symtab.cc

// Copyright 2015 Google Inc. 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.

// +build ignore

//#define ENABLE_TID_CHECK

#include "symtab.h"

#ifdef ENABLE_TID_CHECK
#include <pthread.h>
#endif
#include <string.h>

#include <unordered_map>

#include "log.h"
#include "strutil.h"
#include "var.h"

struct SymbolData {
  SymbolData()
      : gv(kUndefined) {
  }

  Var* gv;
};

vector<string*>* g_symbols;
static vector<SymbolData> g_symbol_data;

Symbol kEmptySym = Symbol(Symbol::IsUninitialized());
Symbol kShellSym = Symbol(Symbol::IsUninitialized());

Symbol::Symbol(int v)
    : v_(v) {
}

Var* Symbol::GetGlobalVar() const {
  if (static_cast<size_t>(v_) >= g_symbol_data.size()) {
    g_symbol_data.resize(v_ + 1);
  }
  Var* v = g_symbol_data[v_].gv;
  if (v->Origin() == VarOrigin::ENVIRONMENT ||
      v->Origin() == VarOrigin::ENVIRONMENT_OVERRIDE) {
    Vars::add_used_env_vars(*this);
  }
  return v;
}

void Symbol::SetGlobalVar(Var* v) const {
  if (static_cast<size_t>(v_) >= g_symbol_data.size()) {
    g_symbol_data.resize(v_ + 1);
  }
  Var* orig = g_symbol_data[v_].gv;
  if (orig->Origin() == VarOrigin::OVERRIDE ||
      orig->Origin() == VarOrigin::ENVIRONMENT_OVERRIDE) {
    return;
  }
  if (orig->Origin() == VarOrigin::AUTOMATIC) {
    ERROR("overriding automatic variable is not implemented yet");
  }
  if (orig->IsDefined())
    delete orig;
  g_symbol_data[v_].gv = v;
}

ScopedGlobalVar::ScopedGlobalVar(Symbol name, Var* var)
    : name_(name), orig_(NULL) {
  orig_ = name.GetGlobalVar();
  g_symbol_data[name_.val()].gv = var;
}

ScopedGlobalVar::~ScopedGlobalVar() {
  g_symbol_data[name_.val()].gv = orig_;
}

class Symtab {
 public:
  Symtab() {
#ifdef ENABLE_TID_CHECK
    tid_ = pthread_self();
#endif

    CHECK(g_symbols == NULL);
    g_symbols = &symbols_;

    Symbol s = InternImpl("");
    CHECK(s.v_ == 0);
    CHECK(Intern("") == s);
    char b[2];
    b[1] = 0;
    for (int i = 1; i < 256; i++) {
      b[0] = i;
      s = InternImpl(b);
      CHECK(s.val() == i);
    }

    kEmptySym = Intern("");
    kShellSym = Intern("SHELL");
  }

  ~Symtab() {
    LOG_STAT("%zu symbols", symbols_.size());
    for (string* s : symbols_)
      delete s;
  }

  Symbol InternImpl(StringPiece s) {
    auto found = symtab_.find(s);
    if (found != symtab_.end()) {
      return found->second;
    }
    symbols_.push_back(new string(s.data(), s.size()));
    Symbol sym = Symbol(symtab_.size());
    bool ok = symtab_.emplace(*symbols_.back(), sym).second;
    CHECK(ok);
    return sym;
  }

  Symbol Intern(StringPiece s) {
#ifdef ENABLE_TID_CHECK
    if (tid_ != pthread_self())
      abort();
#endif

    if (s.size() <= 1) {
      return Symbol(s.empty() ? 0 : (unsigned char)s[0]);
    }
    return InternImpl(s);
  }

 private:
  unordered_map<StringPiece, Symbol> symtab_;
  vector<string*> symbols_;
#ifdef ENABLE_TID_CHECK
  pthread_t tid_;
#endif
};

static Symtab* g_symtab;

void InitSymtab() {
  g_symtab = new Symtab;
}

void QuitSymtab() {
  delete g_symtab;
}

Symbol Intern(StringPiece s) {
  return g_symtab->Intern(s);
}

string JoinSymbols(const vector<Symbol>& syms, const char* sep) {
  vector<string> strs;
  for (Symbol s : syms) {
    strs.push_back(s.str());
  }
  return JoinStrings(strs, sep);
}