1 /* 2 * Copyright (C) 2016 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 ART_LIBDEXFILE_DEX_STRING_REFERENCE_H_ 18 #define ART_LIBDEXFILE_DEX_STRING_REFERENCE_H_ 19 20 #include <stdint.h> 21 22 #include <android-base/logging.h> 23 24 #include "dex/dex_file-inl.h" 25 #include "dex/dex_file_reference.h" 26 #include "dex/dex_file_types.h" 27 #include "dex/utf-inl.h" 28 29 namespace art { 30 31 // A string is located by its DexFile and the string_ids_ table index into that DexFile. 32 class StringReference : public DexFileReference { 33 public: StringReference(const DexFile * file,dex::StringIndex index)34 StringReference(const DexFile* file, dex::StringIndex index) 35 : DexFileReference(file, index.index_) {} 36 StringIndex()37 dex::StringIndex StringIndex() const { 38 return dex::StringIndex(index); 39 } 40 GetStringData()41 const char* GetStringData() const { 42 return dex_file->GetStringData(dex_file->GetStringId(StringIndex())); 43 } 44 }; 45 46 // Compare the actual referenced string values. Used for string reference deduplication. 47 struct StringReferenceValueComparator { operatorStringReferenceValueComparator48 bool operator()(const StringReference& sr1, const StringReference& sr2) const { 49 // Note that we want to deduplicate identical strings even if they are referenced 50 // by different dex files, so we need some (any) total ordering of strings, rather 51 // than references. However, the references should usually be from the same dex file, 52 // so we choose the dex file string ordering so that we can simply compare indexes 53 // and avoid the costly string comparison in the most common case. 54 if (sr1.dex_file == sr2.dex_file) { 55 // Use the string order enforced by the dex file verifier. 56 DCHECK_EQ( 57 sr1.index < sr2.index, 58 CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues(sr1.GetStringData(), 59 sr2.GetStringData()) < 0); 60 return sr1.index < sr2.index; 61 } else { 62 // Cannot compare indexes, so do the string comparison. 63 return CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues(sr1.GetStringData(), 64 sr2.GetStringData()) < 0; 65 } 66 } 67 }; 68 69 } // namespace art 70 71 #endif // ART_LIBDEXFILE_DEX_STRING_REFERENCE_H_ 72