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<header>
<copyright>
<year>1996</year><year>2009</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
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<legalnotice>
The contents of this file are subject to the Erlang Public License,
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Software distributed under the License is distributed on an "AS IS"
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<title>ordsets</title>
<prepared>Robert Virding</prepared>
<responsible>Bjarne Dacker</responsible>
<docno>1</docno>
<approved>Bjarne Däcker</approved>
<checked></checked>
<date>99-07-27</date>
<rev>A</rev>
<file>ordsets.sgml</file>
</header>
<module>ordsets</module>
<modulesummary>Functions for Manipulating Sets as Ordered Lists</modulesummary>
<description>
<p>Sets are collections of elements with no duplicate elements.
An <c>ordset</c> is a representation of a set, where an ordered
list is used to store the elements of the set. An ordered list
is more efficient than an unordered list.</p>
<p>This module provides exactly the same interface as the module
<c>sets</c> but with a defined representation. One difference is
that while <c>sets</c> considers two elements as different if they
do not match (<c>=:=</c>), this module considers two elements as
different if and only if they do not compare equal (<c>==</c>).</p>
</description>
<section>
<title>DATA TYPES</title>
<code type="none">
ordered_set()
as returned by new/0</code>
</section>
<funcs>
<func>
<name>new() -> Ordset</name>
<fsummary>Return an empty set</fsummary>
<type>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Returns a new empty ordered set.</p>
</desc>
</func>
<func>
<name>is_set(Ordset) -> bool()</name>
<fsummary>Test for an <c>Ordset</c></fsummary>
<type>
<v>Ordset = term()</v>
</type>
<desc>
<p>Returns <c>true</c> if <c>Ordset</c> is an ordered set of
elements, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name>size(Ordset) -> int()</name>
<fsummary>Return the number of elements in a set</fsummary>
<type>
<v>Ordset = term()</v>
</type>
<desc>
<p>Returns the number of elements in <c>Ordset</c>.</p>
</desc>
</func>
<func>
<name>to_list(Ordset) -> List</name>
<fsummary>Convert an <c>Ordset</c>into a list</fsummary>
<type>
<v>Ordset = ordered_set()</v>
<v>List = [term()]</v>
</type>
<desc>
<p>Returns the elements of <c>Ordset</c> as a list.</p>
</desc>
</func>
<func>
<name>from_list(List) -> Ordset</name>
<fsummary>Convert a list into an <c>Ordset</c></fsummary>
<type>
<v>List = [term()]</v>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Returns an ordered set of the elements in <c>List</c>.</p>
</desc>
</func>
<func>
<name>is_element(Element, Ordset) -> bool()</name>
<fsummary>Test for membership of an <c>Ordset</c></fsummary>
<type>
<v>Element = term()</v>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Returns <c>true</c> if <c>Element</c> is an element of
<c>Ordset</c>, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name>add_element(Element, Ordset1) -> Ordset2</name>
<fsummary>Add an element to an <c>Ordset</c></fsummary>
<type>
<v>Element = term()</v>
<v>Ordset1 = Ordset2 = ordered_set()</v>
</type>
<desc>
<p>Returns a new ordered set formed from <c>Ordset1</c> with
<c>Element</c> inserted.</p>
</desc>
</func>
<func>
<name>del_element(Element, Ordset1) -> Ordset2</name>
<fsummary>Remove an element from an <c>Ordset</c></fsummary>
<type>
<v>Element = term()</v>
<v>Ordset1 = Ordset2 = ordered_set()</v>
</type>
<desc>
<p>Returns <c>Ordset1</c>, but with <c>Element</c> removed.</p>
</desc>
</func>
<func>
<name>union(Ordset1, Ordset2) -> Ordset3</name>
<fsummary>Return the union of two <c>Ordsets</c></fsummary>
<type>
<v>Ordset1 = Ordset2 = Ordset3 = ordered_set()</v>
</type>
<desc>
<p>Returns the merged (union) set of <c>Ordset1</c> and
<c>Ordset2</c>.</p>
</desc>
</func>
<func>
<name>union(OrdsetList) -> Ordset</name>
<fsummary>Return the union of a list of <c>Ordsets</c></fsummary>
<type>
<v>OrdsetList = [ordered_set()]</v>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Returns the merged (union) set of the list of sets.</p>
</desc>
</func>
<func>
<name>intersection(Ordset1, Ordset2) -> Ordset3</name>
<fsummary>Return the intersection of two <c>Ordsets</c></fsummary>
<type>
<v>Ordset1 = Ordset2 = Ordset3 = ordered_set()</v>
</type>
<desc>
<p>Returns the intersection of <c>Ordset1</c> and
<c>Ordset2</c>.</p>
</desc>
</func>
<func>
<name>intersection(OrdsetList) -> Ordset</name>
<fsummary>Return the intersection of a list of <c>Ordsets</c></fsummary>
<type>
<v>OrdsetList = [ordered_set()]</v>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Returns the intersection of the non-empty list of sets.</p>
</desc>
</func>
<func>
<name>is_disjoint(Ordset1, Ordset2) -> bool()</name>
<fsummary>Check whether two <c>Ordsets</c> are disjoint</fsummary>
<type>
<v>Ordset1 = Ordset2 = ordered_set()</v>
</type>
<desc>
<p>Returns <c>true</c> if <c>Ordset1</c> and
<c>Ordset2</c> are disjoint (have no elements in common),
and <c>false</c> otherwise.</p>
</desc>
</func>
<func>
<name>subtract(Ordset1, Ordset2) -> Ordset3</name>
<fsummary>Return the difference of two <c>Ordsets</c></fsummary>
<type>
<v>Ordset1 = Ordset2 = Ordset3 = ordered_set()</v>
</type>
<desc>
<p>Returns only the elements of <c>Ordset1</c> which are not
also elements of <c>Ordset2</c>.</p>
</desc>
</func>
<func>
<name>is_subset(Ordset1, Ordset2) -> bool()</name>
<fsummary>Test for subset</fsummary>
<type>
<v>Ordset1 = Ordset2 = ordered_set()</v>
</type>
<desc>
<p>Returns <c>true</c> when every element of <c>Ordset</c>1 is
also a member of <c>Ordset2</c>, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name>fold(Function, Acc0, Ordset) -> Acc1</name>
<fsummary>Fold over set elements</fsummary>
<type>
<v>Function = fun (E, AccIn) -> AccOut</v>
<v>Acc0 = Acc1 = AccIn = AccOut = term()</v>
<v>Ordset = ordered_set()</v>
</type>
<desc>
<p>Fold <c>Function</c> over every element in <c>Ordset</c>
returning the final value of the accumulator.</p>
</desc>
</func>
<func>
<name>filter(Pred, Ordset1) -> Set2</name>
<fsummary>Filter set elements</fsummary>
<type>
<v>Pred = fun (E) -> bool()</v>
<v>Set1 = Set2 = ordered_set()</v>
</type>
<desc>
<p>Filter elements in <c>Set1</c> with boolean function
<c>Fun</c>.</p>
</desc>
</func>
</funcs>
<section>
<title>See Also</title>
<p><seealso marker="gb_sets">gb_sets(3)</seealso>,
<seealso marker="sets">sets(3)</seealso></p>
</section>
</erlref>
