From a5b61f465defa0c0fe46b970868c1b2fd6f02fef Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Thu, 1 Feb 2024 17:24:03 +1100
Subject: [PATCH] x

---
 libraries/AP_JSONParser/AP_JSONParser.cpp | 36 ++++++++++
 libraries/AP_JSONParser/AP_JSONParser.h   | 11 +++
 libraries/SITL/SIM_XPlane.cpp             | 82 ++++-------------------
 3 files changed, 59 insertions(+), 70 deletions(-)

diff --git a/libraries/AP_JSONParser/AP_JSONParser.cpp b/libraries/AP_JSONParser/AP_JSONParser.cpp
index 2e4f4f323bf4aa..475e695a5c57c2 100644
--- a/libraries/AP_JSONParser/AP_JSONParser.cpp
+++ b/libraries/AP_JSONParser/AP_JSONParser.cpp
@@ -225,4 +225,40 @@ bool AP_JSONParser::shift_token_object(uint16_t &ret)
     return true;
 }
 
+bool AP_JSONParser::shift_struct(const ObjectBits &bits)
+{
+    uint16_t n_object_kv_pairs;
+    if (!shift_token_object(n_object_kv_pairs)) {
+        return false;
+    }
+
+    for (uint8_t i=0;i<n_object_kv_pairs; i++) {
+        char n[50] {};
+        if (!shift_token_string(n, ARRAY_SIZE(n))) {
+            return false;
+        }
+        for (auto &bit : bits) {
+            if (!streq(n, bits->label)) {
+                continue;
+            }
+            switch (bits->type) {
+            case Type::STRING:
+                char unused[50] {};
+                if (!shift_token_string((char*)bits->ptr, bits->ptrsize)) {
+                    return false;
+                }
+                break;
+            case Type::INT32:
+                if (!shift_token_int32_t(*(int32_t*)(bits->ptr))) {
+                    return false;
+                }
+            case Type::FLOAT:
+                if (!shift_token_float(*(float*)(bits->ptr))) {
+                    return false;
+                }
+            }
+        }
+    }
+}
+
 #endif  // AP_JSONPARSER_ENABLED
diff --git a/libraries/AP_JSONParser/AP_JSONParser.h b/libraries/AP_JSONParser/AP_JSONParser.h
index e0b2543d9d212d..b8dcb788af970a 100644
--- a/libraries/AP_JSONParser/AP_JSONParser.h
+++ b/libraries/AP_JSONParser/AP_JSONParser.h
@@ -57,6 +57,17 @@ class AP_JSONParser
     bool shift_token_vector3f(Vector3f &ret) WARN_IF_UNUSED;
     bool shift_token_object(uint16_t &count) WARN_IF_UNUSED;
 
+    struct ObjectBits {
+        enum class Type {
+            STRING,
+            INT32,
+            FLOAT,
+        };
+        const char *label;  // e.g. "channel", "mask", "type"
+        int8_t jsmn_type;
+        void *data_ptr;  // this is where the data goes...
+    };
+
 private:
 
     // this object may be declared on the stack, so initialise:
diff --git a/libraries/SITL/SIM_XPlane.cpp b/libraries/SITL/SIM_XPlane.cpp
index ae8328d04dd2b6..643d69eb8df731 100644
--- a/libraries/SITL/SIM_XPlane.cpp
+++ b/libraries/SITL/SIM_XPlane.cpp
@@ -141,43 +141,13 @@ bool XPlane::handle_axis(const char *label, class ::AP_JSONParser &json_parser)
         return false;
     }
 
-    for (uint8_t i=0;i<n_object_kv_pairs; i++) {
-        char n[50] {};
-        if (!json_parser.shift_token_string(n, ARRAY_SIZE(n))) {
-            return false;
-        }
-        if (streq(n, "channel")) {
-            int32_t value;
-            if (!json_parser.shift_token_int32_t(value)) {
-                return false;
-            }
-            j->channel = value;
-            continue;
-        }
-        if (streq(n, "input_min")) {
-            float value;
-            if (!json_parser.shift_token_float(value)) {
-                return false;
-            }
-            j->input_min = value;
-            continue;
-        }
-        if (streq(n, "input_max")) {
-            float value;
-            if (!json_parser.shift_token_float(value)) {
-                return false;
-            }
-            j->input_max = value;
-            continue;
-        }
-        if (streq(n, "type")) {
-            char unused[50] {};
-            if (!json_parser.shift_token_string(unused, ARRAY_SIZE(unused))) {
-                return false;
-            }
-            continue;
-        }
-        ::printf("Unknown axis nv %s\n", n);
+    const struct JSONParser::ObjectBits button_bits {
+        { "channel", JSONParser::ObjectBits::Type::INT32, (void*)&j->channel },
+        { "input_min", JSONParser::ObjectBits::Type::FLAOT, (void*)&j->input_min },
+        { "input_max", JSONParser::ObjectBits::Type::FLAOT, (void*)&j->input_max },
+    };
+
+    if (!json_parser->shift_struct(button_bits)) {
         return false;
     }
 
@@ -197,40 +167,12 @@ bool XPlane::handle_button(const char *label, class ::AP_JSONParser &json_parser
     }
     j->type = JoyType::BUTTON;
 
-    uint16_t n_object_kv_pairs;
-    if (!json_parser.shift_token_object(n_object_kv_pairs)) {
-        return false;
-    }
+    const struct JSONParser::ObjectBits button_bits {
+        { "channel", JSONParser::ObjectBits::Type::INT32, (void*)&j->channel },
+        { "mask", JSONParser::ObjectBits::Type::INT32, (void*)&j->mask },
+    };
 
-    for (uint8_t i=0;i<n_object_kv_pairs; i++) {
-        char n[50] {};
-        if (!json_parser.shift_token_string(n, ARRAY_SIZE(n))) {
-            return false;
-        }
-        if (streq(n, "channel")) {
-            int32_t value;
-            if (!json_parser.shift_token_int32_t(value)) {
-                return false;
-            }
-            j->channel = value;
-            continue;
-        }
-        if (streq(n, "mask")) {
-            int32_t value;
-            if (!json_parser.shift_token_int32_t(value)) {
-                return false;
-            }
-            j->mask = value;
-            continue;
-        }
-        if (streq(n, "type")) {
-            char unused[50] {};
-            if (!json_parser.shift_token_string(unused, ARRAY_SIZE(unused))) {
-                return false;
-            }
-            continue;
-        }
-        ::printf("Unknown button nv %s\n", n);
+    if (!json_parser->shift_struct(button_bits)) {
         return false;
     }