Basic hooking into json parsing.

Also allow customization of the fallback meta-method.

module/Library/JSON.cpp

@@ -2,6 +2,7 @@
 #include "Library/JSON.hpp"
 
 // ------------------------------------------------------------------------------------------------
+#include <sajson.h>
 #include <sqratConst.h>
 
 // ------------------------------------------------------------------------------------------------
@@ -180,6 +181,23 @@ CtxJSON & CtxJSON::CloseArray()
     return *this;
 }
 
+// ------------------------------------------------------------------------------------------------
+CtxJSON & CtxJSON::ReopenArray()
+{
+    // If the last character is a comma then remove it
+    if (mOutput.back() == ',')
+    {
+        mOutput.pop_back();
+    }
+    // If the last character is the array-end character then replace it with a comma
+    if (mOutput.back() == ']')
+    {
+        mOutput.back() = ',';
+    }
+    // Allow chaining
+    return *this;
+}
+
 // ------------------------------------------------------------------------------------------------
 CtxJSON & CtxJSON::OpenObject()
 {
@@ -212,6 +230,23 @@ CtxJSON & CtxJSON::CloseObject()
     return *this;
 }
 
+// ------------------------------------------------------------------------------------------------
+CtxJSON & CtxJSON::ReopenObject()
+{
+    // If the last character is a comma then remove it
+    if (mOutput.back() == ',')
+    {
+        mOutput.pop_back();
+    }
+    // If the last character is the object-end character then replace it with a comma
+    if (mOutput.back() == '}')
+    {
+        mOutput.back() = ',';
+    }
+    // Allow chaining
+    return *this;
+}
+
 // ------------------------------------------------------------------------------------------------
 CtxJSON & CtxJSON::MakeKey()
 {
@@ -225,6 +260,11 @@ CtxJSON & CtxJSON::MakeKey()
     {
         mOutput.push_back(':');
     }
+    // Allow the hook to react
+    if (mKeyHook)
+    {
+        mKeyHook(*this);
+    }
     // Allow chaining
     return *this;
 }
@@ -467,7 +507,7 @@ SQRESULT CtxJSON::SerializeTable(HSQUIRRELVM vm, SQInteger idx) // NOLINT(misc-n
 // ------------------------------------------------------------------------------------------------
 SQRESULT CtxJSON::SerializeInstance(HSQUIRRELVM vm, SQInteger idx)
 {
-    sq_pushstring(vm, _SC("_tojson"), 7);
+    sq_pushstring(vm, mMetaMethod.c_str(), static_cast< SQInteger >(mMetaMethod.size()));
     // Attempt to retrieve the meta-method from the instance
     if(SQRESULT r = sq_get(vm, idx); SQ_FAILED(r))
     {
@@ -629,6 +669,8 @@ void CtxJSON::PushString(const SQChar * str)
     mOutput.append(str);
     mOutput.push_back('"');
     mOutput.push_back(',');
+    // Allow the hook to know
+    mString.assign(str);
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -638,6 +680,8 @@ void CtxJSON::PushString(const SQChar * str, size_t length)
     mOutput.append(str, length);
     mOutput.push_back('"');
     mOutput.push_back(',');
+    // Allow the hook to know
+    mString.assign(str, length);
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -678,6 +722,7 @@ void Register_JSON(HSQUIRRELVM vm)
         // Constructors
         .Ctor()
         .Ctor< bool >()
+        .Ctor< bool, StackStrF & >()
         // Meta-methods
         .SquirrelFunc(_SC("_typename"), &SqCtxJSON::Fn)
         // Properties

module/Library/JSON.hpp

@@ -5,12 +5,13 @@
 #include "Library/IO/Buffer.hpp"
 
 // ------------------------------------------------------------------------------------------------
-#include <sajson.h>
+#include <functional>
+
+// ------------------------------------------------------------------------------------------------
 #include <fmt/args.h>
 #include <fmt/format.h>
 #include <fmt/xchar.h>
 
-
 // ------------------------------------------------------------------------------------------------
 namespace SqMod {
 
@@ -35,6 +36,21 @@ struct CtxJSON
     */
     uint32_t mDepth{0};
 
+    /* --------------------------------------------------------------------------------------------
+     * The meta-method name to use on objects.
+    */
+    String mMetaMethod{"_tojson"};
+
+    /* --------------------------------------------------------------------------------------------
+     * Last pushed string value. Can be used to heck for key name in the hook.
+    */
+    String mString{};
+
+    /* --------------------------------------------------------------------------------------------
+     * Internal utility used to monitor the existence of certain keys to allow overloading.
+    */
+    std::function< void(CtxJSON&) > mKeyHook{};
+
     /* --------------------------------------------------------------------------------------------
      * Default constructor.
     */
@@ -49,6 +65,26 @@ struct CtxJSON
         mObjectOverArray = ooa;
     }
 
+    /* --------------------------------------------------------------------------------------------
+     * Explicit constructor.
+    */
+    CtxJSON(bool ooa, StackStrF & mmname) noexcept
+        : CtxJSON()
+    {
+        mObjectOverArray = ooa;
+        // Allow custom metamethod names
+        mMetaMethod.assign(mmname.mPtr, static_cast< size_t >(mmname.mLen));
+    }
+
+    /* --------------------------------------------------------------------------------------------
+     * Internal constructor.
+    */
+    explicit CtxJSON(std::function< void(CtxJSON&) > && kh) noexcept
+        : CtxJSON()
+    {
+        mKeyHook = std::move(kh);
+    }
+
     /* --------------------------------------------------------------------------------------------
      * Copy constructor.
     */
@@ -135,6 +171,11 @@ struct CtxJSON
     */
     CtxJSON & CloseArray();
 
+    /* --------------------------------------------------------------------------------------------
+     * Resume writing an array.
+    */
+    CtxJSON & ReopenArray();
+
     /* --------------------------------------------------------------------------------------------
      * Begin writing an object.
     */
@@ -145,6 +186,11 @@ struct CtxJSON
     */
     CtxJSON & CloseObject();
 
+    /* --------------------------------------------------------------------------------------------
+     * Resume writing an object.
+    */
+    CtxJSON & ReopenObject();
+
     /* --------------------------------------------------------------------------------------------
      * Begin writing a key value.
     */