Add some json helpers

modules/juce_core/containers/juce_Variant.cpp

@@ -708,6 +708,21 @@ bool var::hasProperty (const Identifier& propertyName) const noexcept
     return false;
 }
 
+juce::StringArray var::getProperties() const
+{
+    if (auto* o = getDynamicObject())
+    {
+        juce::StringArray names;
+
+        for (auto itr : o->getProperties())
+            names.add (itr.name.toString());
+
+        return names;
+    }
+
+    return {};
+}
+
 var::NativeFunction var::getNativeFunction() const
 {
     return isMethod() && (value.methodValue != nullptr) ? *value.methodValue : nullptr;
@@ -893,6 +908,8 @@ var::NativeFunctionArgs::NativeFunctionArgs (const var& t, const var* args, int
 {
 }
 
+//==============================================================================
+
 //==============================================================================
 #if JUCE_ALLOW_STATIC_NULL_VARIABLES
 

modules/juce_core/containers/juce_Variant.h

@@ -262,6 +262,8 @@ public:
     var getProperty (const Identifier& propertyName, const var& defaultReturnValue) const;
     /** Returns true if this variant is an object and if it has the given property. */
     bool hasProperty (const Identifier& propertyName) const noexcept;
+    /** Returns property names if this variant is an object. */
+    juce::StringArray getProperties() const;
 
     /** Invokes a named method call with no arguments. */
     var call (const Identifier& method) const;

modules/juce_core/json/juce_JSONUtils.cpp

@@ -124,6 +124,57 @@ std::optional<var> JSONUtils::setPointer (const var& v,
     return {};
 }
 
+var JSONUtils::getPointer (const var& v, String pointer, const var& defaultValue)
+{
+    if (pointer.isEmpty())
+        return defaultValue;
+
+    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())
+            return object->hasProperty (unescaped) ? object->getProperty (unescaped) : defaultValue;
+        else
+            return getPointer (object->getProperty (unescaped), tail, defaultValue);
+    }
+    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())
+            return isPositiveAndBelow (index, array->size()) ? (*array)[int (index)] : defaultValue;
+        else
+            return getPointer ((*array)[(int) index], tail, defaultValue);
+    }
+
+    return defaultValue;
+}
+
 bool JSONUtils::deepEqual (const var& a, const var& b)
 {
     const auto compareObjects = [] (const DynamicObject& x, const DynamicObject& y)

modules/juce_core/json/juce_JSONUtils.h

@@ -57,6 +57,17 @@ 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,
+        returns the value of the property or array index referenced by the pointer
+
+        If the pointer cannot be followed, due to referencing missing array indices
+        or fields, then this returns defaultValue.
+
+        For more details, check the JSON Pointer RFC 6901:
+        https://datatracker.ietf.org/doc/html/rfc6901
+    */
+    static var getPointer (const var& v, String pointer, const var& defaultValue);
+
     /** Converts the provided key/value pairs into a JSON object. */
     static var makeObject (const std::map<Identifier, var>& source);