ResourceManager: extract functions to manipulate StringNodes

src/ArduinoJson/Memory/ResourceManager.hpp

@@ -118,32 +118,21 @@ class ResourceManager {
   }
 
   StringNode* allocString(size_t length) {
-    auto node = reinterpret_cast<StringNode*>(
-        allocator_->allocate(sizeofString(length)));
-    if (node) {
-      node->length = uint16_t(length);
-      node->references = 1;
-    } else {
+    auto node = StringNode::create(length, allocator_);
+    if (!node)
       overflowed_ = true;
-    }
     return node;
   }
 
   StringNode* reallocString(StringNode* node, size_t length) {
-    ARDUINOJSON_ASSERT(node != nullptr);
-    auto newNode = reinterpret_cast<StringNode*>(
-        allocator_->reallocate(node, sizeofString(length)));
-    if (newNode) {
-      newNode->length = uint16_t(length);
-    } else {
+    node = StringNode::resize(node, length, allocator_);
+    if (!node)
       overflowed_ = true;
-      allocator_->deallocate(node);
-    }
-    return newNode;
+    return node;
   }
 
   void deallocString(StringNode* node) {
-    allocator_->deallocate(node);
+    StringNode::destroy(node, allocator_);
   }
 
   void dereferenceString(const char* s) {
@@ -155,7 +144,7 @@ class ResourceManager {
             prev->next = node->next;
           else
             strings_ = node->next;
-          allocator_->deallocate(node);
+          StringNode::destroy(node, allocator_);
         }
         return;
       }

src/ArduinoJson/Memory/StringNode.hpp

@@ -4,7 +4,9 @@
 
 #pragma once
 
+#include <ArduinoJson/Memory/Allocator.hpp>
 #include <ArduinoJson/Namespace.hpp>
+#include <ArduinoJson/Polyfills/assert.hpp>
 
 #include <stdint.h>  // uint16_t
 
@@ -15,11 +17,41 @@ struct StringNode {
   uint16_t length;
   uint16_t references;
   char data[1];
+
+  static constexpr size_t sizeForLength(size_t n) {
+    return n + 1 + offsetof(StringNode, data);
+  }
+
+  static StringNode* create(size_t length, Allocator* allocator) {
+    auto node = reinterpret_cast<StringNode*>(
+        allocator->allocate(sizeForLength(length)));
+    if (node) {
+      node->length = uint16_t(length);
+      node->references = 1;
+    }
+    return node;
+  }
+
+  static StringNode* resize(StringNode* node, size_t length,
+                            Allocator* allocator) {
+    ARDUINOJSON_ASSERT(node != nullptr);
+    auto newNode = reinterpret_cast<StringNode*>(
+        allocator->reallocate(node, sizeForLength(length)));
+    if (newNode)
+      newNode->length = uint16_t(length);
+    else
+      allocator->deallocate(node);
+    return newNode;
+  }
+
+  static void destroy(StringNode* node, Allocator* allocator) {
+    allocator->deallocate(node);
+  }
 };
 
 // Returns the size (in bytes) of an string with n characters.
 constexpr size_t sizeofString(size_t n) {
-  return n + 1 + offsetof(StringNode, data);
+  return StringNode::sizeForLength(n);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE