src/binaryen/src/support/name.h

   1 /*
   2  * Copyright 2017 WebAssembly Community Group participants
   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 wasm_support_string_h
  18 #define wasm_support_string_h
  19
  20 #include <cstring>
  21
  22 #include "emscripten-optimizer/istring.h"
  23
  24 namespace wasm {
  25
  26 // We use a Name for all of the identifiers. These are IStrings, so they are
  27 // all interned - comparisons etc are just pointer comparisons, so there is no
  28 // perf loss. Having names everywhere makes using the AST much nicer (for
  29 // example, block names are strings and not offsets, which makes composition
  30 // - adding blocks, removing blocks - easy). One exception is local variables,
  31 // where we do use indices, as they are a large proportion of the AST,
  32 // perf matters a lot there, and compositionality is not a problem.
  33 // TODO: as an optimization, IString values < some threshold could be considered
  34 //       numerical indices directly.
  35
  36 struct Name : public cashew::IString {
  37   Name() : cashew::IString() {}
  38   Name(const char* str) : cashew::IString(str, false) {}
  39   Name(cashew::IString str) : cashew::IString(str) {}
  40   Name(const std::string& str) : cashew::IString(str.c_str(), false) {}
  41
  42   friend std::ostream& operator<<(std::ostream& o, Name name) {
  43     assert(name.str);
  44     return o << '$' << name.str; // reference interpreter requires we prefix all names
  45   }
  46
  47   static Name fromInt(size_t i) {
  48     return cashew::IString(std::to_string(i).c_str(), false);
  49   }
  50
  51   bool hasSubstring(cashew::IString substring) {
  52     return strstr(c_str(), substring.c_str()) != nullptr;
  53   }
  54 };
  55
  56 } // namespace wasm
  57
  58 namespace std {
  59
  60 template <> struct hash<wasm::Name> : hash<cashew::IString> {};
  61
  62 } // namespace std
  63
  64
  65 #endif // wasm_support_string_h