--- /dev/null
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Copyright 2019 Louis-Vincent Boudreault <lv.boudreault95@gmail.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This modules provides a new functional interface for `Iterator`.
+module iter_extras
+
+import functional_types
+import cartesian
+
+redef class Array
+
+ # Sorts an array with a function.
+ #
+ # ~~~~nitish
+ # class Person
+ # var name: String
+ # end
+ #
+ # def get_name(p: Person) do return p.name
+ #
+ # var ps = [new Person("Turing"), new Person("Curry"), new Person("Alfredo")]
+ # ps.sort_with(&get_name)
+ # assert ps[0].name == "Alfredo"
+ # assert ps[1].name == "Curry"
+ # assert ps[2].name == "Turing"
+ # ~~~~
+ fun sort_with(f: Fun1[E, Comparable])
+ do
+ var cmp = new ComparatorWith[E](f)
+ if length > 1 then
+ cmp.quick_sort(self, 0, length - 1)
+ end
+ end
+end
+
+redef interface Iterator[E]
+
+ # Applies a function to every elements
+ #
+ # ~~~~nitish
+ # fun add(x: Int): Int do return x + 1
+ #
+ # var f = &add
+ # var xs = [1,2,3,4,5]
+ # var actual = xs.iterator.map(f).to_a
+ # assert actual == [2,3,4,5,6]
+ # ~~~~
+ fun map(f: Fun1[E,Object]): MapIter[E,Object]
+ do
+ return new MapIter[E,Object](self, f)
+ end
+
+ # Iterator that gives the current count and element as a pair
+ fun enumerate: EnumerateIter[E]
+ do
+ return new EnumerateIter[E](self)
+ end
+
+ # Iterator that filters elements by a predicate
+ #
+ # ~~~~nitish
+ # fun lt10(x: Int): Bool do return x < 10
+ #
+ # var pred = <10
+ # var xs = [1..20]
+ # var actual = xs.iterator.filter(pred).to_a
+ # assert actual == [1..9].to_a
+ # ~~~~
+ fun filter(pred: Fun1[E,Bool]): FilterIter[E]
+ do
+ return new FilterIter[E](self,pred)
+ end
+
+ # Checks if at least one element respects a predicate
+ #
+ # ~~~~nitish
+ # fun eq10(x: Int): Bool do return x == 10
+ #
+ # var pred = &eq10
+ # var xs = [1,2,5,7,9,10,44]
+ # assert xs.iterator.any(pred)
+ # var ys = []
+ # assert not ys.iterator.any(pred)
+ # assert not [1,2,44].iterator.any(pred)
+ # ~~~~
+ fun any(pred: Fun1[E,Bool]): Bool
+ do
+ for x in self do
+ if pred.call(x) then
+ return true
+ end
+ end
+ return false
+ end
+
+ # Checks if all elements respect a predicate
+ #
+ # ~~~~nitish
+ # fun lt10(x: Int): Bool do return x < 10
+ #
+ # var pred = <10
+ # var xs = [1..9]
+ # assert xs.iterator.all(pred)
+ # assert [].iterator.all(pred)
+ # assert not [1..10].iterator.all(pred)
+ # ~~~~
+ fun all(pred: Fun1[E,Bool]): Bool
+ do
+ for x in self do
+ if not pred.call(x) then
+ return false
+ end
+ end
+ return true
+ end
+
+ # Folds an iterator from the left
+ #
+ # ~~~~nitish
+ # fun adder(x: Int, y: Int): Int do return x + y
+ #
+ # var xs = [1..10]
+ # assert xs.iterator.fold(0, &adder) == 55
+ # ~~~~
+ fun fold(acc: Object, f: Fun2[Object, E, Object]): Object
+ do
+ for x in self do
+ acc = f.call(acc, x)
+ end
+ return acc
+ end
+
+ # Folds and apply two element at a time
+ #
+ # ~~~~nitish
+ # fun min_int(x: Int, y: Int): Int
+ # do
+ # if x < y then return x
+ # return y
+ # end
+ #
+ # var xs = [100,423,51,1,-19,55,999,-18]
+ # assert xs.iterator.fold1(&min_int) == -19
+ # ~~~~
+ # REQUIRE : length > 1
+ fun fold1(f: Fun2[E,E,E]): E
+ do
+ var a1 = item
+ next
+ var a2 = item
+ next
+ var res = f.call(a1,a2)
+ for x in self do
+ res = f.call(res, x)
+ end
+ return res
+ end
+
+ # Apply a mutation function over all elements
+ #
+ # ~~~~nitish
+ # class Person
+ # var age: Int
+ # def incr_age
+ # do
+ # age += 1
+ # end
+ # end
+ #
+ # var ps = [new Persone(1), new Person(2), new Person(3)]
+ # var ages = ps.iterator.for_each(&Person::incr_age).map(&Person::age).to_a
+ # assert ages == [2,3,4]
+ # ~~~~
+ fun for_each(f: Proc1[E])
+ do
+ for x in self do
+ f.call(x)
+ end
+ end
+
+ # Maps every element to a nested structure then flattens it
+ #
+ # ~~~~nitish
+ # fun chars_fn(s: String): Iterator[Char]
+ # do
+ # return s.chars.iterator
+ # end
+ # var cs = ["aaa","bbb","ccc"]
+ # assert cs.iterator.flat_map(&chars_fn).to_a.join == "aaabbbccc"
+ # ~~~~
+ fun flat_map(f: Fun1[E, Iterator[Object]]): FlatMapIter[E, Object]
+ do
+ return new FlatMapIter[E, Object](self, f)
+ end
+
+ # Generates an `Iterator` whose elements are sorted by the function
+ # passed in argument.
+ #
+ # ~~~~nitish
+ # class Person
+ # var name: String
+ # end
+ #
+ # def get_name(p: Person) do return p.name
+ #
+ # var ps = [new Person("Turing"), new Person("Curry"), new Person("Alfredo")]
+ # var ordered_names = ps.iterator.order_by(&get_name).map(&get_name).to_a
+ # assert ordered_names == ["Alfredo", "Curry", "Turing"]
+ # ~~~~
+ fun order_by(f: Fun1[E, Comparable]): OrderedIter[E]
+ do
+ return new OrderedIter[E](self, f)
+ end
+
+end
+
+# Base class for all iterators using functional types.
+private abstract class FunIter[OLD,NEW]
+ super Iterator[NEW]
+ var my_iter: Iterator[OLD]
+
+ redef fun next
+ do
+ my_iter.next
+ end
+
+ redef fun start
+ do
+ my_iter.start
+ end
+
+ redef fun finish
+ do
+ my_iter.finish
+ end
+
+ redef fun is_ok
+ do
+ return my_iter.is_ok
+ end
+end
+
+# An iterator that maps each item with `f`.
+class MapIter[A,B]
+ super FunIter[A,B]
+ var f: Fun1[A, B]
+
+ redef fun item
+ do
+ return f.call(my_iter.item)
+ end
+
+end
+
+# An iterator that maps each item to a pair containing the item with its
+# current count.
+class EnumerateIter[E]
+ super FunIter[E, Pair[Int,E]]
+
+ redef fun item
+ do
+ return new Pair[Int,E](0, my_iter.item)
+ end
+end
+
+# An tierator that filter its element by a predicate `pred`.
+class FilterIter[E]
+ super FunIter[E,nullable E]
+ var pred: Fun1[E, Bool]
+
+ redef init
+ do
+ if is_ok and not pred.call(my_iter.item) then next
+ end
+
+ redef fun item
+ do
+ assert is_ok
+ return my_iter.item
+ end
+
+ redef fun next
+ do
+ loop
+ my_iter.next
+ if not is_ok then
+ break
+ end
+ var x = my_iter.item
+ if pred.call(x) then
+ break
+ end
+ end
+ end
+end
+
+# An iterator that maps each item to an iterator and yield
+# each item from it.
+class FlatMapIter[A,B]
+ super FunIter[A,B]
+ var f: Fun1[A, Iterator[B]]
+ protected var inner: nullable Iterator[B] = null
+
+ redef init
+ do
+ try_compute_inner
+ end
+
+ redef fun item
+ do
+ return inner.as(not null).item
+ end
+
+ redef fun is_ok
+ do
+ return inner != null
+ end
+
+ redef fun next
+ do
+ inner.next
+ if not inner.is_ok then
+ super
+ try_compute_inner
+ end
+ end
+
+ # Tries to resolve the inner iterator.
+ # Assigns null to `inner` if it fails.
+ protected fun try_compute_inner
+ do
+ inner = null
+ if not my_iter.is_ok then return
+ var res = f.call(my_iter.item)
+ if res.is_ok then inner = res
+ end
+end
+
+# An iterator that yield each item in order
+class OrderedIter[E]
+ super FunIter[E,E]
+ var f: Fun1[E, Comparable]
+
+ private var sorted_iter: Iterator[E] is noinit
+ private var sorted_arr: Array[E] is noinit
+
+ redef init
+ do
+ sorted_arr = my_iter.to_a
+ sorted_arr.sort_with(f)
+ sorted_iter = sorted_arr.iterator
+ end
+
+ redef fun next
+ do
+ sorted_iter.next
+ end
+
+ redef fun item
+ do
+ return sorted_iter.item
+ end
+
+ redef fun is_ok
+ do
+ return sorted_iter.is_ok
+ end
+
+ redef fun finish
+ do
+ sorted_iter.finish
+ end
+
+ redef fun to_a
+ do
+ return sorted_arr
+ end
+end
+
+# Comparator that use a function provided by the user to compare between elements.
+class ComparatorWith[E]
+ super Comparator
+ redef type COMPARED: E
+
+ var f: Fun1[E, Comparable]
+
+ redef fun compare(a,b)
+ do
+ var x = f.call(a)
+ var y = f.call(b)
+ if x < y then return -1
+ if x > y then return 1
+ return 0
+ end
+end
nitlanguage / nit.git / blobdiff