Added JSONUtils::updatePointer

Author: FigBug

modules/juce_core/json/juce_JSONUtils.cpp

@@ -124,6 +124,74 @@ std::optional<var> JSONUtils::setPointer (const var& v,
     return {};
 }
 
+bool JSONUtils::updatePointer (var& v, String pointer, const var& newValue)
+{
+    if (pointer.isEmpty())
+        return false;
+
+    if (! pointer.startsWith ("/"))
+    {
+        // This is not a well-formed JSON pointer
+        jassertfalse;
+        return {};
+    }
+
+    const auto findResult = pointer.indexOfChar (1, '/');
+    const auto pos = findResult < 0 ? pointer.length() : findResult;
+    const String head (pointer.begin() + 1, pointer.begin() + pos);
+    const String tail (pointer.begin() + pos, pointer.end());
+
+    const auto unescaped = head.replace ("~1", "/").replace ("~0", "~");
+
+    if (auto* object = v.getDynamicObject())
+    {
+        if (tail.isEmpty())
+        {
+            object->setProperty (unescaped, newValue);
+            return true;
+        }
+
+        auto v = object->getProperty (unescaped);
+        return updatePointer (v, tail, newValue);
+    }
+    else if (auto* array = v.getArray())
+    {
+        const auto index = [&]() -> size_t
+        {
+            if (unescaped == "-")
+                return (size_t) array->size();
+
+            if (unescaped == "0")
+                return 0;
+
+            if (! unescaped.startsWith ("0"))
+                return (size_t) unescaped.getLargeIntValue();
+
+            return std::numeric_limits<size_t>::max();
+        }();
+
+        if (tail.isEmpty())
+        {
+            if (isPositiveAndBelow (index, array->size()))
+            {
+                array->set (int (index), newValue);
+                return true;
+            }
+
+            if (index == array->size())
+            {
+                array->add (newValue);
+                return true;
+            }
+        }
+
+        auto v = (*array)[(int) index];
+        return updatePointer (v, tail, newValue);
+    }
+
+    return false;
+}
+
 var JSONUtils::getPointer (const var& v, String pointer, const var& defaultValue)
 {
     if (pointer.isEmpty())

modules/juce_core/json/juce_JSONUtils.h

@@ -57,6 +57,18 @@ struct JSONUtils
     */
     static std::optional<var> setPointer (const var& v, String pointer, const var& newValue);
 
+    /** Given a JSON array/object 'v', a string representing a JSON pointer,
+        and a new property value 'newValue', updates 'v' where the
+        property or array index referenced by the pointer has been set to 'newValue'.
+
+        If the pointer cannot be followed, due to referencing missing array indices
+        or fields, then this returns false.
+
+        For more details, check the JSON Pointer RFC 6901:
+        https://datatracker.ietf.org/doc/html/rfc6901
+    */
+    static bool updatePointer (var& v, String pointer, const var& newValue);
+
     /** Given a JSON array/object 'v', a string representing a JSON pointer,
         returns the value of the property or array index referenced by the pointer