Improve map insertions

snapshot/mac/mach_o_image_symbol_table_reader.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "snapshot/mac/mach_o_image_symbol_table_reader.h"
 
 #include <mach-o/loader.h>
 #include <mach-o/nlist.h>
 
+#include <utility>
+
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "util/mac/checked_mach_address_range.h"
 #include "util/mach/task_memory.h"
 
 namespace crashpad {
 
 namespace internal {
 
 //! \brief The internal implementation for MachOImageSymbolTableReader.
@@ skipping 116 matching lines @@
             return false;
           }
 
           if (symbol_type == N_SECT && symbol.n_sect == NO_SECT) {
             LOG(WARNING) << base::StringPrintf(
                                 "N_SECT symbol %s in section NO_SECT",
                                 name.c_str()) << symbol_info;
             return false;
           }
 
-          if (external_defined_symbols->count(name)) {
-            LOG(WARNING) << "duplicate symbol " << name << symbol_info;
-            return false;
-          }
-
           MachOImageSymbolTableReader::SymbolInformation this_symbol_info;
           this_symbol_info.value = symbol.n_value;
           this_symbol_info.section = symbol.n_sect;
-          (*external_defined_symbols)[name] = this_symbol_info;
+          if (!external_defined_symbols->insert(
+                  std::make_pair(name, this_symbol_info)).second) {
+            LOG(WARNING) << "duplicate symbol " << name << symbol_info;
+            return false;
+          }
         } else {
           // External indirect symbols may be found in the portion of the symbol
           // table used for external symbols as opposed to indirect symbols when
           // the indirect symbols are also external. These can be produced by
           // Xcode 5.1 ld64-236.3/src/ld/LinkEditClassic.hpp
           // ld::tool::SymbolTableAtom<>::addGlobal(). Indirect symbols are not
           // currently supported by this symbol table reader, so ignore them
           // without failing or logging a message when encountering them. See
           // https://groups.google.com/a/chromium.org/d/topic/crashpad-dev/k7QkLwO71Zo
           valid_symbol = symbol_type == N_INDR;
@@ skipping 107 matching lines @@
   INITIALIZATION_STATE_DCHECK_VALID(initialized_);
 
   const auto& iterator = external_defined_symbols_.find(name);
   if (iterator == external_defined_symbols_.end()) {
     return nullptr;
   }
   return &iterator->second;
 }
 
 }  // namespace crashpad