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regex.ex
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regex.ex
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defmodule Regex do
@moduledoc ~S"""
Provides regular expressions for Elixir.
Regex is based on PCRE (Perl Compatible Regular Expressions) and
built on top of Erlang's `:re` module. More information can be found
in the [`:re` module documentation](`:re`).
Regular expressions in Elixir can be created using the sigils
`~r` (see `sigil_r/2`):
# A simple regular expression that matches foo anywhere in the string
~r/foo/
# A regular expression with case insensitive and Unicode options
~r/foo/iu
Regular expressions created via sigils are pre-compiled and stored
in the `.beam` file. Note that this may be a problem if you are precompiling
Elixir, see the "Precompilation" section for more information.
A Regex is represented internally as the `Regex` struct. Therefore,
`%Regex{}` can be used whenever there is a need to match on them.
Keep in mind that all of the structs fields are private. There is
also not guarantee two regular expressions from the same source are
equal, for example:
~r/(?<foo>.)(?<bar>.)/ == ~r/(?<foo>.)(?<bar>.)/
may return `true` or `false` depending on your machine, endianness,
available optimizations and others. You can, however, retrieve the source
of a compiled regular expression by accessing the `source` field, and then
compare those directly:
~r/(?<foo>.)(?<bar>.)/.source == ~r/(?<foo>.)(?<bar>.)/.source
## Escapes
Escape sequences are split into two categories.
### Non-printing characters
* `\a` - Alarm, that is, the BEL character (hex 07)
* `\e` - Escape (hex 1B)
* `\f` - Form feed (hex 0C)
* `\n` - Line feed (hex 0A)
* `\r` - Carriage return (hex 0D)
* `\t` - Tab (hex 09)
* `\xhh` - Character with hex code hh
* `\x{hhh..}` - Character with hex code hhh..
`\u` and `\U` are not supported. Other escape sequences, such as `\ddd`
for octals, are supported but discouraged.
### Generic character types
* `\d` - Any decimal digit
* `\D` - Any character that is not a decimal digit
* `\h` - Any horizontal whitespace character
* `\H` - Any character that is not a horizontal whitespace character
* `\s` - Any whitespace character
* `\S` - Any character that is not a whitespace character
* `\v` - Any vertical whitespace character
* `\V` - Any character that is not a vertical whitespace character
* `\w` - Any "word" character
* `\W` - Any "non-word" character
## Modifiers
The modifiers available when creating a Regex are:
* `:unicode` (u) - enables Unicode specific patterns like `\p` and causes
character classes like `\w`, `\W`, `\s`, and the like to also match on Unicode
(see examples below in "Character classes"). It expects valid Unicode
strings to be given on match
* `:caseless` (i) - adds case insensitivity
* `:dotall` (s) - causes dot to match newlines and also set newline to
anycrlf; the new line setting can be overridden by setting `(*CR)` or
`(*LF)` or `(*CRLF)` or `(*ANY)` according to `:re` documentation
* `:multiline` (m) - causes `^` and `$` to mark the beginning and end of
each line; use `\A` and `\z` to match the end or beginning of the string
* `:extended` (x) - whitespace characters are ignored except when escaped
and allow `#` to delimit comments
* `:firstline` (f) - forces the unanchored pattern to match before or at the
first newline, though the matched text may continue over the newline
* `:ungreedy` (U) - inverts the "greediness" of the regexp
(the previous `r` option is deprecated in favor of `U`)
The options not available are:
* `:anchored` - not available, use `^` or `\A` instead
* `:dollar_endonly` - not available, use `\z` instead
* `:no_auto_capture` - not available, use `?:` instead
* `:newline` - not available, use `(*CR)` or `(*LF)` or `(*CRLF)` or
`(*ANYCRLF)` or `(*ANY)` at the beginning of the regexp according to the
`:re` documentation
## Captures
Many functions in this module handle what to capture in a regex
match via the `:capture` option. The supported values are:
* `:all` - all captured subpatterns including the complete matching string
(this is the default)
* `:first` - only the first captured subpattern, which is always the
complete matching part of the string; all explicitly captured subpatterns
are discarded
* `:all_but_first` - all but the first matching subpattern, i.e. all
explicitly captured subpatterns, but not the complete matching part of
the string
* `:none` - does not return matching subpatterns at all
* `:all_names` - captures all named subpattern matches in the Regex as a list
ordered **alphabetically** by the names of the subpatterns
* `list(binary)` - a list of named captures to capture
## Character classes
Regex supports several built in named character classes. These are used by
enclosing the class name in `[: :]` inside a group. For example:
iex> String.match?("123", ~r/^[[:alnum:]]+$/)
true
iex> String.match?("123 456", ~r/^[[:alnum:][:blank:]]+$/)
true
The supported class names are:
* alnum - Letters and digits
* alpha - Letters
* blank - Space or tab only
* cntrl - Control characters
* digit - Decimal digits (same as \\d)
* graph - Printing characters, excluding space
* lower - Lowercase letters
* print - Printing characters, including space
* punct - Printing characters, excluding letters, digits, and space
* space - Whitespace (the same as \s from PCRE 8.34)
* upper - Uppercase letters
* word - "Word" characters (same as \w)
* xdigit - Hexadecimal digits
There is another character class, `ascii`, that erroneously matches
Latin-1 characters instead of the 0-127 range specified by POSIX. This
cannot be fixed without altering the behaviour of other classes, so we
recommend matching the range with `[\\0-\x7f]` instead.
Note the behaviour of those classes may change according to the Unicode
and other modifiers:
iex> String.match?("josé", ~r/^[[:lower:]]+$/)
false
iex> String.match?("josé", ~r/^[[:lower:]]+$/u)
true
iex> Regex.replace(~r/\s/, "Unicode\u00A0spaces", "-")
"Unicode spaces"
iex> Regex.replace(~r/\s/u, "Unicode\u00A0spaces", "-")
"Unicode-spaces"
## Precompilation
Regular expressions built with sigil are precompiled and stored in `.beam`
files. Precompiled regexes will be checked in runtime and may work slower
between operating systems and OTP releases. This is rarely a problem, as most Elixir code
shared during development is compiled on the target (such as dependencies,
archives, and escripts) and, when running in production, the code must either
be compiled on the target (via `mix compile` or similar) or released on the
host (via `mix releases` or similar) with a matching OTP, operating system
and architecture as the target.
If you know you are running on a different system than the current one and
you are doing multiple matches with the regex, you can manually invoke
`Regex.recompile/1` or `Regex.recompile!/1` to perform a runtime version
check and recompile the regex if necessary.
"""
defstruct re_pattern: nil, source: "", opts: "", re_version: ""
@type t :: %__MODULE__{re_pattern: term, source: binary, opts: binary | [term]}
defmodule CompileError do
@moduledoc """
An exception raised when a regular expression could not be compiled.
"""
defexception message: "regex could not be compiled"
end
@doc """
Compiles the regular expression.
The given options can either be a binary with the characters
representing the same regex options given to the
`~r` (see `sigil_r/2`) sigil, or a list of options, as
expected by the Erlang's [`:re`](`:re`) module.
It returns `{:ok, regex}` in case of success,
`{:error, reason}` otherwise.
## Examples
iex> Regex.compile("foo")
{:ok, ~r/foo/}
iex> Regex.compile("*foo")
{:error, {'nothing to repeat', 0}}
iex> Regex.compile("foo", "i")
{:ok, ~r/foo/i}
iex> Regex.compile("foo", [:caseless])
{:ok, Regex.compile!("foo", [:caseless])}
"""
@spec compile(binary, binary | [term]) :: {:ok, t} | {:error, any}
def compile(source, options \\ "") when is_binary(source) do
compile(source, options, version())
end
defp compile(source, options, version) when is_binary(options) do
case translate_options(options, []) do
{:error, rest} ->
{:error, {:invalid_option, rest}}
translated_options ->
compile(source, translated_options, options, version)
end
end
defp compile(source, options, version) when is_list(options) do
compile(source, options, "", version)
end
defp compile(source, opts, doc_opts, version) do
case :re.compile(source, opts) do
{:ok, re_pattern} ->
doc_opts = format_doc_opts(doc_opts, opts)
{:ok, %Regex{re_pattern: re_pattern, re_version: version, source: source, opts: doc_opts}}
error ->
error
end
end
defp format_doc_opts(_doc_opts = "", _opts = []), do: ""
defp format_doc_opts(_doc_opts = "", opts), do: opts
defp format_doc_opts(doc_opts, _opts), do: doc_opts
@doc """
Compiles the regular expression and raises `Regex.CompileError` in case of errors.
"""
@spec compile!(binary, binary | [term]) :: t
def compile!(source, options \\ "") when is_binary(source) do
case compile(source, options) do
{:ok, regex} -> regex
{:error, {reason, at}} -> raise Regex.CompileError, "#{reason} at position #{at}"
end
end
@doc """
Recompiles the existing regular expression if necessary.
This checks the version stored in the regular expression
and recompiles the regex in case of version mismatch.
"""
@doc since: "1.4.0"
@spec recompile(t) :: {:ok, t} | {:error, any}
def recompile(%Regex{} = regex) do
version = version()
case regex do
%{re_version: ^version} ->
{:ok, regex}
_ ->
%{source: source, opts: opts} = regex
compile(source, opts, version)
end
end
@doc """
Recompiles the existing regular expression and raises `Regex.CompileError` in case of errors.
"""
@doc since: "1.4.0"
@spec recompile!(t) :: t
def recompile!(regex) do
case recompile(regex) do
{:ok, regex} -> regex
{:error, {reason, at}} -> raise Regex.CompileError, "#{reason} at position #{at}"
end
end
@doc """
Returns the version of the underlying Regex engine.
"""
@doc since: "1.4.0"
@spec version :: term()
def version do
{:re.version(), :erlang.system_info(:endian)}
end
@doc """
Returns a boolean indicating whether there was a match or not.
## Examples
iex> Regex.match?(~r/foo/, "foo")
true
iex> Regex.match?(~r/foo/, "bar")
false
Elixir also provides text-based match operator `=~/2` and function `String.match?/2` as
an alternative to test strings against regular expressions and
strings.
"""
@spec match?(t, String.t()) :: boolean
def match?(%Regex{} = regex, string) when is_binary(string) do
safe_run(regex, string, [{:capture, :none}]) == :match
end
@doc false
@deprecated "Use Kernel.is_struct(term, Regex) or pattern match on %Regex{} instead"
def regex?(term)
def regex?(%Regex{}), do: true
def regex?(_), do: false
@doc """
Runs the regular expression against the given string until the first match.
It returns a list with all captures or `nil` if no match occurred.
## Options
* `:return` - when set to `:index`, returns byte index and match length.
Defaults to `:binary`.
* `:capture` - what to capture in the result. Check the moduledoc for `Regex`
to see the possible capture values.
* `:offset` - (since v1.12.0) specifies the starting offset to match in the given string.
Defaults to zero.
## Examples
iex> Regex.run(~r/c(d)/, "abcd")
["cd", "d"]
iex> Regex.run(~r/e/, "abcd")
nil
iex> Regex.run(~r/c(d)/, "abcd", return: :index)
[{2, 2}, {3, 1}]
"""
@spec run(t, binary, [term]) :: nil | [binary] | [{integer, integer}]
def run(regex, string, options \\ [])
def run(%Regex{} = regex, string, options) when is_binary(string) do
return = Keyword.get(options, :return, :binary)
captures = Keyword.get(options, :capture, :all)
offset = Keyword.get(options, :offset, 0)
case safe_run(regex, string, [{:capture, captures, return}, {:offset, offset}]) do
:nomatch -> nil
:match -> []
{:match, results} -> results
end
end
@doc """
Returns the given captures as a map or `nil` if no captures are found.
## Options
* `:return` - when set to `:index`, returns byte index and match length.
Defaults to `:binary`.
## Examples
iex> Regex.named_captures(~r/c(?<foo>d)/, "abcd")
%{"foo" => "d"}
iex> Regex.named_captures(~r/a(?<foo>b)c(?<bar>d)/, "abcd")
%{"bar" => "d", "foo" => "b"}
iex> Regex.named_captures(~r/a(?<foo>b)c(?<bar>d)/, "efgh")
nil
"""
@spec named_captures(t, String.t(), [term]) :: map | nil
def named_captures(regex, string, options \\ []) when is_binary(string) do
names = names(regex)
options = Keyword.put(options, :capture, names)
results = run(regex, string, options)
if results, do: Enum.zip(names, results) |> Enum.into(%{})
end
@doc """
Returns the underlying `re_pattern` in the regular expression.
"""
@spec re_pattern(t) :: term
def re_pattern(%Regex{re_pattern: compiled}) do
compiled
end
@doc """
Returns the regex source as a binary.
## Examples
iex> Regex.source(~r/foo/)
"foo"
"""
@spec source(t) :: String.t()
def source(%Regex{source: source}) do
source
end
@doc """
Returns the regex options, as a string or list depending on how
it was compiled.
See the documentation of `Regex.compile/2` for more information.
## Examples
iex> Regex.opts(~r/foo/m)
"m"
iex> Regex.opts(Regex.compile!("foo", [:caseless]))
[:caseless]
"""
@spec opts(t) :: String.t() | [term]
def opts(%Regex{opts: opts}) do
opts
end
@doc """
Returns a list of names in the regex.
## Examples
iex> Regex.names(~r/(?<foo>bar)/)
["foo"]
"""
@spec names(t) :: [String.t()]
def names(%Regex{re_pattern: compiled, re_version: version, source: source}) do
re_pattern =
case version() do
^version ->
compiled
_ ->
{:ok, recompiled} = :re.compile(source)
recompiled
end
{:namelist, names} = :re.inspect(re_pattern, :namelist)
names
end
@doc ~S"""
Same as `run/3`, but scans the target several times collecting all
matches of the regular expression.
A list of lists is returned, where each entry in the primary list represents a
match and each entry in the secondary list represents the captured contents.
## Options
* `:return` - when set to `:index`, returns byte index and match length.
Defaults to `:binary`.
* `:capture` - what to capture in the result. Check the moduledoc for `Regex`
to see the possible capture values.
* `:offset` - (since v1.12.0) specifies the starting offset to match in the given string.
Defaults to zero.
## Examples
iex> Regex.scan(~r/c(d|e)/, "abcd abce")
[["cd", "d"], ["ce", "e"]]
iex> Regex.scan(~r/c(?:d|e)/, "abcd abce")
[["cd"], ["ce"]]
iex> Regex.scan(~r/e/, "abcd")
[]
iex> Regex.scan(~r/\p{Sc}/u, "$, £, and €")
[["$"], ["£"], ["€"]]
iex> Regex.scan(~r/=+/, "=ü†ƒ8===", return: :index)
[[{0, 1}], [{9, 3}]]
"""
@spec scan(t(), String.t(), [term()]) :: [[String.t()]] | [[{integer(), integer()}]]
def scan(regex, string, options \\ [])
def scan(%Regex{} = regex, string, options) when is_binary(string) do
return = Keyword.get(options, :return, :binary)
captures = Keyword.get(options, :capture, :all)
offset = Keyword.get(options, :offset, 0)
options = [{:capture, captures, return}, :global, {:offset, offset}]
case safe_run(regex, string, options) do
:match -> []
:nomatch -> []
{:match, results} -> results
end
end
defp safe_run(
%Regex{re_pattern: compiled, source: source, re_version: version, opts: compile_opts},
string,
options
) do
case version() do
^version -> :re.run(string, compiled, options)
_ -> :re.run(string, source, translate_options(compile_opts, options))
end
end
@doc """
Splits the given target based on the given pattern and in the given number of
parts.
## Options
* `:parts` - when specified, splits the string into the given number of
parts. If not specified, `:parts` defaults to `:infinity`, which will
split the string into the maximum number of parts possible based on the
given pattern.
* `:trim` - when `true`, removes empty strings (`""`) from the result.
Defaults to `false`.
* `:on` - specifies which captures to split the string on, and in what
order. Defaults to `:first` which means captures inside the regex do not
affect the splitting process. Check the moduledoc for `Regex`
to see the possible capture values.
* `:include_captures` - when `true`, includes in the result the matches of
the regular expression. The matches are not counted towards the maximum
number of parts if combined with the `:parts` option. Defaults to `false`.
## Examples
iex> Regex.split(~r{-}, "a-b-c")
["a", "b", "c"]
iex> Regex.split(~r{-}, "a-b-c", parts: 2)
["a", "b-c"]
iex> Regex.split(~r{-}, "abc")
["abc"]
iex> Regex.split(~r{}, "abc")
["", "a", "b", "c", ""]
iex> Regex.split(~r{a(?<second>b)c}, "abc")
["", ""]
iex> Regex.split(~r{a(?<second>b)c}, "abc", on: [:second])
["a", "c"]
iex> Regex.split(~r{(x)}, "Elixir", include_captures: true)
["Eli", "x", "ir"]
iex> Regex.split(~r{a(?<second>b)c}, "abc", on: [:second], include_captures: true)
["a", "b", "c"]
"""
@spec split(t, String.t(), [term]) :: [String.t()]
def split(regex, string, options \\ [])
def split(%Regex{}, "", opts) do
if Keyword.get(opts, :trim, false) do
[]
else
[""]
end
end
def split(%Regex{} = regex, string, opts)
when is_binary(string) and is_list(opts) do
on = Keyword.get(opts, :on, :first)
case safe_run(regex, string, [:global, capture: on]) do
{:match, matches} ->
index = parts_to_index(Keyword.get(opts, :parts, :infinity))
trim = Keyword.get(opts, :trim, false)
include_captures = Keyword.get(opts, :include_captures, false)
do_split(matches, string, 0, index, trim, include_captures)
:match ->
[string]
:nomatch ->
[string]
end
end
defp parts_to_index(:infinity), do: 0
defp parts_to_index(n) when is_integer(n) and n > 0, do: n
defp do_split(_, string, offset, _counter, true, _with_captures)
when byte_size(string) <= offset do
[]
end
defp do_split(_, string, offset, 1, _trim, _with_captures),
do: [binary_part(string, offset, byte_size(string) - offset)]
defp do_split([], string, offset, _counter, _trim, _with_captures),
do: [binary_part(string, offset, byte_size(string) - offset)]
defp do_split([[{pos, _} | h] | t], string, offset, counter, trim, with_captures)
when pos - offset < 0 do
do_split([h | t], string, offset, counter, trim, with_captures)
end
defp do_split([[] | t], string, offset, counter, trim, with_captures),
do: do_split(t, string, offset, counter, trim, with_captures)
defp do_split([[{pos, length} | h] | t], string, offset, counter, trim, true) do
new_offset = pos + length
keep = pos - offset
<<_::binary-size(^offset), part::binary-size(^keep), match::binary-size(^length), _::binary>> =
string
if keep == 0 and trim do
[match | do_split([h | t], string, new_offset, counter - 1, trim, true)]
else
[part, match | do_split([h | t], string, new_offset, counter - 1, trim, true)]
end
end
defp do_split([[{pos, length} | h] | t], string, offset, counter, trim, false) do
new_offset = pos + length
keep = pos - offset
if keep == 0 and trim do
do_split([h | t], string, new_offset, counter, trim, false)
else
<<_::binary-size(^offset), part::binary-size(^keep), _::binary>> = string
[part | do_split([h | t], string, new_offset, counter - 1, trim, false)]
end
end
@doc ~S"""
Receives a regex, a binary and a replacement, returns a new
binary where all matches are replaced by the replacement.
The replacement can be either a string or a function that returns a string.
The resulting string is used as a replacement for every match.
When the replacement is a string, it allows specific captures of the match
using brackets at the regex expression and accessing them in the replacement
via `\N` or `\g{N}`, where `N` is the number of the capture. In case `\0` is
used, the whole match is inserted. Note that in regexes the backslash needs
to be escaped, hence in practice you'll need to use `\\N` and `\\g{N}`.
When the replacement is a function, it allows specific captures too.
The function may have arity N where each argument maps to a capture,
with the first argument being the whole match. If the function expects more
arguments than captures found, the remaining arguments will receive `""`.
## Options
* `:global` - when `false`, replaces only the first occurrence
(defaults to `true`)
## Examples
iex> Regex.replace(~r/d/, "abc", "d")
"abc"
iex> Regex.replace(~r/b/, "abc", "d")
"adc"
iex> Regex.replace(~r/b/, "abc", "[\\0]")
"a[b]c"
iex> Regex.replace(~r/a(b|d)c/, "abcadc", "[\\1]")
"[b][d]"
iex> Regex.replace(~r/\.(\d)$/, "500.5", ".\\g{1}0")
"500.50"
iex> Regex.replace(~r/a(b|d)c/, "abcadc", fn _, x -> "[#{x}]" end)
"[b][d]"
iex> Regex.replace(~r/(\w+)@(\w+).(\w+)/, "abc@def.com", fn _full, _c1, _c2, c3 -> "TLD: #{c3}" end)
"TLD: com"
iex> Regex.replace(~r/a/, "abcadc", "A", global: false)
"Abcadc"
"""
@spec replace(t, String.t(), String.t() | (... -> String.t()), [term]) :: String.t()
def replace(%Regex{} = regex, string, replacement, options \\ [])
when is_binary(string) and is_list(options) do
opts = if Keyword.get(options, :global) != false, do: [:global], else: []
opts = [{:capture, :all, :index} | opts]
case safe_run(regex, string, opts) do
:nomatch ->
string
{:match, [mlist | t]} when is_list(mlist) ->
apply_list(string, precompile_replacement(replacement), [mlist | t])
|> IO.iodata_to_binary()
{:match, slist} ->
apply_list(string, precompile_replacement(replacement), [slist])
|> IO.iodata_to_binary()
end
end
defp precompile_replacement(replacement) when is_function(replacement) do
{:arity, arity} = Function.info(replacement, :arity)
{replacement, arity}
end
defp precompile_replacement(""), do: []
defp precompile_replacement(<<?\\, ?g, ?{, rest::binary>>) when byte_size(rest) > 0 do
{ns, <<?}, rest::binary>>} = pick_int(rest)
[List.to_integer(ns) | precompile_replacement(rest)]
end
defp precompile_replacement(<<?\\, ?\\, rest::binary>>) do
[<<?\\>> | precompile_replacement(rest)]
end
defp precompile_replacement(<<?\\, x, rest::binary>>) when x in ?0..?9 do
{ns, rest} = pick_int(rest)
[List.to_integer([x | ns]) | precompile_replacement(rest)]
end
defp precompile_replacement(<<x, rest::binary>>) do
case precompile_replacement(rest) do
[head | t] when is_binary(head) ->
[<<x, head::binary>> | t]
other ->
[<<x>> | other]
end
end
defp pick_int(<<x, rest::binary>>) when x in ?0..?9 do
{found, rest} = pick_int(rest)
{[x | found], rest}
end
defp pick_int(bin) do
{[], bin}
end
defp apply_list(string, replacement, list) do
apply_list(string, string, 0, replacement, list)
end
defp apply_list(_, "", _, _, []) do
[]
end
defp apply_list(_, string, _, _, []) do
string
end
defp apply_list(whole, string, pos, replacement, [[{mpos, _} | _] | _] = list)
when mpos > pos do
length = mpos - pos
<<untouched::binary-size(^length), rest::binary>> = string
[untouched | apply_list(whole, rest, mpos, replacement, list)]
end
defp apply_list(whole, string, pos, replacement, [[{pos, length} | _] = head | tail]) do
<<_::size(^length)-binary, rest::binary>> = string
new_data = apply_replace(whole, replacement, head)
[new_data | apply_list(whole, rest, pos + length, replacement, tail)]
end
defp apply_replace(string, {fun, arity}, indexes) do
apply(fun, get_indexes(string, indexes, arity))
end
defp apply_replace(_, [bin], _) when is_binary(bin) do
bin
end
defp apply_replace(string, repl, indexes) do
indexes = List.to_tuple(indexes)
for part <- repl do
cond do
is_binary(part) ->
part
part >= tuple_size(indexes) ->
""
true ->
get_index(string, elem(indexes, part))
end
end
end
defp get_index(_string, {pos, _length}) when pos < 0 do
""
end
defp get_index(string, {pos, length}) do
<<_::size(^pos)-binary, res::size(^length)-binary, _::binary>> = string
res
end
defp get_indexes(_string, _, 0) do
[]
end
defp get_indexes(string, [], arity) do
["" | get_indexes(string, [], arity - 1)]
end
defp get_indexes(string, [h | t], arity) do
[get_index(string, h) | get_indexes(string, t, arity - 1)]
end
@doc ~S"""
Escapes a string to be literally matched in a regex.
## Examples
iex> Regex.escape(".")
"\\."
iex> Regex.escape("\\what if")
"\\\\what\\ if"
"""
@spec escape(String.t()) :: String.t()
def escape(string) when is_binary(string) do
string
|> escape(_length = 0, string)
|> IO.iodata_to_binary()
end
@escapable :binary.bin_to_list(".^$*+?()[]{}|#-\\\t\n\v\f\r\s")
defp escape(<<char, rest::binary>>, length, original) when char in @escapable do
escape_char(rest, length, original, char)
end
defp escape(<<_, rest::binary>>, length, original) do
escape(rest, length + 1, original)
end
defp escape(<<>>, _length, original) do
original
end
defp escape_char(<<rest::binary>>, 0, _original, char) do
[?\\, char | escape(rest, 0, rest)]
end
defp escape_char(<<rest::binary>>, length, original, char) do
[binary_part(original, 0, length), ?\\, char | escape(rest, 0, rest)]
end
# Helpers
defp translate_options(<<?u, t::binary>>, acc), do: translate_options(t, [:unicode, :ucp | acc])
defp translate_options(<<?i, t::binary>>, acc), do: translate_options(t, [:caseless | acc])
defp translate_options(<<?x, t::binary>>, acc), do: translate_options(t, [:extended | acc])
defp translate_options(<<?f, t::binary>>, acc), do: translate_options(t, [:firstline | acc])
defp translate_options(<<?U, t::binary>>, acc), do: translate_options(t, [:ungreedy | acc])
defp translate_options(<<?s, t::binary>>, acc),
do: translate_options(t, [:dotall, {:newline, :anycrlf} | acc])
defp translate_options(<<?m, t::binary>>, acc), do: translate_options(t, [:multiline | acc])
defp translate_options(<<?r, t::binary>>, acc) do
IO.warn("the /r modifier in regular expressions is deprecated, please use /U instead")
translate_options(t, [:ungreedy | acc])
end
defp translate_options(<<>>, acc), do: acc
defp translate_options(rest, _acc), do: {:error, rest}
end