[Feature]Support array reuse field (#219)

* support multi add different field for one doc #200 

* fix field data delete values but not make length reset #208

src/core/CLucene/document/Document.cpp

@@ -85,6 +85,13 @@ CL_NS_DEF(document)
       return boost;
    }
 
+   void Document::setNeedResetFieldData(bool needResetFieldData) {
+       this->needResetFieldData = needResetFieldData;
+   }
+
+        bool Document::getNeedResetFieldData() const {
+         return needResetFieldData;
+        }
 
 	 Field* Document::getField(const TCHAR* name) const{
     CND_PRECONDITION(name != NULL, "name is NULL");

src/core/CLucene/document/Document.h

@@ -35,6 +35,7 @@ class CLUCENE_EXPORT Document:LUCENE_BASE {
 private:
 	FieldsType* _fields;
 	float_t boost;
+        bool needResetFieldData = false;
 public:
 	/** Constructs a new document with no fields. */
 	Document();
@@ -66,7 +67,11 @@ class CLUCENE_EXPORT Document:LUCENE_BASE {
 	*
 	* @see #setBoost(float_t)
 	*/
-	float_t getBoost() const;
+        float_t getBoost() const;
+
+        void setNeedResetFieldData(bool needResetFieldData);
+
+        bool getNeedResetFieldData() const;
 
 	/**
 	* <p>Adds a field to a document.  Several fields may be added with

src/core/CLucene/index/SDocumentWriter.cpp

@@ -126,6 +126,31 @@ SDocumentsWriter<T>::ThreadState::~ThreadState() {
         _CLDELETE(allFieldDataArray.values[i]);
 }
 
+template<typename T>
+void SDocumentsWriter<T>::ThreadState::resetCurrentFieldData(Document *doc) {
+    const Document::FieldsType &docFields = *doc->getFields();
+    const int32_t numDocFields = docFields.size();
+
+    if (FieldData* fp = fieldDataArray.values[0]; fp && numDocFields > 0) {
+        numFieldData = 1;
+        // reset fp for new fields
+        fp->fieldCount = 0;
+	// delete values is not make length reset to 0, so resize can not make sure new docFields values
+        fp->docFields.deleteValues();
+	fp->docFields.length = 0;
+        fp->docFields.resize(1);
+        for (int32_t i = 0; i < numDocFields; i++) {
+            Field *field = docFields[i];
+            if (fp->fieldCount == fp->docFields.length) {
+                fp->docFields.resize(fp->docFields.length * 2);
+            }
+
+            fp->docFields.values[fp->fieldCount++] = field;
+        }
+    }
+    return;
+}
+
 template<typename T>
 typename SDocumentsWriter<T>::ThreadState *SDocumentsWriter<T>::getThreadState(Document *doc) {
     if (threadState == nullptr) {
@@ -135,6 +160,8 @@ typename SDocumentsWriter<T>::ThreadState *SDocumentsWriter<T>::getThreadState(D
     if (segment.empty()) {
         segment = writer->newSegmentName();
         threadState->init(doc, nextDocID);
+    } else if (doc->getNeedResetFieldData()) {
+        threadState->resetCurrentFieldData(doc);
     }
 
     threadState->docID = nextDocID;

src/core/CLucene/index/SDocumentWriter.h

@@ -390,6 +390,8 @@ class SDocumentsWriter : public IDocumentsWriter {
         /** Tokenizes the fields of a document into Postings */
         void processDocument(CL_NS(analysis)::Analyzer *sanalyzer);
 
+        void resetCurrentFieldData(CL_NS(document)::Document *doc);
+
         /** If there are fields we've seen but did not see again
       *  in the last run, then free them up.  Also reduce
       *  postings hash size. */