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Diffstat (limited to 'lib/stdlib/doc/src/binary.xml')
| -rw-r--r-- | lib/stdlib/doc/src/binary.xml | 564 |
1 files changed, 298 insertions, 266 deletions
diff --git a/lib/stdlib/doc/src/binary.xml b/lib/stdlib/doc/src/binary.xml index 933157fc34..6a86d6c7ba 100644 --- a/lib/stdlib/doc/src/binary.xml +++ b/lib/stdlib/doc/src/binary.xml @@ -35,285 +35,311 @@ <file>binary.xml</file> </header> <module>binary</module> - <modulesummary>Library for handling binary data</modulesummary> + <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 + binaries. Although the majority of functions could be provided 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> + 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> + <p>The module is provided according to Erlang Enhancement Proposal + (EEP) 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> + <p>The library handles byte-oriented data. For bitstrings that are not + binaries (does not contain whole octets of bits) a <c>badarg</c> + exception is 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><p>Opaque data type representing a compiled + search pattern. Guaranteed to be a <c>tuple()</c> 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 + <desc><p>A representaion of a part (or range) in a binary. <c>Start</c> is + a zero-based offset into a <c>binary()</c> and <c>Length</c> 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> + <c>Length</c>, so that the part of the binary begins at <c>Start</c> + + <c>Length</c> and is -<c>Length</c> long. This is useful for referencing + the last <c>N</c> bytes of a binary as <c>{size(Binary), -N}</c>. The + functions in this module always return <c>part()</c>s with positive + <c>Length</c>.</p> </desc> </datatype> </datatypes> + <funcs> <func> <name name="at" arity="2"/> - <fsummary>Returns the byte at a specific position in a binary</fsummary> + <fsummary>Return 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> >= <c>byte_size(<anno>Subject</anno>)</c>, - a <c>badarg</c> - exception is raised.</p> - + <p>Returns the byte at position <c><anno>Pos</anno></c> (zero-based) in + binary <c><anno>Subject</anno></c> as an integer. If + <c><anno>Pos</anno></c> >= <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> + <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> + <p>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> + <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. <c>part()</c> denotes which part of + the <c>binary()</c> to convert.</p> - <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> + <p><em>Example:</em></p> <code> -1> binary:bin_to_list(<<"erlang">>,{1,3}). +1> binary:bin_to_list(<<"erlang">>, {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> +%% 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> + <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> + <p>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> + <fsummary>Precompile 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 + search pattern, later to be used in functions + <seealso marker="#match-3"><c>match/3</c></seealso>, + <seealso marker="#matches-3"><c>matches/3</c></seealso>, + <seealso marker="#split-3"><c>split/3</c></seealso>, or + <seealso marker="#replace-4"><c>replace/4</c></seealso>. + The <c>cp()</c> returned is guaranteed to be a + <c>tuple()</c> to allow programs to distinguish it from + non-precompiled search patterns.</p> + + <p>When a list of binaries is specified, it denotes a set of + alternative binaries to search for. For example, if <c>[<<"functional">>,<<"programming">>]</c> - is given as <c><anno>Pattern</anno></c>, this - means "either <c><<"functional">></c> or + is specified as <c><anno>Pattern</anno></c>, this + means either <c><<"functional">></c> or <c><<"programming">></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> + alternatives; when only a single binary is specified, the set has + only one element. The order of alternatives in a pattern is + not significant.</p> - <p>If <c><anno>Pattern</anno></c> is not a binary or a flat proper list of binaries with length > 0, - a <c>badarg</c> exception will be raised.</p> + <p>The list of binaries used for search alternatives must 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 > 0, a <c>badarg</c> exception is raised.</p> </desc> </func> + <func> <name name="copy" arity="1"/> - <fsummary>Creates a duplicate of a binary</fsummary> + <fsummary>Create a duplicate of a binary.</fsummary> <desc> - <p>The same as <c>copy(<anno>Subject</anno>, 1)</c>.</p> + <p>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> + <fsummary>Duplicate a binary <c>N</c> times and create 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>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> + <p>This function always creates a new binary, even if <c><anno>N</anno> = + 1</c>. By using <seealso marker="#copy/1"><c>copy/1</c></seealso> + on a binary referencing a larger binary, one + can 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 + a larger binary, one can, 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> + copying can be a good idea.</p> + </note> - <p>If <c><anno>N</anno></c> < <c>0</c>, a <c>badarg</c> exception is raised.</p> + <p>If <c><anno>N</anno></c> < <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> + <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> + <p>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> + <fsummary>Decode a whole binary into an integer of arbitrary size. + </fsummary> <desc> + <p>Converts the binary digit representation, in big endian or little + endian, of a positive integer in <c><anno>Subject</anno></c> to an Erlang + <c>integer()</c>.</p> - <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> + <p><em>Example:</em></p> <code> 1> binary:decode_unsigned(<<169,138,199>>,big). -11111111 - </code> +11111111</code> </desc> </func> + <func> <name name="encode_unsigned" arity="1"/> - <fsummary>Encodes an unsigned integer into the minimal binary</fsummary> + <fsummary>Encode an unsigned integer into the minimal binary.</fsummary> <desc> - <p>The same as <c>encode_unsigned(<anno>Unsigned</anno>, big)</c>.</p> + <p>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> + <fsummary>Encode 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 + representation in a binary digit representation, either big endian or little endian.</p> - <p>Example:</p> + <p><em>Example:</em></p> <code> -1> binary:encode_unsigned(11111111,big). -<<169,138,199>> - </code> +1> binary:encode_unsigned(11111111, big). +<<169,138,199>></code> </desc> </func> + <func> <name name="first" arity="1"/> - <fsummary>Returns the first byte of a binary</fsummary> + <fsummary>Return 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> - + <p>Returns the first byte of 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> + <fsummary>Return 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> - + <p>Returns the last byte of 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> + <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> + <p>Works exactly as + <seealso marker="erts:erlang#list_to_binary/1"><c>erlang:list_to_binary/1</c></seealso>, + 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> + <fsummary>Return 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> + binaries in list <c><anno>Binaries</anno></c>.</p> + + <p><em>Example:</em></p> <code> -1> binary:longest_common_prefix([<<"erlang">>,<<"ergonomy">>]). +1> binary:longest_common_prefix([<<"erlang">>, <<"ergonomy">>]). 2 -2> binary:longest_common_prefix([<<"erlang">>,<<"perl">>]). -0 -</code> +2> binary:longest_common_prefix([<<"erlang">>, <<"perl">>]). +0</code> - <p>If <c><anno>Binaries</anno></c> is not a flat list of binaries, a <c>badarg</c> exception is raised.</p> + <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> + <fsummary>Return 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> + binaries in list <c><anno>Binaries</anno></c>.</p> + + <p><em>Example:</em></p> <code> -1> binary:longest_common_suffix([<<"erlang">>,<<"fang">>]). +1> binary:longest_common_suffix([<<"erlang">>, <<"fang">>]). 3 -2> binary:longest_common_suffix([<<"erlang">>,<<"perl">>]). -0 -</code> - - <p>If <c>Binaries</c> is not a flat list of binaries, a <c>badarg</c> exception is raised.</p> +2> binary:longest_common_suffix([<<"erlang">>, <<"perl">>]). +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> + <fsummary>Search 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> + <p>Same as <c>match(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>. + </p> </desc> </func> + <func> <name name="match" arity="3"/> - <fsummary>Searches for the first match of a pattern in a binary</fsummary> + <fsummary>Search for the first match of a pattern in a binary.</fsummary> <type name="part"/> <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>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 returns <c>{Pos, Length}</c> for the binary + in <c><anno>Pattern</anno></c>, starting at the lowest position in + <c><anno>Subject</anno></c>.</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> + <p><em>Example:</em></p> <code> -1> binary:match(<<"abcde">>, [<<"bcde">>,<<"cd">>],[]). -{1,4} -</code> +1> binary:match(<<"abcde">>, [<<"bcde">>, <<"cd">>],[]). +{1,4}</code> <p>Even though <c><<"cd">></c> ends before <c><<"bcde">></c>, <c><<"bcde">></c> @@ -325,41 +351,44 @@ <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> + <item><p>Only the specified 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 section Data Types in 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>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>For a description of <c><anno>Pattern</anno></c>, see function + <seealso marker="#compile_pattern-1"><c>compile_pattern/1</c></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 + <p>If <c>{scope, {Start,Length}}</c> is specified in the options such + that <c>Start</c> > size of <c>Subject</c>, <c>Start</c> + + <c>Length</c> < 0 or <c>Start</c> + <c>Length</c> > 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> + <fsummary>Search 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> + <p>Same as <c>matches(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>. + </p> </desc> </func> + <func> <name name="matches" arity="3"/> - <fsummary>Searches for all matches of a pattern in a binary</fsummary> + <fsummary>Search for all matches of a pattern in a binary.</fsummary> <type name="part"/> <desc> - - <p>Works like <c>match/2</c>, but the <c><anno>Subject</anno></c> is searched until + <p>As <seealso marker="#match-2"><c>match/2</c></seealso>, + but <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> + <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> @@ -367,76 +396,84 @@ <code> 1> binary:matches(<<"abcde">>, [<<"bcde">>,<<"bc">>,<<"de">>],[]). -[{1,4}] -</code> - - <p>The result shows that <<"bcde">> is selected instead of the - shorter match <<"bc">> (which would have given raise to one - more match,<<"de">>). 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 +[{1,4}]</code> + + <p>The result shows that <<"bcde">> is selected instead of + the shorter match <<"bc">> (which would have given raise to + one more match, <<"de">>). + This corresponds to the behavior of + POSIX regular expressions (and programs like awk), but is not + consistent with alternative matches in <c>re</c> (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 none of the strings in a pattern is found, an empty list is + returned.</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> + <p>For a description of <c><anno>Pattern</anno></c>, see + <seealso marker="#compile_pattern-1"><c>compile_pattern/1</c></seealso>. + For a description of available options, see + <seealso marker="#match-3"><c>match/3</c></seealso>.</p> + <p>If <c>{scope, {<anno>Start</anno>,<anno>Length</anno>}}</c> is + specified in the options such that <c><anno>Start</anno></c> > size + of <c><anno>Subject</anno></c>, <c><anno>Start</anno> + + <anno>Length</anno></c> < 0 or <c><anno>Start</anno> + + <anno>Length</anno></c> is > 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> + <fsummary>Extract a part of a binary.</fsummary> <desc> + <p>Extracts the part of binary <c><anno>Subject</anno></c> described by + <c><anno>PosLen</anno></c>.</p> - <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> + <p>A negative length can be used to extract bytes at the end of a + binary:</p> <code> 1> Bin = <<1,2,3,4,5,6,7,8,9,10>>. -2> binary:part(Bin,{byte_size(Bin), -5}). -<<6,7,8,9,10>> -</code> +2> binary:part(Bin, {byte_size(Bin), -5}). +<<6,7,8,9,10>></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 + <p><seealso marker="#part-2">part/2</seealso> and + <seealso marker="#part-3">part/3</seealso> are also available in the + <seealso marker="erts:erlang"><c>erlang</c></seealso> + 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> - + <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> + <fsummary>Extract a part of a binary.</fsummary> <desc> - <p>The same as <c>part(<anno>Subject</anno>, {<anno>Pos</anno>, <anno>Len</anno>})</c>.</p> + <p>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> + <fsummary>Determine the size of the binary pointed out by a subbinary. + </fsummary> <desc> + <p>If a binary references a larger binary (often described as + being a subbinary), it can be useful to get the size of the + referenced binary. This function can be used in a program to trigger the + use of <seealso marker="#copy/1"><c>copy/1</c></seealso>. By copying a + binary, one can dereference the original, possibly large, binary that a + smaller binary is a reference to.</p> - <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> + <p><em>Example:</em></p> <code> store(Binary, GBSet) -> @@ -447,26 +484,24 @@ store(Binary, GBSet) -> _ -> Binary end, - gb_sets:insert(NewBin,GBSet). - </code> + 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> + inserting it in <c>gb_sets:set()</c> if it references a binary more than + twice the data size we want to keep. Of course, + different rules apply when copying to different programs.</p> - <p>Binary sharing will occur whenever binaries are taken apart, - this is the fundamental reason why binaries are fast, + <p>Binary sharing occurs 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 + function together with <c>copy/1</c> can be useful when optimizing for memory use.</p> <p>Example of binary sharing:</p> <code> -1> A = binary:copy(<<1>>,100). +1> A = binary:copy(<<1>>, 100). <<1,1,1,1,1 ... 2> byte_size(A). 100 @@ -477,141 +512,138 @@ store(Binary, GBSet) -> 5> byte_size(B). 10 6> binary:referenced_byte_size(B) -100 - </code> +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 + process uses only consumes more memory and does 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> + 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> + <fsummary>Replace 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> + <p>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> + <fsummary>Replace bytes in a binary according to a pattern.</fsummary> <type_desc variable="OnePos">An integer() =< 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> + <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 subpart of <c><anno>Subject</anno></c> giving raise + to the replacement is to be inserted in the result, option + <c>{insert_replaced, <anno>InsPos</anno>}</c> inserts the matching part + into <c><anno>Replacement</anno></c> at the specified position (or + positions) before inserting <c><anno>Replacement</anno></c> into + <c><anno>Subject</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> + <p><em>Example:</em></p> <code> -1> binary:replace(<<"abcde">>,<<"b">>,<<"[]">>,[{insert_replaced,1}]). +1> binary:replace(<<"abcde">>,<<"b">>,<<"[]">>, [{insert_replaced,1}]). <<"a[b]cde">> -2> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>, - [global,{insert_replaced,1}]). +2> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>,[global,{insert_replaced,1}]). <<"a[b]c[d]e">> -3> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>, - [global,{insert_replaced,[1,1]}]). +3> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>,[global,{insert_replaced,[1,1]}]). <<"a[bb]c[dd]e">> -4> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[-]">>, - [global,{insert_replaced,[1,2]}]). -<<"a[b-b]c[d-d]e">> -</code> +4> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[-]">>,[global,{insert_replaced,[1,2]}]). +<<"a[b-b]c[d-d]e">></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>If any position specified in <c><anno>InsPos</anno></c> > 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>Options <c>global</c> and <c>{scope, part()}</c> work as for + <seealso marker="#split-3"><c>split/3</c></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> + <p>For a description of <c><anno>Pattern</anno></c>, see + <seealso marker="#compile_pattern-1"><c>compile_pattern/1</c></seealso>. + </p> </desc> </func> + <func> <name name="split" arity="2"/> - <fsummary>Splits a binary according to a pattern</fsummary> + <fsummary>Split a binary according to a pattern.</fsummary> <desc> - <p>The same as <c>split(<anno>Subject</anno>, <anno>Pattern</anno>, [])</c>.</p> + <p>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> + <fsummary>Split 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 option <c>global</c> is not specified, + only the first occurrence of <c><anno>Pattern</anno></c> in + <c><anno>Subject</anno></c> gives rise to a split.</p> - <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> found in + <c><anno>Subject</anno></c> are not included in the result.</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> + <p><em>Example:</em></p> <code> 1> binary:split(<<1,255,4,0,0,0,2,3>>, [<<0,0,0>>,<<2>>],[]). [<<1,255,4>>, <<2,3>>] 2> binary:split(<<0,1,0,0,4,255,255,9>>, [<<0,0>>, <<255,255>>],[global]). -[<<0,1>>,<<4>>,<<9>>] -</code> +[<<0,1>>,<<4>>,<<9>>]</code> <p>Summary of options:</p> - <taglist> + <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 + <item><p>Works as in <seealso marker="#match-3"><c>match/3</c></seealso> + and <seealso marker="#matches-3"><c>matches/3</c></seealso>. Notice 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> - + it does not cut the binary before splitting. The bytes before and after + the scope are kept in the result. See the 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> - + <item><p>Removes trailing empty parts of the result (as does <c>trim</c> + in <seealso marker="re#split/3"><c>re:split/3</c></seealso>.</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> - + <item><p>Repeats the split until <c><anno>Subject</anno></c> is + exhausted. Conceptually option <c>global</c> makes split work + on the positions returned by + <seealso marker="#matches-3"><c>matches/3</c></seealso>, while it + normally works on the position returned by + <seealso marker="#match-3"><c>match/3</c></seealso>.</p></item> </taglist> <p>Example of the difference between a scope and taking the binary apart before splitting:</p> <code> -1> binary:split(<<"banana">>,[<<"a">>],[{scope,{2,3}}]). +1> binary:split(<<"banana">>, [<<"a">>],[{scope,{2,3}}]). [<<"ban">>,<<"na">>] -2> binary:split(binary:part(<<"banana">>,{2,3}),[<<"a">>],[]). -[<<"n">>,<<"n">>] -</code> +2> binary:split(binary:part(<<"banana">>,{2,3}), [<<"a">>],[]). +[<<"n">>,<<"n">>]</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> + referencing <c><anno>Subject</anno></c>. This means that the data in + <c><anno>Subject</anno></c> is not 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"><c>compile_pattern/1</c></seealso>. + </p> </desc> </func> </funcs> |