path: root/lib/stdlib/doc/src/binary.xml

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2009</year>
      <year>2014</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  The contents of this file are subject to the Erlang Public License,
  Version 1.1, (the "License"); you may not use this file except in
  compliance with the License. You should have received a copy of the
  Erlang Public License along with this software. If not, it can be
  retrieved on line at http://www.erlang.org/.

  Software distributed under the License is distributed on an "AS IS"
  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  the License for the specific language governing rights and limitations
  under the License.

  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>binary</title>
    <prepared>Patrik Nyblom</prepared>
    <responsible>Kenneth Lundin</responsible>
    <docno>1</docno>
    <approved></approved>
    <checked></checked>
    <date>2010-05-05</date>
    <rev>A</rev>
    <file>binary.xml</file>
  </header>
  <module>binary</module>
  <modulesummary>Library for handling binary data</modulesummary>
  <description>

    <p>This module contains functions for manipulating byte-oriented
    binaries. Although the majority of functions could be implemented
    using bit-syntax, the functions in this library are highly
    optimized and are expected to either execute faster or consume
    less memory (or both) than a counterpart written in pure Erlang.</p>

    <p>The module is implemented according to the EEP (Erlang Enhancement Proposal) 31.</p>

    <note>
      <p>
      The library handles byte-oriented data. Bitstrings that are not
      binaries (does not contain whole octets of bits) will result in a <c>badarg</c>
      exception being thrown from any of the functions in this
      module.
      </p>
    </note>
  </description>
  <datatypes>
    <datatype>
      <name name="cp"/>
      <desc><p>Opaque data-type representing a compiled
        search-pattern. Guaranteed to be a tuple() to allow programs to
        distinguish it from non precompiled search patterns.</p>
      </desc>
    </datatype>
    <datatype>
      <name name="part"/>
      <desc><p>A representaion of a part (or range) in a binary. Start is a
        zero-based offset into a binary() and Length is the length of
        that part. As input to functions in this module, a reverse
        part specification is allowed, constructed with a negative
        Length, so that the part of the binary begins at Start +
        Length and is -Length long. This is useful for referencing the
        last N bytes of a binary as {size(Binary), -N}. The functions
        in this module always return part()'s with positive Length.</p>
      </desc>
    </datatype>
  </datatypes>
  <funcs>
    <func>
    <name name="at" arity="2"/>
      <fsummary>Returns the byte at a specific position in a binary</fsummary>
      <desc>

      <p>Returns the byte at position <c><anno>Pos</anno></c> (zero-based) in the binary
      <c><anno>Subject</anno></c> as an integer. If <c><anno>Pos</anno></c> &gt;= <c>byte_size(<anno>Subject</anno>)</c>,
      a <c>badarg</c>
      exception is raised.</p>

      </desc>
    </func>
    <func>
      <name name="bin_to_list" arity="1"/>
      <fsummary>Convert a binary to a list of integers</fsummary>
      <desc>
      <p>The same as <c>bin_to_list(<anno>Subject</anno>,{0,byte_size(<anno>Subject</anno>)})</c>.</p>
      </desc>
    </func>
    <func>
      <name name="bin_to_list" arity="2"/>
      <fsummary>Convert a binary to a list of integers</fsummary>
      <desc>

      <p>Converts <c><anno>Subject</anno></c> to a list of <c>byte()</c>s, each representing
      the value of one byte. The <c>part()</c> denotes which part of the
      <c>binary()</c> to convert. Example:</p>

<code>
1> binary:bin_to_list(&lt;&lt;"erlang"&gt;&gt;,{1,3}).
"rla"
%% or [114,108,97] in list notation.
</code>
      <p>If <c><anno>PosLen</anno></c> in any way references outside the binary, a <c>badarg</c> exception is raised.</p>
      </desc>
    </func>
    <func>
      <name name="bin_to_list" arity="3"/>
      <fsummary>Convert a binary to a list of integers</fsummary>
      <desc>
      <p>The same as<c> bin_to_list(<anno>Subject</anno>,{<anno>Pos</anno>,<anno>Len</anno>})</c>.</p>
      </desc>
    </func>
    <func>
      <name name="compile_pattern" arity="1"/>
      <fsummary>Pre-compiles a binary search pattern</fsummary>
      <desc>

      <p>Builds an internal structure representing a compilation of a
      search-pattern, later to be used in the <seealso marker="#match-3">match/3</seealso>,
      <seealso marker="#matches-3">matches/3</seealso>,
      <seealso marker="#split-3">split/3</seealso> or
      <seealso marker="#replace-4">replace/4</seealso>
      functions. The <c>cp()</c> returned is guaranteed to be a
      <c>tuple()</c> to allow programs to distinguish it from non
      pre-compiled search patterns</p>

      <p>When a list of binaries is given, it denotes a set of
      alternative binaries to search for. I.e if
      <c>[&lt;&lt;"functional"&gt;&gt;,&lt;&lt;"programming"&gt;&gt;]</c>
      is given as <c><anno>Pattern</anno></c>, this
      means "either <c>&lt;&lt;"functional"&gt;&gt;</c> or
      <c>&lt;&lt;"programming"&gt;&gt;</c>". The pattern is a set of
      alternatives; when only a single binary is given, the set has
      only one element. The order of alternatives in a pattern is not significant.</p>

      <p>The list of binaries used for search alternatives shall be flat and proper.</p>

      <p>If <c><anno>Pattern</anno></c> is not a binary or a flat proper list of binaries with length &gt; 0,
      a <c>badarg</c> exception will be raised.</p>

      </desc>
    </func>
    <func>
      <name name="copy" arity="1"/>
      <fsummary>Creates a duplicate of a binary</fsummary>
      <desc>
      <p>The same as <c>copy(<anno>Subject</anno>, 1)</c>.</p>
      </desc>
    </func>
    <func>
      <name name="copy" arity="2"/>
      <fsummary>Duplicates a binary N times and creates a new</fsummary>
      <desc>
      <p>Creates a binary with the content of <c><anno>Subject</anno></c> duplicated <c><anno>N</anno></c> times.</p>

      <p>This function will always create a new binary, even if <c><anno>N</anno> =
      1</c>. By using <c>copy/1</c> on a binary referencing a larger binary, one
      might free up the larger binary for garbage collection.</p>

      <note>
      <p>By deliberately copying a single binary to avoid referencing
      a larger binary, one might, instead of freeing up the larger
      binary for later garbage collection, create much more binary
      data than needed. Sharing binary data is usually good. Only in
      special cases, when small parts reference large binaries and the
      large binaries are no longer used in any process, deliberate
      copying might be a good idea.</p> </note>

      <p>If <c><anno>N</anno></c> &lt; <c>0</c>, a <c>badarg</c> exception is raised.</p>
      </desc>
    </func>
    <func>
      <name name="decode_unsigned" arity="1"/>
      <fsummary>Decode a whole binary into an integer of arbitrary size</fsummary>
      <desc>
      <p>The same as <c>decode_unsigned(<anno>Subject</anno>, big)</c>.</p>
      </desc>
    </func>
    <func>
      <name name="decode_unsigned" arity="2"/>
      <fsummary>Decode a whole binary into an integer of arbitrary size</fsummary>
      <desc>

      <p>Converts the binary digit representation, in big or little
      endian, of a positive integer in <c><anno>Subject</anno></c> to an Erlang <c>integer()</c>.</p>

      <p>Example:</p>

      <code>
1> binary:decode_unsigned(&lt;&lt;169,138,199&gt;&gt;,big).
11111111
      </code>
      </desc>
    </func>
    <func>
      <name name="encode_unsigned" arity="1"/>
      <fsummary>Encodes an unsigned integer into the minimal binary</fsummary>
      <desc>
      <p>The same as <c>encode_unsigned(<anno>Unsigned</anno>, big)</c>.</p>
      </desc>
    </func>
    <func>
      <name name="encode_unsigned" arity="2"/>
      <fsummary>Encodes an unsigned integer into the minimal binary</fsummary>
      <desc>

      <p>Converts a positive integer to the smallest possible
      representation in a binary digit representation, either big
      or little endian.</p>

      <p>Example:</p>

      <code>
1> binary:encode_unsigned(11111111,big).
&lt;&lt;169,138,199&gt;&gt;
      </code>
      </desc>
    </func>
    <func>
      <name name="first" arity="1"/>
      <fsummary>Returns the first byte of a binary</fsummary>
      <desc>

      <p>Returns the first byte of the binary <c><anno>Subject</anno></c> as an integer. If the
      size of <c><anno>Subject</anno></c> is zero, a <c>badarg</c> exception is raised.</p>

      </desc>
    </func>
    <func>
      <name name="last" arity="1"/>
      <fsummary>Returns the last byte of a binary</fsummary>
      <desc>

      <p>Returns the last byte of the binary <c><anno>Subject</anno></c> as an integer. If the
      size of <c><anno>Subject</anno></c> is zero, a <c>badarg</c> exception is raised.</p>

      </desc>
    </func>
    <func>
      <name name="list_to_bin" arity="1"/>
      <fsummary>Convert a list of integers and binaries to a binary</fsummary>
      <desc>
      <p>Works exactly as <c>erlang:list_to_binary/1</c>, added for completeness.</p>
      </desc>
    </func>
    <func>
      <name name="longest_common_prefix" arity="1"/>
      <fsummary>Returns length of longest common prefix for a set of binaries</fsummary>
      <desc>

      <p>Returns the length of the longest common prefix of the
      binaries in the list <c><anno>Binaries</anno></c>. Example:</p>

<code>
1> binary:longest_common_prefix([&lt;&lt;"erlang"&gt;&gt;,&lt;&lt;"ergonomy"&gt;&gt;]).
2
2> binary:longest_common_prefix([&lt;&lt;"erlang"&gt;&gt;,&lt;&lt;"perl"&gt;&gt;]).
0
</code>

      <p>If <c><anno>Binaries</anno></c> is not a flat list of binaries, a <c>badarg</c> exception is raised.</p>
      </desc>
    </func>
    <func>
      <name name="longest_common_suffix" arity="1"/>
      <fsummary>Returns length of longest common suffix for a set of binaries</fsummary>
      <desc>

      <p>Returns the length of the longest common suffix of the
      binaries in the list <c><anno>Binaries</anno></c>. Example:</p>

<code>
1> binary:longest_common_suffix([&lt;&lt;"erlang"&gt;&gt;,&lt;&lt;"fang"&gt;&gt;]).
3
2> binary:longest_common_suffix([&lt;&lt;"erlang"&gt;&gt;,&lt;&lt;"perl"&gt;&gt;]).
0
</code>

      <p>If <c>Binaries</c> is not a flat list of binaries, a <c>badarg</c> exception is raised.</p>

      </desc>
    </func>
    <func>
      <name name="match" arity="2"/>
      <fsummary>Searches for the first match of a pattern in a binary</fsummary>
      <desc>
      <p>The same as <c>match(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>.</p>
      </desc>
    </func>
    <func>
      <name name="match" arity="3"/>
      <type name="part"/>
      <fsummary>Searches for the first match of a pattern in a binary</fsummary>
      <desc>

      <p>Searches for the first occurrence of <c><anno>Pattern</anno></c> in <c><anno>Subject</anno></c> and
      returns the position and length.</p>

      <p>The function will return <c>{Pos, Length}</c> for the binary
      in <c><anno>Pattern</anno></c> starting at the lowest position in
      <c><anno>Subject</anno></c>, Example:</p>

<code>
1> binary:match(&lt;&lt;"abcde"&gt;&gt;, [&lt;&lt;"bcde"&gt;&gt;,&lt;&lt;"cd"&gt;&gt;],[]).
{1,4}
</code>

      <p>Even though <c>&lt;&lt;"cd"&gt;&gt;</c> ends before
      <c>&lt;&lt;"bcde"&gt;&gt;</c>, <c>&lt;&lt;"bcde"&gt;&gt;</c>
      begins first and is therefore the first match. If two
      overlapping matches begin at the same position, the longest is
      returned.</p>

      <p>Summary of the options:</p>

      <taglist>
      <tag>{scope, {<anno>Start</anno>, <anno>Length</anno>}}</tag>
      <item><p>Only the given part is searched. Return values still have
      offsets from the beginning of <c><anno>Subject</anno></c>. A negative <c>Length</c> is
      allowed as described in the <c>DATA TYPES</c> section of this manual.</p></item>
      </taglist>

      <p>If none of the strings in
      <c><anno>Pattern</anno></c> is found, the atom <c>nomatch</c> is returned.</p>

      <p>For a description of <c><anno>Pattern</anno></c>, see
      <seealso marker="#compile_pattern-1">compile_pattern/1</seealso>.</p>

      <p>If <c>{scope, {Start,Length}}</c> is given in the options
      such that <c>Start</c> is larger than the size of
      <c>Subject</c>, <c>Start + Length</c> is less than zero or
      <c>Start + Length</c> is larger than the size of
      <c>Subject</c>, a <c>badarg</c> exception is raised.</p>

      </desc>
    </func>
    <func>
      <name name="matches" arity="2"/>
      <fsummary>Searches for all matches of a pattern in a binary</fsummary>
      <desc>
      <p>The same as <c>matches(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>.</p>
      </desc>
    </func>
    <func>
      <name name="matches" arity="3"/>
      <type name="part"/>
      <fsummary>Searches for all matches of a pattern in a binary</fsummary>
      <desc>

      <p>Works like <c>match/2</c>, but the <c><anno>Subject</anno></c> is searched until
      exhausted and a list of all non-overlapping parts matching
      <c><anno>Pattern</anno></c> is returned (in order). </p>

      <p>The first and longest match is preferred to a shorter,
      which is illustrated by the following example:</p>

<code>
1> binary:matches(&lt;&lt;"abcde"&gt;&gt;,
                  [&lt;&lt;"bcde"&gt;&gt;,&lt;&lt;"bc"&gt;&gt;>,&lt;&lt;"de"&gt;&gt;],[]).
[{1,4}]
</code>

       <p>The result shows that &lt;&lt;"bcde"&gt;&gt; is selected instead of the
       shorter match &lt;&lt;"bc"&gt;&gt; (which would have given raise to one
       more match,&lt;&lt;"de"&gt;&gt;). This corresponds to the behavior of posix
       regular expressions (and programs like awk), but is not
       consistent with alternative matches in re (and Perl), where
       instead lexical ordering in the search pattern selects which
       string matches.</p>

       <p>If none of the strings in pattern is found, an empty list is returned.</p>

       <p>For a description of <c><anno>Pattern</anno></c>, see <seealso marker="#compile_pattern-1">compile_pattern/1</seealso> and for a
       description of available options, see <seealso marker="#match-3">match/3</seealso>.</p>

       <p>If <c>{scope, {<anno>Start</anno>,<anno>Length</anno>}}</c> is given in the options such that
       <c><anno>Start</anno></c> is larger than the size of <c><anno>Subject</anno></c>, <c><anno>Start</anno> + <anno>Length</anno></c> is
       less than zero or <c><anno>Start</anno> + <anno>Length</anno></c> is larger than the size of
       <c><anno>Subject</anno></c>, a <c>badarg</c> exception is raised.</p>

     </desc>
    </func>
    <func>
      <name name="part" arity="2"/>
      <fsummary>Extracts a part of a binary</fsummary>
      <desc>

      <p>Extracts the part of the binary <c><anno>Subject</anno></c> described by <c><anno>PosLen</anno></c>.</p>

      <p>Negative length can be used to extract bytes at the end of a binary:</p>

<code>
1> Bin = &lt;&lt;1,2,3,4,5,6,7,8,9,10&gt;&gt;.
2> binary:part(Bin,{byte_size(Bin), -5}).
&lt;&lt;6,7,8,9,10&gt;&gt;
</code>

      <note>
      <p><seealso marker="#part-2">part/2</seealso>and <seealso
      marker="#part-3">part/3</seealso> are also available in the
      <c>erlang</c> module under the names <c>binary_part/2</c> and
      <c>binary_part/3</c>. Those BIFs are allowed in guard tests.</p>
      </note>

      <p>If <c><anno>PosLen</anno></c> in any way references outside the binary, a <c>badarg</c> exception
      is raised.</p>

      </desc>
    </func>
    <func>
      <name name="part" arity="3"/>
      <fsummary>Extracts a part of a binary</fsummary>
      <desc>
      <p>The same as <c>part(<anno>Subject</anno>, {<anno>Pos</anno>, <anno>Len</anno>})</c>.</p>
      </desc>
    </func>
    <func>
      <name name="referenced_byte_size" arity="1"/>
      <fsummary>Determines the size of the actual binary pointed out by a sub-binary</fsummary>
      <desc>

     <p>If a binary references a larger binary (often described as
     being a sub-binary), it can be useful to get the size of the
     actual referenced binary. This function can be used in a program
     to trigger the use of <c>copy/1</c>. By copying a binary, one might
     dereference the original, possibly large, binary which a smaller
     binary is a reference to.</p>

      <p>Example:</p>

      <code>
store(Binary, GBSet) ->
  NewBin =
      case binary:referenced_byte_size(Binary) of
          Large when Large > 2 * byte_size(Binary) ->
             binary:copy(Binary);
          _ ->
             Binary
      end,
  gb_sets:insert(NewBin,GBSet).
      </code>

      <p>In this example, we chose to copy the binary content before
      inserting it in the <c>gb_sets:set()</c> if it references a binary more than
      twice the size of the data we're going to keep. Of course
      different rules for when copying will apply to different
      programs.</p>

      <p>Binary sharing will occur whenever binaries are taken apart,
      this is the fundamental reason why binaries are fast,
      decomposition can always be done with O(1) complexity. In rare
      circumstances this data sharing is however undesirable, why this
      function together with <c>copy/1</c> might be useful when optimizing
      for memory use.</p>

      <p>Example of binary sharing:</p>

      <code>
1> A = binary:copy(&lt;&lt;1&gt;&gt;,100).
&lt;&lt;1,1,1,1,1 ...
2> byte_size(A).
100
3> binary:referenced_byte_size(A)
100
4> &lt;&lt;_:10/binary,B:10/binary,_/binary&gt;&gt; = A.
&lt;&lt;1,1,1,1,1 ...
5> byte_size(B).
10
6> binary:referenced_byte_size(B)
100
      </code>

      <note>
      <p>Binary data is shared among processes. If another process
      still references the larger binary, copying the part this
      process uses only consumes more memory and will not free up the
      larger binary for garbage collection. Use this kind of intrusive
      functions with extreme care, and only if a real problem is
      detected.</p>
      </note>

      </desc>
    </func>
    <func>
      <name name="replace" arity="3"/>
      <fsummary>Replaces bytes in a binary according to a pattern</fsummary>
      <desc>
      <p>The same as <c>replace(<anno>Subject</anno>,<anno>Pattern</anno>,<anno>Replacement</anno>,[])</c>.</p>
      </desc>
    </func>
    <func>
      <name name="replace" arity="4"/>
      <fsummary>Replaces bytes in a binary according to a pattern</fsummary>
      <type_desc variable="OnePos">An integer() =&lt; byte_size(<anno>Replacement</anno>)
      </type_desc>
      <desc>

      <p>Constructs a new binary by replacing the parts in
      <c><anno>Subject</anno></c> matching <c><anno>Pattern</anno></c> with the content of
      <c><anno>Replacement</anno></c>.</p>

      <p>If the matching sub-part of <c><anno>Subject</anno></c> giving raise to the
      replacement is to be inserted in the result, the option
      <c>{insert_replaced, <anno>InsPos</anno>}</c> will insert the matching part into
      <c><anno>Replacement</anno></c> at the given position (or positions) before actually
      inserting <c><anno>Replacement</anno></c> into the <c><anno>Subject</anno></c>. Example:</p>

<code>
1> binary:replace(&lt;&lt;"abcde"&gt;&gt;,&lt;&lt;"b"&gt;&gt;,&lt;&lt;"[]"&gt;&gt;,[{insert_replaced,1}]).
&lt;&lt;"a[b]cde"&gt;&gt;
2> binary:replace(&lt;&lt;"abcde"&gt;&gt;,[&lt;&lt;"b"&gt;&gt;,&lt;&lt;"d"&gt;&gt;],&lt;&lt;"[]"&gt;&gt;,
                 [global,{insert_replaced,1}]).
&lt;&lt;"a[b]c[d]e"&gt;&gt;
3> binary:replace(&lt;&lt;"abcde"&gt;&gt;,[&lt;&lt;"b"&gt;&gt;,&lt;&lt;"d"&gt;&gt;],&lt;&lt;"[]"&gt;&gt;,
                 [global,{insert_replaced,[1,1]}]).
&lt;&lt;"a[bb]c[dd]e"&gt;&gt;
4> binary:replace(&lt;&lt;"abcde"&gt;&gt;,[&lt;&lt;"b"&gt;&gt;,&lt;&lt;"d"&gt;&gt;],&lt;&lt;"[-]"&gt;&gt;,
                 [global,{insert_replaced,[1,2]}]).
&lt;&lt;"a[b-b]c[d-d]e"&gt;&gt;
</code>

        <p>If any position given in <c><anno>InsPos</anno></c> is greater than the size of the replacement binary, a <c>badarg</c> exception is raised.</p>

	<p>The options <c>global</c> and <c>{scope, part()}</c> work as for <seealso marker="#split-3">split/3</seealso>. The return type is always a <c>binary()</c>.</p>

	<p>For a description of <c><anno>Pattern</anno></c>, see <seealso marker="#compile_pattern-1">compile_pattern/1</seealso>.</p>
      </desc>
    </func>
    <func>
      <name name="split" arity="2"/>
      <fsummary>Splits a binary according to a pattern</fsummary>
      <desc>
      <p>The same as <c>split(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>.</p>
      </desc>
    </func>
    <func>
      <name name="split" arity="3"/>
      <fsummary>Splits a binary according to a pattern</fsummary>
      <desc>

      <p>Splits <c><anno>Subject</anno></c> into a list of binaries based on <c><anno>Pattern</anno></c>. If
      the option global is not given, only the first occurrence of
      <c><anno>Pattern</anno></c> in <c><anno>Subject</anno></c> will give rise to a split.</p>

      <p>The parts of <c><anno>Pattern</anno></c> actually found in <c><anno>Subject</anno></c> are not included in the result.</p>

      <p>Example:</p>

<code>
1> binary:split(&lt;&lt;1,255,4,0,0,0,2,3&gt;&gt;, [&lt;&lt;0,0,0&gt;&gt;,&lt;&lt;2&gt;&gt;],[]).
[&lt;&lt;1,255,4&gt;&gt;, &lt;&lt;2,3&gt;&gt;]
2> binary:split(&lt;&lt;0,1,0,0,4,255,255,9&gt;&gt;, [&lt;&lt;0,0&gt;&gt;, &lt;&lt;255,255&gt;&gt;],[global]).
[&lt;&lt;0,1&gt;&gt;,&lt;&lt;4&gt;&gt;,&lt;&lt;9&gt;&gt;]
</code>

      <p>Summary of options:</p>
      <taglist>

      <tag>{scope, part()}</tag>

      <item><p>Works as in <seealso marker="#match-3">match/3</seealso> and
      <seealso marker="#matches-3">matches/3</seealso>. Note that
      this only defines the scope of the search for matching strings,
      it does not cut the binary before splitting. The bytes before
      and after the scope will be kept in the result. See example
      below.</p></item>

      <tag>trim</tag>

      <item><p>Removes trailing empty parts of the result (as does trim in <c>re:split/3</c>)</p></item>

      <tag>trim_all</tag>

      <item><p>Removes all empty parts of the result.</p></item>

      <tag>global</tag>

      <item><p>Repeats the split until the <c><anno>Subject</anno></c> is
      exhausted. Conceptually the global option makes split work on
      the positions returned by <seealso marker="#matches-3">matches/3</seealso>,
      while it normally
      works on the position returned by
      <seealso marker="#match-3">match/3</seealso>.</p></item>

      </taglist>

     <p>Example of the difference between a scope and taking the
     binary apart before splitting:</p>

<code>
1> binary:split(&lt;&lt;"banana"&gt;&gt;,[&lt;&lt;"a"&gt;&gt;],[{scope,{2,3}}]).
[&lt;&lt;"ban"&gt;&gt;,&lt;&lt;"na"&gt;&gt;]
2> binary:split(binary:part(&lt;&lt;"banana"&gt;&gt;,{2,3}),[&lt;&lt;"a"&gt;&gt;],[]).
[&lt;&lt;"n"&gt;&gt;,&lt;&lt;"n"&gt;&gt;]
</code>

      <p>The return type is always a list of binaries that are all
      referencing <c><anno>Subject</anno></c>. This means that the data in <c><anno>Subject</anno></c> is not
      actually copied to new binaries and that <c><anno>Subject</anno></c> cannot be
      garbage collected until the results of the split are no longer
      referenced.</p>

      <p>For a description of <c><anno>Pattern</anno></c>, see <seealso marker="#compile_pattern-1">compile_pattern/1</seealso>.</p>

      </desc>
    </func>
  </funcs>
</erlref>