#include "sem/SymbolTable.h"

#include <stdexcept>

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

void SymbolTable::ExitScope() {
  if (scopes_.empty()) {
    throw std::runtime_error("作用域栈为空，无法退出");
  }
  scopes_.pop_back();
}

bool SymbolTable::Declare(const std::string& name, const SymbolInfo* symbol) {
  if (scopes_.empty()) {
    EnterScope();
  }
  auto& scope = scopes_.back();
  return scope.emplace(name, symbol).second;
}

const SymbolInfo* 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;
}

const SymbolInfo* SymbolTable::LookupCurrent(const std::string& name) const {
  if (scopes_.empty()) {
    return nullptr;
  }
  auto found = scopes_.back().find(name);
  return found == scopes_.back().end() ? nullptr : found->second;
}