kernel/Key.h

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/**
 *  \file IMP/kernel/Key.h    \brief Keys to cache lookup of attribute strings.
 *
 *  Copyright 2007-2015 IMP Inventors. All rights reserved.
 *
 */

#ifndef IMPKERNEL_KEY_H
#define IMPKERNEL_KEY_H

#include "utility.h"
#include "internal/key_helpers.h"
#include <IMP/base/check_macros.h>
#include <IMP/base/comparison_macros.h>
#include <IMP/base/hash_macros.h>
#include <IMP/base/thread_macros.h>
#include <IMP/base/Value.h>
#include <vector>

IMPKERNEL_BEGIN_NAMESPACE

//! A base class for Keys
/** This class does internal caching of the strings to accelerate the
    name lookup. It is better to create a Key and reuse it
    rather than recreate it many times from strings.

    If you use this with a new type, you must add a new definition of
    attribute_table_index. Yes, this is an evil hack, but I couldn't
    get linking to work with static members of the template class.

    The keys in \imp maintain a cached mapping between strings and indexes.
    This mapping is global--that is all \imp Models and Particles in the
    same program use the same mapping for each type of key. The type of
    the key is determined by an integer which should be unique for
    each type. If the integer is not unique, everything works, just
    more memory is wasted and types are interconvertible.

    Keys used for storing attributes in particles should never be statically
    initialized. While this is annoying, statically initializing them is bad,
    as unused attribute keys can result in wasted memory in each particle.

    If LazyAdd is true, keys created with a new string will be added,
    otherwise this is an error.
 */
template <unsigned int ID, bool LazyAdd>
class Key : public base::Value {
  int str_;

  static const internal::KeyData::Map& get_map() {
    return IMP::kernel::internal::get_key_data(ID).get_map();
  }
  static const internal::KeyData::RMap& get_rmap() {
    return IMP::kernel::internal::get_key_data(ID).get_rmap();
  }

  static unsigned int find_index(std::string sc) {
    IMP_USAGE_CHECK(!sc.empty(), "Can't create a key with an empty name");
    unsigned int val;
    IMP_OMP_PRAGMA(critical(imp_key)) {
      if (get_map().find(sc) == get_map().end()) {
        IMP_INTERNAL_CHECK(LazyAdd, "You must explicitly create the type"
                                        << " first: " << sc);
        val = IMP::kernel::internal::get_key_data(ID).add_key(sc);
      } else {
        val = get_map().find(sc)->second;
      }
    }
    return val;
  }

 private:
  bool is_default() const;

 public:
#if !defined(IMP_DOXYGEN) && !defined(SWIG)
  static unsigned int get_ID() { return ID; }

  static const std::string get_string(int i) {
    std::string val;
    IMP_OMP_PRAGMA(critical(imp_key)) {
      if (static_cast<unsigned int>(i) < get_rmap().size()) {
        val = get_rmap()[i];
      }
    }
    if (val.empty()) {
      IMP_FAILURE("Corrupted Key Table asking for key "
                  << i << " with a table of size " << get_rmap().size());
    }
    return val;
  }

#endif
  //! make a default key in a well-defined null state
  Key() : str_(-1) {}

  //! Generate a key from the given string
  /** This operation can be expensive, so please cache the result.*/
  explicit Key(std::string c) : str_(find_index(c)) {}

#if !defined(IMP_DOXYGEN)
  explicit Key(unsigned int i) : str_(i) {
    IMP_INTERNAL_CHECK(str_ >= 0, "Invalid initializer " << i);
    // cannot check here as we need a past end iterator
  }
#endif

  static unsigned int add_key(std::string sc) {
    IMP_USAGE_CHECK(!sc.empty(), "Can't create a key with an empty name");
    unsigned int val;
    IMP_OMP_PRAGMA(critical(imp_key))
    val = IMP::kernel::internal::get_key_data(ID).add_key(sc);
    return val;
  }

  //! Return true if there already is a key with that string
  static bool get_key_exists(std::string sc) {
    bool val;
    IMP_OMP_PRAGMA(critical(imp_key))
    val = get_map().find(sc) != get_map().end();
    return val;
  }

  //! Turn a key into a pretty string
  const std::string get_string() const {
    if (is_default()) return std::string("nullptr");
    std::string val;
    val = get_string(str_);
    return val;
  }

  IMP_COMPARISONS_1(Key, str_);

  IMP_HASHABLE_INLINE(Key, return str_;)

  IMP_SHOWABLE_INLINE(Key, out << "\"" << get_string() << "\"";);

  //! Make new_name an alias for old_key
  /** Afterwards
      \code
      Key<ID>(old_key.get_string()) == Key<ID>(new_name)
      \endcode
   */
  static Key<ID, LazyAdd> add_alias(Key<ID, LazyAdd> old_key,
                                    std::string new_name) {
    IMP_INTERNAL_CHECK(
        get_map().find(new_name) == get_map().end(),
        "The name is already taken with an existing key or alias");
    IMP::kernel::internal::get_key_data(ID)
        .add_alias(new_name, old_key.get_index());
    return Key<ID, LazyAdd>(new_name.c_str());
  }

#ifndef DOXYGEN
  unsigned int get_index() const {
    IMP_INTERNAL_CHECK(!is_default(),
                       "Cannot get index on defaultly constructed Key");
    return str_;
  }
#endif

  //! Show all the keys of this type
  static void show_all(std::ostream& out);

  //! Get a list of all of the keys of this type
  /**
     This can be used to check for typos and similar keys.
   */
  static base::Vector<std::string> get_all_strings();

  //! Get the total number of keys of this type
  /**
     This is mostly for debugging to make sure that there are no extra
     keys created.
   */
  static unsigned int get_number_unique() { return get_rmap().size(); }

#ifndef SWIG
  /** \todo These should be protected, I'll try to work how
   */
  Key& operator++() {
    ++str_;
    return *this;
  }
  Key& operator--() {
    --str_;
    return *this;
  }
  Key operator+(int o) const {
    Key c = *this;
    c.str_ += o;
    return c;
  }
#endif
};

#ifndef IMP_DOXYGEN

template <unsigned int ID, bool LA>
inline std::ostream& operator<<(std::ostream& out, Key<ID, LA> k) {
  k.show(out);
  return out;
}

template <unsigned int ID, bool LA>
inline bool Key<ID, LA>::is_default() const {
  return str_ == -1;
}

template <unsigned int ID, bool LA>
inline void Key<ID, LA>::show_all(std::ostream& out) {
  IMP_OMP_PRAGMA(critical(imp_key))
  internal::get_key_data(ID).show(out);
}

template <unsigned int ID, bool LA>
base::Vector<std::string> Key<ID, LA>::get_all_strings() {
  base::Vector<std::string> str;
  IMP_OMP_PRAGMA(critical(imp_key))
  for (internal::KeyData::Map::const_iterator it = get_map().begin();
       it != get_map().end(); ++it) {
    str.push_back(it->first);
  }
  return str;
}
#endif

IMPKERNEL_END_NAMESPACE

#endif /* IMPKERNEL_KEY_H */