From 68d53c01b0b8e9a007a6a30158c19e34b2d2a34e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 18 May 2016 15:53:35 +0200 Subject: Update STDLIB documentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Language cleaned up by the technical writers xsipewe and tmanevik from Combitech. Proofreading and corrections by Björn Gustavsson and Hans Bolinder. --- lib/stdlib/doc/src/binary.xml | 564 ++++++++++++++++++++++-------------------- 1 file changed, 298 insertions(+), 266 deletions(-) (limited to 'lib/stdlib/doc/src/binary.xml') 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 @@ binary.xml binary - Library for handling binary data + Library for handling binary data.

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.

+ less memory, or both, than a counterpart written in pure Erlang.

-

The module is implemented according to the EEP (Erlang Enhancement Proposal) 31.

+

The module is provided according to Erlang Enhancement Proposal + (EEP) 31.

-

- The library handles byte-oriented data. Bitstrings that are not - binaries (does not contain whole octets of bits) will result in a badarg - exception being thrown from any of the functions in this - module. -

+

The library handles byte-oriented data. For bitstrings that are not + binaries (does not contain whole octets of bits) a badarg + exception is thrown from any of the functions in this module.

 + -

Opaque data-type representing a compiled - search-pattern. Guaranteed to be a tuple() to allow programs to - distinguish it from non precompiled search patterns.

+

Opaque data type representing a compiled + search pattern. Guaranteed to be a tuple() to allow programs to + distinguish it from non-precompiled search patterns.

 -

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 +

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.

+ 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.

 + - Returns the byte at a specific position in a binary + Return the byte at a specific position in a binary. - -

Returns the byte at position Pos (zero-based) in the binary - Subject as an integer. If Pos >= byte_size(Subject), - a badarg - exception is raised.

- +

Returns the byte at position Pos (zero-based) in + binary Subject as an integer. If + Pos >= byte_size(Subject), + a badarg exception is raised.

 + - Convert a binary to a list of integers + Convert a binary to a list of integers. -

The same as bin_to_list(Subject,{0,byte_size(Subject)}).

+

Same as bin_to_list(Subject, {0,byte_size(Subject)}).

 + - Convert a binary to a list of integers + Convert a binary to a list of integers. +

Converts Subject to a list of byte()s, each + representing the value of one byte. part() denotes which part of + the binary() to convert.

-

Converts Subject to a list of byte()s, each representing - the value of one byte. The part() denotes which part of the - binary() to convert. Example:

+

Example:

-1> binary:bin_to_list(<<"erlang">>,{1,3}). +1> binary:bin_to_list(<<"erlang">>, {1,3}). "rla" -%% or [114,108,97] in list notation. - -

If PosLen in any way references outside the binary, a badarg exception is raised.

+%% or [114,108,97] in list notation. + +

If PosLen in any way references outside the binary, + a badarg exception is raised.

 + - Convert a binary to a list of integers + Convert a binary to a list of integers. -

The same as bin_to_list(Subject,{Pos,Len}).

+

Same as bin_to_list(Subject, {Pos, Len}).

 + - Pre-compiles a binary search pattern + Precompile a binary search pattern. -

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

- -

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 + match/3, + matches/3, + split/3, or + replace/4. + The cp() returned is guaranteed to be a + tuple() to allow programs to distinguish it from + non-precompiled search patterns.

+ +

When a list of binaries is specified, it denotes a set of + alternative binaries to search for. For example, if [<<"functional">>,<<"programming">>] - is given as Pattern, this - means "either <<"functional">> or + is specified as Pattern, this + means either <<"functional">> or <<"programming">>". 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.

- -

The list of binaries used for search alternatives shall be flat and proper.

+ alternatives; when only a single binary is specified, the set has + only one element. The order of alternatives in a pattern is + not significant.

-

If Pattern is not a binary or a flat proper list of binaries with length > 0, - a badarg exception will be raised.

+

The list of binaries used for search alternatives must be flat and + proper.

+

If Pattern is not a binary or a flat proper list of + binaries with length > 0, a badarg exception is raised.

 + - Creates a duplicate of a binary + Create a duplicate of a binary. -

The same as copy(Subject, 1).

+

Same as copy(Subject, 1).

 + - Duplicates a binary N times and creates a new + Duplicate a binary N times and create a new. -

Creates a binary with the content of Subject duplicated N times.

+

Creates a binary with the content of Subject + duplicated N times.

-

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

+

This function always creates a new binary, even if N = + 1. By using copy/1 + on a binary referencing a larger binary, one + can free up the larger binary for garbage collection.

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.

 + copying can be a good idea.

+ -

If N < 0, a badarg exception is raised.

+

If N < 0, a badarg exception is + raised.

 + - Decode a whole binary into an integer of arbitrary size + Decode a whole binary into an integer of arbitrary size. + -

The same as decode_unsigned(Subject, big).

+

Same as decode_unsigned(Subject, big).

 + - Decode a whole binary into an integer of arbitrary size + Decode a whole binary into an integer of arbitrary size. + +

Converts the binary digit representation, in big endian or little + endian, of a positive integer in Subject to an Erlang + integer().

-

Converts the binary digit representation, in big or little - endian, of a positive integer in Subject to an Erlang integer().

- -

Example:

+

Example:

1> binary:decode_unsigned(<<169,138,199>>,big). -11111111 - +11111111 + - Encodes an unsigned integer into the minimal binary + Encode an unsigned integer into the minimal binary. -

The same as encode_unsigned(Unsigned, big).

+

Same as encode_unsigned(Unsigned, big).

 + - Encodes an unsigned integer into the minimal binary + Encode an unsigned integer into the minimal binary. -

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.

-

Example:

+

Example:

-1> binary:encode_unsigned(11111111,big). -<<169,138,199>> - +1> binary:encode_unsigned(11111111, big). +<<169,138,199>> + - Returns the first byte of a binary + Return the first byte of a binary. - -

Returns the first byte of the binary Subject as an integer. If the - size of Subject is zero, a badarg exception is raised.

- +

Returns the first byte of binary Subject as an + integer. If the size of Subject is zero, a + badarg exception is raised.

 + - Returns the last byte of a binary + Return the last byte of a binary. - -

Returns the last byte of the binary Subject as an integer. If the - size of Subject is zero, a badarg exception is raised.

- +

Returns the last byte of binary Subject as an + integer. If the size of Subject is zero, a + badarg exception is raised.

 + - Convert a list of integers and binaries to a binary + Convert a list of integers and binaries to a binary. -

Works exactly as erlang:list_to_binary/1, added for completeness.

+

Works exactly as + erlang:list_to_binary/1, + added for completeness.

 + - Returns length of longest common prefix for a set of binaries + Return length of longest common prefix for a set of binaries. + -

Returns the length of the longest common prefix of the - binaries in the list Binaries. Example:

+ binaries in list Binaries.

+ +

Example:

-1> binary:longest_common_prefix([<<"erlang">>,<<"ergonomy">>]). +1> binary:longest_common_prefix([<<"erlang">>, <<"ergonomy">>]). 2 -2> binary:longest_common_prefix([<<"erlang">>,<<"perl">>]). -0 - +2> binary:longest_common_prefix([<<"erlang">>, <<"perl">>]). +0 -

If Binaries is not a flat list of binaries, a badarg exception is raised.

+

If Binaries is not a flat list of binaries, a + badarg exception is raised.

 + - Returns length of longest common suffix for a set of binaries + Return length of longest common suffix for a set of binaries. + -

Returns the length of the longest common suffix of the - binaries in the list Binaries. Example:

+ binaries in list Binaries.

+ +

Example:

-1> binary:longest_common_suffix([<<"erlang">>,<<"fang">>]). +1> binary:longest_common_suffix([<<"erlang">>, <<"fang">>]). 3 -2> binary:longest_common_suffix([<<"erlang">>,<<"perl">>]). -0 - - -

If Binaries is not a flat list of binaries, a badarg exception is raised.

+2> binary:longest_common_suffix([<<"erlang">>, <<"perl">>]). +0 +

If Binaries is not a flat list of binaries, a badarg + exception is raised.

 + - Searches for the first match of a pattern in a binary + Search for the first match of a pattern in a binary. -

The same as match(Subject, Pattern, []).

+

Same as match(Subject, Pattern, []). +

+ - Searches for the first match of a pattern in a binary + Search for the first match of a pattern in a binary. +

Searches for the first occurrence of Pattern in + Subject and returns the position and length.

-

Searches for the first occurrence of Pattern in Subject and - returns the position and length.

+

The function returns {Pos, Length} for the binary + in Pattern, starting at the lowest position in + Subject.

-

The function will return {Pos, Length} for the binary - in Pattern starting at the lowest position in - Subject, Example:

+

Example:

-1> binary:match(<<"abcde">>, [<<"bcde">>,<<"cd">>],[]). -{1,4} - +1> binary:match(<<"abcde">>, [<<"bcde">>, <<"cd">>],[]). +{1,4}

Even though <<"cd">> ends before <<"bcde">>, <<"bcde">> @@ -325,41 +351,44 @@ {scope, {Start, Length}} -

Only the given part is searched. Return values still have - offsets from the beginning of Subject. A negative Length is - allowed as described in the DATA TYPES section of this manual.

+

Only the specified part is searched. Return values still have + offsets from the beginning of Subject. A negative + Length is allowed as described in section Data Types in this + manual.

 -

If none of the strings in - Pattern is found, the atom nomatch is returned.

+

If none of the strings in Pattern is found, the + atom nomatch is returned.

-

For a description of Pattern, see - compile_pattern/1.

+

For a description of Pattern, see function + compile_pattern/1. +

-

If {scope, {Start,Length}} is given in the options - such that Start is larger than the size of - Subject, Start + Length is less than zero or - Start + Length is larger than the size of +

If {scope, {Start,Length}} is specified in the options such + that Start > size of Subject, Start + + Length < 0 or Start + Length > size of Subject, a badarg exception is raised.

- + - Searches for all matches of a pattern in a binary + Search for all matches of a pattern in a binary. -

The same as matches(Subject, Pattern, []).

+

Same as matches(Subject, Pattern, []). +

+ - Searches for all matches of a pattern in a binary + Search for all matches of a pattern in a binary. - -

Works like match/2, but the Subject is searched until +

As match/2, + but Subject is searched until exhausted and a list of all non-overlapping parts matching - Pattern is returned (in order).

+ Pattern is returned (in order).

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

@@ -367,76 +396,84 @@ 1> binary:matches(<<"abcde">>, [<<"bcde">>,<<"bc">>,<<"de">>],[]). -[{1,4}] - - -

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}] + +

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 instead lexical ordering in the search pattern selects which string matches.

-

If none of the strings in pattern is found, an empty list is returned.

- -

For a description of Pattern, see compile_pattern/1 and for a - description of available options, see match/3.

+

If none of the strings in a pattern is found, an empty list is + returned.

-

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

+

For a description of Pattern, see + compile_pattern/1. + For a description of available options, see + match/3.

+

If {scope, {Start,Length}} is + specified in the options such that Start > size + of Subject, Start + + Length < 0 or Start + + Length is > size of Subject, + a badarg exception is raised.

 + - Extracts a part of a binary + Extract a part of a binary. +

Extracts the part of binary Subject described by + PosLen.

-

Extracts the part of the binary Subject described by PosLen.

- -

Negative length can be used to extract bytes at the end of a binary:

+

A negative length can be used to extract bytes at the end of a + binary:

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>> - +2> binary:part(Bin, {byte_size(Bin), -5}). +<<6,7,8,9,10>> -

part/2and part/3 are also available in the - erlang module under the names binary_part/2 and +

part/2 and + part/3 are also available in the + erlang + module under the names binary_part/2 and binary_part/3. Those BIFs are allowed in guard tests.

 -

If PosLen in any way references outside the binary, a badarg exception - is raised.

- +

If PosLen in any way references outside the binary, + a badarg exception is raised.

 + - Extracts a part of a binary + Extract a part of a binary. -

The same as part(Subject, {Pos, Len}).

+

Same as part(Subject, {Pos, + Len}).

 + - Determines the size of the actual binary pointed out by a sub-binary + Determine the size of the binary pointed out by a subbinary. + +

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 copy/1. By copying a + binary, one can dereference the original, possibly large, binary that a + smaller binary is a reference to.

-

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 copy/1. By copying a binary, one might - dereference the original, possibly large, binary which a smaller - binary is a reference to.

- -

Example:

+

Example:

store(Binary, GBSet) -> @@ -447,26 +484,24 @@ store(Binary, GBSet) -> _ -> Binary end, - gb_sets:insert(NewBin,GBSet). - + gb_sets:insert(NewBin,GBSet).

In this example, we chose to copy the binary content before - inserting it in the gb_sets:set() 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.

+ inserting it in gb_sets:set() 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.

-

Binary sharing will occur whenever binaries are taken apart, - this is the fundamental reason why binaries are fast, +

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 copy/1 might be useful when optimizing + function together with copy/1 can be useful when optimizing for memory use.

Example of binary sharing:

-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 - +100

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.

+ functions with extreme care and only if a real problem is detected.

 - + - Replaces bytes in a binary according to a pattern + Replace bytes in a binary according to a pattern. -

The same as replace(Subject,Pattern,Replacement,[]).

+

Same as replace(Subject, Pattern, Replacement,[]).

 + - Replaces bytes in a binary according to a pattern + Replace bytes in a binary according to a pattern. An integer() =< byte_size(Replacement) -

Constructs a new binary by replacing the parts in - Subject matching Pattern with the content of - Replacement.

+ Subject matching Pattern with + the content of Replacement.

+ +

If the matching subpart of Subject giving raise + to the replacement is to be inserted in the result, option + {insert_replaced, InsPos} inserts the matching part + into Replacement at the specified position (or + positions) before inserting Replacement into + Subject.

-

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

+

Example:

-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">> - +4> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[-]">>,[global,{insert_replaced,[1,2]}]). +<<"a[b-b]c[d-d]e">> -

If any position given in InsPos is greater than the size of the replacement binary, a badarg exception is raised.

+

If any position specified in InsPos > size + of the replacement binary, a badarg exception is raised.

-

The options global and {scope, part()} work as for split/3. The return type is always a binary().

+

Options global and {scope, part()} work as for + split/3. + The return type is always a binary().

-

For a description of Pattern, see compile_pattern/1.

+

For a description of Pattern, see + compile_pattern/1. +

+ - Splits a binary according to a pattern + Split a binary according to a pattern. -

The same as split(Subject, Pattern, []).

+

Same as split(Subject, Pattern, + []).

 + - Splits a binary according to a pattern + Split a binary according to a pattern. +

Splits Subject into a list of binaries based on + Pattern. If option global is not specified, + only the first occurrence of Pattern in + Subject gives rise to a split.

-

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

+

The parts of Pattern found in + Subject are not included in the result.

-

The parts of Pattern actually found in Subject are not included in the result.

- -

Example:

+

Example:

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>>] - +[<<0,1>>,<<4>>,<<9>>]

Summary of options:

- + {scope, part()} - -

Works as in match/3 and - matches/3. Note that +

Works as in match/3 + and matches/3. 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.

 - + it does not cut the binary before splitting. The bytes before and after + the scope are kept in the result. See the example below.

trim - -

Removes trailing empty parts of the result (as does trim in re:split/3)

 - +

Removes trailing empty parts of the result (as does trim + in re:split/3.

 trim_all -

Removes all empty parts of the result.

 - global - -

Repeats the split until the Subject is - exhausted. Conceptually the global option makes split work on - the positions returned by matches/3, - while it normally - works on the position returned by - match/3.

 - +

Repeats the split until Subject is + exhausted. Conceptually option global makes split work + on the positions returned by + matches/3, while it + normally works on the position returned by + match/3.

Example of the difference between a scope and taking the binary apart before splitting:

-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">>] - +2> binary:split(binary:part(<<"banana">>,{2,3}), [<<"a">>],[]). +[<<"n">>,<<"n">>]

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

- -

For a description of Pattern, see compile_pattern/1.

+ referencing Subject. This means that the data in + Subject is not copied to new binaries, and that + Subject cannot be garbage collected until the results + of the split are no longer referenced.

+

For a description of Pattern, see + compile_pattern/1. +

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