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.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008800 } /* Keyword.Pseudo */
.highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */
.highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */
.highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */
.highlight .na { color: #336699 } /* Name.Attribute */
.highlight .nb { color: #003388 } /* Name.Builtin */
.highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */
.highlight .no { color: #003366; font-weight: bold } /* Name.Constant */
.highlight .nd { color: #555555 } /* Name.Decorator */
.highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */
.highlight .nl { color: #336699; font-style: italic } /* Name.Label */
.highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */
.highlight .py { color: #336699; font-weight: bold } /* Name.Property */
.highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #336699 } /* Name.Variable */
.highlight .ow { color: #008800 } /* Operator.Word */
.highlight .w { color: #bbbbbb } /* Text.Whitespace */
.highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */
.highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */
.highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */
.highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */
.highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */
.highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */
.highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */
.highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */
.highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */
.highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */
.highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */
.highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */
.highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */
.highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */
.highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */
.highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */
.highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */
.highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */
.highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */
.highlight .vc { color: #336699 } /* Name.Variable.Class */
.highlight .vg { color: #dd7700 } /* Name.Variable.Global */
.highlight .vi { color: #3333bb } /* Name.Variable.Instance */
.highlight .vm { color: #336699 } /* Name.Variable.Magic */
.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
//
//
//           The Nimrod Compiler
//        (c) Copyright 2009 Andreas Rumpf
//
//    See the file "copying.txt", included in this
//    distribution, for details about the copyright.
//
unit main;

// implements the command dispatcher and several commands as well as the
// module handling
{$include 'config.inc'}

interface

uses
  nsystem, llstream, strutils, ast, astalgo, scanner, syntaxes, rnimsyn, 
  options, msgs, nos, lists, condsyms, paslex, pasparse, rodread, rodwrite,
  ropes, trees, wordrecg, sem, semdata, idents, passes, docgen,
  extccomp, cgen, ecmasgen, platform, interact, nimconf, importer,
  passaux, depends, transf, evals, types;

procedure MainCommand(const cmd, filename: string);

implementation

// ------------------ module handling -----------------------------------------

type
  TFileModuleRec = record
    filename: string;
    module: PSym;
  end;
  TFileModuleMap = array of TFileModuleRec;
var
  compMods: TFileModuleMap = {@ignore} nil {@emit @[]};
    // all compiled modules

procedure registerModule(const filename: string; module: PSym);
var
  len: int;
begin
  len := length(compMods);
  setLength(compMods, len+1);
  compMods[len].filename := filename;
  compMods[len].module := module;
end;

function getModule(const filename: string): PSym;
var
  i: int;
begin
  for i := 0 to high(compMods) do
    if sameFile(compMods[i].filename, filename) then begin
      result := compMods[i].module; exit end;
  result := nil;
end;

// ----------------------------------------------------------------------------

function newModule(const filename: string): PSym;
begin
  // We cannot call ``newSym`` here, because we have to circumvent the ID
  // mechanism, which we do in order to assign each module a persistent ID. 
  new(result);
{@ignore}
  fillChar(result^, sizeof(result^), 0);
{@emit}
  result.id := -1; // for better error checking
  result.kind := skModule;
  result.name := getIdent(splitFile(filename).name);
  result.owner := result; // a module belongs to itself
  result.info := newLineInfo(filename, 1, 1);
  include(result.flags, sfUsed);
  initStrTable(result.tab);
  RegisterModule(filename, result);

  StrTableAdd(result.tab, result); // a module knows itself
end;

function CompileModule(const filename: string;
                       isMainFile, isSystemFile: bool): PSym; forward;

function importModule(const filename: string): PSym;
// this is called by the semantic checking phase
begin
  result := getModule(filename);
  if result = nil then begin
    // compile the module
    result := compileModule(filename, false, false);
  end
  else if sfSystemModule in result.flags then
    liMessage(result.info, errAttemptToRedefine, result.Name.s);
end;

function CompileModule(const filename: string;
                       isMainFile, isSystemFile: bool): PSym;
var
  rd: PRodReader;
  f: string;
begin
  rd := nil;
  f := addFileExt(filename, nimExt);
  result := newModule(filename);
  if isMainFile then include(result.flags, sfMainModule);
  if isSystemFile then include(result.flags, sfSystemModule);
  if (gCmd = cmdCompileToC) or (gCmd = cmdCompileToCpp) then begin
    rd := handleSymbolFile(result, f);
    if result.id < 0 then
      InternalError('handleSymbolFile should have set the module''s ID');
  end
  else
    result.id := getID();
  processModule(result, f, nil, rd);
end;

procedure CompileProject(const filename: string);
begin
  {@discard} CompileModule(
    JoinPath(options.libpath, addFileExt('system', nimExt)), false, true);
  {@discard} CompileModule(addFileExt(filename, nimExt), true, false);
end;

procedure pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #ffffcc }
.highlight .c { color: #888888 } /* Comment */
.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
.highlight .k { color: #008800; font-weight: bold } /* Keyword */
.highlight .ch { color: #888888 } /* Comment.Hashbang */
.highlight .cm { color: #888888 } /* Comment.Multiline */
.highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */
.highlight .cpf { color: #888888 } /* Comment.PreprocFile */
.highlight .c1 { color: #888888 } /* Comment.Single */
.highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */
.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008800 } /* Keyword.Pseudo */
.highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */
.highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */
.highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */
.highlight .na { color: #336699 } /* Name.Attribute */
.highlight .nb { color: #003388 } /* Name.Builtin */
.highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */
.highlight .no { color: #003366; font-weight: bold } /* Name.Constant */
.highlight .nd { color: #555555 } /* Name.Decorator */
.highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */
.highlight .nl { color: #336699; font-style: italic } /* Name.Label */
.highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */
.highlight .py { color: #336699; font-weight: bold } /* Name.Property */
.highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #336699 } /* Name.Variable */
.highlight .ow { color: #008800 } /* Operator.Word */
.highlight .w { color: #bbbbbb } /* Text.Whitespace */
.highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */
.highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */
.highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */
.highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */
.highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */
.highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */
.highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */
.highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */
.highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */
.highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */
.highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */
.highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */
.highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */
.highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */
.highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */
.highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */
.highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */
.highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */
.highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */
.highlight .vc { color: #336699 } /* Name.Variable.Class */
.highlight .vg { color: #dd7700 } /* Name.Variable.Global */
.highlight .vi { color: #3333bb } /* Name.Variable.Instance */
.highlight .vm { color: #336699 } /* Name.Variable.Magic */
.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
#
#
#            Nim's Runtime Library
#        (c) Copyright 2015 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

## The `tables` module implements variants of an efficient `hash table`:idx:
## (also often named `dictionary`:idx: in other programming languages) that is
## a mapping from keys to values.
##
## There are several different types of hash tables available:
## * `Table<#Table>`_ is the usual hash table,
## * `OrderedTable<#OrderedTable>`_ is like `Table` but remembers insertion order,
## * `CountTable<#CountTable>`_ is a mapping from a key to its number of occurrences
##
## For consistency with every other data type in Nim these have **value**
## semantics, this means that `=` performs a copy of the hash table.
##
## For `ref semantics<manual.html#types-reference-and-pointer-types>`_
## use their `Ref` variants: `TableRef<#TableRef>`_,
## `OrderedTableRef<#OrderedTableRef>`_, and `CountTableRef<#CountTableRef>`_.
##
## To give an example, when `a` is a `Table`, then `var b = a` gives `b`
## as a new independent table. `b` is initialised with the contents of `a`.
## Changing `b` does not affect `a` and vice versa:

runnableExamples:
  var
    a = {1: "one", 2: "two"}.toTable  # creates a Table
    b = a

  assert a == b

  b[3] = "three"
  assert 3 notin a
  assert 3 in b
  assert a != b

## On the other hand, when `a` is a `TableRef` instead, then changes to `b`
## also affect `a`. Both `a` and `b` **ref** the same data structure:

runnableExamples:
  var
    a = {1: "one", 2: "two"}.newTable  # creates a TableRef
    b = a

  assert a == b

  b[3] = "three"

  assert 3 in a
  assert 3 in b
  assert a == b

##
## ----
##

## # Basic usage


## ## Table
runnableExamples:
  from std/sequtils import zip

  let
    names = ["John", "Paul", "George", "Ringo"]
    years = [1940, 1942, 1943, 1940]

  var beatles = initTable[string, int]()

  for pairs in zip(names, years):
    let (name, birthYear) = pairs
    beatles[name] = birthYear

  assert beatles == {"George": 1943, "Ringo": 1940, "Paul": 1942, "John": 1940}.toTable


  var beatlesByYear = initTable[int, seq[string]]()

  for pairs in zip(years, names):
    let (birthYear, name) = pairs
    if not beatlesByYear.hasKey(birthYear):
      # if a key doesn't exist, we create one with an empty sequence
      # before we can add elements to it
      beatlesByYear[birthYear] = @[]
    beatlesByYear[birthYear].add(name)

  assert beatlesByYear == {1940: @["John", "Ringo"], 1942: @["Paul"], 1943: @["George"]}.toTable

## ## OrderedTable
## `OrderedTable<#OrderedTable>`_ is used when it is important to preserve
## the insertion order of keys.

runnableExamples:
  let
    a = [('z', 1), ('y', 2), ('x', 3)]
    ot = a.toOrderedTable  # ordered tables

  assert $ot == """{'z': 1, 'y': 2, 'x': 3}"""

## ## CountTable
## `CountTable<#CountTable>`_ is useful for counting number of items of some
## container (e.g. string, sequence or array), as it is a mapping where the
## items are the keys, and their number of occurrences are the values.
## For that purpose `toCountTable proc<#toCountTable,openArray[A]>`_
## comes handy:

runnableExamples:
  let myString = "abracadabra"
  let letterFrequencies = toCountTable(myString)
  assert $letterFrequencies == "{'a': 5, 'd': 1, 'b': 2, 'r': 2, 'c': 1}"

## The same could have been achieved by manually iterating over a container
## and increasing each key's value with `inc proc
## <#inc,CountTable[A],A,int>`_:

runnableExamples:
  let myString = "abracadabra"
  var letterFrequencies = initCountTable[char]()
  for c in myString:
    letterFrequencies.inc(c)
  assert $letterFrequencies == "{'d': 1, 'r': 2, 'c': 1, 'a': 5, 'b': 2}"

##
## ----
##

## ## Hashing
##
## If you are using simple standard types like `int` or `string` for the
## keys of the table you won't have any problems, but as soon as you try to use
## a more complex object as a key you will be greeted by a strange compiler
## error:
##
##     Error: type mismatch: got (Person)
##     but expected one of:
##     hashes.hash(x: openArray[A]): Hash
##     hashes.hash(x: int): Hash
##     hashes.hash(x: float): Hash
##
## What is happening here is that the types used for table keys require to have
## a `hash()` proc which will convert them to a `Hash <hashes.html#Hash>`_
## value, and the compiler is listing all the hash functions it knows.
## Additionally there has to be a `==` operator that provides the same
## semantics as its corresponding `hash` proc.
##
## After you add `hash` and `==` for your custom type everything will work.
## Currently, however, `hash` for objects is not defined, whereas
## `system.==` for objects does exist and performs a "deep" comparison (every
## field is compared) which is usually what you want. So in the following
## example implementing only `hash` suffices:

runnableExamples:
  import std/hashes

  type
    Person = object
      firstName, lastName: string

  proc hash(x: Person): Hash =
    ## Piggyback on the already available string hash proc.
    ##
    ## Without this proc nothing works!
    result = x.firstName.hash !& x.lastName.hash
    result = !$result

  var
    salaries = initTable[Person, int]()
    p1, p2: Person

  p1.firstName = "Jon"
  p1.lastName = "Ross"
  salaries[p1] = 30_000

  p2.firstName = "소진"
  p2.lastName = "박"
  salaries[p2] = 45_000

##
## ----
##

## # See also
##
## * `json module<json.html>`_ for table-like structure which allows
##   heterogeneous members
## * `strtabs module<strtabs.html>`_ for efficient hash tables
##   mapping from strings to strings
## * `hashes module<hashes.html>`_ for helper functions for hashing


import std/private/since
import std/[hashes, math, algorithm]


when not defined(nimHasEffectsOf):
  {.pragma: effectsOf.}

type
  KeyValuePair[A, B] = tuple[hcode: Hash, key: A, val: B]
  KeyValuePairSeq[A, B] = seq[KeyValuePair[A, B]]
  Table*[A, B] = object
    ## Generic hash table, consisting of a key-value pair.
    ##
    ## `data` and `counter` are internal implementation details which
    ## can't be accessed.
    ##
    ## For creating an empty Table, use `initTable proc<#initTable>`_.
    data: KeyValuePairSeq[A, B]
    counter: int
  TableRef*[A, B] = ref Table[A, B] ## Ref version of `Table<#Table>`_.
    ##
    ## For creating a new empty TableRef, use `newTable proc
    ## <#newTable>`_.


# ------------------------------ helpers ---------------------------------

# Do NOT move these to tableimpl.nim, because sharedtables uses that
# file and has its own implementation.
template maxHash(t): untyped = high(t.data)
template dataLen(t): untyped = len(t.data)

include tableimpl

proc raiseKeyError[T](key: T) {.noinline, noreturn.} =
  when compiles($key):
    raise newException(KeyError, "key not found: " & $key)
  else:
    raise newException(KeyError, "key not found")

template get(t, key): untyped =
  ## retrieves the value at `t[key]`. The value can be modified.
  ## If `key` is not in `t`, the `KeyError` exception is raised.
  mixin rawGet
  var hc: Hash
  var index = rawGet(t, key, hc)
  if index >= 0: result = t.data[index].val
  else:
    raiseKeyError(key)

proc enlarge[A, B](t: var Table[A, B]) =
  var n: KeyValuePairSeq[A, B]
  newSeq(n, len(t.data) * growthFactor)
  swap(t.data, n)
  for i in countup(0, high(n)):
    let eh = n[i].hcode
    if isFilled(eh):
      var j: Hash = eh and maxHash(t)
      while isFilled(t.data[j].hcode):
        j = nextTry(j, maxHash(t))
      when defined(js):
        rawInsert(t, t.data, n[i].key, n[i].val, eh, j)
      else:
        rawInsert(t, t.data, move n[i].key, move n[i].val, eh, j)




# -------------------------------------------------------------------
# ------------------------------ Table ------------------------------
# -------------------------------------------------------------------

proc initTable*[A, B](initialSize = defaultInitialSize): Table[A, B] =
  ## Creates a new hash table that is empty.
  ##
  ## Starting from Nim v0.20, tables are initialized by default and it is
  ## not necessary to call this function explicitly.
  ##
  ## See also:
  ## * `toTable proc<#toTable,openArray[]>`_
  ## * `newTable proc<#newTable>`_ for creating a `TableRef`
  runnableExamples:
    let
      a = initTable[int, string]()
      b = initTable[char, seq[int]]()
  initImpl(result, initialSize)

proc `[]=`*[A, B](t: var Table[A, B], key: A, val: sink B) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `hasKeyOrPut proc<#hasKeyOrPut,Table[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,Table[A,B],A,B>`_
  ## * `del proc<#del,Table[A,B],A>`_ for removing a key from the table
  runnableExamples:
    var a = initTable[char, int]()
    a['x'] = 7
    a['y'] = 33
    doAssert a == {'x': 7, 'y': 33}.toTable

  putImpl(enlarge)

proc toTable*[A, B](pairs: openArray[(A, B)]): Table[A, B] =
  ## Creates a new hash table that contains the given `pairs`.
  ##
  ## `pairs` is a container consisting of `(key, value)` tuples.
  ##
  ## See also:
  ## * `initTable proc<#initTable>`_
  ## * `newTable proc<#newTable,openArray[]>`_ for a `TableRef` version
  runnableExamples:
    let a = [('a', 5), ('b', 9)]
    let b = toTable(a)
    assert b == {'a': 5, 'b': 9}.toTable

  result = initTable[A, B](pairs.len)
  for key, val in items(pairs): result[key] = val

proc `[]`*[A, B](t: Table[A, B], key: A): lent B =
  ## Retrieves the value at `t[key]`.
  ##
  ## If `key` is not in `t`, the `KeyError` exception is raised.
  ## One can check with `hasKey proc<#hasKey,Table[A,B],A>`_ whether
  ## the key exists.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,Table[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_ for checking if a key is in
  ##   the table
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert a['a'] == 5
    doAssertRaises(KeyError):
      echo a['z']
  get(t, key)

proc `[]`*[A, B](t: var Table[A, B], key: A): var B =
  ## Retrieves the value at `t[key]`. The value can be modified.
  ##
  ## If `key` is not in `t`, the `KeyError` exception is raised.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,Table[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_ for checking if a key is in
  ##   the table
  get(t, key)

proc hasKey*[A, B](t: Table[A, B], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,Table[A,B],A>`_ for use with the `in` operator
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert a.hasKey('a') == true
    doAssert a.hasKey('z') == false

  var hc: Hash
  result = rawGet(t, key, hc) >= 0

proc contains*[A, B](t: Table[A, B], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,Table[A,B],A>`_ for use with
  ## the `in` operator.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert 'b' in a == true
    doAssert a.contains('z') == false

  return hasKey[A, B](t, key)

proc hasKeyOrPut*[A, B](t: var Table[A, B], key: A, val: B): bool =
  ## Returns true if `key` is in the table, otherwise inserts `value`.
  ##
  ## See also:
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.toTable
    if a.hasKeyOrPut('a', 50):
      a['a'] = 99
    if a.hasKeyOrPut('z', 50):
      a['z'] = 99
    doAssert a == {'a': 99, 'b': 9, 'z': 50}.toTable

  hasKeyOrPutImpl(enlarge)

proc getOrDefault*[A, B](t: Table[A, B], key: A): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## default initialization value for type `B` is returned (e.g. 0 for any
  ## integer type).
  ##
  ## See also:
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,Table[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,Table[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert a.getOrDefault('a') == 5
    doAssert a.getOrDefault('z') == 0
  result = default(B)
  getOrDefaultImpl(t, key)

proc getOrDefault*[A, B](t: Table[A, B], key: A, default: B): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise, `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,Table[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,Table[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert a.getOrDefault('a', 99) == 5
    doAssert a.getOrDefault('z', 99) == 99
  result = default(B)
  getOrDefaultImpl(t, key, default)

proc mgetOrPut*[A, B](t: var Table[A, B], key: A, val: B): var B =
  ## Retrieves value at `t[key]` or puts `val` if not present, either way
  ## returning a value which can be modified.
  ##
  ##
  ## Note that while the value returned is of type `var B`,
  ## it is easy to accidentally create a copy of the value at `t[key]`.
  ## Remember that seqs and strings are value types, and therefore
  ## cannot be copied into a separate variable for modification.
  ## See the example below.
  ##
  ## See also:
  ## * `[] proc<#[],Table[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,Table[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,Table[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,Table[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.toTable
    doAssert a.mgetOrPut('a', 99) == 5
    doAssert a.mgetOrPut('z', 99) == 99
    doAssert a == {'a': 5, 'b': 9, 'z': 99}.toTable

    # An example of accidentally creating a copy
    var t = initTable[int, seq[int]]()
    # In this example, we expect t[10] to be modified,
    # but it is not.
    var copiedSeq = t.mgetOrPut(10, @[10])
    copiedSeq.add(20)
    doAssert t[10] == @[10]
    # Correct
    t.mgetOrPut(25, @[25]).add(35)
    doAssert t[25] == @[25, 35]

  mgetOrPutImpl(enlarge)

proc mgetOrPut*[A, B](t: var Table[A, B], key: A): var B =
  ## Retrieves the value at `t[key]` or puts the
  ## default initialization value for type `B` (e.g. 0 for any
  ## integer type).
  runnableExamples:
    var a = {'a': 5}.newTable
    doAssert a.mgetOrPut('a') == 5
    a.mgetOrPut('z').inc
    doAssert a == {'a': 5, 'z': 1}.newTable

  mgetOrPutImpl(enlarge)

proc len*[A, B](t: Table[A, B]): int =
  ## Returns the number of keys in `t`.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toTable
    doAssert len(a) == 2

  result = t.counter

proc add*[A, B](t: var Table[A, B], key: A, val: sink B) {.deprecated:
    "Deprecated since v1.4; it was more confusing than useful, use `[]=`".} =
  ## Puts a new `(key, value)` pair into `t` even if `t[key]` already exists.
  ##
  ## **This can introduce duplicate keys into the table!**
  ##
  ## Use `[]= proc<#[]=,Table[A,B],A,sinkB>`_ for inserting a new
  ## (key, value) pair in the table without introducing duplicates.
  addImpl(enlarge)

template tabMakeEmpty(i) = t.data[i].hcode = 0
template tabCellEmpty(i) = isEmpty(t.data[i].hcode)
template tabCellHash(i)  = t.data[i].hcode

proc del*[A, B](t: var Table[A, B], key: A) =
  ## Deletes `key` from hash table `t`. Does nothing if the key does not exist.
  ##
  ## .. warning:: If duplicate keys were added (via the now deprecated `add` proc),
  ##   this may need to be called multiple times.
  ##
  ## See also:
  ## * `pop proc<#pop,Table[A,B],A,B>`_
  ## * `clear proc<#clear,Table[A,B]>`_ to empty the whole table
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.toTable
    a.del('a')
    doAssert a == {'b': 9, 'c': 13}.toTable
    a.del('z')
    doAssert a == {'b': 9, 'c': 13}.toTable

  delImpl(tabMakeEmpty, tabCellEmpty, tabCellHash)

proc pop*[A, B](t: var Table[A, B], key: A, val: var B): bool =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## .. warning:: If duplicate keys were added (via the now deprecated `add` proc),
  ##   this may need to be called multiple times.
  ##
  ## See also:
  ## * `del proc<#del,Table[A,B],A>`_
  ## * `clear proc<#clear,Table[A,B]>`_ to empty the whole table
  runnableExamples:
    var
      a = {'a': 5, 'b': 9, 'c': 13}.toTable
      i: int
    doAssert a.pop('b', i) == true
    doAssert a == {'a': 5, 'c': 13}.toTable
    doAssert i == 9
    i = 0
    doAssert a.pop('z', i) == false
    doAssert a == {'a': 5, 'c': 13}.toTable
    doAssert i == 0

  var hc: Hash
  var index = rawGet(t, key, hc)
  result = index >= 0
  if result:
    val = move(t.data[index].val)
    delImplIdx(t, index, tabMakeEmpty, tabCellEmpty, tabCellHash)

proc take*[A, B](t: var Table[A, B], key: A, val: var B): bool {.inline.} =
  ## Alias for:
  ## * `pop proc<#pop,Table[A,B],A,B>`_
  pop(t, key, val)

proc clear*[A, B](t: var Table[A, B]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,Table[A,B],A>`_
  ## * `pop proc<#pop,Table[A,B],A,B>`_
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.toTable
    doAssert len(a) == 3
    clear(a)
    doAssert len(a) == 0

  clearImpl()

proc `$`*[A, B](t: Table[A, B]): string =
  ## The `$` operator for hash tables. Used internally when calling `echo`
  ## on a table.
  dollarImpl()

proc `==`*[A, B](s, t: Table[A, B]): bool =
  ## The `==` operator for hash tables. Returns `true` if the content of both
  ## tables contains the same key-value pairs. Insert order does not matter.
  runnableExamples:
    let
      a = {'a': 5, 'b': 9, 'c': 13}.toTable
      b = {'b': 9, 'c': 13, 'a': 5}.toTable
    doAssert a == b

  equalsImpl(s, t)

proc indexBy*[A, B, C](collection: A, index: proc(x: B): C): Table[C, B] =
  ## Index the collection with the proc provided.
  # TODO: As soon as supported, change collection: A to collection: A[B]
  result = initTable[C, B]()
  for item in collection:
    result[index(item)] = item



template withValue*[A, B](t: var Table[A, B], key: A, value, body: untyped) =
  ## Retrieves the value at `t[key]`.
  ##
  ## `value` can be modified in the scope of the `withValue` call.
  runnableExamples:
    type
      User = object
        name: string
        uid: int

    var t = initTable[int, User]()
    let u = User(name: "Hello", uid: 99)
    t[1] = u

    t.withValue(1, value):
      # block is executed only if `key` in `t`
      value.name = "Nim"
      value.uid = 1314

    t.withValue(2, value):
      value.name = "No"
      value.uid = 521

    assert t[1].name == "Nim"
    assert t[1].uid == 1314

  mixin rawGet
  var hc: Hash
  var index = rawGet(t, key, hc)
  let hasKey = index >= 0
  if hasKey:
    var value {.inject.} = addr(t.data[index].val)
    body

template withValue*[A, B](t: var Table[A, B], key: A,
                          value, body1, body2: untyped) =
  ## Retrieves the value at `t[key]`.
  ##
  ## `value` can be modified in the scope of the `withValue` call.
  runnableExamples:
    type
      User = object
        name: string
        uid: int

    var t = initTable[int, User]()
    let u = User(name: "Hello", uid: 99)
    t[1] = u

    t.withValue(1, value):
      # block is executed only if `key` in `t`
      value.name = "Nim"
      value.uid = 1314

    t.withValue(521, value):
      doAssert false
    do:
      # block is executed when `key` not in `t`
      t[1314] = User(name: "exist", uid: 521)

    assert t[1].name == "Nim"
    assert t[1].uid == 1314
    assert t[1314].name == "exist"
    assert t[1314].uid == 521

  mixin rawGet
  var hc: Hash
  var index = rawGet(t, key, hc)
  let hasKey = index >= 0
  if hasKey:
    var value {.inject.} = addr(t.data[index].val)
    body1
  else:
    body2


iterator pairs*[A, B](t: Table[A, B]): (A, B) =
  ## Iterates over any `(key, value)` pair in the table `t`.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,Table[A,B]>`_
  ## * `keys iterator<#keys.i,Table[A,B]>`_
  ## * `values iterator<#values.i,Table[A,B]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = {
  ##     'o': [1, 5, 7, 9],
  ##     'e': [2, 4, 6, 8]
  ##     }.toTable
  ##
  ##   for k, v in a.pairs:
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: e
  ##   # value: [2, 4, 6, 8]
  ##   # key: o
  ##   # value: [1, 5, 7, 9]
  ##   ```
  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A, B](t: var Table[A, B]): (A, var B) =
  ## Iterates over any `(key, value)` pair in the table `t` (must be
  ## declared as `var`). The values can be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,Table[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,Table[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toTable
    for k, v in a.mpairs:
      v.add(v[0] + 10)
    doAssert a == {'e': @[2, 4, 6, 8, 12], 'o': @[1, 5, 7, 9, 11]}.toTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator keys*[A, B](t: Table[A, B]): lent A =
  ## Iterates over any key in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,Table[A,B]>`_
  ## * `values iterator<#values.i,Table[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toTable
    for k in a.keys:
      a[k].add(99)
    doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.toTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].key
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A, B](t: Table[A, B]): lent B =
  ## Iterates over any value in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,Table[A,B]>`_
  ## * `keys iterator<#keys.i,Table[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,Table[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toTable
    for v in a.values:
      doAssert v.len == 4

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A, B](t: var Table[A, B]): var B =
  ## Iterates over any value in the table `t` (must be
  ## declared as `var`). The values can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,Table[A,B]>`_
  ## * `values iterator<#values.i,Table[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toTable
    for v in a.mvalues:
      v.add(99)
    doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.toTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator allValues*[A, B](t: Table[A, B]; key: A): B {.deprecated:
    "Deprecated since v1.4; tables with duplicated keys are deprecated".} =
  ## Iterates over any value in the table `t` that belongs to the given `key`.
  ##
  ## Used if you have a table with duplicate keys (as a result of using
  ## `add proc<#add,Table[A,B],A,sinkB>`_).
  ##
  runnableExamples:
    import std/[sequtils, algorithm]

    var a = {'a': 3, 'b': 5}.toTable
    for i in 1..3: a.add('z', 10*i)
    doAssert toSeq(a.pairs).sorted == @[('a', 3), ('b', 5), ('z', 10), ('z', 20), ('z', 30)]
    doAssert sorted(toSeq(a.allValues('z'))) == @[10, 20, 30]
  var h: Hash = genHash(key) and high(t.data)
  let L = len(t)
  while isFilled(t.data[h].hcode):
    if t.data[h].key == key:
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")
    h = nextTry(h, high(t.data))



# -------------------------------------------------------------------
# ---------------------------- TableRef -----------------------------
# -------------------------------------------------------------------


proc newTable*[A, B](initialSize = defaultInitialSize): TableRef[A, B] =
  ## Creates a new ref hash table that is empty.
  ##
  ## See also:
  ## * `newTable proc<#newTable,openArray[]>`_ for creating a `TableRef`
  ##   from a collection of `(key, value)` pairs
  ## * `initTable proc<#initTable>`_ for creating a `Table`
  runnableExamples:
    let
      a = newTable[int, string]()
      b = newTable[char, seq[int]]()

  new(result)
  {.noSideEffect.}:
    result[] = initTable[A, B](initialSize)

proc newTable*[A, B](pairs: openArray[(A, B)]): TableRef[A, B] =
  ## Creates a new ref hash table that contains the given `pairs`.
  ##
  ## `pairs` is a container consisting of `(key, value)` tuples.
  ##
  ## See also:
  ## * `newTable proc<#newTable>`_
  ## * `toTable proc<#toTable,openArray[]>`_ for a `Table` version
  runnableExamples:
    let a = [('a', 5), ('b', 9)]
    let b = newTable(a)
    assert b == {'a': 5, 'b': 9}.newTable

  new(result)
  {.noSideEffect.}:
    result[] = toTable[A, B](pairs)

proc newTableFrom*[A, B, C](collection: A, index: proc(x: B): C): TableRef[C, B] =
  ## Index the collection with the proc provided.
  # TODO: As soon as supported, change collection: A to collection: A[B]
  result = newTable[C, B]()
  {.noSideEffect.}:
    for item in collection:
      result[index(item)] = item

proc `[]`*[A, B](t: TableRef[A, B], key: A): var B =
  ## Retrieves the value at `t[key]`.
  ##
  ## If `key` is not in `t`, the  `KeyError` exception is raised.
  ## One can check with `hasKey proc<#hasKey,TableRef[A,B],A>`_ whether
  ## the key exists.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,TableRef[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,TableRef[A,B],A>`_ for checking if a key is in
  ##   the table
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert a['a'] == 5
    doAssertRaises(KeyError):
      echo a['z']

  result = t[][key]

proc `[]=`*[A, B](t: TableRef[A, B], key: A, val: sink B) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKeyOrPut proc<#hasKeyOrPut,TableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,TableRef[A,B],A,B>`_
  ## * `del proc<#del,TableRef[A,B],A>`_ for removing a key from the table
  runnableExamples:
    var a = newTable[char, int]()
    a['x'] = 7
    a['y'] = 33
    doAssert a == {'x': 7, 'y': 33}.newTable

  t[][key] = val

proc hasKey*[A, B](t: TableRef[A, B], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,TableRef[A,B],A>`_ for use with the `in`
  ##   operator
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert a.hasKey('a') == true
    doAssert a.hasKey('z') == false

  result = t[].hasKey(key)

proc contains*[A, B](t: TableRef[A, B], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,TableRef[A,B],A>`_ for use with
  ## the `in` operator.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert 'b' in a == true
    doAssert a.contains('z') == false

  return hasKey[A, B](t, key)

proc hasKeyOrPut*[A, B](t: TableRef[A, B], key: A, val: B): bool =
  ## Returns true if `key` is in the table, otherwise inserts `value`.
  ##
  ## See also:
  ## * `hasKey proc<#hasKey,TableRef[A,B],A>`_
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.newTable
    if a.hasKeyOrPut('a', 50):
      a['a'] = 99
    if a.hasKeyOrPut('z', 50):
      a['z'] = 99
    doAssert a == {'a': 99, 'b': 9, 'z': 50}.newTable

  t[].hasKeyOrPut(key, val)

proc getOrDefault*[A, B](t: TableRef[A, B], key: A): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## default initialization value for type `B` is returned (e.g. 0 for any
  ## integer type).
  ##
  ## See also:
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,TableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,TableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,TableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert a.getOrDefault('a') == 5
    doAssert a.getOrDefault('z') == 0

  getOrDefault(t[], key)

proc getOrDefault*[A, B](t: TableRef[A, B], key: A, default: B): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise, `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,TableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,TableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,TableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert a.getOrDefault('a', 99) == 5
    doAssert a.getOrDefault('z', 99) == 99

  getOrDefault(t[], key, default)

proc mgetOrPut*[A, B](t: TableRef[A, B], key: A, val: B): var B =
  ## Retrieves value at `t[key]` or puts `val` if not present, either way
  ## returning a value which can be modified.
  ##
  ## Note that while the value returned is of type `var B`,
  ## it is easy to accidentally create an copy of the value at `t[key]`.
  ## Remember that seqs and strings are value types, and therefore
  ## cannot be copied into a separate variable for modification.
  ## See the example below.
  ##
  ## See also:
  ## * `[] proc<#[],TableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,TableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,TableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,TableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.newTable
    doAssert a.mgetOrPut('a', 99) == 5
    doAssert a.mgetOrPut('z', 99) == 99
    doAssert a == {'a': 5, 'b': 9, 'z': 99}.newTable

    # An example of accidentally creating a copy
    var t = newTable[int, seq[int]]()
    # In this example, we expect t[10] to be modified,
    # but it is not.
    var copiedSeq = t.mgetOrPut(10, @[10])
    copiedSeq.add(20)
    doAssert t[10] == @[10]
    # Correct
    t.mgetOrPut(25, @[25]).add(35)
    doAssert t[25] == @[25, 35]
  t[].mgetOrPut(key, val)

proc mgetOrPut*[A, B](t: TableRef[A, B], key: A): var B =
  ## Retrieves the value at `t[key]` or puts the
  ## default initialization value for type `B` (e.g. 0 for any
  ## integer type).
  runnableExamples:
    var a = {'a': 5}.newTable
    doAssert a.mgetOrPut('a') == 5
    a.mgetOrPut('z').inc
    doAssert a == {'a': 5, 'z': 1}.newTable

  t[].mgetOrPut(key)

proc len*[A, B](t: TableRef[A, B]): int =
  ## Returns the number of keys in `t`.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newTable
    doAssert len(a) == 2

  result = t.counter

proc add*[A, B](t: TableRef[A, B], key: A, val: sink B) {.deprecated:
    "Deprecated since v1.4; it was more confusing than useful, use `[]=`".} =
  ## Puts a new `(key, value)` pair into `t` even if `t[key]` already exists.
  ##
  ## **This can introduce duplicate keys into the table!**
  ##
  ## Use `[]= proc<#[]=,TableRef[A,B],A,sinkB>`_ for inserting a new
  ## (key, value) pair in the table without introducing duplicates.
  t[].add(key, val)

proc del*[A, B](t: TableRef[A, B], key: A) =
  ## Deletes `key` from hash table `t`. Does nothing if the key does not exist.
  ##
  ## .. warning:: If duplicate keys were added (via the now deprecated `add` proc),
  ##   this may need to be called multiple times.
  ##
  ## See also:
  ## * `pop proc<#pop,TableRef[A,B],A,B>`_
  ## * `clear proc<#clear,TableRef[A,B]>`_ to empty the whole table
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.newTable
    a.del('a')
    doAssert a == {'b': 9, 'c': 13}.newTable
    a.del('z')
    doAssert a == {'b': 9, 'c': 13}.newTable

  t[].del(key)

proc pop*[A, B](t: TableRef[A, B], key: A, val: var B): bool =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## .. warning:: If duplicate keys were added (via the now deprecated `add` proc),
  ##   this may need to be called multiple times.
  ##
  ## See also:
  ## * `del proc<#del,TableRef[A,B],A>`_
  ## * `clear proc<#clear,TableRef[A,B]>`_ to empty the whole table
  runnableExamples:
    var
      a = {'a': 5, 'b': 9, 'c': 13}.newTable
      i: int
    doAssert a.pop('b', i) == true
    doAssert a == {'a': 5, 'c': 13}.newTable
    doAssert i == 9
    i = 0
    doAssert a.pop('z', i) == false
    doAssert a == {'a': 5, 'c': 13}.newTable
    doAssert i == 0

  result = t[].pop(key, val)

proc take*[A, B](t: TableRef[A, B], key: A, val: var B): bool {.inline.} =
  ## Alias for:
  ## * `pop proc<#pop,TableRef[A,B],A,B>`_
  pop(t, key, val)

proc clear*[A, B](t: TableRef[A, B]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,Table[A,B],A>`_
  ## * `pop proc<#pop,Table[A,B],A,B>`_
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.newTable
    doAssert len(a) == 3
    clear(a)
    doAssert len(a) == 0

  clearImpl()

proc `$`*[A, B](t: TableRef[A, B]): string =
  ## The `$` operator for hash tables. Used internally when calling `echo`
  ## on a table.
  dollarImpl()

proc `==`*[A, B](s, t: TableRef[A, B]): bool =
  ## The `==` operator for hash tables. Returns `true` if either both tables
  ## are `nil`, or neither is `nil` and the content of both tables contains the
  ## same key-value pairs. Insert order does not matter.
  runnableExamples:
    let
      a = {'a': 5, 'b': 9, 'c': 13}.newTable
      b = {'b': 9, 'c': 13, 'a': 5}.newTable
    doAssert a == b

  if isNil(s): result = isNil(t)
  elif isNil(t): result = false
  else: equalsImpl(s[], t[])



iterator pairs*[A, B](t: TableRef[A, B]): (A, B) =
  ## Iterates over any `(key, value)` pair in the table `t`.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,TableRef[A,B]>`_
  ## * `keys iterator<#keys.i,TableRef[A,B]>`_
  ## * `values iterator<#values.i,TableRef[A,B]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = {
  ##     'o': [1, 5, 7, 9],
  ##     'e': [2, 4, 6, 8]
  ##     }.newTable
  ##
  ##   for k, v in a.pairs:
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: e
  ##   # value: [2, 4, 6, 8]
  ##   # key: o
  ##   # value: [1, 5, 7, 9]
  ##   ```
  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A, B](t: TableRef[A, B]): (A, var B) =
  ## Iterates over any `(key, value)` pair in the table `t`. The values
  ## can be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,TableRef[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,TableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newTable
    for k, v in a.mpairs:
      v.add(v[0] + 10)
    doAssert a == {'e': @[2, 4, 6, 8, 12], 'o': @[1, 5, 7, 9, 11]}.newTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator keys*[A, B](t: TableRef[A, B]): lent A =
  ## Iterates over any key in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,TableRef[A,B]>`_
  ## * `values iterator<#values.i,TableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newTable
    for k in a.keys:
      a[k].add(99)
    doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.newTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].key
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A, B](t: TableRef[A, B]): lent B =
  ## Iterates over any value in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,TableRef[A,B]>`_
  ## * `keys iterator<#keys.i,TableRef[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,TableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newTable
    for v in a.values:
      doAssert v.len == 4

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A, B](t: TableRef[A, B]): var B =
  ## Iterates over any value in the table `t`. The values can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,TableRef[A,B]>`_
  ## * `values iterator<#values.i,TableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newTable
    for v in a.mvalues:
      v.add(99)
    doAssert a == {'e': @[2, 4, 6, 8, 99], 'o': @[1, 5, 7, 9, 99]}.newTable

  let L = len(t)
  for h in 0 .. high(t.data):
    if isFilled(t.data[h].hcode):
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")








# ---------------------------------------------------------------------------
# ------------------------------ OrderedTable -------------------------------
# ---------------------------------------------------------------------------

type
  OrderedKeyValuePair[A, B] = tuple[
    hcode: Hash, next: int, key: A, val: B]
  OrderedKeyValuePairSeq[A, B] = seq[OrderedKeyValuePair[A, B]]
  OrderedTable*[A, B] = object
    ## Hash table that remembers insertion order.
    ##
    ## For creating an empty OrderedTable, use `initOrderedTable proc
    ## <#initOrderedTable>`_.
    data: OrderedKeyValuePairSeq[A, B]
    counter, first, last: int
  OrderedTableRef*[A, B] = ref OrderedTable[A, B] ## Ref version of
    ## `OrderedTable<#OrderedTable>`_.
    ##
    ## For creating a new empty OrderedTableRef, use `newOrderedTable proc
    ## <#newOrderedTable>`_.


# ------------------------------ helpers ---------------------------------

proc rawGetKnownHC[A, B](t: OrderedTable[A, B], key: A, hc: Hash): int =
  rawGetKnownHCImpl()

proc rawGetDeep[A, B](t: OrderedTable[A, B], key: A, hc: var Hash): int {.inline.} =
  rawGetDeepImpl()

proc rawGet[A, B](t: OrderedTable[A, B], key: A, hc: var Hash): int =
  rawGetImpl()

proc rawInsert[A, B](t: var OrderedTable[A, B],
                     data: var OrderedKeyValuePairSeq[A, B],
                     key: A, val: sink B, hc: Hash, h: Hash) =
  rawInsertImpl()
  data[h].next = -1
  if t.first < 0: t.first = h
  if t.last >= 0: data[t.last].next = h
  t.last = h

proc enlarge[A, B](t: var OrderedTable[A, B]) =
  var n: OrderedKeyValuePairSeq[A, B]
  newSeq(n, len(t.data) * growthFactor)
  var h = t.first
  t.first = -1
  t.last = -1
  swap(t.data, n)
  while h >= 0:
    var nxt = n[h].next
    let eh = n[h].hcode
    if isFilled(eh):
      var j: Hash = eh and maxHash(t)
      while isFilled(t.data[j].hcode):
        j = nextTry(j, maxHash(t))
      rawInsert(t, t.data, move n[h].key, move n[h].val, n[h].hcode, j)
    h = nxt

template forAllOrderedPairs(yieldStmt: untyped) {.dirty.} =
  if t.counter > 0:
    var h = t.first
    while h >= 0:
      var nxt = t.data[h].next
      if isFilled(t.data[h].hcode):
        yieldStmt
      h = nxt

# ----------------------------------------------------------------------

proc initOrderedTable*[A, B](initialSize = defaultInitialSize): OrderedTable[A, B] =
  ## Creates a new ordered hash table that is empty.
  ##
  ## Starting from Nim v0.20, tables are initialized by default and it is
  ## not necessary to call this function explicitly.
  ##
  ## See also:
  ## * `toOrderedTable proc<#toOrderedTable,openArray[]>`_
  ## * `newOrderedTable proc<#newOrderedTable>`_ for creating an
  ##   `OrderedTableRef`
  runnableExamples:
    let
      a = initOrderedTable[int, string]()
      b = initOrderedTable[char, seq[int]]()
  initImpl(result, initialSize)

proc `[]=`*[A, B](t: var OrderedTable[A, B], key: A, val: sink B) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTable[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTable[A,B],A,B>`_
  ## * `del proc<#del,OrderedTable[A,B],A>`_ for removing a key from the table
  runnableExamples:
    var a = initOrderedTable[char, int]()
    a['x'] = 7
    a['y'] = 33
    doAssert a == {'x': 7, 'y': 33}.toOrderedTable

  putImpl(enlarge)

proc toOrderedTable*[A, B](pairs: openArray[(A, B)]): OrderedTable[A, B] =
  ## Creates a new ordered hash table that contains the given `pairs`.
  ##
  ## `pairs` is a container consisting of `(key, value)` tuples.
  ##
  ## See also:
  ## * `initOrderedTable proc<#initOrderedTable>`_
  ## * `newOrderedTable proc<#newOrderedTable,openArray[]>`_ for an
  ##   `OrderedTableRef` version
  runnableExamples:
    let a = [('a', 5), ('b', 9)]
    let b = toOrderedTable(a)
    assert b == {'a': 5, 'b': 9}.toOrderedTable

  result = initOrderedTable[A, B](pairs.len)
  for key, val in items(pairs): result[key] = val

proc `[]`*[A, B](t: OrderedTable[A, B], key: A): lent B =
  ## Retrieves the value at `t[key]`.
  ##
  ## If `key` is not in `t`, the  `KeyError` exception is raised.
  ## One can check with `hasKey proc<#hasKey,OrderedTable[A,B],A>`_ whether
  ## the key exists.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,OrderedTable[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_ for checking if a
  ##   key is in the table
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert a['a'] == 5
    doAssertRaises(KeyError):
      echo a['z']

  get(t, key)

proc `[]`*[A, B](t: var OrderedTable[A, B], key: A): var B =
  ## Retrieves the value at `t[key]`. The value can be modified.
  ##
  ## If `key` is not in `t`, the `KeyError` exception is raised.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,OrderedTable[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_ for checking if a
  ##   key is in the table
  get(t, key)

proc hasKey*[A, B](t: OrderedTable[A, B], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,OrderedTable[A,B],A>`_ for use with the `in`
  ##   operator
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert a.hasKey('a') == true
    doAssert a.hasKey('z') == false

  var hc: Hash
  result = rawGet(t, key, hc) >= 0

proc contains*[A, B](t: OrderedTable[A, B], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,OrderedTable[A,B],A>`_ for use with
  ## the `in` operator.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert 'b' in a == true
    doAssert a.contains('z') == false

  return hasKey[A, B](t, key)

proc hasKeyOrPut*[A, B](t: var OrderedTable[A, B], key: A, val: B): bool =
  ## Returns true if `key` is in the table, otherwise inserts `value`.
  ##
  ## See also:
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.toOrderedTable
    if a.hasKeyOrPut('a', 50):
      a['a'] = 99
    if a.hasKeyOrPut('z', 50):
      a['z'] = 99
    doAssert a == {'a': 99, 'b': 9, 'z': 50}.toOrderedTable

  hasKeyOrPutImpl(enlarge)

proc getOrDefault*[A, B](t: OrderedTable[A, B], key: A): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## default initialization value for type `B` is returned (e.g. 0 for any
  ## integer type).
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTable[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTable[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert a.getOrDefault('a') == 5
    doAssert a.getOrDefault('z') == 0
  result = default(B)
  getOrDefaultImpl(t, key)

proc getOrDefault*[A, B](t: OrderedTable[A, B], key: A, default: B): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise, `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTable[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTable[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert a.getOrDefault('a', 99) == 5
    doAssert a.getOrDefault('z', 99) == 99
  result = default(B)
  getOrDefaultImpl(t, key, default)

proc mgetOrPut*[A, B](t: var OrderedTable[A, B], key: A, val: B): var B =
  ## Retrieves value at `t[key]` or puts `val` if not present, either way
  ## returning a value which can be modified.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTable[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTable[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTable[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTable[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert a.mgetOrPut('a', 99) == 5
    doAssert a.mgetOrPut('z', 99) == 99
    doAssert a == {'a': 5, 'b': 9, 'z': 99}.toOrderedTable

  mgetOrPutImpl(enlarge)

proc mgetOrPut*[A, B](t: var OrderedTable[A, B], key: A): var B =
  ## Retrieves the value at `t[key]` or puts the
  ## default initialization value for type `B` (e.g. 0 for any
  ## integer type).
  runnableExamples:
    var a = {'a': 5}.toOrderedTable
    doAssert a.mgetOrPut('a') == 5
    a.mgetOrPut('z').inc
    doAssert a == {'a': 5, 'z': 1}.toOrderedTable

  mgetOrPutImpl(enlarge)

proc len*[A, B](t: OrderedTable[A, B]): int {.inline.} =
  ## Returns the number of keys in `t`.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.toOrderedTable
    doAssert len(a) == 2

  result = t.counter

proc add*[A, B](t: var OrderedTable[A, B], key: A, val: sink B) {.deprecated:
    "Deprecated since v1.4; it was more confusing than useful, use `[]=`".} =
  ## Puts a new `(key, value)` pair into `t` even if `t[key]` already exists.
  ##
  ## **This can introduce duplicate keys into the table!**
  ##
  ## Use `[]= proc<#[]=,OrderedTable[A,B],A,sinkB>`_ for inserting a new
  ## (key, value) pair in the table without introducing duplicates.
  addImpl(enlarge)

proc del*[A, B](t: var OrderedTable[A, B], key: A) =
  ## Deletes `key` from hash table `t`. Does nothing if the key does not exist.
  ##
  ## O(n) complexity.
  ##
  ## See also:
  ## * `pop proc<#pop,OrderedTable[A,B],A,B>`_
  ## * `clear proc<#clear,OrderedTable[A,B]>`_ to empty the whole table
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
    a.del('a')
    doAssert a == {'b': 9, 'c': 13}.toOrderedTable
    a.del('z')
    doAssert a == {'b': 9, 'c': 13}.toOrderedTable

  if t.counter == 0: return
  var n: OrderedKeyValuePairSeq[A, B]
  newSeq(n, len(t.data))
  var h = t.first
  t.first = -1
  t.last = -1
  swap(t.data, n)
  let hc = genHash(key)
  while h >= 0:
    var nxt = n[h].next
    if isFilled(n[h].hcode):
      if n[h].hcode == hc and n[h].key == key:
        dec t.counter
      else:
        var j = -1 - rawGetKnownHC(t, n[h].key, n[h].hcode)
        rawInsert(t, t.data, move n[h].key, move n[h].val, n[h].hcode, j)
    h = nxt

proc pop*[A, B](t: var OrderedTable[A, B], key: A, val: var B): bool {.since: (1, 1).} =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## O(n) complexity.
  ##
  ## See also:
  ## * `del proc<#del,OrderedTable[A,B],A>`_
  ## * `clear proc<#clear,OrderedTable[A,B]>`_ to empty the whole table
  runnableExamples:
    var
      a = {'c': 5, 'b': 9, 'a': 13}.toOrderedTable
      i: int
    doAssert a.pop('b', i) == true
    doAssert a == {'c': 5, 'a': 13}.toOrderedTable
    doAssert i == 9
    i = 0
    doAssert a.pop('z', i) == false
    doAssert a == {'c': 5, 'a': 13}.toOrderedTable
    doAssert i == 0

  var hc: Hash
  var index = rawGet(t, key, hc)
  result = index >= 0
  if result:
    val = move(t.data[index].val)
    del(t, key)

proc clear*[A, B](t: var OrderedTable[A, B]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,OrderedTable[A,B],A>`_
  ## * `pop proc<#pop,OrderedTable[A,B],A,B>`_
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
    doAssert len(a) == 3
    clear(a)
    doAssert len(a) == 0

  clearImpl()
  t.first = -1
  t.last = -1

proc sort*[A, B](t: var OrderedTable[A, B], cmp: proc (x, y: (A, B)): int,
    order = SortOrder.Ascending) {.effectsOf: cmp.} =
  ## Sorts `t` according to the function `cmp`.
  ##
  ## This modifies the internal list
  ## that kept the insertion order, so insertion order is lost after this
  ## call but key lookup and insertions remain possible after `sort` (in
  ## contrast to the `sort proc<#sort,CountTable[A]>`_ for count tables).
  runnableExamples:
    import std/[algorithm]
    var a = initOrderedTable[char, int]()
    for i, c in "cab":
      a[c] = 10*i
    doAssert a == {'c': 0, 'a': 10, 'b': 20}.toOrderedTable
    a.sort(system.cmp)
    doAssert a == {'a': 10, 'b': 20, 'c': 0}.toOrderedTable
    a.sort(system.cmp, order = SortOrder.Descending)
    doAssert a == {'c': 0, 'b': 20, 'a': 10}.toOrderedTable

  var list = t.first
  var
    p, q, e, tail, oldhead: int
    nmerges, psize, qsize, i: int
  if t.counter == 0: return
  var insize = 1
  while true:
    p = list; oldhead = list
    list = -1; tail = -1; nmerges = 0
    while p >= 0:
      inc(nmerges)
      q = p
      psize = 0
      i = 0
      while i < insize:
        inc(psize)
        q = t.data[q].next
        if q < 0: break
        inc(i)
      qsize = insize
      while psize > 0 or (qsize > 0 and q >= 0):
        if psize == 0:
          e = q; q = t.data[q].next; dec(qsize)
        elif qsize == 0 or q < 0:
          e = p; p = t.data[p].next; dec(psize)
        elif cmp((t.data[p].key, t.data[p].val),
                 (t.data[q].key, t.data[q].val)) * order <= 0:
          e = p; p = t.data[p].next; dec(psize)
        else:
          e = q; q = t.data[q].next; dec(qsize)
        if tail >= 0: t.data[tail].next = e
        else: list = e
        tail = e
      p = q
    t.data[tail].next = -1
    if nmerges <= 1: break
    insize = insize * 2
  t.first = list
  t.last = tail

proc `$`*[A, B](t: OrderedTable[A, B]): string =
  ## The `$` operator for ordered hash tables. Used internally when calling
  ## `echo` on a table.
  dollarImpl()

proc `==`*[A, B](s, t: OrderedTable[A, B]): bool =
  ## The `==` operator for ordered hash tables. Returns `true` if both the
  ## content and the order are equal.
  runnableExamples:
    let
      a = {'a': 5, 'b': 9, 'c': 13}.toOrderedTable
      b = {'b': 9, 'c': 13, 'a': 5}.toOrderedTable
    doAssert a != b

  if s.counter != t.counter:
    return false
  if s.counter == 0 and t.counter == 0:
    return true
  var ht = t.first
  var hs = s.first
  while ht >= 0 and hs >= 0:
    var nxtt = t.data[ht].next
    var nxts = s.data[hs].next
    if isFilled(t.data[ht].hcode) and isFilled(s.data[hs].hcode):
      if (s.data[hs].key != t.data[ht].key) or (s.data[hs].val != t.data[ht].val):
        return false
    ht = nxtt
    hs = nxts
  return true



iterator pairs*[A, B](t: OrderedTable[A, B]): (A, B) =
  ## Iterates over any `(key, value)` pair in the table `t` in insertion
  ## order.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,OrderedTable[A,B]>`_
  ## * `keys iterator<#keys.i,OrderedTable[A,B]>`_
  ## * `values iterator<#values.i,OrderedTable[A,B]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = {
  ##     'o': [1, 5, 7, 9],
  ##     'e': [2, 4, 6, 8]
  ##     }.toOrderedTable
  ##
  ##   for k, v in a.pairs:
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: o
  ##   # value: [1, 5, 7, 9]
  ##   # key: e
  ##   # value: [2, 4, 6, 8]
  ##   ```

  let L = len(t)
  forAllOrderedPairs:
    yield (t.data[h].key, t.data[h].val)
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A, B](t: var OrderedTable[A, B]): (A, var B) =
  ## Iterates over any `(key, value)` pair in the table `t` (must be
  ## declared as `var`) in insertion order. The values can be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTable[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,OrderedTable[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toOrderedTable
    for k, v in a.mpairs:
      v.add(v[0] + 10)
    doAssert a == {'o': @[1, 5, 7, 9, 11],
                   'e': @[2, 4, 6, 8, 12]}.toOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield (t.data[h].key, t.data[h].val)
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator keys*[A, B](t: OrderedTable[A, B]): lent A =
  ## Iterates over any key in the table `t` in insertion order.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTable[A,B]>`_
  ## * `values iterator<#values.i,OrderedTable[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toOrderedTable
    for k in a.keys:
      a[k].add(99)
    doAssert a == {'o': @[1, 5, 7, 9, 99],
                   'e': @[2, 4, 6, 8, 99]}.toOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].key
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A, B](t: OrderedTable[A, B]): lent B =
  ## Iterates over any value in the table `t` in insertion order.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTable[A,B]>`_
  ## * `keys iterator<#keys.i,OrderedTable[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,OrderedTable[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toOrderedTable
    for v in a.values:
      doAssert v.len == 4

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].val
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A, B](t: var OrderedTable[A, B]): var B =
  ## Iterates over any value in the table `t` (must be
  ## declared as `var`) in insertion order. The values
  ## can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,OrderedTable[A,B]>`_
  ## * `values iterator<#values.i,OrderedTable[A,B]>`_
  runnableExamples:
    var a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.toOrderedTable
    for v in a.mvalues:
      v.add(99)
    doAssert a == {'o': @[1, 5, 7, 9, 99],
                   'e': @[2, 4, 6, 8, 99]}.toOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].val
    assert(len(t) == L, "the length of the table changed while iterating over it")

# ---------------------------------------------------------------------------
# --------------------------- OrderedTableRef -------------------------------
# ---------------------------------------------------------------------------

proc newOrderedTable*[A, B](initialSize = defaultInitialSize): OrderedTableRef[A, B] =
  ## Creates a new ordered ref hash table that is empty.
  ##
  ## See also:
  ## * `newOrderedTable proc<#newOrderedTable,openArray[]>`_ for creating
  ##   an `OrderedTableRef` from a collection of `(key, value)` pairs
  ## * `initOrderedTable proc<#initOrderedTable>`_ for creating an
  ##   `OrderedTable`
  runnableExamples:
    let
      a = newOrderedTable[int, string]()
      b = newOrderedTable[char, seq[int]]()
  new(result)
  {.noSideEffect.}:
    result[] = initOrderedTable[A, B](initialSize)

proc newOrderedTable*[A, B](pairs: openArray[(A, B)]): OrderedTableRef[A, B] =
  ## Creates a new ordered ref hash table that contains the given `pairs`.
  ##
  ## `pairs` is a container consisting of `(key, value)` tuples.
  ##
  ## See also:
  ## * `newOrderedTable proc<#newOrderedTable>`_
  ## * `toOrderedTable proc<#toOrderedTable,openArray[]>`_ for an
  ##   `OrderedTable` version
  runnableExamples:
    let a = [('a', 5), ('b', 9)]
    let b = newOrderedTable(a)
    assert b == {'a': 5, 'b': 9}.newOrderedTable

  result = newOrderedTable[A, B](pairs.len)
  {.noSideEffect.}:
    for key, val in items(pairs): result[key] = val


proc `[]`*[A, B](t: OrderedTableRef[A, B], key: A): var B =
  ## Retrieves the value at `t[key]`.
  ##
  ## If `key` is not in `t`, the  `KeyError` exception is raised.
  ## One can check with `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_ whether
  ## the key exists.
  ##
  ## See also:
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]=,OrderedTableRef[A,B],A,sinkB>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_ for checking if
  ##   a key is in the table
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert a['a'] == 5
    doAssertRaises(KeyError):
      echo a['z']
  result = t[][key]

proc `[]=`*[A, B](t: OrderedTableRef[A, B], key: A, val: sink B) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `del proc<#del,OrderedTableRef[A,B],A>`_ for removing a key from the table
  runnableExamples:
    var a = newOrderedTable[char, int]()
    a['x'] = 7
    a['y'] = 33
    doAssert a == {'x': 7, 'y': 33}.newOrderedTable

  t[][key] = val

proc hasKey*[A, B](t: OrderedTableRef[A, B], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,OrderedTableRef[A,B],A>`_ for use with the `in`
  ##   operator
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert a.hasKey('a') == true
    doAssert a.hasKey('z') == false

  result = t[].hasKey(key)

proc contains*[A, B](t: OrderedTableRef[A, B], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_ for use with
  ## the `in` operator.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert 'b' in a == true
    doAssert a.contains('z') == false

  return hasKey[A, B](t, key)

proc hasKeyOrPut*[A, B](t: OrderedTableRef[A, B], key: A, val: B): bool =
  ## Returns true if `key` is in the table, otherwise inserts `value`.
  ##
  ## See also:
  ## * `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.newOrderedTable
    if a.hasKeyOrPut('a', 50):
      a['a'] = 99
    if a.hasKeyOrPut('z', 50):
      a['z'] = 99
    doAssert a == {'a': 99, 'b': 9, 'z': 50}.newOrderedTable

  result = t[].hasKeyOrPut(key, val)

proc getOrDefault*[A, B](t: OrderedTableRef[A, B], key: A): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## default initialization value for type `B` is returned (e.g. 0 for any
  ## integer type).
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert a.getOrDefault('a') == 5
    doAssert a.getOrDefault('z') == 0

  getOrDefault(t[], key)

proc getOrDefault*[A, B](t: OrderedTableRef[A, B], key: A, default: B): B =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise, `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `mgetOrPut proc<#mgetOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert a.getOrDefault('a', 99) == 5
    doAssert a.getOrDefault('z', 99) == 99

  getOrDefault(t[], key, default)

proc mgetOrPut*[A, B](t: OrderedTableRef[A, B], key: A, val: B): var B =
  ## Retrieves value at `t[key]` or puts `val` if not present, either way
  ## returning a value which can be modified.
  ##
  ## See also:
  ## * `[] proc<#[],OrderedTableRef[A,B],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,OrderedTableRef[A,B],A>`_
  ## * `hasKeyOrPut proc<#hasKeyOrPut,OrderedTableRef[A,B],A,B>`_
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A>`_ to return
  ##   a default value (e.g. zero for int) if the key doesn't exist
  ## * `getOrDefault proc<#getOrDefault,OrderedTableRef[A,B],A,B>`_ to return
  ##   a custom value if the key doesn't exist
  runnableExamples:
    var a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert a.mgetOrPut('a', 99) == 5
    doAssert a.mgetOrPut('z', 99) == 99
    doAssert a == {'a': 5, 'b': 9, 'z': 99}.newOrderedTable

  result = t[].mgetOrPut(key, val)

proc mgetOrPut*[A, B](t: OrderedTableRef[A, B], key: A): var B =
  ## Retrieves the value at `t[key]` or puts the
  ## default initialization value for type `B` (e.g. 0 for any
  ## integer type).
  runnableExamples:
    var a = {'a': 5}.toOrderedTable
    doAssert a.mgetOrPut('a') == 5
    a.mgetOrPut('z').inc
    doAssert a == {'a': 5, 'z': 1}.toOrderedTable

  t[].mgetOrPut(key)

proc len*[A, B](t: OrderedTableRef[A, B]): int {.inline.} =
  ## Returns the number of keys in `t`.
  runnableExamples:
    let a = {'a': 5, 'b': 9}.newOrderedTable
    doAssert len(a) == 2

  result = t.counter

proc add*[A, B](t: OrderedTableRef[A, B], key: A, val: sink B) {.deprecated:
    "Deprecated since v1.4; it was more confusing than useful, use `[]=`".} =
  ## Puts a new `(key, value)` pair into `t` even if `t[key]` already exists.
  ##
  ## **This can introduce duplicate keys into the table!**
  ##
  ## Use `[]= proc<#[]=,OrderedTableRef[A,B],A,sinkB>`_ for inserting a new
  ## (key, value) pair in the table without introducing duplicates.
  t[].add(key, val)

proc del*[A, B](t: OrderedTableRef[A, B], key: A) =
  ## Deletes `key` from hash table `t`. Does nothing if the key does not exist.
  ##
  ## See also:
  ## * `clear proc<#clear,OrderedTableRef[A,B]>`_ to empty the whole table
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
    a.del('a')
    doAssert a == {'b': 9, 'c': 13}.newOrderedTable
    a.del('z')
    doAssert a == {'b': 9, 'c': 13}.newOrderedTable

  t[].del(key)

proc pop*[A, B](t: OrderedTableRef[A, B], key: A, val: var B): bool {.since: (1, 1).} =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## See also:
  ## * `del proc<#del,OrderedTableRef[A,B],A>`_
  ## * `clear proc<#clear,OrderedTableRef[A,B]>`_ to empty the whole table
  runnableExamples:
    var
      a = {'c': 5, 'b': 9, 'a': 13}.newOrderedTable
      i: int
    doAssert a.pop('b', i) == true
    doAssert a == {'c': 5, 'a': 13}.newOrderedTable
    doAssert i == 9
    i = 0
    doAssert a.pop('z', i) == false
    doAssert a == {'c': 5, 'a': 13}.newOrderedTable
    doAssert i == 0

  pop(t[], key, val)

proc clear*[A, B](t: OrderedTableRef[A, B]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,OrderedTableRef[A,B],A>`_
  runnableExamples:
    var a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
    doAssert len(a) == 3
    clear(a)
    doAssert len(a) == 0

  clear(t[])

proc sort*[A, B](t: OrderedTableRef[A, B], cmp: proc (x, y: (A, B)): int,
    order = SortOrder.Ascending) {.effectsOf: cmp.} =
  ## Sorts `t` according to the function `cmp`.
  ##
  ## This modifies the internal list
  ## that kept the insertion order, so insertion order is lost after this
  ## call but key lookup and insertions remain possible after `sort` (in
  ## contrast to the `sort proc<#sort,CountTableRef[A]>`_ for count tables).
  runnableExamples:
    import std/[algorithm]
    var a = newOrderedTable[char, int]()
    for i, c in "cab":
      a[c] = 10*i
    doAssert a == {'c': 0, 'a': 10, 'b': 20}.newOrderedTable
    a.sort(system.cmp)
    doAssert a == {'a': 10, 'b': 20, 'c': 0}.newOrderedTable
    a.sort(system.cmp, order = SortOrder.Descending)
    doAssert a == {'c': 0, 'b': 20, 'a': 10}.newOrderedTable

  t[].sort(cmp, order = order)

proc `$`*[A, B](t: OrderedTableRef[A, B]): string =
  ## The `$` operator for hash tables. Used internally when calling `echo`
  ## on a table.
  dollarImpl()

proc `==`*[A, B](s, t: OrderedTableRef[A, B]): bool =
  ## The `==` operator for ordered hash tables. Returns true if either both
  ## tables are `nil`, or neither is `nil` and the content and the order of
  ## both are equal.
  runnableExamples:
    let
      a = {'a': 5, 'b': 9, 'c': 13}.newOrderedTable
      b = {'b': 9, 'c': 13, 'a': 5}.newOrderedTable
    doAssert a != b

  if isNil(s): result = isNil(t)
  elif isNil(t): result = false
  else: result = s[] == t[]



iterator pairs*[A, B](t: OrderedTableRef[A, B]): (A, B) =
  ## Iterates over any `(key, value)` pair in the table `t` in insertion
  ## order.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,OrderedTableRef[A,B]>`_
  ## * `keys iterator<#keys.i,OrderedTableRef[A,B]>`_
  ## * `values iterator<#values.i,OrderedTableRef[A,B]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = {
  ##     'o': [1, 5, 7, 9],
  ##     'e': [2, 4, 6, 8]
  ##     }.newOrderedTable
  ##
  ##   for k, v in a.pairs:
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: o
  ##   # value: [1, 5, 7, 9]
  ##   # key: e
  ##   # value: [2, 4, 6, 8]
  ##   ```

  let L = len(t)
  forAllOrderedPairs:
    yield (t.data[h].key, t.data[h].val)
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A, B](t: OrderedTableRef[A, B]): (A, var B) =
  ## Iterates over any `(key, value)` pair in the table `t` in insertion
  ## order. The values can be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTableRef[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,OrderedTableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newOrderedTable
    for k, v in a.mpairs:
      v.add(v[0] + 10)
    doAssert a == {'o': @[1, 5, 7, 9, 11],
                   'e': @[2, 4, 6, 8, 12]}.newOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield (t.data[h].key, t.data[h].val)
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator keys*[A, B](t: OrderedTableRef[A, B]): lent A =
  ## Iterates over any key in the table `t` in insertion order.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTableRef[A,B]>`_
  ## * `values iterator<#values.i,OrderedTableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newOrderedTable
    for k in a.keys:
      a[k].add(99)
    doAssert a == {'o': @[1, 5, 7, 9, 99], 'e': @[2, 4, 6, 8,
        99]}.newOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].key
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A, B](t: OrderedTableRef[A, B]): lent B =
  ## Iterates over any value in the table `t` in insertion order.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,OrderedTableRef[A,B]>`_
  ## * `keys iterator<#keys.i,OrderedTableRef[A,B]>`_
  ## * `mvalues iterator<#mvalues.i,OrderedTableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newOrderedTable
    for v in a.values:
      doAssert v.len == 4

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].val
    assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A, B](t: OrderedTableRef[A, B]): var B =
  ## Iterates over any value in the table `t` in insertion order. The values
  ## can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,OrderedTableRef[A,B]>`_
  ## * `values iterator<#values.i,OrderedTableRef[A,B]>`_
  runnableExamples:
    let a = {
      'o': @[1, 5, 7, 9],
      'e': @[2, 4, 6, 8]
      }.newOrderedTable
    for v in a.mvalues:
      v.add(99)
    doAssert a == {'o': @[1, 5, 7, 9, 99],
                   'e': @[2, 4, 6, 8, 99]}.newOrderedTable

  let L = len(t)
  forAllOrderedPairs:
    yield t.data[h].val
    assert(len(t) == L, "the length of the table changed while iterating over it")







# -------------------------------------------------------------------------
# ------------------------------ CountTable -------------------------------
# -------------------------------------------------------------------------

type
  CountTable*[A] = object
    ## Hash table that counts the number of each key.
    ##
    ## For creating an empty CountTable, use `initCountTable proc
    ## <#initCountTable>`_.
    data: seq[tuple[key: A, val: int]]
    counter: int
    isSorted: bool
  CountTableRef*[A] = ref CountTable[A] ## Ref version of
    ## `CountTable<#CountTable>`_.
    ##
    ## For creating a new empty CountTableRef, use `newCountTable proc
    ## <#newCountTable>`_.


# ------------------------------ helpers ---------------------------------

proc ctRawInsert[A](t: CountTable[A], data: var seq[tuple[key: A, val: int]],
                  key: A, val: int) =
  var h: Hash = hash(key) and high(data)
  while data[h].val != 0: h = nextTry(h, high(data))
  data[h].key = key
  data[h].val = val

proc enlarge[A](t: var CountTable[A]) =
  var n: seq[tuple[key: A, val: int]]
  newSeq(n, len(t.data) * growthFactor)
  for i in countup(0, high(t.data)):
    if t.data[i].val != 0: ctRawInsert(t, n, move t.data[i].key, move t.data[i].val)
  swap(t.data, n)

proc rawGet[A](t: CountTable[A], key: A): int =
  if t.data.len == 0:
    return -1
  var h: Hash = hash(key) and high(t.data) # start with real hash value
  while t.data[h].val != 0:
    if t.data[h].key == key: return h
    h = nextTry(h, high(t.data))
  result = -1 - h # < 0 => MISSING; insert idx = -1 - result

template ctget(t, key, default: untyped): untyped =
  var index = rawGet(t, key)
  result = if index >= 0: t.data[index].val else: default

proc inc*[A](t: var CountTable[A], key: A, val = 1)

# ----------------------------------------------------------------------

proc initCountTable*[A](initialSize = defaultInitialSize): CountTable[A] =
  ## Creates a new count table that is empty.
  ##
  ## Starting from Nim v0.20, tables are initialized by default and it is
  ## not necessary to call this function explicitly.
  ##
  ## See also:
  ## * `toCountTable proc<#toCountTable,openArray[A]>`_
  ## * `newCountTable proc<#newCountTable>`_ for creating a
  ##   `CountTableRef`
  initImpl(result, initialSize)

proc toCountTable*[A](keys: openArray[A]): CountTable[A] =
  ## Creates a new count table with every member of a container `keys`
  ## having a count of how many times it occurs in that container.
  result = initCountTable[A](keys.len)
  for key in items(keys): result.inc(key)

proc `[]`*[A](t: CountTable[A], key: A): int =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise `0` is returned.
  ##
  ## See also:
  ## * `getOrDefault<#getOrDefault,CountTable[A],A,int>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `[]= proc<#[]%3D,CountTable[A],A,int>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,CountTable[A],A>`_ for checking if a key
  ##   is in the table
  assert(not t.isSorted, "CountTable must not be used after sorting")
  ctget(t, key, 0)

template cntMakeEmpty(i) = t.data[i].val = 0
template cntCellEmpty(i) = t.data[i].val == 0
template cntCellHash(i)  = hash(t.data[i].key)

proc `[]=`*[A](t: var CountTable[A], key: A, val: int) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],CountTable[A],A>`_ for retrieving a value of a key
  ## * `inc proc<#inc,CountTable[A],A,int>`_ for incrementing a
  ##   value of a key
  assert(not t.isSorted, "CountTable must not be used after sorting")
  assert val >= 0
  if val == 0:
    delImplNoHCode(cntMakeEmpty, cntCellEmpty, cntCellHash)
  else:
    let h = rawGet(t, key)
    if h >= 0:
      t.data[h].val = val
    else:
      insertImpl()

proc inc*[A](t: var CountTable[A], key: A, val = 1) =
  ## Increments `t[key]` by `val` (default: 1).
  runnableExamples:
    var a = toCountTable("aab")
    a.inc('a')
    a.inc('b', 10)
    doAssert a == toCountTable("aaabbbbbbbbbbb")

  assert(not t.isSorted, "CountTable must not be used after sorting")
  var index = rawGet(t, key)
  if index >= 0:
    inc(t.data[index].val, val)
    if t.data[index].val == 0:
      delImplIdx(t, index, cntMakeEmpty, cntCellEmpty, cntCellHash)
  else:
    if val != 0:
      insertImpl()

proc len*[A](t: CountTable[A]): int =
  ## Returns the number of keys in `t`.
  result = t.counter

proc smallest*[A](t: CountTable[A]): tuple[key: A, val: int] =
  ## Returns the `(key, value)` pair with the smallest `val`. Efficiency: O(n)
  ##
  ## See also:
  ## * `largest proc<#largest,CountTable[A]>`_
  assert t.len > 0, "counttable is empty"
  var minIdx = -1
  for h in 0 .. high(t.data):
    if t.data[h].val > 0 and (minIdx == -1 or t.data[minIdx].val > t.data[h].val):
      minIdx = h
  result.key = t.data[minIdx].key
  result.val = t.data[minIdx].val

proc largest*[A](t: CountTable[A]): tuple[key: A, val: int] =
  ## Returns the `(key, value)` pair with the largest `val`. Efficiency: O(n)
  ##
  ## See also:
  ## * `smallest proc<#smallest,CountTable[A]>`_
  assert t.len > 0, "counttable is empty"
  var maxIdx = 0
  for h in 1 .. high(t.data):
    if t.data[maxIdx].val < t.data[h].val: maxIdx = h
  result.key = t.data[maxIdx].key
  result.val = t.data[maxIdx].val

proc hasKey*[A](t: CountTable[A], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,CountTable[A],A>`_ for use with the `in`
  ##   operator
  ## * `[] proc<#[],CountTable[A],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,CountTable[A],A,int>`_ to return
  ##   a custom value if the key doesn't exist
  assert(not t.isSorted, "CountTable must not be used after sorting")
  result = rawGet(t, key) >= 0

proc contains*[A](t: CountTable[A], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,CountTable[A],A>`_ for use with
  ## the `in` operator.
  return hasKey[A](t, key)

proc getOrDefault*[A](t: CountTable[A], key: A; default: int = 0): int =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## integer value of `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],CountTable[A],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,CountTable[A],A>`_ for checking if a key
  ##   is in the table
  ctget(t, key, default)

proc del*[A](t: var CountTable[A], key: A) {.since: (1, 1).} =
  ## Deletes `key` from table `t`. Does nothing if the key does not exist.
  ##
  ## See also:
  ## * `pop proc<#pop,CountTable[A],A,int>`_
  ## * `clear proc<#clear,CountTable[A]>`_ to empty the whole table
  runnableExamples:
    var a = toCountTable("aabbbccccc")
    a.del('b')
    assert a == toCountTable("aaccccc")
    a.del('b')
    assert a == toCountTable("aaccccc")
    a.del('c')
    assert a == toCountTable("aa")

  delImplNoHCode(cntMakeEmpty, cntCellEmpty, cntCellHash)

proc pop*[A](t: var CountTable[A], key: A, val: var int): bool {.since: (1, 1).} =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## See also:
  ## * `del proc<#del,CountTable[A],A>`_
  ## * `clear proc<#clear,CountTable[A]>`_ to empty the whole table
  runnableExamples:
    var a = toCountTable("aabbbccccc")
    var i = 0
    assert a.pop('b', i)
    assert i == 3
    i = 99
    assert not a.pop('b', i)
    assert i == 99

  var index = rawGet(t, key)
  result = index >= 0
  if result:
    val = move(t.data[index].val)
    delImplIdx(t, index, cntMakeEmpty, cntCellEmpty, cntCellHash)

proc clear*[A](t: var CountTable[A]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,CountTable[A],A>`_
  ## * `pop proc<#pop,CountTable[A],A,int>`_
  clearImpl()
  t.isSorted = false

func ctCmp[T](a, b: tuple[key: T, val: int]): int =
  result = system.cmp(a.val, b.val)

proc sort*[A](t: var CountTable[A], order = SortOrder.Descending) =
  ## Sorts the count table so that, by default, the entry with the
  ## highest counter comes first.
  ##
  ## .. warning:: This is destructive! Once sorted, you must not modify `t` afterwards!
  ##
  ## You can use the iterators `pairs<#pairs.i,CountTable[A]>`_,
  ## `keys<#keys.i,CountTable[A]>`_, and `values<#values.i,CountTable[A]>`_
  ## to iterate over `t` in the sorted order.
  runnableExamples:
    import std/[algorithm, sequtils]
    var a = toCountTable("abracadabra")
    doAssert a == "aaaaabbrrcd".toCountTable
    a.sort()
    doAssert toSeq(a.values) == @[5, 2, 2, 1, 1]
    a.sort(SortOrder.Ascending)
    doAssert toSeq(a.values) == @[1, 1, 2, 2, 5]

  t.data.sort(cmp = ctCmp, order = order)
  t.isSorted = true

proc merge*[A](s: var CountTable[A], t: CountTable[A]) =
  ## Merges the second table into the first one (must be declared as `var`).
  runnableExamples:
    var a = toCountTable("aaabbc")
    let b = toCountTable("bcc")
    a.merge(b)
    doAssert a == toCountTable("aaabbbccc")

  assert(not s.isSorted, "CountTable must not be used after sorting")
  for key, value in t:
    s.inc(key, value)

when (NimMajor, NimMinor) <= (1, 0):
  proc merge*[A](s, t: CountTable[A]): CountTable[A] =
    ## Merges the two tables into a new one.
    runnableExamples:
      let
        a = toCountTable("aaabbc")
        b = toCountTable("bcc")
      doAssert merge(a, b) == toCountTable("aaabbbccc")

    result = initCountTable[A](nextPowerOfTwo(max(s.len, t.len)))
    for table in @[s, t]:
      for key, value in table:
        result.inc(key, value)

proc `$`*[A](t: CountTable[A]): string =
  ## The `$` operator for count tables. Used internally when calling `echo`
  ## on a table.
  dollarImpl()

proc `==`*[A](s, t: CountTable[A]): bool =
  ## The `==` operator for count tables. Returns `true` if both tables
  ## contain the same keys with the same count. Insert order does not matter.
  equalsImpl(s, t)


iterator pairs*[A](t: CountTable[A]): (A, int) =
  ## Iterates over any `(key, value)` pair in the table `t`.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,CountTable[A]>`_
  ## * `keys iterator<#keys.i,CountTable[A]>`_
  ## * `values iterator<#values.i,CountTable[A]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = toCountTable("abracadabra")
  ##
  ##   for k, v in pairs(a):
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: a
  ##   # value: 5
  ##   # key: b
  ##   # value: 2
  ##   # key: c
  ##   # value: 1
  ##   # key: d
  ##   # value: 1
  ##   # key: r
  ##   # value: 2
  ##   ```
  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A](t: var CountTable[A]): (A, var int) =
  ## Iterates over any `(key, value)` pair in the table `t` (must be
  ## declared as `var`). The values can be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTable[A]>`_
  ## * `mvalues iterator<#mvalues.i,CountTable[A]>`_
  runnableExamples:
    var a = toCountTable("abracadabra")
    for k, v in mpairs(a):
      v = 2
    doAssert a == toCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator keys*[A](t: CountTable[A]): lent A =
  ## Iterates over any key in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTable[A]>`_
  ## * `values iterator<#values.i,CountTable[A]>`_
  runnableExamples:
    var a = toCountTable("abracadabra")
    for k in keys(a):
      a[k] = 2
    doAssert a == toCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].key
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A](t: CountTable[A]): int =
  ## Iterates over any value in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTable[A]>`_
  ## * `keys iterator<#keys.i,CountTable[A]>`_
  ## * `mvalues iterator<#mvalues.i,CountTable[A]>`_
  runnableExamples:
    let a = toCountTable("abracadabra")
    for v in values(a):
      assert v < 10

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A](t: var CountTable[A]): var int =
  ## Iterates over any value in the table `t` (must be
  ## declared as `var`). The values can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,CountTable[A]>`_
  ## * `values iterator<#values.i,CountTable[A]>`_
  runnableExamples:
    var a = toCountTable("abracadabra")
    for v in mvalues(a):
      v = 2
    doAssert a == toCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")







# ---------------------------------------------------------------------------
# ---------------------------- CountTableRef --------------------------------
# ---------------------------------------------------------------------------

proc inc*[A](t: CountTableRef[A], key: A, val = 1)

proc newCountTable*[A](initialSize = defaultInitialSize): CountTableRef[A] =
  ## Creates a new ref count table that is empty.
  ##
  ## See also:
  ## * `newCountTable proc<#newCountTable,openArray[A]>`_ for creating
  ##   a `CountTableRef` from a collection
  ## * `initCountTable proc<#initCountTable>`_ for creating a
  ##   `CountTable`
  new(result)
  {.noSideEffect.}:
    result[] = initCountTable[A](initialSize)

proc newCountTable*[A](keys: openArray[A]): CountTableRef[A] =
  ## Creates a new ref count table with every member of a container `keys`
  ## having a count of how many times it occurs in that container.
  result = newCountTable[A](keys.len)
  {.noSideEffect.}:
    for key in items(keys): result.inc(key)

proc `[]`*[A](t: CountTableRef[A], key: A): int =
  ## Retrieves the value at `t[key]` if `key` is in `t`.
  ## Otherwise `0` is returned.
  ##
  ## See also:
  ## * `getOrDefault<#getOrDefault,CountTableRef[A],A,int>`_ to return
  ##   a custom value if the key doesn't exist
  ## * `inc proc<#inc,CountTableRef[A],A,int>`_ to inc even if missing
  ## * `[]= proc<#[]%3D,CountTableRef[A],A,int>`_ for inserting a new
  ##   (key, value) pair in the table
  ## * `hasKey proc<#hasKey,CountTableRef[A],A>`_ for checking if a key
  ##   is in the table
  result = t[][key]

proc `[]=`*[A](t: CountTableRef[A], key: A, val: int) =
  ## Inserts a `(key, value)` pair into `t`.
  ##
  ## See also:
  ## * `[] proc<#[],CountTableRef[A],A>`_ for retrieving a value of a key
  ## * `inc proc<#inc,CountTableRef[A],A,int>`_ for incrementing a
  ##   value of a key
  assert val > 0
  {.noSideEffect.}:
    t[][key] = val

proc inc*[A](t: CountTableRef[A], key: A, val = 1) =
  ## Increments `t[key]` by `val` (default: 1).
  runnableExamples:
    var a = newCountTable("aab")
    a.inc('a')
    a.inc('b', 10)
    doAssert a == newCountTable("aaabbbbbbbbbbb")
  {.noSideEffect.}:
    t[].inc(key, val)

proc smallest*[A](t: CountTableRef[A]): tuple[key: A, val: int] =
  ## Returns the `(key, value)` pair with the smallest `val`. Efficiency: O(n)
  ##
  ## See also:
  ## * `largest proc<#largest,CountTableRef[A]>`_
  t[].smallest

proc largest*[A](t: CountTableRef[A]): tuple[key: A, val: int] =
  ## Returns the `(key, value)` pair with the largest `val`. Efficiency: O(n)
  ##
  ## See also:
  ## * `smallest proc<#smallest,CountTable[A]>`_
  t[].largest

proc hasKey*[A](t: CountTableRef[A], key: A): bool =
  ## Returns true if `key` is in the table `t`.
  ##
  ## See also:
  ## * `contains proc<#contains,CountTableRef[A],A>`_ for use with the `in`
  ##   operator
  ## * `[] proc<#[],CountTableRef[A],A>`_ for retrieving a value of a key
  ## * `getOrDefault proc<#getOrDefault,CountTableRef[A],A,int>`_ to return
  ##   a custom value if the key doesn't exist
  result = t[].hasKey(key)

proc contains*[A](t: CountTableRef[A], key: A): bool =
  ## Alias of `hasKey proc<#hasKey,CountTableRef[A],A>`_ for use with
  ## the `in` operator.
  return hasKey[A](t, key)

proc getOrDefault*[A](t: CountTableRef[A], key: A, default: int): int =
  ## Retrieves the value at `t[key]` if `key` is in `t`. Otherwise, the
  ## integer value of `default` is returned.
  ##
  ## See also:
  ## * `[] proc<#[],CountTableRef[A],A>`_ for retrieving a value of a key
  ## * `hasKey proc<#hasKey,CountTableRef[A],A>`_ for checking if a key
  ##   is in the table
  result = t[].getOrDefault(key, default)

proc len*[A](t: CountTableRef[A]): int =
  ## Returns the number of keys in `t`.
  result = t.counter

proc del*[A](t: CountTableRef[A], key: A) {.since: (1, 1).} =
  ## Deletes `key` from table `t`. Does nothing if the key does not exist.
  ##
  ## See also:
  ## * `pop proc<#pop,CountTableRef[A],A,int>`_
  ## * `clear proc<#clear,CountTableRef[A]>`_ to empty the whole table
  del(t[], key)

proc pop*[A](t: CountTableRef[A], key: A, val: var int): bool {.since: (1, 1).} =
  ## Deletes the `key` from the table.
  ## Returns `true`, if the `key` existed, and sets `val` to the
  ## mapping of the key. Otherwise, returns `false`, and the `val` is
  ## unchanged.
  ##
  ## See also:
  ## * `del proc<#del,CountTableRef[A],A>`_
  ## * `clear proc<#clear,CountTableRef[A]>`_ to empty the whole table
  pop(t[], key, val)

proc clear*[A](t: CountTableRef[A]) =
  ## Resets the table so that it is empty.
  ##
  ## See also:
  ## * `del proc<#del,CountTableRef[A],A>`_
  ## * `pop proc<#pop,CountTableRef[A],A,int>`_
  clear(t[])

proc sort*[A](t: CountTableRef[A], order = SortOrder.Descending) =
  ## Sorts the count table so that, by default, the entry with the
  ## highest counter comes first.
  ##
  ## **This is destructive! You must not modify `t` afterwards!**
  ##
  ## You can use the iterators `pairs<#pairs.i,CountTableRef[A]>`_,
  ## `keys<#keys.i,CountTableRef[A]>`_, and `values<#values.i,CountTableRef[A]>`_
  ## to iterate over `t` in the sorted order.
  t[].sort(order = order)

proc merge*[A](s, t: CountTableRef[A]) =
  ## Merges the second table into the first one.
  runnableExamples:
    let
      a = newCountTable("aaabbc")
      b = newCountTable("bcc")
    a.merge(b)
    doAssert a == newCountTable("aaabbbccc")

  s[].merge(t[])

proc `$`*[A](t: CountTableRef[A]): string =
  ## The `$` operator for count tables. Used internally when calling `echo`
  ## on a table.
  dollarImpl()

proc `==`*[A](s, t: CountTableRef[A]): bool =
  ## The `==` operator for count tables. Returns `true` if either both tables
  ## are `nil`, or neither is `nil` and both contain the same keys with the same
  ## count. Insert order does not matter.
  if isNil(s): result = isNil(t)
  elif isNil(t): result = false
  else: result = s[] == t[]


iterator pairs*[A](t: CountTableRef[A]): (A, int) =
  ## Iterates over any `(key, value)` pair in the table `t`.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,CountTableRef[A]>`_
  ## * `keys iterator<#keys.i,CountTableRef[A]>`_
  ## * `values iterator<#values.i,CountTableRef[A]>`_
  ##
  ## **Examples:**
  ##
  ##   ```Nim
  ##   let a = newCountTable("abracadabra")
  ##
  ##   for k, v in pairs(a):
  ##     echo "key: ", k
  ##     echo "value: ", v
  ##
  ##   # key: a
  ##   # value: 5
  ##   # key: b
  ##   # value: 2
  ##   # key: c
  ##   # value: 1
  ##   # key: d
  ##   # value: 1
  ##   # key: r
  ##   # value: 2
  ##   ```
  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mpairs*[A](t: CountTableRef[A]): (A, var int) =
  ## Iterates over any `(key, value)` pair in the table `t`. The values can
  ## be modified.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTableRef[A]>`_
  ## * `mvalues iterator<#mvalues.i,CountTableRef[A]>`_
  runnableExamples:
    let a = newCountTable("abracadabra")
    for k, v in mpairs(a):
      v = 2
    doAssert a == newCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield (t.data[h].key, t.data[h].val)
      assert(len(t) == L, "table modified while iterating over it")

iterator keys*[A](t: CountTableRef[A]): A =
  ## Iterates over any key in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTable[A]>`_
  ## * `values iterator<#values.i,CountTable[A]>`_
  runnableExamples:
    let a = newCountTable("abracadabra")
    for k in keys(a):
      a[k] = 2
    doAssert a == newCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].key
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator values*[A](t: CountTableRef[A]): int =
  ## Iterates over any value in the table `t`.
  ##
  ## See also:
  ## * `pairs iterator<#pairs.i,CountTableRef[A]>`_
  ## * `keys iterator<#keys.i,CountTableRef[A]>`_
  ## * `mvalues iterator<#mvalues.i,CountTableRef[A]>`_
  runnableExamples:
    let a = newCountTable("abracadabra")
    for v in values(a):
      assert v < 10

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

iterator mvalues*[A](t: CountTableRef[A]): var int =
  ## Iterates over any value in the table `t`. The values can be modified.
  ##
  ## See also:
  ## * `mpairs iterator<#mpairs.i,CountTableRef[A]>`_
  ## * `values iterator<#values.i,CountTableRef[A]>`_
  runnableExamples:
    var a = newCountTable("abracadabra")
    for v in mvalues(a):
      v = 2
    doAssert a == newCountTable("aabbccddrr")

  let L = len(t)
  for h in 0 .. high(t.data):
    if t.data[h].val != 0:
      yield t.data[h].val
      assert(len(t) == L, "the length of the table changed while iterating over it")

proc hash*[K,V](s: Table[K,V]): Hash =
  for p in pairs(s):
    result = result xor hash(p)
  result = !$result

proc hash*[K,V](s: OrderedTable[K,V]): Hash =
  for p in pairs(s):
    result = result !& hash(p)
  result = !$result

proc hash*[V](s: CountTable[V]): Hash =
  for p in pairs(s):
    result = result xor hash(p)
  result = !$result