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authorHans Bolinder <[email protected]>2015-05-12 14:15:40 +0200
committerHans Bolinder <[email protected]>2015-05-18 09:04:52 +0200
commitf584a60d0e5a6fa0a8002a13e8dda2a790031427 (patch)
tree6d5056ad30a2920c68f64aae6d5e046f70210f73 /lib/stdlib/src
parentddc4e717df1da722682b6ccdbf152a6b7e15f378 (diff)
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stdlib: Add gb_sets:iterator_from
Diffstat (limited to 'lib/stdlib/src')
-rw-r--r--lib/stdlib/src/gb_sets.erl24
1 files changed, 22 insertions, 2 deletions
diff --git a/lib/stdlib/src/gb_sets.erl b/lib/stdlib/src/gb_sets.erl
index 393fb07229..d3fbd542f7 100644
--- a/lib/stdlib/src/gb_sets.erl
+++ b/lib/stdlib/src/gb_sets.erl
@@ -137,6 +137,10 @@
%% approach is that it does not require the complete list of all
%% elements to be built in memory at one time.
%%
+%% - iterator_from(X, S): returns an iterator that can be used for
+%% traversing the elements of set S greater than or equal to X;
+%% see `next'.
+%%
%% - next(T): returns {X, T1} where X is the smallest element referred
%% to by the iterator T, and T1 is the new iterator to be used for
%% traversing the remaining elements, or the atom `none' if no
@@ -157,8 +161,8 @@
insert/2, add/2, delete/2, delete_any/2, balance/1, union/2,
union/1, intersection/2, intersection/1, is_disjoint/2, difference/2,
is_subset/2, to_list/1, from_list/1, from_ordset/1, smallest/1,
- largest/1, take_smallest/1, take_largest/1, iterator/1, next/1,
- filter/2, fold/3, is_set/1]).
+ largest/1, take_smallest/1, take_largest/1, iterator/1,
+ iterator_from/2, next/1, filter/2, fold/3, is_set/1]).
%% `sets' compatibility aliases:
@@ -500,6 +504,22 @@ iterator({_, L, _} = T, As) ->
iterator(nil, As) ->
As.
+-spec iterator_from(Element, Set) -> Iter when
+ Set :: set(Element),
+ Iter :: iter(Element).
+
+iterator_from(S, {_, T}) ->
+ iterator_from(S, T, []).
+
+iterator_from(S, {K, _, T}, As) when K < S ->
+ iterator_from(S, T, As);
+iterator_from(_, {_, nil, _} = T, As) ->
+ [T | As];
+iterator_from(S, {_, L, _} = T, As) ->
+ iterator_from(S, L, [T | As]);
+iterator_from(_, nil, As) ->
+ As.
+
-spec next(Iter1) -> {Element, Iter2} | 'none' when
Iter1 :: iter(Element),
Iter2 :: iter(Element).