Migrated tensorflow/core/platform/ to use tstring.

Updated char* tstring::data() to conform to C++11.

This is a part of a larger migration effort for tensorflow::tstring.
See: tensorflow/community#91
PiperOrigin-RevId: 262752692

Author: gharibian

tensorflow/core/platform/tensor_coding.cc

@@ -33,7 +33,7 @@ void AssignRefCounted(StringPiece src, core::RefCounted* obj, string* out) {
   out->assign(src.data(), src.size());
 }
 
-void EncodeStringList(const string* strings, int64 n, string* out) {
+void EncodeStringList(const tstring* strings, int64 n, string* out) {
   out->clear();
   for (int i = 0; i < n; ++i) {
     core::PutVarint32(out, strings[i].size());
@@ -43,7 +43,7 @@ void EncodeStringList(const string* strings, int64 n, string* out) {
   }
 }
 
-bool DecodeStringList(const string& src, string* strings, int64 n) {
+bool DecodeStringList(const string& src, tstring* strings, int64 n) {
   std::vector<uint32> sizes(n);
   StringPiece reader(src);
   int64 tot = 0;
@@ -55,7 +55,7 @@ bool DecodeStringList(const string& src, string* strings, int64 n) {
     return false;
   }
 
-  string* data = strings;
+  tstring* data = strings;
   for (int64 i = 0; i < n; ++i, ++data) {
     auto size = sizes[i];
     if (size > reader.size()) {
@@ -144,7 +144,7 @@ void AssignRefCounted(StringPiece src, core::RefCounted* obj, Cord* out) {
                             cleanup);
 }
 
-void EncodeStringList(const string* strings, int64 n, Cord* out) {
+void EncodeStringList(const tstring* strings, int64 n, Cord* out) {
   out->Clear();
   for (int i = 0; i < n; ++i) {
     ::strings::CordAppendVarint(strings[i].size(), out);
@@ -154,7 +154,7 @@ void EncodeStringList(const string* strings, int64 n, Cord* out) {
   }
 }
 
-bool DecodeStringList(const Cord& src, string* strings, int64 n) {
+bool DecodeStringList(const Cord& src, tstring* strings, int64 n) {
   std::vector<uint32> sizes(n);
   CordReader reader(src);
   int64 tot = 0;
@@ -165,14 +165,27 @@ bool DecodeStringList(const Cord& src, string* strings, int64 n) {
   if (tot != reader.Available()) {
     return false;
   }
-  string* data = strings;
+  tstring* data = strings;
   for (int i = 0; i < n; ++i, ++data) {
     auto size = sizes[i];
     if (size > reader.Available()) {
       return false;
     }
+#ifdef USE_TSTRING
+    // TODO(dero): Consider adding resize_uninitialized() to tstring once the
+    // tstring placeholder is replaced with the actual implementation.
+    //
+    // Currently, in the case of USE_TSTRING, the placeholder tstring class
+    // encapsulates a single std::string.  We avoid using
+    // gtl::STLStringResizeUninitialized (and its associated header-include) in
+    // tstring.h as we have no intention in using it in the actual
+    // implementation. Thus, in the interim, we resort to resize().
+    data->resize(size);
+    reader.ReadN(size, data->data());
+#else   // USE_TSTRING
     gtl::STLStringResizeUninitialized(data, size);
     reader.ReadN(size, gtl::string_as_array(data));
+#endif  // USE_TSTRING
   }
   return true;
 }

tensorflow/core/platform/tensor_coding.h

@@ -47,11 +47,11 @@ inline void CopySubrangeToArray(const string& src, size_t pos, size_t n,
 }
 
 // Store encoding of strings[0..n-1] in *out.
-void EncodeStringList(const string* strings, int64 n, string* out);
+void EncodeStringList(const tstring* strings, int64 n, string* out);
 
 // Decode n strings from src and store in strings[0..n-1].
 // Returns true if successful, false on parse error.
-bool DecodeStringList(const string& src, string* strings, int64 n);
+bool DecodeStringList(const string& src, tstring* strings, int64 n);
 
 // Assigns base[0..bytes-1] to *s
 void CopyFromArray(string* s, const char* base, size_t bytes);
@@ -112,11 +112,11 @@ inline void CopySubrangeToArray(const Cord& src, int64 pos, int64 n,
 }
 
 // Store encoding of strings[0..n-1] in *out.
-void EncodeStringList(const string* strings, int64 n, Cord* out);
+void EncodeStringList(const tstring* strings, int64 n, Cord* out);
 
 // Decode n strings from src and store in strings[0..n-1].
 // Returns true if successful, false on parse error.
-bool DecodeStringList(const Cord& src, string* strings, int64 n);
+bool DecodeStringList(const Cord& src, tstring* strings, int64 n);
 
 // Assigns base[0..bytes-1] to *c
 void CopyFromArray(Cord* c, const char* base, size_t bytes);

tensorflow/core/platform/tstring.h

@@ -123,7 +123,7 @@ class tstring {
 
   const char& operator[](size_t i) const { return str_[i]; }
 
-  char* data() { return str_.data(); }
+  char* data() { return &str_[0]; }
 
   char& operator[](size_t i) { return str_[i]; }