299 lines
7.8 KiB
Elixir
299 lines
7.8 KiB
Elixir
% In Elixir, strings are represented as binaries. A binary is a bit
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% string where its size is a multiple of eight. A BitString created
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% conforming to this condition will be automatically mapped as String:
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%
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% <<72, 73, 74>>.__parent__ % => String
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%
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% Notice that Erlang represents strings as lists. For this reason,
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% sometimes you need to convert a String to a list of chars, using
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% the `to_char_list` method. Also, you may want to convert a list
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% to a binary (i.e. a string) using the `to_bin` method.
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%
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% TODO: We need to inherit from BitString once we have inheritance.
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module String
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module Instance
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% Retrieves a number that represents the given character.
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%
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% ## Examples
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%
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% "elixir"[3] % => 140
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% "elixir"[-3] % => 140
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%
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def [](number)
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Erlang.binary_to_list(self)[number]
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end
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% Slice the string in the given *start* and *length* arguments. If length
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% is less than zero, it is the negative index to the end of the string.
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%
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% ## Examples
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%
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% "[1,2,3]"[0,3] % => "[1,"
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% "[1,2,3]"[1,-2] % => "1,2,3"
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%
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def [](start, length)
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if length < 0
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Erlang.binary_part(self, start, Erlang.size(self) - start + length + 1)
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else
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Erlang.binary_part(self, start, length)
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end
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end
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% Concatenate two strings.
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%
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% ## Examples
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%
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% "eli" + "xir" % => "elixir"
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%
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def +(another)
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<<self|binary, another|binary>>
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end
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% Returns the length of the string. All strings parsed by the
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% interpreter are handled as utf-8. Any I/O driver should be
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% responsible to convert to utf-8.
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%
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% ## Examples
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%
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% "elixir".length % => 6
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% "josé".length % => 4
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%
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def length
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Erlang.size(self)
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end
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% Returns the list representation of this String.
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def to_list
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Erlang.binary_to_list(self)
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end
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% Returns the list of chars represantion of this String.
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def to_char_list
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Erlang.binary_to_list(self)
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end
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% Check if the current string includes the given string.
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%
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% ## Examples
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%
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% true = "elixir".include?("el")
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% false = "elixir".include?("ex")
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%
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def include?(string)
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cl1 = to_char_list
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cl2 = string.to_char_list
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include?(cl1, cl2, cl1.length, cl2.length)
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end
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% Returns the index of the first occurence of the given substring or matching regex.
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% Returns nil if nothing is found.
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%
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% ## Examples
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%
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% 1 = "hello".index('e')
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% 3 = "hello".index('lo')
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% nil = "hello".index('a')
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%
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def index(given)
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if given.__module_name__ == 'Regexp::Behavior
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[{x,_}] = given.run(to_char_list, 'all, 0, 'index)
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x
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else
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result = Erlang.string.str(to_char_list, given.to_char_list)
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case result
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match 0 then nil
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match _ then result - 1
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end
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end
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end
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% Substitute the first occurrence of *given* in the string by *replacement*.
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% Please check `Regexp#replace` for more information about the characters
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% allowed in *replacement*.
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%
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% ## Examples
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%
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% "abc" = "abc".sub(~r(d), "d")
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% "adc" = "abc".sub(~r(b), "d")
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% "a[b]c" = "abc".sub(~r(b), "[&]")
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% "a[&]c" = "abc".sub(~r(b), "[\\&]")
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% "a[b]c" = "abc".sub(~r[(b)], "[\\1]")
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%
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def sub(given, replacement)
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if given.__module_name__ == 'Regexp::Behavior
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given.replace(self, replacement)
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else
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Regexp.new(Regexp.escape(given)).replace(self, replacement)
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end
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end
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% Substitute the **all** occurrence of *given* in the string by *replacement*.
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% Please check `Regexp#replace` for more information about the characters
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% allowed in *replacement*.
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%
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% ## Examples
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%
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% "abcbe" = "abcbe".gsub(~r(d), "d")
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% "adcde" = "abcbe".gsub(~r(b), "d")
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% "a[b]c[b]e" = "abcbe".gsub(~r(b), "[&]")
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% "a[&]c[&]e" = "abcbe".gsub(~r(b), "[\\&]")
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% "a[b]c[b]e" = "abcbe".gsub(~r[(b)], "[\\1]")
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def gsub(given, replacement)
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if given.__module_name__ == 'Regexp::Behavior
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given.replace_all(self, replacement)
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else
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Regexp.new(Regexp.escape(given)).replace_all(self, replacement)
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end
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end
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% Remove all space characters from the beginning and end of the string.
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def strip
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gsub(~r"\A\s*|\s*\z", "")
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end
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% Remove all space characters from the beginning of the string.
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def lstrip
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gsub(~r"\A\s*", "")
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end
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% Remove all space characters from the end of the string.
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def rstrip
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gsub(~r"\s*\z", "")
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end
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% Returns a string representation of this string.
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%
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% ## Examples
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%
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% "elixir".inspect % => "\"elixir\""
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%
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def inspect
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list = Erlang.binary_to_list(self)
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if Erlang.io_lib.printable_unicode_list(list)
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<<$\", self|binary, $\">>
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else
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Erlang.io_lib.format($"~w", [self]).to_bin
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end
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end
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% Receives a regular expression and split the string. An optional number
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% of parts to split the string can be given. By default is the atom infinity.
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%
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% ## Examples
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%
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% ["foo", "baz", "bat"] = "foobarbazbarbat".split(~r"bar")
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% ["foo", "bazbarbat"] = "foobarbazbarbat".split(~r"bar", 2)
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%
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def split(given, parts := 'infinity)
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if given.__module_name__ == 'Regexp::Behavior
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given.split(self, parts)
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else
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Regexp.new(Regexp.escape(given)).split(self, parts)
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end
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end
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% Scan the whole string returning all matches.
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%
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% ## Examples
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%
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% "abc" = "key1=value1; key2=value2".scan(~r"(?:(\w+)=(\w+);?)")
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%
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def scan(given, offset := 0)
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if given.__module_name__ == 'Regexp::Behavior
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given.scan(self, 'all, offset)
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else
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Regexp.new(Regexp.escape(given)).scan(self, 'all, offset)
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end
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end
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% Return a string with the last character removed. If the string end
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% with \r\n then both characters are removed.
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%
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% ## Examples
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%
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% "foo".chop % => "fo"
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% "foo\r\n".chop % => "foo"
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% "foo\n\r".chop % => "foo\n"
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% "x".chop.chop % => ""
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%
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def chop
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sub(~r"(\r\n|.)\z", "")
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end
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% Returns true if the string is empty.
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def empty?
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Erlang.size(self) == 0
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end
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% Returns the string itself.
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def to_bin
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self
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end
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% Returns the string itself.
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def to_s
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self
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end
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def to_atom
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Erlang.binary_to_atom(self, 'utf8)
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end
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% Returns a copy of the original string with all lowercase letters replaced with their uppercase counterparts.
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def upcase
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Erlang.string.to_upper(to_char_list).to_bin
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end
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% Returns a copy of the original string with all uppercase letters replaced with their lowercase counterparts.
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def downcase
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Erlang.string.to_lower(to_char_list).to_bin
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end
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% Returns a copy of the origin string with the first character converted to uppercase and the rest to lowercase.
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def capitalize
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[h|t] = Erlang.string.to_lower(to_char_list)
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[Erlang.string.to_upper(h)|t].to_bin
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end
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% Returns a new string with the characters from original string in reverse order.
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def reverse
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to_char_list.reverse.to_bin
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end
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private
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def include?([], _, _, _)
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false
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end
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def include?(original, compare, l1, l2)
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if prefix(compare, original, l2, l1)
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true
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else
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[_|t] = original
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include? t, compare, l1 - 1, l2
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end
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end
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def prefix(pre, string, l1, l2)
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if l2 < l1
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false
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else
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prefix(pre, string)
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end
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end
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def prefix([h|pre], [h|string])
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prefix(pre, string)
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end
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def prefix([], _)
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true
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end
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def prefix(_, _)
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false
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end
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end
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end
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