Update StringBuilder

Author: bblanchon

extras/tests/JsonDeserializer/object.cpp

@@ -292,22 +292,23 @@ TEST_CASE("deserialize JSON object") {
     }
 
     SECTION("Repeated key") {
-      DeserializationError err = deserializeJson(doc, "{a:{b:{c:1}},a:2}");
+      DeserializationError err =
+          deserializeJson(doc, "{alfa:{bravo:{charlie:1}},alfa:2}");
 
       REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(doc.as<std::string>() == "{\"a\":2}");
+      REQUIRE(doc.as<std::string>() == "{\"alfa\":2}");
       REQUIRE(spy.log() ==
               AllocatorLog{
                   Allocate(sizeofStringBuffer()),
                   Allocate(sizeofPool()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("a")),
+                  Reallocate(sizeofStringBuffer(), sizeofString("alfa")),
                   Allocate(sizeofStringBuffer()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("b")),
+                  Reallocate(sizeofStringBuffer(), sizeofString("bravo")),
                   Allocate(sizeofStringBuffer()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("c")),
+                  Reallocate(sizeofStringBuffer(), sizeofString("charlie")),
                   Allocate(sizeofStringBuffer()),
-                  Deallocate(sizeofString("b")),
-                  Deallocate(sizeofString("c")),
+                  Deallocate(sizeofString("bravo")),
+                  Deallocate(sizeofString("charlie")),
                   Deallocate(sizeofStringBuffer()),
                   Reallocate(sizeofPool(), sizeofObject(2) + sizeofObject(1)),
               });
@@ -389,11 +390,11 @@ TEST_CASE("deserialize JSON object under memory constraints") {
 
   SECTION("string allocation fails") {
     timebomb.setCountdown(3);
-    char input[] = "{\"a\":\"b\"}";
+    char input[] = "{\"alfa\":\"bravo\"}";
 
     DeserializationError err = deserializeJson(doc, input);
 
     REQUIRE(err == DeserializationError::NoMemory);
-    REQUIRE(doc.as<std::string>() == "{\"a\":null}");
+    REQUIRE(doc.as<std::string>() == "{\"alfa\":null}");
   }
 }

extras/tests/ResourceManager/StringBuilder.cpp

@@ -22,13 +22,31 @@ TEST_CASE("StringBuilder") {
     str.startString();
     str.save(&data);
 
-    REQUIRE(resources.size() == sizeofString(""));
     REQUIRE(resources.overflowed() == false);
-    REQUIRE(spyingAllocator.log() ==
-            AllocatorLog{
-                Allocate(sizeofStringBuffer()),
-                Reallocate(sizeofStringBuffer(), sizeofString("")),
-            });
+    REQUIRE(spyingAllocator.log() == AllocatorLog{
+                                         Allocate(sizeofStringBuffer()),
+                                     });
+    REQUIRE(data.type() == VariantType::TinyString);
+  }
+
+  SECTION("Tiny string") {
+    StringBuilder str(&resources);
+
+    str.startString();
+    str.append("url");
+
+    REQUIRE(str.isValid() == true);
+    REQUIRE(str.str() == "url");
+    REQUIRE(spyingAllocator.log() == AllocatorLog{
+                                         Allocate(sizeofStringBuffer()),
+                                     });
+
+    VariantData data;
+    str.save(&data);
+
+    REQUIRE(resources.overflowed() == false);
+    REQUIRE(data.type() == VariantType::TinyString);
+    REQUIRE(data.asString() == "url");
   }
 
   SECTION("Short string fits in first allocation") {
@@ -149,18 +167,18 @@ TEST_CASE("StringBuilder::save() deduplicates strings") {
 
   SECTION("Don't overrun") {
     auto s1 = saveString(builder, "hello world");
-    auto s2 = saveString(builder, "wor");
+    auto s2 = saveString(builder, "worl");
 
     REQUIRE(s1 == "hello world"_s);
-    REQUIRE(s2 == "wor"_s);
+    REQUIRE(s2 == "worl"_s);
     REQUIRE(s2 != s1);
 
     REQUIRE(spy.log() ==
             AllocatorLog{
                 Allocate(sizeofStringBuffer()),
                 Reallocate(sizeofStringBuffer(), sizeofString("hello world")),
                 Allocate(sizeofStringBuffer()),
-                Reallocate(sizeofStringBuffer(), sizeofString("wor")),
+                Reallocate(sizeofStringBuffer(), sizeofString("worl")),
             });
   }
 }

src/ArduinoJson/Memory/StringBuilder.hpp

@@ -28,8 +28,15 @@ class StringBuilder {
   void save(VariantData* variant) {
     ARDUINOJSON_ASSERT(variant != nullptr);
     ARDUINOJSON_ASSERT(node_ != nullptr);
-    node_->data[size_] = 0;
-    StringNode* node = resources_->getString(adaptString(node_->data, size_));
+
+    char* p = node_->data;
+    if (isTinyString(p, size_)) {
+      variant->setTinyString(p, static_cast<uint8_t>(size_));
+      return;
+    }
+
+    p[size_] = 0;
+    StringNode* node = resources_->getString(adaptString(p, size_));
     if (!node) {
       node = resources_->resizeString(node_, size_);
       ARDUINOJSON_ASSERT(node != nullptr);  // realloc to smaller can't fail