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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef LIBTEXTCLASSIFIER_COMMON_FILE_UTILS_H_
     18 #define LIBTEXTCLASSIFIER_COMMON_FILE_UTILS_H_
     19 
     20 #include <cstddef>
     21 #include <memory>
     22 #include <string>
     23 
     24 #include "common/config.h"
     25 
     26 #if PORTABLE_SAFT_MOBILE
     27 #include <google/protobuf/io/zero_copy_stream_impl_lite.h>
     28 #endif
     29 
     30 #include "common/mmap.h"
     31 #include "util/strings/stringpiece.h"
     32 
     33 namespace libtextclassifier {
     34 namespace nlp_core {
     35 
     36 namespace file_utils {
     37 
     38 // Reads the entire content of a file into a string.  Returns true on success,
     39 // false on error.
     40 bool GetFileContent(const std::string &filename, std::string *content);
     41 
     42 // Parses a proto from its serialized representation in memory.  That
     43 // representation starts at address sp.data() and contains exactly sp.size()
     44 // bytes.  Returns true on success, false otherwise.
     45 template<class Proto>
     46 bool ParseProtoFromMemory(StringPiece sp, Proto *proto) {
     47   if (!sp.data()) {
     48     // Avoid passing a nullptr to ArrayInputStream below.
     49     return false;
     50   }
     51 #if PORTABLE_SAFT_MOBILE
     52   ::google::protobuf::io::ArrayInputStream stream(sp.data(), sp.size());
     53   return proto->ParseFromZeroCopyStream(&stream);
     54 #else
     55 
     56   std::string data(sp.data(), sp.size());
     57   return proto->ParseFromString(data);
     58 #endif
     59 }
     60 
     61 // Parses a proto from a file.  Returns true on success, false otherwise.
     62 //
     63 // Note: the entire content of the file should be the binary (not
     64 // human-readable) serialization of a protocol buffer.
     65 //
     66 // Note: when we compile for Android, the proto parsing methods need to know the
     67 // type of the message they are parsing.  We use template polymorphism for that.
     68 template<class Proto>
     69 bool ReadProtoFromFile(const std::string &filename, Proto *proto) {
     70   ScopedMmap scoped_mmap(filename);
     71   const MmapHandle &handle = scoped_mmap.handle();
     72   if (!handle.ok()) {
     73     return false;
     74   }
     75   return ParseProtoFromMemory(handle.to_stringpiece(), proto);
     76 }
     77 
     78 // Returns true if filename is the name of an existing file, and false
     79 // otherwise.
     80 bool FileExists(const std::string &filename);
     81 
     82 // Returns true if dirpath is the path to an existing directory, and false
     83 // otherwise.
     84 bool DirectoryExists(const std::string &dirpath);
     85 
     86 }  // namespace file_utils
     87 
     88 }  // namespace nlp_core
     89 }  // namespace libtextclassifier
     90 
     91 #endif  // LIBTEXTCLASSIFIER_COMMON_FILE_UTILS_H_
     92