mirror of
https://github.com/nim-lang/Nim.git
synced 2026-02-14 23:33:28 +00:00
216 lines
6.7 KiB
Nim
216 lines
6.7 KiB
Nim
#
|
|
#
|
|
# Nimrod's Runtime Library
|
|
# (c) Copyright 2011 Alex Mitchell
|
|
#
|
|
# See the file "copying.txt", included in this
|
|
# distribution, for details about the copyright.
|
|
#
|
|
|
|
## :Author: Alex Mitchell
|
|
##
|
|
## This module implements operations for the built-in `seq`:idx: type which
|
|
## were inspired by functional programming languages. If you are looking for
|
|
## the typical `map` function which applies a function to every element in a
|
|
## sequence, it already exists as the `each` proc in the `system
|
|
## <system.html>`_ module in both mutable and immutable styles.
|
|
##
|
|
## Also, for functional style programming you may want to pass `anonymous procs
|
|
## <manual.html#anonymous-procs>`_ to procs like ``filter`` to reduce typing.
|
|
## Anonymous procs can use `the special do notation <manual.html#do-notation>`_
|
|
## which is more convenient in certain situations.
|
|
##
|
|
## **Note**: This interface will change as soon as the compiler supports
|
|
## closures and proper coroutines.
|
|
|
|
when not defined(nimhygiene):
|
|
{.pragma: dirty.}
|
|
|
|
proc concat*[T](seqs: varargs[seq[T]]): seq[T] =
|
|
## Takes several sequences' items and returns them inside a new sequence.
|
|
##
|
|
## Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## s1 = @[1, 2, 3]
|
|
## s2 = @[4, 5]
|
|
## s3 = @[6, 7]
|
|
## total = concat(s1, s2, s3)
|
|
## assert total == @[1, 2, 3, 4, 5, 6, 7]
|
|
var L = 0
|
|
for seqitm in items(seqs): inc(L, len(seqitm))
|
|
newSeq(result, L)
|
|
var i = 0
|
|
for s in items(seqs):
|
|
for itm in items(s):
|
|
result[i] = itm
|
|
inc(i)
|
|
|
|
proc distnct*[T](seq1: seq[T]): seq[T] =
|
|
## Returns a new sequence without duplicates.
|
|
##
|
|
## This proc is `misspelled` on purpose to avoid a clash with the keyword
|
|
## ``distinct`` used to `define a derived type incompatible with its base
|
|
## type <manual.html#distinct-type>`_. Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## dup1 = @[1, 1, 3, 4, 2, 2, 8, 1, 4]
|
|
## dup2 = @["a", "a", "c", "d", "d"]
|
|
## unique1 = distnct(dup1)
|
|
## unique2 = distnct(dup2)
|
|
## assert unique1 == @[1, 3, 4, 2, 8]
|
|
## assert unique2 == @["a", "c", "d"]
|
|
result = @[]
|
|
for itm in items(seq1):
|
|
if not result.contains(itm): result.add(itm)
|
|
|
|
proc zip*[S, T](seq1: seq[S], seq2: seq[T]): seq[tuple[a: S, b: T]] =
|
|
## Returns a new sequence with a combination of the two input sequences.
|
|
##
|
|
## For convenience you can access the returned tuples through the named
|
|
## fields `a` and `b`. If one sequence is shorter, the remaining items in the
|
|
## longer sequence are discarded. Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## short = @[1, 2, 3]
|
|
## long = @[6, 5, 4, 3, 2, 1]
|
|
## words = @["one", "two", "three"]
|
|
## zip1 = zip(short, long)
|
|
## zip2 = zip(short, words)
|
|
## assert zip1 == @[(1, 6), (2, 5), (3, 4)]
|
|
## assert zip2 == @[(1, "one"), (2, "two"), (3, "three")]
|
|
## assert zip1[2].b == 4
|
|
## assert zip2[2].b == "three"
|
|
var m = min(seq1.len, seq2.len)
|
|
newSeq(result, m)
|
|
for i in 0 .. m-1: result[i] = (seq1[i], seq2[i])
|
|
|
|
iterator filter*[T](seq1: seq[T], pred: proc(item: T): bool {.closure.}): T =
|
|
## Iterates through a sequence and yields every item that fulfills the
|
|
## predicate.
|
|
##
|
|
## Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let numbers = @[1, 4, 5, 8, 9, 7, 4]
|
|
## for n in filter(numbers, proc (x: int): bool = x mod 2 == 0):
|
|
## echo($n)
|
|
## # echoes 4, 8, 4 in separate lines
|
|
for i in countup(0, len(seq1) -1):
|
|
var item = seq1[i]
|
|
if pred(item): yield seq1[i]
|
|
|
|
proc filter*[T](seq1: seq[T], pred: proc(item: T): bool {.closure.}): seq[T] =
|
|
## Returns a new sequence with all the items that fulfilled the predicate.
|
|
##
|
|
## Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## colors = @["red", "yellow", "black"]
|
|
## f1 = filter(colors, proc(x: string): bool = x.len < 6)
|
|
## f2 = filter(colors) do (x: string) -> bool : x.len > 5
|
|
## assert f1 == @["red", "black"]
|
|
## assert f2 == @["yellow"]
|
|
accumulateResult(filter(seq1, pred))
|
|
|
|
template filterIt*(seq1, pred: expr): expr {.immediate, dirty.} =
|
|
## Returns a new sequence with all the items that fulfilled the predicate.
|
|
##
|
|
## Unlike the `proc` version, the predicate needs to be an expression using
|
|
## the ``it`` variable for testing, like: ``filterIt("abcxyz", it == 'x')``.
|
|
## Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## temperatures = @[-272.15, -2.0, 24.5, 44.31, 99.9, -113.44]
|
|
## acceptable = filterIt(temperatures, it < 50 and it > -10)
|
|
## assert acceptable == @[-2.0, 24.5, 44.31]
|
|
block:
|
|
var result: type(seq1) = @[]
|
|
for it in items(seq1):
|
|
if pred: result.add(it)
|
|
result
|
|
|
|
template toSeq*(iter: expr): expr {.immediate.} =
|
|
## Transforms any iterator into a sequence.
|
|
##
|
|
## Example:
|
|
##
|
|
## .. code-block:: nimrod
|
|
## let
|
|
## numeric = @[1, 2, 3, 4, 5, 6, 7, 8, 9]
|
|
## odd_numbers = toSeq(filter(numeric) do (x: int) -> bool:
|
|
## if x mod 2 == 1:
|
|
## result = true)
|
|
## assert odd_numbers == @[1, 3, 5, 7, 9]
|
|
##
|
|
var result {.gensym.}: seq[type(iter)] = @[]
|
|
for x in iter: add(result, x)
|
|
result
|
|
|
|
when isMainModule:
|
|
import strutils
|
|
proc toStr(x: int): string {.procvar.} = $x
|
|
# concat test
|
|
let
|
|
s1 = @[1, 2, 3]
|
|
s2 = @[4, 5]
|
|
s3 = @[6, 7]
|
|
total = concat(s1, s2, s3)
|
|
assert total == @[1, 2, 3, 4, 5, 6, 7]
|
|
|
|
# duplicates test
|
|
let
|
|
dup1 = @[1, 1, 3, 4, 2, 2, 8, 1, 4]
|
|
dup2 = @["a", "a", "c", "d", "d"]
|
|
unique1 = distnct(dup1)
|
|
unique2 = distnct(dup2)
|
|
assert unique1 == @[1, 3, 4, 2, 8]
|
|
assert unique2 == @["a", "c", "d"]
|
|
|
|
# zip test
|
|
let
|
|
short = @[1, 2, 3]
|
|
long = @[6, 5, 4, 3, 2, 1]
|
|
words = @["one", "two", "three"]
|
|
zip1 = zip(short, long)
|
|
zip2 = zip(short, words)
|
|
assert zip1 == @[(1, 6), (2, 5), (3, 4)]
|
|
assert zip2 == @[(1, "one"), (2, "two"), (3, "three")]
|
|
assert zip1[2].b == 4
|
|
assert zip2[2].b == "three"
|
|
|
|
# filter proc test
|
|
let
|
|
colors = @["red", "yellow", "black"]
|
|
f1 = filter(colors, proc(x: string): bool = x.len < 6)
|
|
f2 = filter(colors) do (x: string) -> bool : x.len > 5
|
|
assert f1 == @["red", "black"]
|
|
assert f2 == @["yellow"]
|
|
|
|
# filter iterator test
|
|
let numbers = @[1, 4, 5, 8, 9, 7, 4]
|
|
for n in filter(numbers, proc (x: int): bool = x mod 2 == 0):
|
|
echo($n)
|
|
# echoes 4, 8, 4 in separate lines
|
|
|
|
# filterIt test
|
|
let
|
|
temperatures = @[-272.15, -2.0, 24.5, 44.31, 99.9, -113.44]
|
|
acceptable = filterIt(temperatures, it < 50 and it > -10)
|
|
assert acceptable == @[-2.0, 24.5, 44.31]
|
|
|
|
# toSeq test
|
|
let
|
|
numeric = @[1, 2, 3, 4, 5, 6, 7, 8, 9]
|
|
odd_numbers = toSeq(filter(numeric) do (x: int) -> bool:
|
|
if x mod 2 == 1:
|
|
result = true)
|
|
assert odd_numbers == @[1, 3, 5, 7, 9]
|
|
|
|
echo "Finished doc tests"
|