1 files changed, 97 insertions, 0 deletions
diff --git a/source/core/StarJsonPatch.cpp b/source/core/StarJsonPatch.cpp
new file mode 100644
index 0000000..e1ab6de
--- /dev/null
+++ b/source/core/StarJsonPatch.cpp
@@ -0,0 +1,97 @@
+#include "StarJsonPatch.hpp"
+#include "StarJsonPath.hpp"
+#include "StarLexicalCast.hpp"
+
+namespace Star {
+
+Json jsonPatch(Json const& base, JsonArray const& patch) {
+  auto res = base;
+  try {
+    for (auto const& operation : patch) {
+      res = JsonPatching::applyOperation(res, operation);
+    }
+    return res;
+  } catch (JsonException const& e) {
+    throw JsonPatchException(strf("Could not apply patch to base. %s", e.what()));
+  }
+}
+
+namespace JsonPatching {
+
+  static const StringMap<std::function<Json(Json, Json)>> functionMap = StringMap<std::function<Json(Json, Json)>>{
+      {"test", std::bind(applyTestOperation, _1, _2)},
+      {"remove", std::bind(applyRemoveOperation, _1, _2)},
+      {"add", std::bind(applyAddOperation, _1, _2)},
+      {"replace", std::bind(applyReplaceOperation, _1, _2)},
+      {"move", std::bind(applyMoveOperation, _1, _2)},
+      {"copy", std::bind(applyCopyOperation, _1, _2)},
+  };
+
+  Json applyOperation(Json const& base, Json const& op) {
+    try {
+      auto operation = op.getString("op");
+      return JsonPatching::functionMap.get(operation)(base, op);
+    } catch (JsonException const& e) {
+      throw JsonPatchException(strf("Could not apply operation to base. %s", e.what()));
+    } catch (MapException const&) {
+      throw JsonPatchException(strf("Invalid operation: %s", op.getString("op")));
+    }
+  }
+
+  Json applyTestOperation(Json const& base, Json const& op) {
+    auto path = op.getString("path");
+    auto value = op.opt("value");
+    auto inverseTest = op.getBool("inverse", false);
+
+    auto pointer = JsonPath::Pointer(path);
+
+    try {
+      auto testValue = pointer.get(base);
+      if (!value) {
+        if (inverseTest)
+          throw JsonPatchTestFail(strf("Test operation failure, expected %s to be missing.", op.getString("path")));
+        return base;
+      }
+
+      if ((value && (testValue == *value)) ^ inverseTest) {
+        return base;
+      }
+
+      throw JsonPatchTestFail(strf("Test operation failure, expected %s found %s.", value, testValue));
+    } catch (JsonPath::TraversalException& e) {
+      if (inverseTest)
+        return base;
+      throw JsonPatchTestFail(strf("Test operation failure: %s", e.what()));
+    }
+  }
+
+  Json applyRemoveOperation(Json const& base, Json const& op) {
+    return JsonPath::Pointer(op.getString("path")).remove(base);
+  }
+
+  Json applyAddOperation(Json const& base, Json const& op) {
+    return JsonPath::Pointer(op.getString("path")).add(base, op.get("value"));
+  }
+
+  Json applyReplaceOperation(Json const& base, Json const& op) {
+    auto pointer = JsonPath::Pointer(op.getString("path"));
+    return pointer.add(pointer.remove(base), op.get("value"));
+  }
+
+  Json applyMoveOperation(Json const& base, Json const& op) {
+    auto fromPointer = JsonPath::Pointer(op.getString("from"));
+    auto toPointer = JsonPath::Pointer(op.getString("path"));
+
+    Json value = fromPointer.get(base);
+    return toPointer.add(fromPointer.remove(base), value);
+  }
+
+  Json applyCopyOperation(Json const& base, Json const& op) {
+    auto fromPointer = JsonPath::Pointer(op.getString("from"));
+    auto toPointer = JsonPath::Pointer(op.getString("path"));
+
+    return toPointer.add(base, fromPointer.get(base));
+  }
+}
+
+}