Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

295 lines (239 sloc) 7.226 kB
/*
Copyright © 2011, 2012 MLstate
This file is part of Opa.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
@author AUDOUIN Maxime
@author ???
**/
/*
* <!> totally untested
*/
/**
* {1 About this module}
*
* Generic iterators
*
* {1 Where should I start?}
*
* {1 What if I need more?}
*/
/**
* {1 Types defined in this module}
*/
@opacapi
type iter('a) =
{ next: -> option(('a, iter('a))) }
/**
* {1 Interface}
*/
Iter = {{
/**
* {2 Constructors}
*/
cons(elt, i) =
{ next() = some((elt, i)) } : iter
empty = { next() = none } : iter
of_list(li) =
{ next() =
match li
| [] -> none
| [e | l] -> some((e, of_list(l)))
} : iter
unfold(first, f) =
{ next() =
match f(first) : option
| {some=res} -> some((res.f1, unfold(res.f2, f)))
| {none} -> none
} : iter
init(first, f, cond) =
{ next() =
if cond(first) then
some((first, init(f(first), f, cond)))
else
none
} : iter
/**
* {2 Methods}
*/
is_empty(s) = to_list(take(1, s)) == []
/**
* Returns from an iterator a new iterator where iteration will be cached.
*
* For each calls to the [next] function the original iteration (from [iter])
* is computed, then its cached (the original iteration will never be called).
*
* @param iter An iterator
* @return A cached iterator from [iter]
*/
cache(iter:iter('a)):iter('a) =
ref = Reference.create({unevaluated})
{next = ->
match Reference.get(ref) with
| {unevaluated} ->
result = iter.next()
result = Option.map((a, n) -> (a, cache(n)), result)
@atomic(match Reference.get(ref) with /* CAS */
| {unevaluated} ->
do Reference.set(ref, ~{result})
result
| ~{result} -> result)
| ~{result} -> result
}
/**
* Lazy
*/
map(f, iter : iter) =
{ next() =
match iter.next() : option
| {some=res} -> some((f(res.f1), map(f, res.f2)))
| {none} -> none
} : iter
/**
* Lazy
*/
filter(f, iter: iter) =
{ next() =
match iter.next() : option
| {some=res} ->
if f(res.f1) then
some((res.f1, filter(f, res.f2):iter))
else
(filter(f, res.f2):iter).next()
| {none} -> none
} : iter
fold(f, i:iter, acc) =
match i.next() : option
| {some=res} -> fold(f, res.f2, f(res.f1, acc))
| {none} -> acc
iter(f:'a->void, i:iter) =
match i.next()
| {none} -> void
| {some=res} -> do f(res.f1); iter(f, res.f2)
/**
* Lazy
*/
take(n, i: iter) =
{ next() =
if n == 0 then none else
match i.next() : option
| {some=res} -> some((res.f1, take(n-1, res.f2)))
| {none} -> none
} : iter
skip(n, i: iter) =
if n == 0 then i else
match i.next() : option
| {some=res} -> skip(n-1, res.f2 : iter)
| {none} -> empty
/**
* Lazy
*/
append(e1:iter, e2: iter) =
{ next() =
match e1.next() : option
| {some=res} -> some((res.f1, append(res.f2, e2)))
| {none} -> e2.next()
} : iter
seq(x: int, y: int) =
if x > y then init(x, _ + 1, _ <= y) : iter(int)
else init(x, _ - 1, _ >= y) : iter(int)
transform(f, it) =
map((
x -> match x : option with
| {none} -> error("transform")
| {some} -> some),
filter(
_ != none,
map(f, it)))
zip(it1 : iter, it2 : iter) =
{ next() =
match (it1.next() :option, it2.next() : option) with
| ({none}, _) -> {none}:option
| (_, {none}) -> {none}:option
| ({some=i1}, {some=i2}) ->
some((
(i1.f1, i2.f1),
zip(i1.f2, i2.f2)
))} : iter
index(it) = zip(it, init(0, _+1, (_ -> true)) )
count(it:iter) =
rec f(it:iter, c) =
match it.next() :option with
| {none} -> c
| {~some} -> f( some.f2, c+1)
f(it, 0)
take_while(f, it : iter) =
{ next() =
match it.next() : option with
| {none} -> {none} : option
| {some=s} -> if f(s.f1)
then {some = (s.f1, take_while(f, s.f2) ) }:option
else {none} : option
} : iter
skip_while(f, it : iter) =
rec aux(it: iter) =
match it.next() : option with
| {none} -> empty
| {some=s} -> if f(s.f1)
then aux(s.f2)
else it
aux(it)
exists(f, it) = not(is_empty(skip_while(not @ f, it)))
find(f, it) = match skip_while(not @ f, it).next() : option
| {none} -> {none} : option
| {some=s} -> {some=s.f1} : option
flatten(itits : iter) =
rec g(it_hd : iter, it_tl:iter) =
{ next() =
match it_hd.next() : option
| {none} -> flatten(it_tl).next()
| {~some} -> {some = (some.f1, g(some.f2, it_tl) ) } : option
} : iter('a)
match itits.next() :option
| {none} -> empty
| {some = (it_hd,it_tl)} ->
g(it_hd, it_tl)
distinct_by(f, it:iter) =
{ next() =
match it.next() : option with
| {none} -> {none} : option
| {~some} -> {some = (some.f1, distinct_by(f, filter( x -> f(x) != f(some.f1), some.f2 ))) } : option
} : iter
min_by(f, iter:iter) = match iter.next() :option with
| {none} -> {none}:option
| {~some} -> {some=fold(
(v, m -> if f(v) <= f(m) then v else m),
some.f2,
some.f1)
}:option
//
max_by(f, iter:iter) = match iter.next() :option with
| {none} -> {none}:option
| {~some} -> {some=fold(
(v, m -> if f(v) >= f(m) then v else m),
some.f2,
some.f1)
}:option
distinct(it:iter) = distinct_by(x -> x, it)
min(it:iter) = min_by(x -> x, it)
max(it:iter) = max_by(x -> x, it)
to_list(iter:iter) =
rec aux(acc,iter:iter) =
match iter.next() : option
| {none} -> List.rev(acc)
| {some=(v,iter)} -> aux([v|acc],iter)
aux([],iter)
}}
`--` = Iter.seq
StringIter =
{{
to_iter(s) =
l = String.length(s)
Iter.map( ( String.get(_, s) ), Iter.seq(0, l-1))
to_rev_iter(s) =
l = String.length(s)
Iter.map( ( String.get(_, s) ), Iter.seq(l-1, 0))
}}
Jump to Line
Something went wrong with that request. Please try again.