copy from an old project

include/json.hpp

@@ -0,0 +1,75 @@
+#ifndef JSON_HPP
+#define JSON_HPP
+
+#include <cstddef>
+#include <cstdint>
+
+#include <zephyr/data/json.h>
+
+#include <log.hpp>
+
+namespace JsonParser
+{
+void init();
+void add_text(uint8_t* buf, size_t size);
+int json_printer(const char* bytes, size_t len, void* data);
+
+class HandlerBase
+{
+public:
+    /* private but accessible from static functions */
+    HandlerBase* _next;
+
+    HandlerBase();
+    virtual bool handle(const char* buf, size_t size) = 0;
+};
+
+template <typename Struct, size_t DESC_SIZE, typename Fct>
+class Handler: public HandlerBase
+{
+    const Struct& _s;
+    const json_obj_descr* _da;
+    Fct _fct;
+    bool _allow_partial;
+
+    const int64_t _all_fields;
+
+public:
+    Handler(Struct default_s, const json_obj_descr (&da)[DESC_SIZE], Fct fct, bool allow_partial=false):
+            _s {default_s},
+            _da {da},
+            _fct {fct},
+            _allow_partial{allow_partial},
+            _all_fields {(1 << DESC_SIZE) - 1}
+    {
+    }
+
+    void print( const Struct& s) { json_obj_encode(_da, DESC_SIZE, &s, json_printer, NULL); }
+
+    bool handle(const char* buf, size_t size) override
+    {
+        Struct s{_s};
+        int64_t ret = json_obj_parse((char*)buf, size, _da, DESC_SIZE, &s);
+        if (ret <= 0)
+        {
+            return false;
+        }
+        if(ret != _all_fields && !_allow_partial)
+        {
+            return false;
+        }
+        if (!_fct(s, ret, _all_fields))
+        {
+            return false;
+        }
+
+        // info("received a valid json\n");
+        // print(s);
+        // info("\n");
+        return true;
+    }
+};
+
+} // namespace JsonParser
+
+#endif /* JSON_HPP */

src/json.cpp

@@ -0,0 +1,111 @@
+#include <json.hpp>
+
+static constexpr size_t BUF_SIZE = 64 + 1;
+char _buf[BUF_SIZE];
+size_t _idx;
+size_t _indent;
+
+JsonParser::HandlerBase* _handlers;
+
+JsonParser::HandlerBase::HandlerBase()
+{
+    _next     = _handlers;
+    _handlers = this;
+}
+
+int JsonParser::json_printer(const char* bytes, size_t len, void* data)
+{
+    // info("[[%d]]\n", len);
+    // for (size_t i = 0; i < len; i++)
+    // {
+    //     info("%c", bytes[i]);
+    // }
+    // return 0;
+
+    for (size_t i = 0; i < len; i++)
+    {
+        bool nl = true;
+        if (bytes[i] == '}' || bytes[i] == ']')
+        {
+            nl = false;
+            _indent--;
+            info("\n");
+            for (size_t i = 0; i < _indent; i++)
+            {
+                info("  ");
+            }
+        }
+        info("%c", bytes[i]);
+        if (bytes[i] == '{' || bytes[i] == '[')
+        {
+            _indent++;
+        }
+        if (nl
+            && (bytes[i] == ',' || bytes[i] == '{' || bytes[i] == '}'
+                || bytes[i] == '[' || bytes[i] == ']'))
+        {
+            info("\n");
+            for (size_t i = 0; i < _indent; i++)
+            {
+                info("  ");
+            }
+        }
+    }
+    return 0;
+}
+
+void commit()
+{
+    _buf[_idx] = '\0';
+    bool ok                    = false;
+    JsonParser::HandlerBase* h = _handlers;
+    while (h)
+    {
+        if (h->handle(_buf, _idx))
+        {
+            ok = true;
+            break;
+        }
+        h = h->_next;
+    };
+    _idx = 0;
+    if (!ok)
+    {
+        info("parse end error\n");
+    }
+}
+
+void flush_error()
+{
+    _idx = 0;
+    error("input buffer overflow, flushing\n");
+}
+
+void JsonParser::init()
+{
+    /* nothing to do */
+}
+
+void JsonParser::add_text(uint8_t* buf, size_t size)
+{
+    for (size_t i = 0; i < size; i++)
+    {
+        if (buf[i] == ' ' || buf[i] == '\r' || buf[i] == '\n')
+        {
+            continue;
+        }
+        if (buf[i] == '}')
+        {
+            _buf[_idx] = buf[i];
+            _idx++;
+            commit();
+            continue;
+        }
+        _buf[_idx] = buf[i];
+        _idx++;
+        if (_idx >= BUF_SIZE)
+        {
+            flush_error();
+        }
+    }
+}

zephyr_module.cmake

@@ -0,0 +1,7 @@
+target_include_directories(app PRIVATE
+  ${CMAKE_CURRENT_LIST_DIR}/include
+)
+
+target_sources(app PRIVATE
+  ${CMAKE_CURRENT_LIST_DIR}/src/json.cpp
+)