// 维护局部变量声明的注册与查找。

#include "sem/SymbolTable.h"

void SymbolTable::EnterScope() { scopes_.emplace_back(); }

void SymbolTable::ExitScope() {
  if (!scopes_.empty()) {
    scopes_.pop_back();
  }
}

bool SymbolTable::ContainsInCurrentScope(const std::string& name) const {
  if (scopes_.empty()) {
    return false;
  }
  return scopes_.back().find(name) != scopes_.back().end();
}

void SymbolTable::Add(const std::string& name, const SymbolEntry& entry) {
  if (scopes_.empty()) {
    EnterScope();
  }
  scopes_.back()[name] = entry;
}

const SymbolEntry* SymbolTable::Lookup(const std::string& name) const {
  for (auto it = scopes_.rbegin(); it != scopes_.rend(); ++it) {
    auto found = it->find(name);
    if (found != it->end()) {
      return &found->second;
    }
  }
  return nullptr;
}