# <!-- rdoc-file=ext/dbm/dbm.c -->
# ## Introduction
#
# The DBM class provides a wrapper to a Unix-style
# [dbm](https://en.wikipedia.org/wiki/Dbm) or Database Manager library.
#
# Dbm databases do not have tables or columns; they are simple key-value data
# stores, like a Ruby Hash except not resident in RAM. Keys and values must be
# strings.
#
# The exact library used depends on how Ruby was compiled. It could be any of
# the following:
#
# *   The original ndbm library is released in 4.3BSD. It is based on dbm
#     library in Unix Version 7 but has different API to support multiple
#     databases in a process.
# *   [Berkeley DB](https://en.wikipedia.org/wiki/Berkeley_DB) versions 1 thru
#     6, also known as BDB and Sleepycat DB, now owned by Oracle Corporation.
# *   Berkeley DB 1.x, still found in 4.4BSD derivatives (FreeBSD, OpenBSD,
#     etc).
# *   [gdbm](http://www.gnu.org/software/gdbm/), the GNU implementation of dbm.
# *   [qdbm](http://fallabs.com/qdbm/index.html), another open source
#     reimplementation of dbm.
#
#
# All of these dbm implementations have their own Ruby interfaces available,
# which provide richer (but varying) APIs.
#
# ## Cautions
#
# Before you decide to use DBM, there are some issues you should consider:
#
# *   Each implementation of dbm has its own file format. Generally, dbm
#     libraries will not read each other's files. This makes dbm files a bad
#     choice for data exchange.
#
# *   Even running the same OS and the same dbm implementation, the database
#     file format may depend on the CPU architecture. For example, files may not
#     be portable between PowerPC and 386, or between 32 and 64 bit Linux.
#
# *   Different versions of Berkeley DB use different file formats. A change to
#     the OS may therefore break DBM access to existing files.
#
# *   Data size limits vary between implementations. Original Berkeley DB was
#     limited to 2GB of data. Dbm libraries also sometimes limit the total size
#     of a key/value pair, and the total size of all the keys that hash to the
#     same value. These limits can be as little as 512 bytes. That said, gdbm
#     and recent versions of Berkeley DB do away with these limits.
#
#
# Given the above cautions, DBM is not a good choice for long term storage of
# important data. It is probably best used as a fast and easy alternative to a
# Hash for processing large amounts of data.
#
# ## Example
#
#     require 'dbm'
#     db = DBM.open('rfcs', 0666, DBM::WRCREAT)
#     db['822'] = 'Standard for the Format of ARPA Internet Text Messages'
#     db['1123'] = 'Requirements for Internet Hosts - Application and Support'
#     db['3068'] = 'An Anycast Prefix for 6to4 Relay Routers'
#     puts db['822']
#
class DBM
  include Enumerable[[ String, String ]]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - DBM.open(filename[, mode[, flags]]) -> dbm
  #   - DBM.open(filename[, mode[, flags]]) {|dbm| block}
  # -->
  # Open a dbm database and yields it if a block is given. See also `DBM.new`.
  #
  def self.open: (String filename, ?Integer mode, ?Integer flags) -> DBM
               | [T] (String filename, ?Integer mode, ?Integer flags) { (DBM) -> T } -> T

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm[key] -> string value or nil
  # -->
  # Return a value from the database by locating the key string provided.  If the
  # key is not found, returns nil.
  #
  def []: (String) -> String?

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.store(key, value) -> value
  #   - dbm[key] = value
  # -->
  # Stores the specified string value in the database, indexed via the string key
  # provided.
  #
  def []=: (String, String) -> String

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.clear
  # -->
  # Deletes all data from the database.
  #
  def clear: () -> self

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.close
  # -->
  # Closes the database.
  #
  def close: () -> void

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.closed? -> true or false
  # -->
  # Returns true if the database is closed, false otherwise.
  #
  def closed?: () -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.delete(key)
  # -->
  # Deletes an entry from the database.
  #
  def delete: (String) -> void

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.reject! {|key, value| block} -> self
  #   - dbm.delete_if {|key, value| block} -> self
  # -->
  # Deletes all entries for which the code block returns true. Returns self.
  #
  def delete_if: () { (String) -> boolish } -> self

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.each_pair {|key,value| block} -> self
  # -->
  # Calls the block once for each [key, value] pair in the database. Returns self.
  #
  def each: () { ([ String, String ]) -> void } -> self
          | () -> Enumerator[[ String, String ], self]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.each_key {|key| block} -> self
  # -->
  # Calls the block once for each key string in the database. Returns self.
  #
  def each_key: () { (String) -> void } -> self
              | () -> Enumerator[String, self]

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Calls the block once for each [key, value] pair in the database. Returns self.
  #
  def each_pair: () { ([ String, String ]) -> void } -> self
               | () -> Enumerator[[ String, String ], self]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.each_value {|value| block} -> self
  # -->
  # Calls the block once for each value string in the database. Returns self.
  #
  def each_value: () { (String) -> void } -> self
                | () -> Enumerator[String, self]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.empty?
  # -->
  # Returns true if the database is empty, false otherwise.
  #
  def empty?: () -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.fetch(key[, ifnone]) -> value
  # -->
  # Return a value from the database by locating the key string provided.  If the
  # key is not found, returns `ifnone`. If `ifnone` is not given, raises
  # IndexError.
  #
  def fetch: (String key, ?String ifnone) -> String

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Returns true if the database contains the specified key, false otherwise.
  #
  def has_key?: (String) -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.has_value?(value) -> boolean
  #   - dbm.value?(value) -> boolean
  # -->
  # Returns true if the database contains the specified string value, false
  # otherwise.
  #
  def has_value?: () -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.include?(key) -> boolean
  #   - dbm.has_key?(key) -> boolean
  #   - dbm.member?(key) -> boolean
  #   - dbm.key?(key) -> boolean
  # -->
  # Returns true if the database contains the specified key, false otherwise.
  #
  def include?: (String) -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.invert -> hash
  # -->
  # Returns a Hash (not a DBM database) created by using each value in the
  # database as a key, with the corresponding key as its value.
  #
  def invert: () -> Hash[String, String]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.key(value) -> string
  # -->
  # Returns the key for the specified value.
  #
  def key: (String) -> String?

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Returns true if the database contains the specified key, false otherwise.
  #
  def key?: (String) -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.keys -> array
  # -->
  # Returns an array of all the string keys in the database.
  #
  def keys: () -> Array[String]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.length -> integer
  #   - dbm.size -> integer
  # -->
  # Returns the number of entries in the database.
  #
  def length: () -> Integer

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Returns true if the database contains the specified key, false otherwise.
  #
  def member?: (String) -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.reject {|key,value| block} -> Hash
  # -->
  # Converts the contents of the database to an in-memory Hash, then calls
  # Hash#reject with the specified code block, returning a new Hash.
  #
  def reject: () { (String, String) -> boolish } -> Hash[String, String]

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Deletes all entries for which the code block returns true. Returns self.
  #
  def reject!: () { (String, String) -> boolish } -> self

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.replace(obj)
  # -->
  # Replaces the contents of the database with the contents of the specified
  # object. Takes any object which implements the each_pair method, including Hash
  # and DBM objects.
  #
  def replace: (_ReplaceSource) -> ::DBM

  interface _ReplaceSource
    def each_pair: () { ([ String, String ]) -> void } -> void
  end

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.select {|key, value| block} -> array
  # -->
  # Returns a new array consisting of the [key, value] pairs for which the code
  # block returns true.
  #
  def select: () { ([ String, String ]) -> boolish } -> Array[[ String, String ]]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.shift() -> [key, value]
  # -->
  # Removes a [key, value] pair from the database, and returns it. If the database
  # is empty, returns nil. The order in which values are removed/returned is not
  # guaranteed.
  #
  def shift: () -> [ String, String ]?

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Returns the number of entries in the database.
  #
  def size: () -> Integer

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Stores the specified string value in the database, indexed via the string key
  # provided.
  #
  def store: (String, String) -> String

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.to_a -> array
  # -->
  # Converts the contents of the database to an array of [key, value] arrays, and
  # returns it.
  #
  def to_a: () -> Array[[ String, String ]]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.to_hash -> hash
  # -->
  # Converts the contents of the database to an in-memory Hash object, and returns
  # it.
  #
  def to_hash: () -> Hash[String, String]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.update(obj)
  # -->
  # Updates the database with multiple values from the specified object. Takes any
  # object which implements the each_pair method, including Hash and DBM objects.
  #
  def update: (_UpdateSource) -> ::DBM

  interface _UpdateSource
    def each_pair: () { ([ String, String ]) -> void } -> void
  end

  # <!-- rdoc-file=ext/dbm/dbm.c -->
  # Returns true if the database contains the specified string value, false
  # otherwise.
  #
  def value?: (String) -> bool

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.values -> array
  # -->
  # Returns an array of all the string values in the database.
  #
  def values: () -> Array[String]

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - dbm.values_at(key, ...) -> Array
  # -->
  # Returns an array containing the values associated with the given keys.
  #
  def values_at: (*String) -> Array[String]

  private

  # <!--
  #   rdoc-file=ext/dbm/dbm.c
  #   - DBM.new(filename[, mode[, flags]]) -> dbm
  # -->
  # Open a dbm database with the specified name, which can include a directory
  # path. Any file extensions needed will be supplied automatically by the dbm
  # library. For example, Berkeley DB appends '.db', and GNU gdbm uses two
  # physical files with extensions '.dir' and '.pag'.
  #
  # The mode should be an integer, as for Unix chmod.
  #
  # Flags should be one of READER, WRITER, WRCREAT or NEWDB.
  #
  def initialize: (String filename, ?Integer mode, ?Integer flags) -> void
end

# <!-- rdoc-file=ext/dbm/dbm.c -->
# Indicates that dbm_open() should open the database in read/write mode, create
# it if it does not already exist, and delete all contents if it does already
# exist.
#
DBM::NEWDB: Integer

# <!-- rdoc-file=ext/dbm/dbm.c -->
# Indicates that dbm_open() should open the database in read-only mode
#
DBM::READER: Integer

# <!-- rdoc-file=ext/dbm/dbm.c -->
# Identifies ndbm library version.
#
# Examples:
#
# *   "ndbm (4.3BSD)"
# *   "Berkeley DB 4.8.30: (April  9, 2010)"
# *   "Berkeley DB (unknown)" (4.4BSD, maybe)
# *   "GDBM version 1.8.3. 10/15/2002 (built Jul  1 2011 12:32:45)"
# *   "QDBM 1.8.78"
#
DBM::VERSION: String

# <!-- rdoc-file=ext/dbm/dbm.c -->
# Indicates that dbm_open() should open the database in read/write mode, and
# create it if it does not already exist
#
DBM::WRCREAT: Integer

# <!-- rdoc-file=ext/dbm/dbm.c -->
# Indicates that dbm_open() should open the database in read/write mode
#
DBM::WRITER: Integer