xs_regex

An OTP library that translates XML Schema regular expressions (described here) into the Erlang flavor.

XML Schema Features

Character classes (including the shorthands \i, \I, \c, \C, \d, \D, \w, \W).
Character class subtraction ([a-z-[s-u]] returns [a-rv-z]).
Alternation and groups.
Greedy quantifiers
Unicode properties and language blocks.

XPath / XQuery Features

Anchors ("^", "$").
Lazy quantifiers.
Back-references (also in replacement text using $1 notation).
Capturing groups.
i, s, m, x, and q flags

Flags

s - "dot-all", "." matches newline
m - Multi-line mode
i - Case-insensitive
x - "extended", whitespaces outside character classes are removed
q - All characters are treated as literals (s, m, and x have no effect)

Usage

1> xs_regex:translate("[a-z-[s-u]]").
{ok,"[a-rv-z]"}

The xs_regex:compile/2 function returns a boolean stating if the pattern matches the empty string, and the compiled pattern.

1> xs_regex:compile("[a-z-[s-u]]", "ix").
{false,{re_pattern,0,1,1,
                   <<69,82,67,80,112,0,0,0,9,8,64,36,1,0,0,0,255,255,255,
                     255,255,255,...>>}}

"$1" notation is transformed to "\g{1}" notation.

1> Pattern = "(a)|(b)|(c)|(d)|(e)|(f)|(g)|(h)|(i)|(j)".
"(a)|(b)|(c)|(d)|(e)|(f)|(g)|(h)|(i)|(j)"
2> {_, MP} = xs_regex:compile(Pattern, "").
{false,{re_pattern,10,1,1,
                   <<69,82,67,80,198,0,0,0,32,8,64,36,1,0,0,0,255,255,255,
                     255,255,255,...>>}}
3> {ok, Depth} = xs_regex:get_depth(Pattern).
{ok,10}
4> {ok, Repl} = xs_regex:transform_replace("$1|$4",Depth).
{ok,"\\g{1}|\\g{4}"}
5> re:replace("abcdefghijk", MP, Repl, [{return,list},global]).
"a||||d||||||k"

Arabic decimal digits:

2> xs_regex:translate("[\\p{IsArabic}-[\\P{Nd}]]").
{ok,"[\\x{660}-\\x{669}\\x{6F0}-\\x{6F9}]"}

Opening XML tag:

3> xs_regex:translate("<\\i\\c*>").
{ok,"<(?-i:[\\x{3A}A-Z\\x{5F}a-z\\x{C0}-\\x{D6}\\x{D8}-\\x{F6}\\x{F8}-\\x{2FF}\\x{370}-\\x{37D}\\x{37F}-\\x{1FFF}\\x{200C}-\\x{200D}\\x{2070}-\\x{218F}\\x{2C00}-\\x{2FEF}\\x{3001}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFFD}\\x{10000}-\\x{EFFFF}])(?-i:[\\x{2D}-\\x{2E}0-\\x{3A}A-Z\\x{5F}a-z\\x{B7}\\x{C0}-\\x{D6}\\x{D8}-\\x{F6}\\x{F8}-\\x{37D}\\x{37F}-\\x{1FFF}\\x{200C}-\\x{200D}\\x{203F}-\\x{2040}\\x{2070}-\\x{218F}\\x{2C00}-\\x{2FEF}\\x{3001}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFFD}\\x{10000}-\\x{EFFFF}])*>"}

Upper-case Greek:

4> xs_regex:translate("^(?:[\\p{IsGreek}-[\\P{Lu}]]+)$").
{ok,"^(?:[\\x{370}\\x{372}\\x{376}\\x{37F}-\\x{383}\\x{386}\\x{388}-\\x{38F}\\x{391}-\\x{3AB}\\x{3CF}\\x{3D2}-\\x{3D4}\\x{3D8}\\x{3DA}\\x{3DC}\\x{3DE}\\x{3E0}\\x{3E2}\\x{3E4}\\x{3E6}\\x{3E8}\\x{3EA}\\x{3EC}\\x{3EE}\\x{3F4}\\x{3F7}\\x{3F9}-\\x{3FA}\\x{3FD}-\\x{3FF}]+)$"}

Using non-ascii codepoints in a regex:

5> {ok,R} = xs_regex:normalize("^what(?:[&#50806;-&#50809;])s\\sthat$").
{ok,[94,119,104,97,116,40,63,58,91,50806,45,50809,93,41,115,
     92,115,116,104,97,116,36]}
6> xs_regex:translate(R).
{ok,"^what(?:[\\x{C676}-\\x{C679}])s(?-i:[\\x{9}\\x{A}\\x{D}\\x{20}])that$"}

7> {ok,R1} = xs_regex:normalize("^what(?:[&#xABC0;-&#xABCF;])s\\sthis$").
{ok,[94,119,104,97,116,40,63,58,91,43968,45,43983,93,41,115,
     92,115,116,104,105,115,36]}
8> xs_regex:translate(R1).
{ok,"^what(?:[\\x{ABC0}-\\x{ABCF}])s(?-i:[\\x{9}\\x{A}\\x{D}\\x{20}])this$"}

Build

$ rebar3 compile

zadean / xs_regex