style fix - initializing and assigning empty std::string properly

std::string s(""); s = ""; calls the copy constructor, which in turn calls strlen(), … assigning a default-constructed string generates fewer instructions and is therefore preferred.

With C++11 uniform initialization, you’d simply write s = { } instead.

code/AssetLib/3DS/3DSConverter.cpp

@@ -212,7 +212,7 @@ void Discreet3DSImporter::ConvertMaterial(D3DS::Material &oldMat,
         mat.AddProperty(&tex, AI_MATKEY_GLOBAL_BACKGROUND_IMAGE);
 
         // Be sure this is only done for the first material
-        mBackgroundImage = std::string("");
+        mBackgroundImage = std::string();
     }
 
     // At first add the base ambient color of the scene to the material

code/AssetLib/3DS/3DSLoader.cpp

@@ -164,7 +164,7 @@ void Discreet3DSImporter::InternReadFile(const std::string &pFile,
     mRootNode->mHierarchyIndex = -1;
     mRootNode->mParent = nullptr;
     mMasterScale = 1.0f;
-    mBackgroundImage = "";
+    mBackgroundImage = std::string();
     bHasBG = false;
     bIsPrj = false;
 

code/AssetLib/3MF/D3MFOpcPackage.cpp

@@ -188,7 +188,7 @@ bool D3MFOpcPackage::validate() {
 std::string D3MFOpcPackage::ReadPackageRootRelationship(IOStream *stream) {
     XmlParser xmlParser;
     if (!xmlParser.parse(stream)) {
-        return "";
+        return std::string();
     }
 
     OpcPackageRelationshipReader reader(xmlParser);

code/AssetLib/AC/ACLoader.h

@@ -123,9 +123,9 @@ public:
     struct Object {
         Object() :
                 type(World),
-                name(""),
+                name(),
                 children(),
-                texture(""),
+                texture(),
                 texRepeat(1.f, 1.f),
                 texOffset(0.0f, 0.0f),
                 rotation(),

code/AssetLib/ASE/ASEParser.cpp

@@ -685,7 +685,7 @@ void Parser::ParseLV3MapBlock(Texture &map) {
                     // Files with 'None' as map name are produced by
                     // an Maja to ASE exporter which name I forgot ..
                     ASSIMP_LOG_WARN("ASE: Skipping invalid map entry");
-                    map.mMapName = "";
+                    map.mMapName = std::string();
                 }
 
                 continue;

code/AssetLib/Collada/ColladaLoader.cpp

@@ -1241,7 +1241,7 @@ void ColladaLoader::CreateAnimation(aiScene *pScene, const ColladaParser &pParse
                     continue;
                 }
                 entry.mTargetId = entry.mTransformId;
-                entry.mTransformId = "";
+                entry.mTransformId = std::string();
             }
 
             entry.mChannel = &(*cit);

code/AssetLib/FBX/FBXMeshGeometry.cpp

@@ -330,7 +330,7 @@ void MeshGeometry::ReadVertexData(const std::string& type, int index, const Scop
         }
 
         const Element* Name = source["Name"];
-        m_uvNames[index] = "";
+        m_uvNames[index] = std::string();
         if(Name) {
             m_uvNames[index] = ParseTokenAsString(GetRequiredToken(*Name,0));
         }

code/AssetLib/FBX/FBXParser.cpp

@@ -462,7 +462,7 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
 
     if (t.Type() != TokenType_DATA) {
         err_out = "expected TOK_DATA token";
-        return "";
+        return std::string();
     }
 
     if(t.IsBinary())
@@ -470,7 +470,7 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
         const char* data = t.begin();
         if (data[0] != 'S') {
             err_out = "failed to parse S(tring), unexpected data type (binary)";
-            return "";
+            return std::string();
         }
 
         // read string length
@@ -484,13 +484,13 @@ std::string ParseTokenAsString(const Token& t, const char*& err_out)
     const size_t length = static_cast<size_t>(t.end() - t.begin());
     if(length < 2) {
         err_out = "token is too short to hold a string";
-        return "";
+        return std::string();
     }
 
     const char* s = t.begin(), *e = t.end() - 1;
     if (*s != '\"' || *e != '\"') {
         err_out = "expected double quoted string";
-        return "";
+        return std::string();
     }
 
     return std::string(s+1,length-2);

code/AssetLib/FBX/FBXProperties.cpp

@@ -155,7 +155,7 @@ std::string PeekPropertyName(const Element& element)
     ai_assert(element.KeyToken().StringContents() == "P");
     const TokenList& tok = element.Tokens();
     if(tok.size() < 4) {
-        return "";
+        return std::string();
     }
 
     return ParseTokenAsString(*tok[0]);

code/AssetLib/IFC/IFCLoader.cpp

@@ -567,7 +567,7 @@ typedef std::map<std::string, std::string> Metadata;
 
 // ------------------------------------------------------------------------------------------------
 void ProcessMetadata(const Schema_2x3::ListOf<Schema_2x3::Lazy<Schema_2x3::IfcProperty>, 1, 0> &set, ConversionData &conv, Metadata &properties,
-        const std::string &prefix = "",
+        const std::string &prefix = std::string(),
         unsigned int nest = 0) {
     for (const Schema_2x3::IfcProperty &property : set) {
         const std::string &key = prefix.length() > 0 ? (prefix + "." + property.Name) : property.Name;
@@ -618,7 +618,7 @@ void ProcessMetadata(const Schema_2x3::ListOf<Schema_2x3::Lazy<Schema_2x3::IfcPr
                 ProcessMetadata(complexProp->HasProperties, conv, properties, key, nest + 1);
             }
         } else {
-            properties[key] = "";
+            properties[key] = std::string();
         }
     }
 }

code/AssetLib/Irr/IRRLoader.cpp

@@ -859,7 +859,7 @@ void IRRImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
 	// Check whether we can read from the file
 	if (file.get() == nullptr) {
-		throw DeadlyImportError("Failed to open IRR file " + pFile + "");
+		throw DeadlyImportError("Failed to open IRR file " + pFile);
 	}
 
 	// Construct the irrXML parser

code/AssetLib/Irr/IRRMeshLoader.cpp

@@ -135,7 +135,7 @@ void IRRMeshImporter::InternReadFile(const std::string &pFile,
 
 	// Check whether we can read from the file
 	if (file.get() == NULL)
-		throw DeadlyImportError("Failed to open IRRMESH file " + pFile + "");
+		throw DeadlyImportError("Failed to open IRRMESH file " + pFile);
 
 	// Construct the irrXML parser
 	XmlParser parser;

code/AssetLib/LWO/LWOFileData.h

@@ -502,7 +502,7 @@ struct Surface {
     Surface() :
             mColor(0.78431f, 0.78431f, 0.78431f), bDoubleSided(false), mDiffuseValue(1.f), mSpecularValue(0.f), mTransparency(0.f), mGlossiness(0.4f), mLuminosity(0.f), mColorHighlights(0.f), mMaximumSmoothAngle(0.f) // 0 == not specified, no smoothing
             ,
-            mVCMap(""),
+            mVCMap(),
             mVCMapType(AI_LWO_RGBA),
             mIOR(1.f) // vakuum
             ,

code/AssetLib/LWS/LWSLoader.h

@@ -88,7 +88,7 @@ struct NodeDesc {
             id(),
             number(0),
             parent(0),
-            name(""),
+            name(),
             isPivotSet(false),
             lightColor(1.f, 1.f, 1.f),
             lightIntensity(1.f),

code/AssetLib/MDL/HalfLife/UniqueNameGenerator.cpp

@@ -95,7 +95,7 @@ void UniqueNameGenerator::make_unique(std::vector<std::string> &names) {
     auto generate_unique_name = [&](const std::string &base_name) -> std::string {
         auto *duplicate_info = &names_to_duplicates[base_name];
 
-        std::string new_name = "";
+        std::string new_name;
 
         bool found_identical_name;
         bool tried_with_base_name_only = false;

code/AssetLib/MMD/MMDImporter.cpp

@@ -75,7 +75,7 @@ using namespace std;
 //  Default constructor
 MMDImporter::MMDImporter() :
         m_Buffer(),
-        m_strAbsPath("") {
+        m_strAbsPath() {
     DefaultIOSystem io;
     m_strAbsPath = io.getOsSeparator();
 }

code/AssetLib/MMD/MMDPmxParser.cpp

@@ -91,7 +91,7 @@ namespace pmx
 		std::vector<char> buffer;
 		if (size == 0)
 		{
-			return std::string("");
+			return std::string();
 		}
 		buffer.reserve(size);
 		stream->read((char*) buffer.data(), size);

code/AssetLib/OpenGEX/OpenGEXImporter.cpp

@@ -206,7 +206,7 @@ USE_ODDLPARSER_NS
 
 //------------------------------------------------------------------------------------------------
 static void propId2StdString(Property *prop, std::string &name, std::string &key) {
-    name = key = "";
+    name = key = std::string();
     if (nullptr == prop) {
         return;
     }

code/AssetLib/OpenGEX/OpenGEXImporter.h

@@ -79,7 +79,7 @@ struct MetricInfo {
     int m_intValue;
 
     MetricInfo()
-    : m_stringValue( "" )
+    : m_stringValue( )
     , m_floatValue( 0.0f )
     , m_intValue( -1 ) {
         // empty

code/AssetLib/Q3BSP/Q3BSPFileData.h

@@ -178,7 +178,7 @@ struct Q3BSPModel {
         m_Textures(),
         m_Lightmaps(),
         m_EntityData(),
-        m_ModelName( "" )
+        m_ModelName()
     {
         // empty
     }

code/AssetLib/Q3BSP/Q3BSPFileImporter.cpp

@@ -113,7 +113,7 @@ static void extractIds(const std::string &key, int &id1, int &id2) {
 // ------------------------------------------------------------------------------------------------
 //  Local helper function to normalize filenames.
 static void normalizePathName(const std::string &rPath, std::string &normalizedPath) {
-    normalizedPath = "";
+    normalizedPath = std::string();
     if (rPath.empty()) {
         return;
     }
@@ -183,7 +183,7 @@ void Q3BSPFileImporter::InternReadFile(const std::string &rFile, aiScene *scene,
         throw DeadlyImportError("Failed to open file ", rFile, ".");
     }
 
-    std::string archiveName(""), mapName("");
+    std::string archiveName, mapName;
     separateMapName(rFile, archiveName, mapName);
 
     if (mapName.empty()) {
@@ -202,8 +202,8 @@ void Q3BSPFileImporter::InternReadFile(const std::string &rFile, aiScene *scene,
 // ------------------------------------------------------------------------------------------------
 //  Separates the map name from the import name.
 void Q3BSPFileImporter::separateMapName(const std::string &importName, std::string &archiveName, std::string &mapName) {
-    archiveName = "";
+    archiveName = std::string();
-    mapName = "";
+    mapName = std::string();
     if (importName.empty()) {
         return;
     }
@@ -221,7 +221,7 @@ void Q3BSPFileImporter::separateMapName(const std::string &importName, std::stri
 // ------------------------------------------------------------------------------------------------
 //  Returns the first map in the map archive.
 bool Q3BSPFileImporter::findFirstMapInArchive(ZipArchiveIOSystem &bspArchive, std::string &mapName) {
-    mapName = "";
+    mapName = std::string();
     std::vector<std::string> fileList;
     bspArchive.getFileListExtension(fileList, "bsp");
     if (fileList.empty()) {
@@ -440,7 +440,7 @@ void Q3BSPFileImporter::createMaterials(const Q3BSP::Q3BSPModel *pModel, aiScene
         if (-1 != textureId) {
             sQ3BSPTexture *pTexture = pModel->m_Textures[textureId];
             if (nullptr != pTexture) {
-                std::string tmp("*"), texName("");
+                std::string tmp("*"), texName;
                 tmp += pTexture->strName;
                 tmp += ".jpg";
                 normalizePathName(tmp, texName);
@@ -512,7 +512,7 @@ size_t Q3BSPFileImporter::countTriangles(const std::vector<Q3BSP::sQ3BSPFace *>
 // ------------------------------------------------------------------------------------------------
 //  Creates the faces-to-material map.
 void Q3BSPFileImporter::createMaterialMap(const Q3BSP::Q3BSPModel *pModel) {
-    std::string key("");
+    std::string key;
     std::vector<sQ3BSPFace *> *pCurFaceArray = nullptr;
     for (size_t idx = 0; idx < pModel->m_Faces.size(); idx++) {
         Q3BSP::sQ3BSPFace *pQ3BSPFace = pModel->m_Faces[idx];
@@ -660,7 +660,7 @@ bool Q3BSPFileImporter::expandFile(ZipArchiveIOSystem *pArchive, const std::stri
 
     if (rExtList.empty()) {
         rFile = rFilename;
-        rExt = "";
+        rExt = std::string();
         return true;
     }
 

code/AssetLib/X/XFileHelper.h

@@ -130,7 +130,7 @@ struct Mesh {
 
     std::vector<Bone> mBones;
 
-    explicit Mesh(const std::string &pName = "") AI_NO_EXCEPT
+    explicit Mesh(const std::string &pName = std::string()) AI_NO_EXCEPT
     : mName( pName )
     , mPositions()
     , mPosFaces()

code/AssetLib/XGL/XGLLoader.cpp

@@ -142,7 +142,7 @@ void XGLImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
 	// check whether we can read from the file
 	if (stream.get() == NULL) {
-		throw DeadlyImportError("Failed to open XGL/ZGL file " + pFile + "");
+		throw DeadlyImportError("Failed to open XGL/ZGL file " + pFile);
 	}
 
 	// see if its compressed, if so uncompress it

code/AssetLib/glTF/glTFAsset.h

@@ -1029,7 +1029,7 @@ namespace glTF
 
         AssetMetadata()
             : premultipliedAlpha(false)
-            , version("")
+            , version()
         {
         }
     };

code/AssetLib/glTF2/glTF2Asset.h

@@ -1067,7 +1067,7 @@ struct AssetMetadata {
     void Read(Document &doc);
 
     AssetMetadata() :
-            version("") {}
+            version() {}
 };
 
 //

code/Common/BaseImporter.cpp

@@ -271,7 +271,7 @@ std::string BaseImporter::GetExtension(const std::string &file) {
 
     // no file extension at all
     if (pos == std::string::npos) {
-        return "";
+        return std::string();
     }
 
     // thanks to Andy Maloney for the hint

code/Common/FileSystemFilter.h

@@ -76,7 +76,7 @@ public:
         if (std::string::npos != (ss2 = mBase.find_last_of("\\/")))  {
             mBase.erase(ss2,mBase.length()-ss2);
         } else {
-            mBase = "";
+            mBase = std::string();
         }
 
         // make sure the directory is terminated properly

code/Common/Importer.cpp

@@ -149,7 +149,7 @@ void AllocateFromAssimpHeap::operator delete[] ( void* data)    {
 Importer::Importer()
  : pimpl( new ImporterPimpl ) {
     pimpl->mScene = nullptr;
-    pimpl->mErrorString = "";
+    pimpl->mErrorString = std::string();
 
     // Allocate a default IO handler
     pimpl->mIOHandler = new DefaultIOSystem;
@@ -387,7 +387,7 @@ void Importer::FreeScene( ) {
     delete pimpl->mScene;
     pimpl->mScene = nullptr;
 
-    pimpl->mErrorString = "";
+    pimpl->mErrorString = std::string();
     pimpl->mException = std::exception_ptr();
     ASSIMP_END_EXCEPTION_REGION(void);
 }
@@ -434,7 +434,7 @@ aiScene* Importer::GetOrphanedScene() {
     ASSIMP_BEGIN_EXCEPTION_REGION();
     pimpl->mScene = nullptr;
 
-    pimpl->mErrorString = ""; // reset error string
+    pimpl->mErrorString = std::string();
     pimpl->mException = std::exception_ptr();
     ASSIMP_END_EXCEPTION_REGION(aiScene*);
     

code/Common/scene.cpp

@@ -43,7 +43,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/scene.h>
 
 aiNode::aiNode()
-: mName("")
+: mName()
 , mParent(nullptr)
 , mNumChildren(0)
 , mChildren(nullptr)

code/PostProcessing/RemoveRedundantMaterials.h

@@ -81,7 +81,7 @@ public:
     /** @brief Set list of fixed (inmutable) materials
      *  @param fixed See #AI_CONFIG_PP_RRM_EXCLUDE_LIST
      */
-    void SetFixedMaterialsString(const std::string& fixed = "") {
+    void SetFixedMaterialsString(const std::string& fixed = std::string()) {
         mConfigFixedMaterials = fixed;
     }
 

include/assimp/DefaultIOStream.h

@@ -119,7 +119,7 @@ private:
 AI_FORCE_INLINE
 DefaultIOStream::DefaultIOStream() AI_NO_EXCEPT
 : mFile(nullptr)
-, mFilename("")
+, mFilename()
 , mCachedSize(SIZE_MAX) {
     // empty
 }

include/assimp/IOSystem.hpp

@@ -294,7 +294,7 @@ bool IOSystem::PushDirectory( const std::string &path ) {
 AI_FORCE_INLINE
 const std::string &IOSystem::CurrentDirectory() const {
     if ( m_pathStack.empty() ) {
-        static const std::string Dummy("");
+        static const std::string Dummy;
         return Dummy;
     }
     return m_pathStack[ m_pathStack.size()-1 ];

include/assimp/Importer.hpp

@@ -286,7 +286,7 @@ public:
      * @see GetPropertyInteger()
      */
     std::string GetPropertyString(const char *szName,
-            const std::string &sErrorReturn = "") const;
+            const std::string &sErrorReturn = std::string()) const;
 
     // -------------------------------------------------------------------
     /** Get a matrix configuration property

include/assimp/XmlParser.h

@@ -239,7 +239,7 @@ public:
     }
 
     static inline bool getValueAsString( XmlNode &node, std::string &text ) {
-        text = "";
+        text = std::string();
         if (node.empty()) {
             return false;
         }