diff options
Diffstat (limited to 'lib/stdlib/doc')
| -rw-r--r-- | lib/stdlib/doc/src/erl_tar.xml | 4 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/gen_event.xml | 18 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/gen_fsm.xml | 19 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/gen_server.xml | 18 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/io_lib.xml | 14 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/rand.xml | 196 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/re.xml | 320 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/sets.xml | 2 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/shell.xml | 4 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/string.xml | 741 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/unicode.xml | 179 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/unicode_usage.xml | 70 |
12 files changed, 1363 insertions, 222 deletions
diff --git a/lib/stdlib/doc/src/erl_tar.xml b/lib/stdlib/doc/src/erl_tar.xml index f28d8b425b..fab7c832d5 100644 --- a/lib/stdlib/doc/src/erl_tar.xml +++ b/lib/stdlib/doc/src/erl_tar.xml @@ -292,6 +292,10 @@ <c>Fd</c> is assumed to be a file descriptor returned from function <c>file:open/2</c>.</p> <p>Otherwise, <c>Name</c> is to be a filename.</p> + <note><p>Leading slashes in tar member names will be removed before + writing the file. That is, absolute paths will be turned into + relative paths. There will be an info message written to the error + logger when paths are changed in this way.</p></note> </desc> </func> diff --git a/lib/stdlib/doc/src/gen_event.xml b/lib/stdlib/doc/src/gen_event.xml index 42e952fd46..56cb7974a2 100644 --- a/lib/stdlib/doc/src/gen_event.xml +++ b/lib/stdlib/doc/src/gen_event.xml @@ -579,6 +579,13 @@ gen_event:stop -----> Module:terminate/2 <v>Extra = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not export it. + If a release upgrade/downgrade with <c>Change={advanced,Extra}</c> + specified in the <c>.appup</c> file is made when <c>code_change/3</c> + isn't implemented the event handler will crash with an <c>undef</c> error + reason.</p> + </note> <p>This function is called for an installed event handler that is to update its internal state during a release upgrade/downgrade, that is, when the instruction @@ -759,6 +766,12 @@ gen_event:stop -----> Module:terminate/2 <v> Id = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_event</c> module provides a default + implementation of this function that logs about the unexpected + <c>Info</c> message, drops it and returns <c>{noreply, State}</c>.</p> + </note> <p>This function is called for each installed event handler when an event manager receives any other message than an event or a synchronous request (or a system message).</p> @@ -815,6 +828,11 @@ gen_event:stop -----> Module:terminate/2 <v> Args = Reason = Term = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_event</c> module provides a default + implementation without cleanup.</p> + </note> <p>Whenever an event handler is deleted from an event manager, this function is called. It is to be the opposite of <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso> diff --git a/lib/stdlib/doc/src/gen_fsm.xml b/lib/stdlib/doc/src/gen_fsm.xml index 719ab2b558..691a039e34 100644 --- a/lib/stdlib/doc/src/gen_fsm.xml +++ b/lib/stdlib/doc/src/gen_fsm.xml @@ -562,6 +562,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <v>Extra = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not export it. + If a release upgrade/downgrade with <c>Change={advanced,Extra}</c> + specified in the <c>appup</c> file is made when <c>code_change/4</c> + isn't implemented the process will crash with an <c>undef</c> exit + reason.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it is to update its internal state data during a release upgrade/downgrade, that is, when instruction <c>{update,Module,Change,...}</c>, @@ -686,6 +693,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <v> Reason = normal | term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_fsm</c> module provides a default + implementation of this function that logs about the unexpected + <c>Info</c> message, drops it and returns + <c>{next_state, StateName, StateData}</c>.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it receives any other message than a synchronous or asynchronous event (or a system message).</p> @@ -899,6 +913,11 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4 <v>StateData = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_fsm</c> module provides a default + implementation without cleanup.</p> + </note> <p>This function is called by a <c>gen_fsm</c> process when it is about to terminate. It is to be the opposite of <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso> diff --git a/lib/stdlib/doc/src/gen_server.xml b/lib/stdlib/doc/src/gen_server.xml index 662076b5f0..4540449792 100644 --- a/lib/stdlib/doc/src/gen_server.xml +++ b/lib/stdlib/doc/src/gen_server.xml @@ -504,6 +504,13 @@ gen_server:abcast -----> Module:handle_cast/2 <v>Reason = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not export it. + If a release upgrade/downgrade with <c>Change={advanced,Extra}</c> + specified in the <c>appup</c> file is made when <c>code_change/3</c> + isn't implemented the process will crash with an <c>undef</c> exit + reason.</p> + </note> <p>This function is called by a <c>gen_server</c> process when it is to update its internal state during a release upgrade/downgrade, that is, when the instruction <c>{update,Module,Change,...}</c>, @@ -690,6 +697,12 @@ gen_server:abcast -----> Module:handle_cast/2 <v> Reason = normal | term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_server</c> module provides a default + implementation of this function that logs about the unexpected + <c>Info</c> message, drops it and returns <c>{noreply, State}</c>.</p> + </note> <p>This function is called by a <c>gen_server</c> process when a time-out occurs or when it receives any other message than a synchronous or asynchronous request (or a system message).</p> @@ -750,6 +763,11 @@ gen_server:abcast -----> Module:handle_cast/2 <v>State = term()</v> </type> <desc> + <note> + <p>This callback is optional, so callback modules need not + export it. The <c>gen_server</c> module provides a default + implementation without cleanup.</p> + </note> <p>This function is called by a <c>gen_server</c> process when it is about to terminate. It is to be the opposite of <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso> diff --git a/lib/stdlib/doc/src/io_lib.xml b/lib/stdlib/doc/src/io_lib.xml index 931e50f6f2..5ae400da62 100644 --- a/lib/stdlib/doc/src/io_lib.xml +++ b/lib/stdlib/doc/src/io_lib.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2017</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -147,7 +147,7 @@ format string (that is, <c>~ts</c> or <c>~tc</c>), the resulting list can contain characters beyond the ISO Latin-1 character range (that is, numbers > 255). If so, the - result is not an ordinary Erlang <c>string()</c>, but can well be + result is still an ordinary Erlang <c>string()</c>, and can well be used in any context where Unicode data is allowed.</p> </desc> </func> @@ -384,6 +384,16 @@ </func> <func> + <name name="write_atom_as_latin1" arity="1"/> + <fsummary>Write an atom.</fsummary> + <desc> + <p>Returns the list of characters needed to print atom + <c><anno>Atom</anno></c>. Non-Latin-1 characters + are escaped.</p> + </desc> + </func> + + <func> <name name="write_char" arity="1"/> <fsummary>Write a character.</fsummary> <desc> diff --git a/lib/stdlib/doc/src/rand.xml b/lib/stdlib/doc/src/rand.xml index 8745e16908..e06d7e467d 100644 --- a/lib/stdlib/doc/src/rand.xml +++ b/lib/stdlib/doc/src/rand.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>2015</year><year>2016</year> + <year>2015</year><year>2017</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -50,26 +50,73 @@ <p>The following algorithms are provided:</p> <taglist> - <tag><c>exsplus</c></tag> + <tag><c>exrop</c></tag> <item> - <p>Xorshift116+, 58 bits precision and period of 2^116-1</p> + <p>Xoroshiro116+, 58 bits precision and period of 2^116-1</p> <p>Jump function: equivalent to 2^64 calls</p> </item> - <tag><c>exs64</c></tag> - <item> - <p>Xorshift64*, 64 bits precision and a period of 2^64-1</p> - <p>Jump function: not available</p> - </item> - <tag><c>exs1024</c></tag> + <tag><c>exs1024s</c></tag> <item> <p>Xorshift1024*, 64 bits precision and a period of 2^1024-1</p> <p>Jump function: equivalent to 2^512 calls</p> </item> + <tag><c>exsp</c></tag> + <item> + <p>Xorshift116+, 58 bits precision and period of 2^116-1</p> + <p>Jump function: equivalent to 2^64 calls</p> + <p> + This is a corrected version of the previous default algorithm, + that now has been superseeded by Xoroshiro116+ (<c>exrop</c>). + Since there is no native 58 bit rotate instruction this + algorithm executes a little (say < 15%) faster than <c>exrop</c>. + See the + <url href="http://xorshift.di.unimi.it">algorithms' homepage</url>. + </p> + </item> </taglist> - <p>The default algorithm is <c>exsplus</c>. If a specific algorithm is + <p> + The default algorithm is <c>exrop</c> (Xoroshiro116+). + If a specific algorithm is required, ensure to always use <seealso marker="#seed-1"> - <c>seed/1</c></seealso> to initialize the state.</p> + <c>seed/1</c></seealso> to initialize the state. + </p> + + <p> + Undocumented (old) algorithms are deprecated but still implemented + so old code relying on them will produce + the same pseudo random sequences as before. + </p> + + <note> + <p> + There were a number of problems in the implementation + of the now undocumented algorithms, which is why + they are deprecated. The new algorithms are a bit slower + but do not have these problems: + </p> + <p> + Uniform integer ranges had a skew in the probability distribution + that was not noticable for small ranges but for large ranges + less than the generator's precision the probability to produce + a low number could be twice the probability for a high. + </p> + <p> + Uniform integer ranges larger than or equal to the generator's + precision used a floating point fallback that only calculated + with 52 bits which is smaller than the requested range + and therefore were not all numbers in the requested range + even possible to produce. + </p> + <p> + Uniform floats had a non-uniform density so small values + i.e less than 0.5 had got smaller intervals decreasing + as the generated value approached 0.0 although still uniformly + distributed for sufficiently large subranges. The new algorithms + produces uniformly distributed floats on the form N * 2.0^(-53) + hence equally spaced. + </p> + </note> <p>Every time a random number is requested, a state is used to calculate it and a new state is produced. The state can either be @@ -99,19 +146,19 @@ R1 = rand:uniform(),</pre> <p>Use a specified algorithm:</p> <pre> -_ = rand:seed(exs1024), +_ = rand:seed(exs1024s), R2 = rand:uniform(),</pre> <p>Use a specified algorithm with a constant seed:</p> <pre> -_ = rand:seed(exs1024, {123, 123534, 345345}), +_ = rand:seed(exs1024s, {123, 123534, 345345}), R3 = rand:uniform(),</pre> <p>Use the functional API with a non-constant seed:</p> <pre> -S0 = rand:seed_s(exsplus), +S0 = rand:seed_s(exrop), {R4, S1} = rand:uniform_s(S0),</pre> <p>Create a standard normal deviate:</p> @@ -119,28 +166,93 @@ S0 = rand:seed_s(exsplus), <pre> {SND0, S2} = rand:normal_s(S1),</pre> + <p>Create a normal deviate with mean -3 and variance 0.5:</p> + + <pre> +{ND0, S3} = rand:normal_s(-3, 0.5, S2),</pre> + <note> - <p>This random number generator is not cryptographically - strong. If a strong cryptographic random number generator is - needed, use one of functions in the - <seealso marker="crypto:crypto"><c>crypto</c></seealso> - module, for example, <seealso marker="crypto:crypto"> - <c>crypto:strong_rand_bytes/1</c></seealso>.</p> + <p>The builtin random number generator algorithms are not + cryptographically strong. If a cryptographically strong + random number generator is needed, use something like + <seealso marker="crypto:crypto#rand_seed-0"><c>crypto:rand_seed/0</c></seealso>. + </p> </note> + <p> + For all these generators the lowest bit(s) has got + a slightly less random behaviour than all other bits. + 1 bit for <c>exrop</c> (and <c>exsp</c>), + and 3 bits for <c>exs1024s</c>. + See for example the explanation in the + <url href="http://xoroshiro.di.unimi.it/xoroshiro128plus.c"> + Xoroshiro128+ + </url> + generator source code: + </p> + <pre> +Beside passing BigCrush, this generator passes the PractRand test suite +up to (and included) 16TB, with the exception of binary rank tests, +which fail due to the lowest bit being an LFSR; all other bits pass all +tests. We suggest to use a sign test to extract a random Boolean value.</pre> + <p> + If this is a problem; to generate a boolean + use something like this: + </p> + <pre>(rand:uniform(16) > 8)</pre> + <p> + And for a general range, with <c>N = 1</c> for <c>exrop</c>, + and <c>N = 3</c> for <c>exs1024s</c>: + </p> + <pre>(((rand:uniform(Range bsl N) - 1) bsr N) + 1)</pre> + <p> + The floating point generating functions in this module + waste the lowest bits when converting from an integer + so they avoid this snag. + </p> + + </description> <datatypes> <datatype> + <name name="builtin_alg"/> + </datatype> + <datatype> <name name="alg"/> </datatype> <datatype> + <name name="alg_handler"/> + </datatype> + <datatype> + <name name="alg_state"/> + </datatype> + <datatype> <name name="state"/> <desc><p>Algorithm-dependent state.</p></desc> </datatype> <datatype> <name name="export_state"/> - <desc><p>Algorithm-dependent state that can be printed or saved to - file.</p></desc> + <desc> + <p> + Algorithm-dependent state that can be printed or saved to file. + </p> + </desc> + </datatype> + <datatype> + <name name="exs64_state"/> + <desc><p>Algorithm specific internal state</p></desc> + </datatype> + <datatype> + <name name="exsplus_state"/> + <desc><p>Algorithm specific internal state</p></desc> + </datatype> + <datatype> + <name name="exs1024_state"/> + <desc><p>Algorithm specific internal state</p></desc> + </datatype> + <datatype> + <name name="exrop_state"/> + <desc><p>Algorithm specific internal state</p></desc> </datatype> </datatypes> @@ -201,6 +313,15 @@ S0 = rand:seed_s(exsplus), </func> <func> + <name name="normal" arity="2"/> + <fsummary>Return a normal distributed random float.</fsummary> + <desc> + <p>Returns a normal N(Mean, Variance) deviate float + and updates the state in the process dictionary.</p> + </desc> + </func> + + <func> <name name="normal_s" arity="1"/> <fsummary>Return a standard normal distributed random float.</fsummary> <desc> @@ -211,12 +332,24 @@ S0 = rand:seed_s(exsplus), </func> <func> + <name name="normal_s" arity="3"/> + <fsummary>Return a normal distributed random float.</fsummary> + <desc> + <p>Returns, for a specified state, a normal N(Mean, Variance) + deviate float and a new state.</p> + </desc> + </func> + + <func> <name name="seed" arity="1"/> <fsummary>Seed random number generator.</fsummary> <desc> <marker id="seed-1"/> - <p>Seeds random number generation with the specifed algorithm and - time-dependent data if <anno>AlgOrExpState</anno> is an algorithm.</p> + <p> + Seeds random number generation with the specifed algorithm and + time-dependent data if <c><anno>AlgOrStateOrExpState</anno></c> + is an algorithm. + </p> <p>Otherwise recreates the exported seed in the process dictionary, and returns the state. See also <seealso marker="#export_seed-0"><c>export_seed/0</c></seealso>.</p> @@ -236,8 +369,11 @@ S0 = rand:seed_s(exsplus), <name name="seed_s" arity="1"/> <fsummary>Seed random number generator.</fsummary> <desc> - <p>Seeds random number generation with the specifed algorithm and - time-dependent data if <anno>AlgOrExpState</anno> is an algorithm.</p> + <p> + Seeds random number generation with the specifed algorithm and + time-dependent data if <c><anno>AlgOrStateOrExpState</anno></c> + is an algorithm. + </p> <p>Otherwise recreates the exported seed and returns the state. See also <seealso marker="#export_seed-0"> <c>export_seed/0</c></seealso>.</p> @@ -258,7 +394,7 @@ S0 = rand:seed_s(exsplus), <fsummary>Return a random float.</fsummary> <desc><marker id="uniform-0"/> <p>Returns a random float uniformly distributed in the value - range <c>0.0 < <anno>X</anno> < 1.0</c> and + range <c>0.0 =< <anno>X</anno> < 1.0</c> and updates the state in the process dictionary.</p> </desc> </func> @@ -269,7 +405,7 @@ S0 = rand:seed_s(exsplus), <desc><marker id="uniform-1"/> <p>Returns, for a specified integer <c><anno>N</anno> >= 1</c>, a random integer uniformly distributed in the value range - <c>1 <= <anno>X</anno> <= <anno>N</anno></c> and + <c>1 =< <anno>X</anno> =< <anno>N</anno></c> and updates the state in the process dictionary.</p> </desc> </func> @@ -279,7 +415,7 @@ S0 = rand:seed_s(exsplus), <fsummary>Return a random float.</fsummary> <desc> <p>Returns, for a specified state, random float - uniformly distributed in the value range <c>0.0 < + uniformly distributed in the value range <c>0.0 =< <anno>X</anno> < 1.0</c> and a new state.</p> </desc> </func> @@ -290,7 +426,7 @@ S0 = rand:seed_s(exsplus), <desc> <p>Returns, for a specified integer <c><anno>N</anno> >= 1</c> and a state, a random integer uniformly distributed in the value - range <c>1 <= <anno>X</anno> <= <anno>N</anno></c> and a + range <c>1 =< <anno>X</anno> =< <anno>N</anno></c> and a new state.</p> </desc> </func> diff --git a/lib/stdlib/doc/src/re.xml b/lib/stdlib/doc/src/re.xml index 7f4f0aa18c..078ca0e38c 100644 --- a/lib/stdlib/doc/src/re.xml +++ b/lib/stdlib/doc/src/re.xml @@ -5,7 +5,7 @@ <header> <copyright> <year>2007</year> - <year>2016</year> + <year>2017</year> <holder>Ericsson AB, All Rights Reserved</holder> </copyright> <legalnotice> @@ -45,9 +45,10 @@ <p>The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and - some parts of the library go beyond what PCRE offers. The sections of - the PCRE documentation that are relevant to this module are included - here.</p> + some parts of the library go beyond what PCRE offers. Currently + PCRE version 8.40 (release date 2017-01-11) is used. The sections + of the PCRE documentation that are relevant to this module are + included here.</p> <note> <p>The Erlang literal syntax for strings uses the "\" @@ -78,6 +79,14 @@ <funcs> <func> + <name name="version" arity="0"/> + <fsummary>Gives the PCRE version of the system in a string format</fsummary> + <desc> + <p>The return of this function is a string with the PCRE version of the system that was used in the Erlang/OTP compilation.</p> + </desc> + </func> + + <func> <name name="compile" arity="1"/> <fsummary>Compile a regular expression into a match program</fsummary> <desc> @@ -149,13 +158,25 @@ </item> <tag><c>extended</c></tag> <item> - <p>Whitespace data characters in the pattern are ignored except - when escaped or inside a character class. Whitespace does not - include character 'vt' (ASCII 11). Characters between an - unescaped <c>#</c> outside a character class and the next newline, - inclusive, are also ignored. This is equivalent to Perl option - <c>/x</c> and can be changed within a pattern by a <c>(?x)</c> - option setting.</p> + <p>If this option is set, most white space characters in the + pattern are totally ignored except when escaped or inside a + character class. However, white space is not allowed within + sequences such as <c>(?></c> that introduce various + parenthesized subpatterns, nor within a numerical quantifier + such as <c>{1,3}</c>. However, ignorable white space is permitted + between an item and a following quantifier and between a + quantifier and a following + that indicates possessiveness. + </p> + <p>White space did not used to include the VT character (code + 11), because Perl did not treat this character as white space. + However, Perl changed at release 5.18, so PCRE followed at + release 8.34, and VT is now treated as white space. + </p> + <p>This also causes characters between an unescaped # + outside a character class and the next newline, inclusive, to + be ignored. This is equivalent to Perl's <c>/x</c> option, and it + can be changed within a pattern by a <c>(?x)</c> option setting. + </p> <p>With this option, comments inside complicated patterns can be included. However, notice that this applies only to data characters. Whitespace characters can never appear within special @@ -1321,6 +1342,8 @@ re:split("Erlang","[lg]",[{return,list},{parts,4}]).</code> VM. Notice that the recursion limit does not affect the stack depth of the VM, as PCRE for Erlang is compiled in such a way that the match function never does recursion on the C stack.</p> + <p>Note that <c>LIMIT_MATCH</c> and <c>LIMIT_RECURSION</c> can only reduce + the value of the limits set by the caller, not increase them.</p> </section> <section> @@ -1444,12 +1467,17 @@ Pattern PCRE matches Perl matches <tag>\n</tag><item>Line feed (hex 0A)</item> <tag>\r</tag><item>Carriage return (hex 0D)</item> <tag>\t</tag><item>Tab (hex 09)</item> + <tag>\0dd</tag><item>Character with octal code 0dd</item> <tag>\ddd</tag><item>Character with octal code ddd, or back reference </item> + <tag>\o{ddd..}</tag><item>character with octal code ddd..</item> <tag>\xhh</tag><item>Character with hex code hh</item> <tag>\x{hhh..}</tag><item>Character with hex code hhh..</item> </taglist> + <note><p>Note that \0dd is always an octal code, and that \8 and \9 are + the literal characters "8" and "9".</p></note> + <p>The precise effect of \cx on ASCII characters is as follows: if x is a lowercase letter, it is converted to upper case. Then bit 6 of the character (hex 40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A @@ -1461,50 +1489,38 @@ Pattern PCRE matches Perl matches <p>The \c facility was designed for use with ASCII characters, but with the extension to Unicode it is even less useful than it once was.</p> - <p>By default, after \x, from zero to two hexadecimal digits are read - (letters can be in upper or lower case). Any number of hexadecimal digits - can appear between \x{ and }, but the character code is constrained as - follows:</p> - - <taglist> - <tag>8-bit non-Unicode mode</tag> - <item>< 0x100</item> - <tag>8-bit UTF-8 mode</tag> - <item>< 0x10ffff and a valid code point</item> - </taglist> - - <p>Invalid Unicode code points are the range 0xd800 to 0xdfff (the so-called - "surrogate" code points), and 0xffef.</p> - - <p>If characters other than hexadecimal digits appear between \x{ and }, - or if there is no terminating }, this form of escape is not recognized. - Instead, the initial \x is interpreted as a basic hexadecimal escape, - with no following digits, giving a character whose value is zero.</p> - - <p>Characters whose value is < 256 can be defined by either of the two - syntaxes for \x. There is no difference in the way they are handled. For - example, \xdc is the same as \x{dc}.</p> - <p>After \0 up to two further octal digits are read. If there are fewer than - two digits, only those that are present are used. Thus the sequence - \0\x\07 specifies two binary zeros followed by a BEL character (code value - 7). Ensure to supply two digits after the initial zero if the pattern - character that follows is itself an octal digit.</p> + two digits, just those that are present are used. Thus the sequence + \0\x\015 specifies two binary zeros followed by a CR character (code value + 13). Make sure you supply two digits after the initial zero if the pattern + character that follows is itself an octal digit.</p> + + <p>The escape \o must be followed by a sequence of octal digits, enclosed + in braces. An error occurs if this is not the case. This escape is a recent + addition to Perl; it provides way of specifying character code points as + octal numbers greater than 0777, and it also allows octal numbers and back + references to be unambiguously specified.</p> + + <p>For greater clarity and unambiguity, it is best to avoid following \ by + a digit greater than zero. Instead, use \o{} or \x{} to specify character + numbers, and \g{} to specify back references. The following paragraphs + describe the old, ambiguous syntax.</p> <p>The handling of a backslash followed by a digit other than 0 is - complicated. Outside a character class, PCRE reads it and any following - digits as a decimal number. If the number is < 10, or if there have + complicated, and Perl has changed in recent releases, causing PCRE also + to change. Outside a character class, PCRE reads the digit and any following + digits as a decimal number. If the number is < 8, or if there have been at least that many previous capturing left parentheses in the expression, the entire sequence is taken as a <em>back reference</em>. A description of how this works is provided later, following the discussion of parenthesized subpatterns.</p> - <p>Inside a character class, or if the decimal number is > 9 and there - have not been that many capturing subpatterns, PCRE re-reads up to three - octal digits following the backslash, and uses them to generate a data - character. Any subsequent digits stand for themselves. The value of the - character is constrained in the same way as characters specified in - hexadecimal. For example:</p> + <p>Inside a character class, or if the decimal number following \ is > + 7 and there have not been that many capturing subpatterns, PCRE handles + \8 and \9 as the literal characters "8" and "9", and otherwise re-reads + up to three octal digits following the backslash, and using them to + generate a data character. Any subsequent digits stand for themselves. + For example:</p> <taglist> <tag>\040</tag> @@ -1526,12 +1542,38 @@ Pattern PCRE matches Perl matches <tag>\377</tag> <item>Can be a back reference, otherwise value 255 (decimal)</item> <tag>\81</tag> - <item>Either a back reference, or a binary zero followed by the two - characters "8" and "1"</item> + <item>Either a back reference, or the two characters "8" and "1"</item> </taglist> - <p>Notice that octal values >= 100 must not be introduced by a leading - zero, as no more than three octal digits are ever read.</p> + <p>Notice that octal values >= 100 that are specified using this syntax + must not be introduced by a leading zero, as no more than three octal digits + are ever read.</p> + + <p>By default, after \x that is not followed by {, from zero to two + hexadecimal digits are read (letters can be in upper or lower case). Any + number of hexadecimal digits may appear between \x{ and }. If a character + other than a hexadecimal digit appears between \x{ and }, or if there is no + terminating }, an error occurs. + </p> + + <p>Characters whose value is less than 256 can be defined by either of the + two syntaxes for \x. There is no difference in the way they are handled. For + example, \xdc is exactly the same as \x{dc}.</p> + + <p><em>Constraints on character values</em></p> + + <p>Characters that are specified using octal or hexadecimal numbers are + limited to certain values, as follows:</p> + <taglist> + <tag>8-bit non-UTF mode</tag> + <item><p>< 0x100</p></item> + <tag>8-bit UTF-8 mode</tag> + <item><p>< 0x10ffff and a valid codepoint</p></item> + </taglist> + <p>Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the + so-called "surrogate" codepoints), and 0xffef.</p> + + <p><em>Escape sequences in character classes</em></p> <p>All the sequences that define a single character value can be used both inside and outside character classes. Also, inside a character class, \b @@ -1597,11 +1639,14 @@ Pattern PCRE matches Perl matches appropriate type. If the current matching point is at the end of the subject string, all fail, as there is no character to match.</p> - <p>For compatibility with Perl, \s does not match the VT character - (code 11). This makes it different from the Posix "space" class. The \s - characters are HT (9), LF (10), FF (12), CR (13), and space (32). If "use - locale;" is included in a Perl script, \s can match the VT character. In - PCRE, it never does.</p> + <p>For compatibility with Perl, \s did not used to match the VT character (code + 11), which made it different from the the POSIX "space" class. However, Perl + added VT at release 5.18, and PCRE followed suit at release 8.34. The default + \s characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space + (32), which are defined as white space in the "C" locale. This list may vary if + locale-specific matching is taking place. For example, in some locales the + "non-breaking space" character (\xA0) is recognized as white space, and in + others the VT character is not.</p> <p>A "word" character is an underscore or any character that is a letter or a digit. By default, the definition of letters and digits is controlled by @@ -1619,9 +1664,9 @@ Pattern PCRE matches Perl matches <taglist> <tag>\d</tag><item>Any character that \p{Nd} matches (decimal digit) </item> - <tag>\s</tag><item>Any character that \p{Z} matches, plus HT, LF, FF, CR + <tag>\s</tag><item>Any character that \p{Z} or \h or \v </item> - <tag>\w</tag><item>Any character that \p{L} or \p{N} matches, plus + <tag>\w</tag><item>Any character that matches \p{L} or \p{N} matches, plus underscore</item> </taglist> @@ -1769,6 +1814,7 @@ Pattern PCRE matches Perl matches <item>Avestan</item> <item>Balinese</item> <item>Bamum</item> + <item>Bassa_Vah</item> <item>Batak</item> <item>Bengali</item> <item>Bopomofo</item> @@ -1777,6 +1823,7 @@ Pattern PCRE matches Perl matches <item>Buhid</item> <item>Canadian_Aboriginal</item> <item>Carian</item> + <item>Caucasian_Albanian</item> <item>Chakma</item> <item>Cham</item> <item>Cherokee</item> @@ -1787,11 +1834,14 @@ Pattern PCRE matches Perl matches <item>Cyrillic</item> <item>Deseret</item> <item>Devanagari</item> + <item>Duployan</item> <item>Egyptian_Hieroglyphs</item> + <item>Elbasan</item> <item>Ethiopic</item> <item>Georgian</item> <item>Glagolitic</item> <item>Gothic</item> + <item>Grantha</item> <item>Greek</item> <item>Gujarati</item> <item>Gurmukhi</item> @@ -1811,40 +1861,56 @@ Pattern PCRE matches Perl matches <item>Kayah_Li</item> <item>Kharoshthi</item> <item>Khmer</item> + <item>Khojki</item> + <item>Khudawadi</item> <item>Lao</item> <item>Latin</item> <item>Lepcha</item> <item>Limbu</item> + <item>Linear_A</item> <item>Linear_B</item> <item>Lisu</item> <item>Lycian</item> <item>Lydian</item> + <item>Mahajani</item> <item>Malayalam</item> <item>Mandaic</item> + <item>Manichaean</item> <item>Meetei_Mayek</item> + <item>Mende_Kikakui</item> <item>Meroitic_Cursive</item> <item>Meroitic_Hieroglyphs</item> <item>Miao</item> + <item>Modi</item> <item>Mongolian</item> + <item>Mro</item> <item>Myanmar</item> + <item>Nabataean</item> <item>New_Tai_Lue</item> <item>Nko</item> <item>Ogham</item> + <item>Ol_Chiki</item> <item>Old_Italic</item> + <item>Old_North_Arabian</item> + <item>Old_Permic</item> <item>Old_Persian</item> <item>Oriya</item> <item>Old_South_Arabian</item> <item>Old_Turkic</item> - <item>Ol_Chiki</item> <item>Osmanya</item> + <item>Pahawh_Hmong</item> + <item>Palmyrene</item> + <item>Pau_Cin_Hau</item> <item>Phags_Pa</item> <item>Phoenician</item> + <item>Psalter_Pahlavi</item> <item>Rejang</item> <item>Runic</item> <item>Samaritan</item> <item>Saurashtra</item> <item>Sharada</item> <item>Shavian</item> + <item>Siddham</item> <item>Sinhala</item> <item>Sora_Sompeng</item> <item>Sundanese</item> @@ -1862,8 +1928,10 @@ Pattern PCRE matches Perl matches <item>Thai</item> <item>Tibetan</item> <item>Tifinagh</item> + <item>Tirhuta</item> <item>Ugaritic</item> <item>Vai</item> + <item>Warang_Citi</item> <item>Yi</item> </list> @@ -2001,10 +2069,10 @@ Pattern PCRE matches Perl matches <p>In addition to the standard Unicode properties described earlier, PCRE supports four more that make it possible to convert traditional escape - sequences, such as \w and \s, and Posix character classes to use Unicode + sequences, such as \w and \s to use Unicode properties. PCRE uses these non-standard, non-Perl properties internally - when <c>PCRE_UCP</c> is set. However, they can also be used explicitly. - The properties are as follows:</p> + when the <c>ucp</c> option is passed. However, they can also be used + explicitly. The properties are as follows:</p> <taglist> <tag>Xan</tag> @@ -2030,6 +2098,16 @@ Pattern PCRE matches Perl matches </item> </taglist> + <p>Perl and POSIX space are now the same. Perl added VT to its space + character set at release 5.18 and PCRE changed at release 8.34.</p> + + <p>Xan matches characters that have either the L (letter) or the N (number) + property. Xps matches the characters tab, linefeed, vertical tab, form feed, + or carriage return, and any other character that has the Z (separator) + property. Xsp is the same as Xps; it used to exclude vertical tab, for Perl + compatibility, but Perl changed, and so PCRE followed at release 8.34. Xwd + matches the same characters as Xan, plus underscore. + </p> <p>There is another non-standard property, Xuc, which matches any character that can be represented by a Universal Character Name in C++ and other programming languages. These are the characters $, @, ` (grave accent), @@ -2062,7 +2140,9 @@ foo\Kbar</code> <p>Perl documents that the use of \K within assertions is "not well defined". In PCRE, \K is acted upon when it occurs inside positive - assertions, but is ignored in negative assertions.</p> + assertions, but is ignored in negative assertions. Note that when a + pattern such as (?=ab\K) matches, the reported start of the match can + be greater than the end of the match.</p> <p><em>Simple Assertions</em></p> @@ -2301,7 +2381,8 @@ foo\Kbar</code> m, inclusive. If a minus character is required in a class, it must be escaped with a backslash or appear in a position where it cannot be interpreted as indicating a range, typically as the first or last - character in the class.</p> + character in the class, or immediately after a range. For example, [b-d-z] + matches letters in the range b to d, a hyphen character, or z.</p> <p>The literal character "]" cannot be the end character of a range. A pattern such as [W-]46] is interpreted as a class of two characters ("W" @@ -2311,6 +2392,11 @@ foo\Kbar</code> followed by two other characters. The octal or hexadecimal representation of "]" can also be used to end a range.</p> + <p>An error is generated if a POSIX character class (see below) or an + escape sequence other than one that defines a single character appears at + a point where a range ending character is expected. For example, [z-\xff] + is valid, but [A-\d] and [A-[:digit:]] are not.</p> + <p>Ranges operate in the collating sequence of character values. They can also be used for characters specified numerically, for example, [\000-\037]. Ranges can include any characters that are valid for the @@ -2353,7 +2439,8 @@ foo\Kbar</code> range)</item> <item>Circumflex (only at the start)</item> <item>Opening square bracket (only when it can be interpreted as - introducing a Posix class name; see the next section)</item> + introducing a Posix class name, or for a special compatibility + feature; see the next two sections)</item> <item>Terminating closing square bracket</item> </list> @@ -2385,16 +2472,18 @@ foo\Kbar</code> <tag>print</tag><item>Printing characters, including space</item> <tag>punct</tag><item>Printing characters, excluding letters, digits, and space</item> - <tag>space</tag><item>Whitespace (not quite the same as \s)</item> + <tag>space</tag><item>Whitespace (the same as \s from PCRE 8.34)</item> <tag>upper</tag><item>Uppercase letters</item> <tag>word</tag><item>"Word" characters (same as \w)</item> <tag>xdigit</tag><item>Hexadecimal digits</item> </taglist> - <p>The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), - and space (32). Notice that this list includes the VT character (code 11). - This makes "space" different to \s, which does not include VT (for Perl - compatibility).</p> + <p>The default "space" characters are HT (9), LF (10), VT (11), FF (12), + CR (13), and space (32). If locale-specific matching is taking place, the + list of space characters may be different; there may be fewer or more of + them. "Space" used to be different to \s, which did not include VT, for + Perl compatibility. However, Perl changed at release 5.18, and PCRE followed + at release 8.34. "Space" and \s now match the same set of characters.</p> <p>The name "word" is a Perl extension, and "blank" is a GNU extension from Perl 5.8. Another Perl extension is negation, which is indicated by a ^ @@ -2408,11 +2497,11 @@ foo\Kbar</code> "ch" is a "collating element", but these are not supported, and an error is given if they are encountered.</p> - <p>By default, in UTF modes, characters with values > 255 do not match + <p>By default, characters with values > 255 do not match any of the Posix character classes. However, if option <c>PCRE_UCP</c> is passed to <c>pcre_compile()</c>, some of the classes are changed so that - Unicode character properties are used. This is achieved by replacing the - Posix classes by other sequences, as follows:</p> + Unicode character properties are used. This is achieved by replacing + certain Posix classes by other sequences, as follows:</p> <taglist> <tag>[:alnum:]</tag><item>Becomes <em>\p{Xan}</em></item> @@ -2425,9 +2514,49 @@ foo\Kbar</code> <tag>[:word:]</tag><item>Becomes <em>\p{Xwd}</em></item> </taglist> - <p>Negated versions, such as [:^alpha:], use \P instead of \p. The other - Posix classes are unchanged, and match only characters with code points - < 256.</p> + <p>Negated versions, such as [:^alpha:], use \P instead of \p. Three other + POSIX classes are handled specially in UCP mode:</p> + <taglist> + <tag>[:graph:]</tag> + <item><p>This matches characters that have glyphs that mark the page + when printed. In Unicode property terms, it matches all characters with + the L, M, N, P, S, or Cf properties, except for:</p> + <taglist> + <tag>U+061C</tag><item><p>Arabic Letter Mark</p></item> + <tag>U+180E</tag><item><p>Mongolian Vowel Separator</p></item> + <tag>U+2066 - U+2069</tag><item><p>Various "isolate"s</p></item> + </taglist> + </item> + <tag>[:print:]</tag> + <item><p>This matches the same characters as [:graph:] plus space + characters that are not controls, that is, characters with the Zs + property.</p></item> + <tag>[:punct:]</tag><item><p>This matches all characters that have + the Unicode P (punctuation) property, plus those characters whose code + points are less than 128 that have the S (Symbol) property.</p></item> + </taglist> + <p>The other POSIX classes are unchanged, and match only characters with + code points less than 128. + </p> + + <p><em>Compatibility Feature for Word Boundaries</em></p> + + <p>In the POSIX.2 compliant library that was included in 4.4BSD Unix, + the ugly syntax [[:<:]] and [[:>:]] is used for matching "start + of word" and "end of word". PCRE treats these items as follows:</p> + <taglist> + <tag>[[:<:]]</tag><item><p>is converted to \b(?=\w)</p></item> + <tag>[[:>:]]</tag><item><p>is converted to \b(?<=\w)</p></item> + </taglist> + <p>Only these exact character sequences are recognized. A sequence such as + [a[:<:]b] provokes error for an unrecognized POSIX class name. This + support is not compatible with Perl. It is provided to help migrations from + other environments, and is best not used in any new patterns. Note that \b + matches at the start and the end of a word (see "Simple assertions" above), + and in a Perl-style pattern the preceding or following character normally + shows which is wanted, without the need for the assertions that are used + above in order to give exactly the POSIX behaviour.</p> + </section> <section> @@ -2476,8 +2605,7 @@ gilbert|sullivan</code> <p>When one of these option changes occurs at top-level (that is, not inside subpattern parentheses), the change applies to the remainder of the - pattern that follows. If the change is placed right at the start of a - pattern, PCRE extracts it into the global options.</p> + pattern that follows.</p> <p>An option change within a subpattern (see section <seealso marker="#sect11">Subpatterns</seealso>) affects only that part of the subpattern that follows it. So, the following matches abc and aBc and @@ -2645,9 +2773,9 @@ the ((?:red|white) (king|queen))</code> parentheses from other parts of the pattern, such as back references, recursion, and conditions, can be made by name and by number.</p> - <p>Names consist of up to 32 alphanumeric characters and underscores. Named - capturing parentheses are still allocated numbers as well as names, - exactly as if the names were not present. + <p>Names consist of up to 32 alphanumeric characters and underscores, but + must start with a non-digit. Named capturing parentheses are still allocated + numbers as well as names, exactly as if the names were not present. The <c>capture</c> specification to <seealso marker="#run/3"> <c>run/3</c></seealso> can use named values if they are present in the regular expression.</p> @@ -3118,7 +3246,14 @@ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</code> purposes of numbering the capturing subpatterns in the whole pattern. However, substring capturing is done only for positive assertions. (Perl sometimes, but not always, performs capturing in negative assertions.)</p> - + <warning> + <p>If a positive assertion containing one or more capturing subpatterns + succeeds, but failure to match later in the pattern causes backtracking over + this assertion, the captures within the assertion are reset only if no higher + numbered captures are already set. This is, unfortunately, a fundamental + limitation of the current implementation, and as PCRE1 is now in + maintenance-only status, it is unlikely ever to change.</p> + </warning> <p>For compatibility with Perl, assertion subpatterns can be repeated. However, it makes no sense to assert the same thing many times, the side effect of capturing parentheses can occasionally be useful. In practice, @@ -3371,12 +3506,7 @@ abcd$</code> <p>Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a used subpattern by name. For compatibility with earlier versions of PCRE, which had this facility before Perl, the syntax (?(name)...) is also - recognized. However, there is a possible ambiguity with this syntax, as - subpattern names can consist entirely of digits. PCRE looks first for a - named subpattern; if it cannot find one and the name consists entirely of - digits, PCRE looks for a subpattern of that number, which must be > 0. - Using subpattern names that consist entirely of digits is not - recommended.</p> + recognized.</p> <p>Rewriting the previous example to use a named subpattern gives:</p> @@ -3958,11 +4088,13 @@ a+(*COMMIT)b</code> 2> re:run("xyzabc","(*COMMIT)abc",[{capture,all,list},no_start_optimize]). nomatch</code> - <p>PCRE knows that any match must start with "a", so the optimization skips - along the subject to "a" before running the first match attempt, which - succeeds. When the optimization is disabled by option - <c>no_start_optimize</c>, the match starts at "x" and so the (*COMMIT) - causes it to fail without trying any other starting points.</p> + <p>For this pattern, PCRE knows that any match must start with "a", so the + optimization skips along the subject to "a" before applying the pattern to the + first set of data. The match attempt then succeeds. In the second call the + <c>no_start_optimize</c> disables the optimization that skips along to the + first character. The pattern is now applied starting at "x", and so the + (*COMMIT) causes the match to fail without trying any other starting + points.</p> <p>The following verb causes the match to fail at the current starting position in the subject if there is a later matching failure that causes @@ -4138,7 +4270,7 @@ A (B(*THEN)C | (*FAIL)) | D</code> ...(*COMMIT)(*PRUNE)...</code> <p>If there is a matching failure to the right, backtracking onto (*PRUNE) - cases it to be triggered, and its action is taken. There can never be a + causes it to be triggered, and its action is taken. There can never be a backtrack onto (*COMMIT).</p> <p><em>Backtracking Verbs in Repeated Groups</em></p> diff --git a/lib/stdlib/doc/src/sets.xml b/lib/stdlib/doc/src/sets.xml index 44dc104645..4dc5d68151 100644 --- a/lib/stdlib/doc/src/sets.xml +++ b/lib/stdlib/doc/src/sets.xml @@ -40,7 +40,7 @@ <p>This module provides the same interface as the <seealso marker="ordsets"><c>ordsets(3)</c></seealso> module - but with a defined representation. One difference is + but with an undefined representation. One difference is that while this module considers two elements as different if they do not match (<c>=:=</c>), <c>ordsets</c> considers two elements as different if and only if they do not compare equal (<c>==</c>).</p> diff --git a/lib/stdlib/doc/src/shell.xml b/lib/stdlib/doc/src/shell.xml index f52bc39deb..ab62c2fcdd 100644 --- a/lib/stdlib/doc/src/shell.xml +++ b/lib/stdlib/doc/src/shell.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2016</year> + <year>1996</year><year>2017</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -854,7 +854,7 @@ q - quit erlang <c>{history, N}</c>, where <c>N</c> is the current command number. The function is to return a list of characters or an atom. This constraint is because of the Erlang I/O protocol. Unicode characters - beyond code point 255 are allowed in the list. Notice + beyond code point 255 are allowed in the list and the atom. Notice that in restricted mode the call <c>Mod:Func(L)</c> must be allowed or the default shell prompt function is called.</p> </section> diff --git a/lib/stdlib/doc/src/string.xml b/lib/stdlib/doc/src/string.xml index dddedf1132..dc83c40a9a 100644 --- a/lib/stdlib/doc/src/string.xml +++ b/lib/stdlib/doc/src/string.xml @@ -36,8 +36,613 @@ <modulesummary>String processing functions.</modulesummary> <description> <p>This module provides functions for string processing.</p> + <p>A string in this module is represented by <seealso marker="unicode#type-chardata"> + <c>unicode:chardata()</c></seealso>, that is, a list of codepoints, + binaries with UTF-8-encoded codepoints + (<em>UTF-8 binaries</em>), or a mix of the two.</p> + <code> +"abcd" is a valid string +<<"abcd">> is a valid string +["abcd"] is a valid string +<<"abc..åäö"/utf8>> is a valid string +<<"abc..åäö">> is NOT a valid string, + but a binary with Latin-1-encoded codepoints +[<<"abc">>, "..åäö"] is a valid string +[atom] is NOT a valid string</code> + <p> + This module operates on grapheme clusters. A <em>grapheme cluster</em> + is a user-perceived character, which can be represented by several + codepoints. + </p> + <code> +"å" [229] or [97, 778] +"e̊" [101, 778]</code> + <p> + The string length of "ß↑e̊" is 3, even though it is represented by the + codepoints <c>[223,8593,101,778]</c> or the UTF-8 binary + <c><<195,159,226,134,145,101,204,138>></c>. + </p> + <p> + Grapheme clusters for codepoints of class <c>prepend</c> + and non-modern (or decomposed) Hangul is not handled for performance + reasons in + <seealso marker="#find/3"><c>find/3</c></seealso>, + <seealso marker="#replace/3"><c>replace/3</c></seealso>, + <seealso marker="#split/2"><c>split/2</c></seealso>, + <seealso marker="#lexemes/2"><c>split/2</c></seealso> and + <seealso marker="#trim/3"><c>trim/3</c></seealso>. + </p> + <p> + Splitting and appending strings is to be done on grapheme clusters + borders. + There is no verification that the results of appending strings are + valid or normalized. + </p> + <p> + Most of the functions expect all input to be normalized to one form, + see for example <seealso marker="unicode#characters_to_nfc_list/1"> + <c>unicode:characters_to_nfc_list/1</c></seealso>. + </p> + <p> + Language or locale specific handling of input is not considered + in any function. + </p> + <p> + The functions can crash for non-valid input strings. For example, + the functions expect UTF-8 binaries but not all functions + verify that all binaries are encoded correctly. + </p> + <p> + Unless otherwise specified the return value type is the same as + the input type. That is, binary input returns binary output, + list input returns a list output, and mixed input can return a + mixed output.</p> + <code> +1> string:trim(" sarah "). +"sarah" +2> string:trim(<<" sarah ">>). +<<"sarah">> +3> string:lexemes("foo bar", " "). +["foo","bar"] +4> string:lexemes(<<"foo bar">>, " "). +[<<"foo">>,<<"bar">>]</code> + <p>This module has been reworked in Erlang/OTP 20 to + handle <seealso marker="unicode#type-chardata"> + <c>unicode:chardata()</c></seealso> and operate on grapheme + clusters. The <seealso marker="#oldapi"> <c>old + functions</c></seealso> that only work on Latin-1 lists as input + are still available but should not be + used. They will be deprecated in Erlang/OTP 21. + </p> </description> + <datatypes> + <datatype> + <name name="direction"/> + <name name="grapheme_cluster"/> + <desc> + <p>A user-perceived character, consisting of one or more + codepoints.</p> + </desc> + </datatype> + </datatypes> + + <funcs> + + <func> + <name name="casefold" arity="1"/> + <fsummary>Convert a string to a comparable string.</fsummary> + <desc> + <p> + Converts <c><anno>String</anno></c> to a case-agnostic + comparable string. Function <c>casefold/1</c> is preferred + over <c>lowercase/1</c> when two strings are to be compared + for equality. See also <seealso marker="#equal/4"><c>equal/4</c></seealso>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:casefold("Ω and ẞ SHARP S").</input> +"ω and ss sharp s"</pre> + </desc> + </func> + + <func> + <name name="chomp" arity="1"/> + <fsummary>Remove trailing end of line control characters.</fsummary> + <desc> + <p> + Returns a string where any trailing <c>\n</c> or + <c>\r\n</c> have been removed from <c><anno>String</anno></c>. + </p> + <p><em>Example:</em></p> + <pre> +182> <input>string:chomp(<<"\nHello\n\n">>).</input> +<<"\nHello">> +183> <input>string:chomp("\nHello\r\r\n").</input> +"\nHello\r"</pre> + </desc> + </func> + + <func> + <name name="equal" arity="2"/> + <name name="equal" arity="3"/> + <name name="equal" arity="4"/> + <fsummary>Test string equality.</fsummary> + <desc> + <p> + Returns <c>true</c> if <c><anno>A</anno></c> and + <c><anno>B</anno></c> are equal, otherwise <c>false</c>. + </p> + <p> + If <c><anno>IgnoreCase</anno></c> is <c>true</c> + the function does <seealso marker="#casefold/1"> + <c>casefold</c>ing</seealso> on the fly before the equality test. + </p> + <p>If <c><anno>Norm</anno></c> is not <c>none</c> + the function applies normalization on the fly before the equality test. + There are four available normalization forms: + <seealso marker="unicode#characters_to_nfc_list/1"> <c>nfc</c></seealso>, + <seealso marker="unicode#characters_to_nfd_list/1"> <c>nfd</c></seealso>, + <seealso marker="unicode#characters_to_nfkc_list/1"> <c>nfkc</c></seealso>, and + <seealso marker="unicode#characters_to_nfkd_list/1"> <c>nfkd</c></seealso>. + </p> + <p>By default, + <c><anno>IgnoreCase</anno></c> is <c>false</c> and + <c><anno>Norm</anno></c> is <c>none</c>.</p> + <p><em>Example:</em></p> + <pre> +1> <input>string:equal("åäö", <<"åäö"/utf8>>).</input> +true +2> <input>string:equal("åäö", unicode:characters_to_nfd_binary("åäö")).</input> +false +3> <input>string:equal("åäö", unicode:characters_to_nfd_binary("ÅÄÖ"), true, nfc).</input> +true</pre> + </desc> + </func> + + <func> + <name name="find" arity="2"/> + <name name="find" arity="3"/> + <fsummary>Find start of substring.</fsummary> + <desc> + <p> + Removes anything before <c><anno>SearchPattern</anno></c> in <c><anno>String</anno></c> + and returns the remainder of the string or <c>nomatch</c> if <c><anno>SearchPattern</anno></c> is not + found. + <c><anno>Dir</anno></c>, which can be <c>leading</c> or + <c>trailing</c>, indicates from which direction characters + are to be searched. + </p> + <p> + By default, <c><anno>Dir</anno></c> is <c>leading</c>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:find("ab..cd..ef", ".").</input> +"..cd..ef" +2> <input>string:find(<<"ab..cd..ef">>, "..", trailing).</input> +<<"..ef">> +3> <input>string:find(<<"ab..cd..ef">>, "x", leading).</input> +nomatch +4> <input>string:find("ab..cd..ef", "x", trailing).</input> +nomatch</pre> + </desc> + </func> + + <func> + <name name="is_empty" arity="1"/> + <fsummary>Check if the string is empty.</fsummary> + <desc> + <p>Returns <c>true</c> if <c><anno>String</anno></c> is the + empty string, otherwise <c>false</c>.</p> + <p><em>Example:</em></p> + <pre> +1> <input>string:is_empty("foo").</input> +false +2> <input>string:is_empty(["",<<>>]).</input> +true</pre> + </desc> + </func> + + <func> + <name name="length" arity="1"/> + <fsummary>Calculate length of the string.</fsummary> + <desc> + <p> + Returns the number of grapheme clusters in <c><anno>String</anno></c>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:length("ß↑e̊").</input> +3 +2> <input>string:length(<<195,159,226,134,145,101,204,138>>).</input> +3</pre> + </desc> + </func> + + <func> + <name name="lexemes" arity="2"/> + <fsummary>Split string into lexemes.</fsummary> + <desc> + <p> + Returns a list of lexemes in <c><anno>String</anno></c>, separated + by the grapheme clusters in <c><anno>SeparatorList</anno></c>. + </p> + <p> + Notice that, as shown in this example, two or more + adjacent separator graphemes clusters in <c><anno>String</anno></c> + are treated as one. That is, there are no empty + strings in the resulting list of lexemes. + See also <seealso marker="#split/3"><c>split/3</c></seealso> which returns + empty strings. + </p> + <p>Notice that <c>[$\r,$\n]</c> is one grapheme cluster.</p> + <p><em>Example:</em></p> + <pre> +1> <input>string:lexemes("abc de̊fxxghix jkl\r\nfoo", "x e" ++ [[$\r,$\n]]).</input> +["abc","de̊f","ghi","jkl","foo"] +2> <input>string:lexemes(<<"abc de̊fxxghix jkl\r\nfoo"/utf8>>, "x e" ++ [$\r,$\n]).</input> +[<<"abc">>,<<"de̊f"/utf8>>,<<"ghi">>,<<"jkl\r\nfoo">>]</pre> + </desc> + </func> + + <func> + <name name="lowercase" arity="1"/> + <fsummary>Convert a string to lowercase</fsummary> + <desc> + <p> + Converts <c><anno>String</anno></c> to lowercase. + </p> + <p> + Notice that function <seealso marker="#casefold/1"><c>casefold/1</c></seealso> + should be used when converting a string to + be tested for equality. + </p> + <p><em>Example:</em></p> + <pre> +2> <input>string:lowercase(string:uppercase("Michał")).</input> +"michał"</pre> + </desc> + </func> + + <func> + <name name="next_codepoint" arity="1"/> + <fsummary>Pick the first codepoint.</fsummary> + <desc> + <p> + Returns the first codepoint in <c><anno>String</anno></c> + and the rest of <c><anno>String</anno></c> in the tail. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:next_codepoint(unicode:characters_to_binary("e̊fg")).</input> +[101|<<"̊fg"/utf8>>]</pre> + </desc> + </func> + + <func> + <name name="next_grapheme" arity="1"/> + <fsummary>Pick the first grapheme cluster.</fsummary> + <desc> + <p> + Returns the first grapheme cluster in <c><anno>String</anno></c> + and the rest of <c><anno>String</anno></c> in the tail. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:next_grapheme(unicode:characters_to_binary("e̊fg")).</input> +["e̊"|<<"fg">>]</pre> + </desc> + </func> + + <func> + <name name="nth_lexeme" arity="3"/> + <fsummary>Pick the nth lexeme.</fsummary> + <desc> + <p>Returns lexeme number <c><anno>N</anno></c> in + <c><anno>String</anno></c>, where lexemes are separated by + the grapheme clusters in <c><anno>SeparatorList</anno></c>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:nth_lexeme("abc.de̊f.ghiejkl", 3, ".e").</input> +"ghi"</pre> + </desc> + </func> + + <func> + <name name="pad" arity="2"/> + <name name="pad" arity="3"/> + <name name="pad" arity="4"/> + <fsummary>Pad a string to given length.</fsummary> + <desc> + <p> + Pads <c><anno>String</anno></c> to <c><anno>Length</anno></c> with + grapheme cluster <c><anno>Char</anno></c>. + <c><anno>Dir</anno></c>, which can be <c>leading</c>, <c>trailing</c>, + or <c>both</c>, indicates where the padding should be added. + </p> + <p>By default, <c><anno>Char</anno></c> is <c>$\s</c> and + <c><anno>Dir</anno></c> is <c>trailing</c>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:pad(<<"He̊llö"/utf8>>, 8).</input> +[<<72,101,204,138,108,108,195,182>>,32,32,32] +2> <input>io:format("'~ts'~n",[string:pad("He̊llö", 8, leading)]).</input> +' He̊llö' +3> <input>io:format("'~ts'~n",[string:pad("He̊llö", 8, both)]).</input> +' He̊llö '</pre> + </desc> + </func> + + <func> + <name name="prefix" arity="2"/> + <fsummary>Remove prefix from string.</fsummary> + <desc> + <p> + If <c><anno>Prefix</anno></c> is the prefix of + <c><anno>String</anno></c>, removes it and returns the + remainder of <c><anno>String</anno></c>, otherwise returns + <c>nomatch</c>. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:prefix(<<"prefix of string">>, "pre").</input> +<<"fix of string">> +2> <input>string:prefix("pre", "prefix").</input> +nomatch</pre> + </desc> + </func> + + <func> + <name name="replace" arity="3"/> + <name name="replace" arity="4"/> + <fsummary>Replace a pattern in string.</fsummary> + <desc> + <p> + Replaces <c><anno>SearchPattern</anno></c> in <c><anno>String</anno></c> + with <c><anno>Replacement</anno></c>. + <c><anno>Where</anno></c>, default <c>leading</c>, indicates whether + the <c>leading</c>, the <c>trailing</c> or <c>all</c> encounters of + <c><anno>SearchPattern</anno></c> are to be replaced. + </p> + <p>Can be implemented as:</p> + <pre>lists:join(Replacement, split(String, SearchPattern, Where)).</pre> + <p><em>Example:</em></p> + <pre> +1> <input>string:replace(<<"ab..cd..ef">>, "..", "*").</input> +[<<"ab">>,"*",<<"cd..ef">>] +2> <input>string:replace(<<"ab..cd..ef">>, "..", "*", all).</input> +[<<"ab">>,"*",<<"cd">>,"*",<<"ef">>]</pre> + </desc> + </func> + + <func> + <name name="reverse" arity="1"/> + <fsummary>Reverses a string</fsummary> + <desc> + <p> + Returns the reverse list of the grapheme clusters in <c><anno>String</anno></c>. + </p> + <p><em>Example:</em></p> + <pre> +1> Reverse = <input>string:reverse(unicode:characters_to_nfd_binary("ÅÄÖ")).</input> +[[79,776],[65,776],[65,778]] +2> <input>io:format("~ts~n",[Reverse]).</input> +ÖÄÅ</pre> + </desc> + </func> + + <func> + <name name="slice" arity="2"/> + <name name="slice" arity="3"/> + <fsummary>Extract a part of string</fsummary> + <desc> + <p>Returns a substring of <c><anno>String</anno></c> of + at most <c><anno>Length</anno></c> grapheme clusters, starting at position + <c><anno>Start</anno></c>.</p> + <p>By default, <c><anno>Length</anno></c> is <c>infinity</c>.</p> + <p><em>Example:</em></p> + <pre> +1> <input>string:slice(<<"He̊llö Wörld"/utf8>>, 4).</input> +<<"ö Wörld"/utf8>> +2> <input>string:slice(["He̊llö ", <<"Wörld"/utf8>>], 4,4).</input> +"ö Wö" +3> <input>string:slice(["He̊llö ", <<"Wörld"/utf8>>], 4,50).</input> +"ö Wörld"</pre> + </desc> + </func> + + <func> + <name name="split" arity="2"/> + <name name="split" arity="3"/> + <fsummary>Split a string into substrings.</fsummary> + <desc> + <p> + Splits <c><anno>String</anno></c> where <c><anno>SearchPattern</anno></c> + is encountered and return the remaining parts. + <c><anno>Where</anno></c>, default <c>leading</c>, indicates whether + the <c>leading</c>, the <c>trailing</c> or <c>all</c> encounters of + <c><anno>SearchPattern</anno></c> will split <c><anno>String</anno></c>. + </p> + <p><em>Example:</em></p> + <pre> +0> <input>string:split("ab..bc..cd", "..").</input> +["ab","bc..cd"] +1> <input>string:split(<<"ab..bc..cd">>, "..", trailing).</input> +[<<"ab..bc">>,<<"cd">>] +2> <input>string:split(<<"ab..bc....cd">>, "..", all).</input> +[<<"ab">>,<<"bc">>,<<>>,<<"cd">>]</pre> + </desc> + </func> + + <func> + <name name="take" arity="2"/> + <name name="take" arity="3"/> + <name name="take" arity="4"/> + <fsummary>Take leading or trailing parts.</fsummary> + <desc> + <p>Takes characters from <c><anno>String</anno></c> as long as + the characters are members of set <c><anno>Characters</anno></c> + or the complement of set <c><anno>Characters</anno></c>. + <c><anno>Dir</anno></c>, + which can be <c>leading</c> or <c>trailing</c>, indicates from + which direction characters are to be taken. + </p> + <p><em>Example:</em></p> + <pre> +5> <input>string:take("abc0z123", lists:seq($a,$z)).</input> +{"abc","0z123"} +6> <input>string:take(<<"abc0z123">>, lists:seq($0,$9), true, leading).</input> +{<<"abc">>,<<"0z123">>} +7> <input>string:take("abc0z123", lists:seq($0,$9), false, trailing).</input> +{"abc0z","123"} +8> <input>string:take(<<"abc0z123">>, lists:seq($a,$z), true, trailing).</input> +{<<"abc0z">>,<<"123">>}</pre> + </desc> + </func> + + <func> + <name name="titlecase" arity="1"/> + <fsummary>Convert a string to titlecase.</fsummary> + <desc> + <p> + Converts <c><anno>String</anno></c> to titlecase. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:titlecase("ß is a SHARP s").</input> +"Ss is a SHARP s"</pre> + </desc> + </func> + + <func> + <name name="to_float" arity="1"/> + <fsummary>Return a float whose text representation is the integers + (ASCII values) of a string.</fsummary> + <desc> + <p>Argument <c><anno>String</anno></c> is expected to start with a + valid text represented float (the digits are ASCII values). + Remaining characters in the string after the float are returned in + <c><anno>Rest</anno></c>.</p> + <p><em>Example:</em></p> + <pre> +> <input>{F1,Fs} = string:to_float("1.0-1.0e-1"),</input> +> <input>{F2,[]} = string:to_float(Fs),</input> +> <input>F1+F2.</input> +0.9 +> <input>string:to_float("3/2=1.5").</input> +{error,no_float} +> <input>string:to_float("-1.5eX").</input> +{-1.5,"eX"}</pre> + </desc> + </func> + + <func> + <name name="to_integer" arity="1"/> + <fsummary>Return an integer whose text representation is the integers + (ASCII values) of a string.</fsummary> + <desc> + <p>Argument <c><anno>String</anno></c> is expected to start with a + valid text represented integer (the digits are ASCII values). + Remaining characters in the string after the integer are returned in + <c><anno>Rest</anno></c>.</p> + <p><em>Example:</em></p> + <pre> +> <input>{I1,Is} = string:to_integer("33+22"),</input> +> <input>{I2,[]} = string:to_integer(Is),</input> +> <input>I1-I2.</input> +11 +> <input>string:to_integer("0.5").</input> +{0,".5"} +> <input>string:to_integer("x=2").</input> +{error,no_integer}</pre> + </desc> + </func> + + <func> + <name name="to_graphemes" arity="1"/> + <fsummary>Convert a string to a list of grapheme clusters.</fsummary> + <desc> + <p> + Converts <c><anno>String</anno></c> to a list of grapheme clusters. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:to_graphemes("ß↑e̊").</input> +[223,8593,[101,778]] +2> <input>string:to_graphemes(<<"ß↑e̊"/utf8>>).</input> +[223,8593,[101,778]]</pre> + </desc> + </func> + + <func> + <name name="trim" arity="1"/> + <name name="trim" arity="2"/> + <name name="trim" arity="3"/> + <fsummary>Trim leading or trailing, or both, characters.</fsummary> + <desc> + <p> + Returns a string, where leading or trailing, or both, + <c><anno>Characters</anno></c> have been removed. + <c><anno>Dir</anno></c> which can be <c>leading</c>, <c>trailing</c>, + or <c>both</c>, indicates from which direction characters + are to be removed. + </p> + <p> Default <c><anno>Characters</anno></c> are the set of + nonbreakable whitespace codepoints, defined as + Pattern_White_Space in + <url href="http://unicode.org/reports/tr31/">Unicode Standard Annex #31</url>. + <c>By default, <anno>Dir</anno></c> is <c>both</c>. + </p> + <p> + Notice that <c>[$\r,$\n]</c> is one grapheme cluster according + to the Unicode Standard. + </p> + <p><em>Example:</em></p> + <pre> +1> <input>string:trim("\t Hello \n").</input> +"Hello" +2> <input>string:trim(<<"\t Hello \n">>, leading).</input> +<<"Hello \n">> +3> <input>string:trim(<<".Hello.\n">>, trailing, "\n.").</input> +<<".Hello">></pre> + </desc> + </func> + + <func> + <name name="uppercase" arity="1"/> + <fsummary>Convert a string to uppercase.</fsummary> + <desc> + <p> + Converts <c><anno>String</anno></c> to uppercase. + </p> + <p>See also <seealso marker="#titlecase/1"><c>titlecase/1</c></seealso>.</p> + <p><em>Example:</em></p> + <pre> +1> <input>string:uppercase("Michał").</input> +"MICHAŁ"</pre> + </desc> + </func> + + </funcs> + + <section> + <marker id="oldapi"/> + <title>Obsolete API functions</title> + <p>Here follows the function of the old API. + These functions only work on a list of Latin-1 characters. + </p> + <note><p> + The functions are kept for backward compatibility, but are + not recommended. + They will be deprecated in Erlang/OTP 21. + </p> + <p>Any undocumented functions in <c>string</c> are not to be used.</p> + </note> + </section> + <funcs> <func> <name name="centre" arity="2"/> @@ -47,17 +652,24 @@ <p>Returns a string, where <c><anno>String</anno></c> is centered in the string and surrounded by blanks or <c><anno>Character</anno></c>. The resulting string has length <c><anno>Number</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#pad/3"><c>pad/3</c></seealso>. + </p> </desc> </func> <func> <name name="chars" arity="2"/> <name name="chars" arity="3"/> - <fsummary>Returns a string consisting of numbers of characters.</fsummary> + <fsummary>Return a string consisting of numbers of characters.</fsummary> <desc> <p>Returns a string consisting of <c><anno>Number</anno></c> characters <c><anno>Character</anno></c>. Optionally, the string can end with string <c><anno>Tail</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="lists#duplicate/2"><c>lists:duplicate/2</c></seealso>.</p> </desc> </func> @@ -69,6 +681,9 @@ <p>Returns the index of the first occurrence of <c><anno>Character</anno></c> in <c><anno>String</anno></c>. Returns <c>0</c> if <c><anno>Character</anno></c> does not occur.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#find/2"><c>find/2</c></seealso>.</p> </desc> </func> @@ -79,6 +694,16 @@ <p>Concatenates <c><anno>String1</anno></c> and <c><anno>String2</anno></c> to form a new string <c><anno>String3</anno></c>, which is returned.</p> + <p> + This function is <seealso marker="#oldapi">obsolete</seealso>. + Use <c>[<anno>String1</anno>, <anno>String2</anno>]</c> as + <c>Data</c> argument, and call + <seealso marker="unicode#characters_to_list/2"> + <c>unicode:characters_to_list/2</c></seealso> or + <seealso marker="unicode#characters_to_binary/2"> + <c>unicode:characters_to_binary/2</c></seealso> + to flatten the output. + </p> </desc> </func> @@ -88,6 +713,9 @@ <desc> <p>Returns a string containing <c><anno>String</anno></c> repeated <c><anno>Number</anno></c> times.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="lists#duplicate/2"><c>lists:duplicate/2</c></seealso>.</p> </desc> </func> @@ -98,6 +726,9 @@ <p>Returns the length of the maximum initial segment of <c><anno>String</anno></c>, which consists entirely of characters not from <c><anno>Chars</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#take/3"><c>take/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:cspan("\t abcdef", " \t"). @@ -106,20 +737,14 @@ </func> <func> - <name name="equal" arity="2"/> - <fsummary>Test string equality.</fsummary> - <desc> - <p>Returns <c>true</c> if <c><anno>String1</anno></c> and - <c><anno>String2</anno></c> are equal, otherwise <c>false</c>.</p> - </desc> - </func> - - <func> <name name="join" arity="2"/> <fsummary>Join a list of strings with separator.</fsummary> <desc> <p>Returns a string with the elements of <c><anno>StringList</anno></c> separated by the string in <c><anno>Separator</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="lists#join/2"><c>lists:join/2</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > join(["one", "two", "three"], ", "). @@ -137,6 +762,10 @@ fixed. If <c>length(<anno>String</anno>)</c> < <c><anno>Number</anno></c>, then <c><anno>String</anno></c> is padded with blanks or <c><anno>Character</anno></c>s.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#pad/2"><c>pad/2</c></seealso> or + <seealso marker="#pad/3"><c>pad/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:left("Hello",10,$.). @@ -149,6 +778,9 @@ <fsummary>Return the length of a string.</fsummary> <desc> <p>Returns the number of characters in <c><anno>String</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#length/1"><c>length/1</c></seealso>.</p> </desc> </func> @@ -160,6 +792,9 @@ <p>Returns the index of the last occurrence of <c><anno>Character</anno></c> in <c><anno>String</anno></c>. Returns <c>0</c> if <c><anno>Character</anno></c> does not occur.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#find/3"><c>find/3</c></seealso>.</p> </desc> </func> @@ -173,6 +808,9 @@ fixed. If the length of <c>(<anno>String</anno>)</c> < <c><anno>Number</anno></c>, then <c><anno>String</anno></c> is padded with blanks or <c><anno>Character</anno></c>s.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#pad/3"><c>pad/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:right("Hello", 10, $.). @@ -188,6 +826,9 @@ <c><anno>SubString</anno></c> begins in <c><anno>String</anno></c>. Returns <c>0</c> if <c><anno>SubString</anno></c> does not exist in <c><anno>String</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#find/3"><c>find/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:rstr(" Hello Hello World World ", "Hello World"). @@ -202,6 +843,9 @@ <p>Returns the length of the maximum initial segment of <c><anno>String</anno></c>, which consists entirely of characters from <c><anno>Chars</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#take/2"><c>take/2</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:span("\t abcdef", " \t"). @@ -217,6 +861,9 @@ <c><anno>SubString</anno></c> begins in <c><anno>String</anno></c>. Returns <c>0</c> if <c><anno>SubString</anno></c> does not exist in <c><anno>String</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#find/2"><c>find/2</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:str(" Hello Hello World World ", "Hello World"). @@ -230,12 +877,15 @@ <name name="strip" arity="3"/> <fsummary>Strip leading or trailing characters.</fsummary> <desc> - <p>Returns a string, where leading and/or trailing blanks or a + <p>Returns a string, where leading or trailing, or both, blanks or a number of <c><anno>Character</anno></c> have been removed. <c><anno>Direction</anno></c>, which can be <c>left</c>, <c>right</c>, or <c>both</c>, indicates from which direction blanks are to be removed. <c>strip/1</c> is equivalent to <c>strip(String, both)</c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#trim/3"><c>trim/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:strip("...Hello.....", both, $.). @@ -251,6 +901,9 @@ <p>Returns a substring of <c><anno>String</anno></c>, starting at position <c><anno>Start</anno></c> to the end of the string, or to and including position <c><anno>Stop</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#slice/3"><c>slice/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> sub_string("Hello World", 4, 8). @@ -266,6 +919,9 @@ sub_string("Hello World", 4, 8). <p>Returns a substring of <c><anno>String</anno></c>, starting at position <c><anno>Start</anno></c>, and ending at the end of the string or at length <c><anno>Length</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#slice/3"><c>slice/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > substr("Hello World", 4, 5). @@ -281,6 +937,9 @@ sub_string("Hello World", 4, 8). <p>Returns the word in position <c><anno>Number</anno></c> of <c><anno>String</anno></c>. Words are separated by blanks or <c><anno>Character</anno></c>s.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#nth_lexeme/3"><c>nth_lexeme/3</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > string:sub_word(" Hello old boy !",3,$o). @@ -289,50 +948,6 @@ sub_string("Hello World", 4, 8). </func> <func> - <name name="to_float" arity="1"/> - <fsummary>Returns a float whose text representation is the integers - (ASCII values) in a string.</fsummary> - <desc> - <p>Argument <c><anno>String</anno></c> is expected to start with a - valid text represented float (the digits are ASCII values). - Remaining characters in the string after the float are returned in - <c><anno>Rest</anno></c>.</p> - <p><em>Example:</em></p> - <code type="none"> -> {F1,Fs} = string:to_float("1.0-1.0e-1"), -> {F2,[]} = string:to_float(Fs), -> F1+F2. -0.9 -> string:to_float("3/2=1.5"). -{error,no_float} -> string:to_float("-1.5eX"). -{-1.5,"eX"}</code> - </desc> - </func> - - <func> - <name name="to_integer" arity="1"/> - <fsummary>Returns an integer whose text representation is the integers - (ASCII values) in a string.</fsummary> - <desc> - <p>Argument <c><anno>String</anno></c> is expected to start with a - valid text represented integer (the digits are ASCII values). - Remaining characters in the string after the integer are returned in - <c><anno>Rest</anno></c>.</p> - <p><em>Example:</em></p> - <code type="none"> -> {I1,Is} = string:to_integer("33+22"), -> {I2,[]} = string:to_integer(Is), -> I1-I2. -11 -> string:to_integer("0.5"). -{0,".5"} -> string:to_integer("x=2"). -{error,no_integer}</code> - </desc> - </func> - - <func> <name name="to_lower" arity="1" clause_i="1"/> <name name="to_lower" arity="1" clause_i="2"/> <name name="to_upper" arity="1" clause_i="1"/> @@ -346,6 +961,11 @@ sub_string("Hello World", 4, 8). <p>The specified string or character is case-converted. Notice that the supported character set is ISO/IEC 8859-1 (also called Latin 1); all values outside this set are unchanged</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso> use + <seealso marker="#lowercase/1"><c>lowercase/1</c></seealso>, + <seealso marker="#uppercase/1"><c>uppercase/1</c></seealso>, + <seealso marker="#titlecase/1"><c>titlecase/1</c></seealso> or + <seealso marker="#casefold/1"><c>casefold/1</c></seealso>.</p> </desc> </func> @@ -363,6 +983,9 @@ sub_string("Hello World", 4, 8). adjacent separator characters in <c><anno>String</anno></c> are treated as one. That is, there are no empty strings in the resulting list of tokens.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#lexemes/2"><c>lexemes/2</c></seealso>.</p> </desc> </func> @@ -373,6 +996,9 @@ sub_string("Hello World", 4, 8). <desc> <p>Returns the number of words in <c><anno>String</anno></c>, separated by blanks or <c><anno>Character</anno></c>.</p> + <p>This function is <seealso marker="#oldapi">obsolete</seealso>. + Use + <seealso marker="#lexemes/2"><c>lexemes/2</c></seealso>.</p> <p><em>Example:</em></p> <code type="none"> > words(" Hello old boy!", $o). @@ -387,10 +1013,7 @@ sub_string("Hello World", 4, 8). other. The reason is that this string package is the combination of two earlier packages and all functions of both packages have been retained.</p> - - <note> - <p>Any undocumented functions in <c>string</c> are not to be used.</p> - </note> </section> + </erlref> diff --git a/lib/stdlib/doc/src/unicode.xml b/lib/stdlib/doc/src/unicode.xml index 93d0d37456..382b253ba1 100644 --- a/lib/stdlib/doc/src/unicode.xml +++ b/lib/stdlib/doc/src/unicode.xml @@ -50,8 +50,35 @@ external entities where this is required. When working inside the Erlang/OTP environment, it is recommended to keep binaries in UTF-8 when representing Unicode characters. ISO Latin-1 encoding is supported both - for backward compatibility and for communication - with external entities not supporting Unicode character sets.</p> + for backward compatibility and for communication + with external entities not supporting Unicode character sets.</p> + <p>Programs should always operate on a normalized form and compare + canonical-equivalent Unicode characters as equal. All characters + should thus be normalized to one form once on the system borders. + One of the following functions can convert characters to their + normalized forms <seealso marker="#characters_to_nfc_list/1"> + <c>characters_to_nfc_list/1</c></seealso>, + <seealso marker="#characters_to_nfc_binary/1"> + <c>characters_to_nfc_binary/1</c></seealso>, + <seealso marker="#characters_to_nfd_list/1"> + <c>characters_to_nfd_list/1</c></seealso> or + <seealso marker="#characters_to_nfd_binary/1"> + <c>characters_to_nfd_binary/1</c></seealso>. + For general text + <seealso marker="#characters_to_nfc_list/1"> + <c>characters_to_nfc_list/1</c></seealso> or + <seealso marker="#characters_to_nfc_binary/1"> + <c>characters_to_nfc_binary/1</c></seealso> is preferred, and + for identifiers one of the compatibility normalization + functions, such as + <seealso marker="#characters_to_nfkc_list/1"> + <c>characters_to_nfkc_list/1</c></seealso>, + is preferred for security reasons. + The normalization functions where introduced in OTP 20. + Additional information on normalization can be found in the + <url href="http://unicode.org/faq/normalization.html">Unicode FAQ</url>. + </p> + </description> <datatypes> @@ -335,6 +362,154 @@ decode_data(Data) -> </func> <func> + <name name="characters_to_nfc_list" arity="1"/> + <fsummary>Normalize characters to a list of canonical equivalent + composed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of canonical equivalent Composed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding. + </p> + <p>The result is a list of characters.</p> + <code> +3> unicode:characters_to_nfc_list([<<"abc..a">>,[778],$a,[776],$o,[776]]). +"abc..åäö" +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfc_binary" arity="1"/> + <fsummary>Normalize characters to a utf8 binary of canonical equivalent + composed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of canonical equivalent Composed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding.</p> + <p>The result is an utf8 encoded binary.</p> + <code> +4> unicode:characters_to_nfc_binary([<<"abc..a">>,[778],$a,[776],$o,[776]]). +<<"abc..åäö"/utf8>> +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfd_list" arity="1"/> + <fsummary>Normalize characters to a list of canonical equivalent + decomposed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of canonical equivalent Decomposed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding. + </p> + <p>The result is a list of characters.</p> + <code> +1> unicode:characters_to_nfd_list("abc..åäö"). +[97,98,99,46,46,97,778,97,776,111,776] +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfd_binary" arity="1"/> + <fsummary>Normalize characters to a utf8 binary of canonical equivalent + decomposed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of canonical equivalent Decomposed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding.</p> + <p>The result is an utf8 encoded binary.</p> + <code> +2> unicode:characters_to_nfd_binary("abc..åäö"). +<<97,98,99,46,46,97,204,138,97,204,136,111,204,136>> +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfkc_list" arity="1"/> + <fsummary>Normalize characters to a list of canonical equivalent + composed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of compatibly equivalent Composed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding. + </p> + <p>The result is a list of characters.</p> + <code> +3> unicode:characters_to_nfkc_list([<<"abc..a">>,[778],$a,[776],$o,[776],[65299,65298]]). +"abc..åäö32" +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfkc_binary" arity="1"/> + <fsummary>Normalize characters to a utf8 binary of compatibly equivalent + composed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of compatibly equivalent Composed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding.</p> + <p>The result is an utf8 encoded binary.</p> + <code> +4> unicode:characters_to_nfkc_binary([<<"abc..a">>,[778],$a,[776],$o,[776],[65299,65298]]). +<<"abc..åäö32"/utf8>> +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfkd_list" arity="1"/> + <fsummary>Normalize characters to a list of compatibly equivalent + decomposed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of compatibly equivalent Decomposed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding. + </p> + <p>The result is a list of characters.</p> + <code> +1> unicode:characters_to_nfkd_list(["abc..åäö",[65299,65298]]). +[97,98,99,46,46,97,778,97,776,111,776,51,50] +</code> + </desc> + </func> + + <func> + <name name="characters_to_nfkd_binary" arity="1"/> + <fsummary>Normalize characters to a utf8 binary of compatibly equivalent + decomposed Unicode characters.</fsummary> + <desc> + <p>Converts a possibly deep list of characters and binaries + into a Normalized Form of compatibly equivalent Decomposed + characters according to the Unicode standard.</p> + <p>Any binaries in the input must be encoded with utf8 + encoding.</p> + <p>The result is an utf8 encoded binary.</p> + <code> +2> unicode:characters_to_nfkd_binary(["abc..åäö",[65299,65298]]). +<<97,98,99,46,46,97,204,138,97,204,136,111,204,136,51,50>> +</code> + </desc> + </func> + + <func> <name name="encoding_to_bom" arity="1"/> <fsummary>Create a binary UTF byte order mark from encoding.</fsummary> <type_desc variable="Bin"> diff --git a/lib/stdlib/doc/src/unicode_usage.xml b/lib/stdlib/doc/src/unicode_usage.xml index a8ef8ff5c5..11b84f552a 100644 --- a/lib/stdlib/doc/src/unicode_usage.xml +++ b/lib/stdlib/doc/src/unicode_usage.xml @@ -65,7 +65,10 @@ <item><p>In Erlang/OTP 20.0, atoms and function can contain Unicode characters. Module names are still restricted to - the ISO-Latin-1 range.</p></item> + the ISO-Latin-1 range.</p> + <p>Support was added for normalizations forms in + <c>unicode</c> and the <c>string</c> module now handles + utf8-encoded binaries.</p></item> </list> <p>This section outlines the current Unicode support and gives some @@ -110,23 +113,27 @@ </item> </list> - <p>So, a conversion function must know not only one character at a time, - but possibly the whole sentence, the natural language to translate to, - the differences in input and output string length, and so on. - Erlang/OTP has currently no Unicode <c>to_upper</c>/<c>to_lower</c> - functionality, but publicly available libraries address these issues.</p> - - <p>Another example is the accented characters, where the same glyph has two - different representations. The Swedish letter "ö" is one example. - The Unicode standard has a code point for it, but you can also write it - as "o" followed by "U+0308" (Combining Diaeresis, with the simplified - meaning that the last letter is to have "¨" above). They have the same - glyph. They are for most purposes the same, but have different - representations. For example, MacOS X converts all filenames to use - Combining Diaeresis, while most other programs (including Erlang) try to - hide that by doing the opposite when, for example, listing directories. - However it is done, it is usually important to normalize such - characters to avoid confusion.</p> + <p>So, a conversion function must know not only one character at a + time, but possibly the whole sentence, the natural language to + translate to, the differences in input and output string length, + and so on. Erlang/OTP has currently no Unicode + <c>uppercase</c>/<c>lowercase</c> functionality with language + specific handling, but publicly available libraries address these + issues.</p> + + <p>Another example is the accented characters, where the same + glyph has two different representations. The Swedish letter "ö" is + one example. The Unicode standard has a code point for it, but + you can also write it as "o" followed by "U+0308" (Combining + Diaeresis, with the simplified meaning that the last letter is to + have "¨" above). They have the same glyph, user perceived + character. They are for most purposes the same, but have different + representations. For example, MacOS X converts all filenames to + use Combining Diaeresis, while most other programs (including + Erlang) try to hide that by doing the opposite when, for example, + listing directories. However it is done, it is usually important + to normalize such characters to avoid confusion. + </p> <p>The list of examples can be made long. One need a kind of knowledge that was not needed when programs only considered one or two languages. The @@ -273,7 +280,7 @@ them. In some cases functionality has been added to already existing interfaces (as the <seealso marker="stdlib:string"><c>string</c></seealso> module now can - handle lists with any code points). In some cases new + handle strings with any code points). In some cases new functionality or options have been added (as in the <seealso marker="stdlib:io"><c>io</c></seealso> module, the file handling, the <seealso @@ -977,7 +984,7 @@ Eshell V5.10.1 (abort with ^G) <p>Fortunately, most textual data has been stored in lists and range checking has been sparse, so modules like <c>string</c> work well for - Unicode lists with little need for conversion or extension.</p> + Unicode strings with little need for conversion or extension.</p> <p>Some modules are, however, changed to be explicitly Unicode-aware. These modules include:</p> @@ -1028,18 +1035,17 @@ Eshell V5.10.1 (abort with ^G) has extensive support for Unicode text.</p></item> </taglist> - <p>The <seealso marker="stdlib:string"><c>string</c></seealso> module works - perfectly for Unicode strings and ISO Latin-1 strings, except the - language-dependent functions - <seealso marker="stdlib:string#to_upper/1"><c>string:to_upper/1</c></seealso> - and - <seealso marker="stdlib:string#to_lower/1"><c>string:to_lower/1</c></seealso>, - which are only correct for the ISO Latin-1 character set. These two - functions can never function correctly for Unicode characters in their - current form, as there are language and locale issues as well as - multi-character mappings to consider when converting text between cases. - Converting case in an international environment is a large subject not - yet addressed in OTP.</p> + <p>The <seealso marker="stdlib:string"><c>string</c></seealso> + module works perfectly for Unicode strings and ISO Latin-1 + strings, except the language-dependent functions <seealso + marker="stdlib:string#uppercase/1"><c>string:uppercase/1</c></seealso> + and <seealso + marker="stdlib:string#lowercase/1"><c>string:lowercase/1</c></seealso>. + These two functions can never function correctly for Unicode + characters in their current form, as there are language and locale + issues to consider when converting text between cases. Converting + case in an international environment is a large subject not yet + addressed in OTP.</p> </section> <section> |