end || *(cursor++) != c) throw "unexpected character";
+    };
+
+    auto parse_until = [&](std::vector<char> delims, std::string &out) -> void {
+        skip_whitespace();
+        while (cursor != end &&
+               !std::ranges::any_of(delims, [&](char c) { return c == *cursor; }))
+            out += *(cursor++);
+    };
+
+    auto parse_delimited = [&](char lhs, std::string &out, char rhs) -> void {
+        skip_whitespace();
+        expect_consume(lhs);
+        parse_until({rhs}, out);
+        expect_consume(rhs);
+    };
+
+    auto parse_value = [&](std::string &out) -> void {
+        skip_whitespace();
+
+        bool quoted = false;
+        unsigned depth = 0;
+        bool in_array = false;
+        while (true) {
+            if (cursor == end) throw "unexpected end of stream";
+            if (is_whitespace(*cursor) && !quoted && depth == 0)
+                break;
+
+            if (depth == 0 && (*cursor == ',' || *cursor == '}' || *cursor == ']'))
+                break;
+            out += *(cursor++);
+
+            if (out.back() == '{')
+                ++depth;
+            else if (out.back() == '}')
+                --depth;
+            else if (out.back() == '[') {
+                in_array = true;
+                ++depth;
+            } else if (out.back() == ']')
+                --depth;
+            else if (out.back() == '"') {
+                if (quoted && depth == 0)
+                    break;
+                quoted = true;
+            }
+        }
+    };
+
+    skip_whitespace();
+    expect_consume('{');
+
+    std::vector<std::meta::info> members;
+    std::vector<std::meta::info> values = {^^void};
+
+    using std::meta::reflect_constant, std::meta::reflect_constant_string;
+    while (cursor != end && *cursor != '}') {
+        std::string field_name;
+        std::string value;
+
+        parse_delimited('"', field_name, '"');
+        expect_consume(':');
+        parse_value(value);
+
+        if (value.empty()) throw "expected value";
+        if (cursor == end) throw "unexpected end of stream";
+
+        if (value[0] == '"') {
+            if (value.back() != '"') throw "expected end of string";
+            std::string_view contents(&value[1], value.size() - 2);
+
+            auto dms = std::meta::data_member_spec(^^char const*, {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(reflect_constant_string(contents));
+        } else if (value == "true") {
+            auto dms = std::meta::data_member_spec(^^bool, {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(reflect_constant(true));
+        } else if (value == "false") {
+            auto dms = std::meta::data_member_spec(^^bool, {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(reflect_constant(false));
+        } else if (value == "null") {
+            auto dms = std::meta::data_member_spec(^^std::nullptr_t, {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(reflect_constant(nullptr));
+        } else if ((value[0] >= '0' && value[0] <= '9') || value[0] == '-') {
+            // Try to parse as integer first
+            bool is_int = true;
+            for (char c : value) {
+                if (c == '.' || c == 'e' || c == 'E') {
+                    is_int = false;
+                    break;
+                }
+            }
+
+            if (is_int) {
+                int contents = [](std::string_view in) {
+                    int out = 0;
+                    bool negative = false;
+                    std::size_t i = 0;
+                    if (in[0] == '-') {
+                        negative = true;
+                        i = 1;
+                    }
+                    for (; i < in.size(); ++i) {
+                        out = out * 10 + (in[i] - '0');
+                    }
+                    return negative ? -out : out;
+                }(value);
+
+                auto dms = std::meta::data_member_spec(^^int, {.name=field_name});
+                members.push_back(reflect_constant(dms));
+                values.push_back(reflect_constant(contents));
+            } else {
+                // Parse as double
+                double contents = [](std::string_view in) {
+                    double result = 0.0;
+                    double sign = 1.0;
+                    std::size_t i = 0;
+
+                    if (in[0] == '-') {
+                        sign = -1.0;
+                        i = 1;
+                    }
+
+                    while (i < in.size() && in[i] >= '0' && in[i] <= '9') {
+                        result = result * 10.0 + (in[i] - '0');
+                        ++i;
+                    }
+
+                    if (i < in.size() && in[i] == '.') {
+                        ++i;
+                        double fraction = 0.0;
+                        double divisor = 1.0;
+                        while (i < in.size() && in[i] >= '0' && in[i] <= '9') {
+                            fraction = fraction * 10.0 + (in[i] - '0');
+                            divisor *= 10.0;
+                            ++i;
+                        }
+                        result += fraction / divisor;
+                    }
+
+                    return result * sign;
+                }(value);
+
+                auto dms = std::meta::data_member_spec(^^double, {.name=field_name});
+                members.push_back(reflect_constant(dms));
+                values.push_back(reflect_constant(contents));
+            }
+        } else if (value[0] == '{') {
+            // Nested object
+            std::meta::info parsed = parse_json_impl(value);
+
+            auto dms = std::meta::data_member_spec(std::meta::type_of(parsed), {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(parsed);
+        } else if (value[0] == '[') {
+            // Array
+            std::meta::info parsed = parse_json_array_impl(value);
+
+            auto dms = std::meta::data_member_spec(std::meta::type_of(parsed), {.name=field_name});
+            members.push_back(reflect_constant(dms));
+            values.push_back(parsed);
+        }
+
+        skip_whitespace();
+        if (cursor != end && *cursor == ',')
+            ++cursor;
+    }
+
+    if (cursor == end) throw "unexpected end";
+    expect_consume('}');
+
+    // The substitute() trick:
+    // 1. Create the type: Cls<member_specs...>
+    values[0] = std::meta::substitute(^^Cls, members);
+    // 2. Create instance: construct_from<Type, values...>
+    return std::meta::substitute(^^construct_from, values);
+}
+
+/**
+ * @brief Main parse_json function - template wrapper
+ */
+template<constevalutil::fixed_string json_str>
+consteval auto parse_json() {
+    constexpr std::meta::info result = parse_json_impl(json_str.view());
+    return [:result:];
+}
+
+/**
+ * @brief JSON validation
+ */
+template<constevalutil::fixed_string json_str>
+consteval bool validate_json() {
+    try {
+        parse_json_impl(json_str.view());
+        return true;
+    } catch (...) {
+        return false;
+    }
+}
+
+} // namespace compile_time
+} // namespace SIMDJSON_IMPLEMENTATION
+} // namespace simdjson
+
+#endif // SIMDJSON_STATIC_REFLECTION
+#endif // SIMDJSON_GENERIC_COMPILE_TIME_JSON_H

tests/ondemand/compile_time_json_tests.cpp

@@ -0,0 +1,418 @@
+/**
+ * @file compile_time_json_tests.cpp
+ * @brief Comprehensive tests for compile-time JSON parsing using C++26 P2996 reflection
+ */
+
+#include "simdjson.h"
+#include "test_ondemand.h"
+
+using namespace simdjson;
+using namespace std::string_view_literals;
+
+namespace compile_time_json_tests {
+
+#if SIMDJSON_STATIC_REFLECTION
+using namespace arm64::compile_time;
+#endif
+
+/**
+ * Test 1: Basic object with primitives
+ */
+bool test_basic_object() {
+    TEST_START();
+
+    constexpr auto config = parse_json<R"({
+        "port": 8080,
+        "host": "localhost",
+        "debug": true,
+        "timeout": 30.5
+    })">();
+
+    static_assert(config.port == 8080);
+    static_assert(std::string_view(config.host) == "localhost");
+    static_assert(config.debug == true);
+    static_assert(config.timeout == 30.5);
+
+    ASSERT_EQUAL(config.port, 8080);
+    ASSERT_EQUAL(std::string_view(config.host), "localhost"sv);
+    ASSERT_TRUE(config.debug);
+    ASSERT_EQUAL(config.timeout, 30.5);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 2: Nested objects
+ */
+bool test_nested_objects() {
+    TEST_START();
+
+    constexpr auto config = parse_json<R"({
+        "server_port": 3000,
+        "enable_ssl": true,
+        "database": {
+            "host": "db.example.com",
+            "port": 5432,
+            "timeout_sec": 30.0
+        }
+    })">();
+
+    static_assert(config.server_port == 3000);
+    static_assert(config.enable_ssl == true);
+    static_assert(std::string_view(config.database.host) == "db.example.com");
+    static_assert(config.database.port == 5432);
+    static_assert(config.database.timeout_sec == 30.0);
+
+    ASSERT_EQUAL(config.server_port, 3000);
+    ASSERT_TRUE(config.enable_ssl);
+    ASSERT_EQUAL(std::string_view(config.database.host), "db.example.com"sv);
+    ASSERT_EQUAL(config.database.port, 5432);
+    ASSERT_EQUAL(config.database.timeout_sec, 30.0);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 3: Deeply nested objects (3+ levels)
+ */
+bool test_deeply_nested_objects() {
+    TEST_START();
+
+    constexpr auto config = parse_json<R"({
+        "app_name": "MyApp",
+        "version": 1.5,
+        "server": {
+            "host": "api.example.com",
+            "port": 443,
+            "tls": {
+                "enabled": true,
+                "cert_path": "/etc/ssl/cert.pem",
+                "min_version": 1.3
+            }
+        }
+    })">();
+
+    static_assert(std::string_view(config.app_name) == "MyApp");
+    static_assert(config.version == 1.5);
+    static_assert(std::string_view(config.server.host) == "api.example.com");
+    static_assert(config.server.port == 443);
+    static_assert(config.server.tls.enabled == true);
+    static_assert(std::string_view(config.server.tls.cert_path) == "/etc/ssl/cert.pem");
+    static_assert(config.server.tls.min_version == 1.3);
+
+    ASSERT_EQUAL(std::string_view(config.app_name), "MyApp"sv);
+    ASSERT_EQUAL(config.server.tls.enabled, true);
+    ASSERT_EQUAL(config.server.tls.min_version, 1.3);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 4: Empty object
+ */
+bool test_empty_object() {
+    TEST_START();
+
+    constexpr auto config = parse_json<"{}">();
+    (void)config;  // Suppress unused warning
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 5: Negative numbers
+ */
+bool test_negative_numbers() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "temperature": -273.15,
+        "count": -42
+    })">();
+
+    static_assert(data.temperature == -273.15);
+    static_assert(data.count == -42);
+
+    ASSERT_EQUAL(data.temperature, -273.15);
+    ASSERT_EQUAL(data.count, -42);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 6: Whitespace handling
+ */
+bool test_whitespace() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"(
+        {
+            "key1"  :  "value1"  ,
+            "key2"  :  42
+        }
+    )">();
+
+    static_assert(std::string_view(data.key1) == "value1");
+    static_assert(data.key2 == 42);
+
+    ASSERT_EQUAL(std::string_view(data.key1), "value1"sv);
+    ASSERT_EQUAL(data.key2, 42);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 7: Real-time system configuration
+ */
+bool test_realtime_config() {
+    TEST_START();
+
+    constexpr auto config = parse_json<R"({
+        "control_loop_hz": 1000,
+        "max_acceleration": 9.8,
+        "min_velocity": -50.0,
+        "max_velocity": 50.0,
+        "enable_safety_checks": true,
+        "log_level": "INFO"
+    })">();
+
+    static_assert(config.control_loop_hz == 1000);
+    static_assert(config.max_acceleration == 9.8);
+    static_assert(config.enable_safety_checks == true);
+
+    ASSERT_EQUAL(config.control_loop_hz, 1000);
+    ASSERT_EQUAL(config.max_acceleration, 9.8);
+    ASSERT_EQUAL(config.min_velocity, -50.0);
+    ASSERT_EQUAL(config.max_velocity, 50.0);
+    ASSERT_TRUE(config.enable_safety_checks);
+    ASSERT_EQUAL(std::string_view(config.log_level), "INFO"sv);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 8: External JSON file (future #embed support)
+ */
+bool test_external_json_embed() {
+    TEST_START();
+
+    // Future C++26 with #embed:
+    // constexpr auto config = parse_json<#embed "test_config.json">();
+
+    // Current workaround - inline the JSON from test_config.json
+    constexpr auto config = parse_json<R"({
+  "system_name": "RealTimeController",
+  "version": "2.1.0",
+  "control_loop_hz": 1000,
+  "max_latency_us": 500,
+  "enable_diagnostics": true,
+  "log_level": "INFO"
+})">();
+
+    static_assert(std::string_view(config.system_name) == "RealTimeController");
+    static_assert(std::string_view(config.version) == "2.1.0");
+    static_assert(config.control_loop_hz == 1000);
+    static_assert(config.max_latency_us == 500);
+    static_assert(config.enable_diagnostics == true);
+    static_assert(std::string_view(config.log_level) == "INFO");
+
+    ASSERT_EQUAL(std::string_view(config.system_name), "RealTimeController"sv);
+    ASSERT_EQUAL(std::string_view(config.version), "2.1.0"sv);
+    ASSERT_EQUAL(config.control_loop_hz, 1000);
+    ASSERT_EQUAL(config.max_latency_us, 500);
+    ASSERT_TRUE(config.enable_diagnostics);
+    ASSERT_EQUAL(std::string_view(config.log_level), "INFO"sv);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 9: JSON validation
+ */
+bool test_json_validation() {
+    TEST_START();
+
+    static_assert(validate_json<R"({"valid": true})">());
+    static_assert(validate_json<R"({"nested": {"deep": 42}})">());
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 10: Null values
+ */
+bool test_null_values() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "nullable_field": null,
+        "number": 42
+    })">();
+
+    static_assert(data.nullable_field == nullptr);
+    static_assert(data.number == 42);
+
+    ASSERT_EQUAL(data.nullable_field, nullptr);
+    ASSERT_EQUAL(data.number, 42);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 11: Arrays of primitives
+ */
+bool test_arrays_primitives() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "values": [1, 2, 3, 4, 5],
+        "flags": [true, false, true]
+    })">();
+
+    static_assert(data.values.size() == 5);
+    static_assert(data.values[0] == 1);
+    static_assert(data.values[4] == 5);
+    static_assert(data.flags.size() == 3);
+    static_assert(data.flags[0] == true);
+    static_assert(data.flags[1] == false);
+
+    ASSERT_EQUAL(data.values.size(), 5);
+    ASSERT_EQUAL(data.values[0], 1);
+    ASSERT_EQUAL(data.values[4], 5);
+    ASSERT_EQUAL(data.flags.size(), 3);
+    ASSERT_TRUE(data.flags[0]);
+    ASSERT_FALSE(data.flags[1]);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 12: Arrays of objects
+ */
+bool test_arrays_of_objects() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "users": [
+            {"name": "Alice", "age": 30},
+            {"name": "Bob", "age": 25}
+        ]
+    })">();
+
+    static_assert(data.users.size() == 2);
+    static_assert(std::string_view(data.users[0].name) == "Alice");
+    static_assert(data.users[0].age == 30);
+    static_assert(std::string_view(data.users[1].name) == "Bob");
+    static_assert(data.users[1].age == 25);
+
+    ASSERT_EQUAL(data.users.size(), 2);
+    ASSERT_EQUAL(std::string_view(data.users[0].name), "Alice"sv);
+    ASSERT_EQUAL(data.users[0].age, 30);
+    ASSERT_EQUAL(std::string_view(data.users[1].name), "Bob"sv);
+    ASSERT_EQUAL(data.users[1].age, 25);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 13: Nested arrays in objects
+ */
+bool test_nested_arrays() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "config": {
+            "ports": [8080, 8081, 8082]
+        }
+    })">();
+
+    static_assert(data.config.ports.size() == 3);
+    static_assert(data.config.ports[0] == 8080);
+    static_assert(data.config.ports[2] == 8082);
+
+    ASSERT_EQUAL(data.config.ports.size(), 3);
+    ASSERT_EQUAL(data.config.ports[0], 8080);
+    ASSERT_EQUAL(data.config.ports[2], 8082);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 14: Complex mixed structure with arrays and nested objects
+ */
+bool test_complex_mixed() {
+    TEST_START();
+
+    constexpr auto config = parse_json<R"({
+        "app": "myapp",
+        "version": 1.0,
+        "config": {
+            "ports": [8080, 8081, 8082],
+            "enabled": true
+        },
+        "servers": [
+            {"host": "server1", "port": 3000},
+            {"host": "server2", "port": 3001}
+        ]
+    })">();
+
+    static_assert(std::string_view(config.app) == "myapp");
+    static_assert(config.version == 1.0);
+    static_assert(config.config.ports[0] == 8080);
+    static_assert(config.config.enabled == true);
+    static_assert(std::string_view(config.servers[0].host) == "server1");
+    static_assert(config.servers[1].port == 3001);
+
+    ASSERT_EQUAL(std::string_view(config.app), "myapp"sv);
+    ASSERT_EQUAL(config.config.ports[0], 8080);
+    ASSERT_EQUAL(std::string_view(config.servers[0].host), "server1"sv);
+    ASSERT_EQUAL(config.servers[1].port, 3001);
+
+    TEST_SUCCEED();
+}
+
+/**
+ * Test 15: Empty arrays
+ */
+bool test_empty_arrays() {
+    TEST_START();
+
+    constexpr auto data = parse_json<R"({
+        "empty": []
+    })">();
+
+    static_assert(data.empty.size() == 0);
+
+    ASSERT_EQUAL(data.empty.size(), 0);
+
+    TEST_SUCCEED();
+}
+
+bool run() {
+    return test_basic_object() &&
+           test_nested_objects() &&
+           test_deeply_nested_objects() &&
+           test_empty_object() &&
+           test_negative_numbers() &&
+           test_whitespace() &&
+           test_realtime_config() &&
+           test_external_json_embed() &&
+           test_json_validation() &&
+           test_null_values() &&
+           test_arrays_primitives() &&
+           test_arrays_of_objects() &&
+           test_nested_arrays() &&
+           test_complex_mixed() &&
+           test_empty_arrays();
+}
+
+} // namespace compile_time_json_tests
+
+int main(int argc, char *argv[]) {
+#if SIMDJSON_STATIC_REFLECTION
+    return test_main(argc, argv, compile_time_json_tests::run);
+#else
+    std::cout << "Compile-time JSON tests require SIMDJSON_STATIC_REFLECTION=ON" << std::endl;
+    return EXIT_SUCCESS;
+#endif
+}

tests/ondemand/test_config.json

@@ -0,0 +1,8 @@
+{
+  "system_name": "RealTimeController",
+  "version": "2.1.0",
+  "control_loop_hz": 1000,
+  "max_latency_us": 500,
+  "enable_diagnostics": true,
+  "log_level": "INFO"
+}