interpret_environment.cc

// Copyright (c) 2019 ASMlover. All rights reserved.
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#include "interpret_errors.hh"
#include "interpret_environment.hh"

namespace loxcc::interpret {

EnvironmentPtr Environment::ancestor(int distance) {
  auto envp(shared_from_this());
  for (int i = 0; i < distance; ++i)
    envp = envp->enclosing_;
  return envp;
}

const Value& Environment::get(const Token& name) const {
  if (auto val_iter = values_.find(name.literal()); val_iter != values_.end())
    return val_iter->second;

  if (enclosing_)
    return enclosing_->get(name);

  throw RuntimeError(name, "undefined variable `" + name.literal() + "`");
}

void Environment::assign(const Token& name, const Value& value) {
  if (auto val_iter = values_.find(name.literal()); val_iter != values_.end()) {
    val_iter->second = value;
    return;
  }

  if (enclosing_) {
    enclosing_->assign(name, value);
    return;
  }

  throw RuntimeError(name, "undefine variable `" + name.literal() + "`");
}

}