JsonDiffPatch for GameMaker Studio 2

Native JSON diff/patch/unpatch for GameMaker Studio 2 using a fast C++ DLL.

This extension wraps the JsonDiffPatch C++ library
and exposes it to GameMaker Studio 2 via three simple functions:

• JDP_Diff(leftJson, rightJson) – Compute a diff between two JSON strings.
• JDP_Patch(leftJson, diff) – Apply a diff to get the patched JSON.
• JDP_Unpatch(rightJson, diff) – Reverse a diff to restore the original JSON.

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📦 Download

⬇️ Download the latest JsonDiffPatchGamemakerExtension.yymps

(or build the DLL yourself from the C++ repo)

The prebuilt DLL for Windows is in bin/windows/JsonDiffPatchDLL.dll.

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🚀 Installation

1. Download JsonDiffPatchGamemakerExtension.yymps from this repository (link above).
2. In GameMaker Studio 2, go to Tools > Import Local Package.
3. Select the .yymps file. The extension and DLL will be added to your project automatically.
4. Make sure the extension is enabled for the Windows platform in the Extension Properties.

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📝 Usage

Example script in GameMaker:

// Test 1: Empty strings
var diff1 = JDP_Diff("", "");
show_debug_message("Diff1: " + diff1);
var patched1 = JDP_Patch("", diff1);
show_debug_message("Patched1: " + patched1);
var unpatched1 = JDP_Unpatch("", diff1);
show_debug_message("Unpatched1: " + unpatched1);

// Test 2: Simple object change
var a = "{\"x\":1,\"y\":2}";
var b = "{\"x\":1,\"y\":3}";
var diff2 = JDP_Diff(a, b);
show_debug_message("Diff2: " + diff2);
var patched2 = JDP_Patch(a, diff2);
show_debug_message("Patched2: " + patched2);
var unpatched2 = JDP_Unpatch(b, diff2);
show_debug_message("Unpatched2: " + unpatched2);

// Test 3: Adding a field
var a3 = "{\"x\":1,\"y\":2}";
var b3 = "{\"x\":1,\"y\":2,\"z\":5}";
var diff3 = JDP_Diff(a3, b3);
show_debug_message("Diff3: " + diff3);
var patched3 = JDP_Patch(a3, diff3);
show_debug_message("Patched3: " + patched3);
var unpatched3 = JDP_Unpatch(b3, diff3);
show_debug_message("Unpatched3: " + unpatched3);

// Test 4: Array change
var a4 = "[1,2,3,4]";
var b4 = "[1,2,5,4]";
var diff4 = JDP_Diff(a4, b4);
show_debug_message("Diff4: " + diff4);
var patched4 = JDP_Patch(a4, diff4);
show_debug_message("Patched4: " + patched4);
var unpatched4 = JDP_Unpatch(b4, diff4);
show_debug_message("Unpatched4: " + unpatched4);

// Test 5: String change
var a5 = "\"Hello world\"";
var b5 = "\"Hello chatGPT\"";
var diff5 = JDP_Diff(a5, b5);
show_debug_message("Diff5: " + diff5);
var patched5 = JDP_Patch(a5, diff5);
show_debug_message("Patched5: " + patched5);
var unpatched5 = JDP_Unpatch(b5, diff5);
show_debug_message("Unpatched5: " + unpatched5);

📄 License

MIT (or zlib) — do whatever you want but keep the copyright notice.