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diff --git a/doc/string.rb b/doc/string.rb new file mode 100644 index 0000000000..304ab60c29 --- /dev/null +++ b/doc/string.rb @@ -0,0 +1,421 @@ +# A +String+ object has an arbitrary sequence of bytes, +# typically representing text or binary data. +# A +String+ object may be created using String::new or as literals. +# +# String objects differ from Symbol objects in that Symbol objects are +# designed to be used as identifiers, instead of text or data. +# +# You can create a +String+ object explicitly with: +# +# - A {string literal}[rdoc-ref:syntax/literals.rdoc@String+Literals]. +# - A {heredoc literal}[rdoc-ref:syntax/literals.rdoc@Here+Document+Literals]. +# +# You can convert certain objects to Strings with: +# +# - Method #String. +# +# Some +String+ methods modify +self+. +# Typically, a method whose name ends with <tt>!</tt> modifies +self+ +# and returns +self+; +# often, a similarly named method (without the <tt>!</tt>) +# returns a new string. +# +# In general, if both bang and non-bang versions of a method exist, +# the bang method mutates and the non-bang method does not. +# However, a method without a bang can also mutate, such as String#replace. +# +# == Substitution Methods +# +# These methods perform substitutions: +# +# - String#sub: One substitution (or none); returns a new string. +# - String#sub!: One substitution (or none); returns +self+ if any changes, +# +nil+ otherwise. +# - String#gsub: Zero or more substitutions; returns a new string. +# - String#gsub!: Zero or more substitutions; returns +self+ if any changes, +# +nil+ otherwise. +# +# Each of these methods takes: +# +# - A first argument, +pattern+ (String or Regexp), +# that specifies the substring(s) to be replaced. +# +# - Either of the following: +# +# - A second argument, +replacement+ (String or Hash), +# that determines the replacing string. +# - A block that will determine the replacing string. +# +# The examples in this section mostly use the String#sub and String#gsub methods; +# the principles illustrated apply to all four substitution methods. +# +# <b>Argument +pattern+</b> +# +# Argument +pattern+ is commonly a regular expression: +# +# s = 'hello' +# s.sub(/[aeiou]/, '*') # => "h*llo" +# s.gsub(/[aeiou]/, '*') # => "h*ll*" +# s.gsub(/[aeiou]/, '') # => "hll" +# s.sub(/ell/, 'al') # => "halo" +# s.gsub(/xyzzy/, '*') # => "hello" +# 'THX1138'.gsub(/\d+/, '00') # => "THX00" +# +# When +pattern+ is a string, all its characters are treated +# as ordinary characters (not as Regexp special characters): +# +# 'THX1138'.gsub('\d+', '00') # => "THX1138" +# +# <b>+String+ +replacement+</b> +# +# If +replacement+ is a string, that string determines +# the replacing string that is substituted for the matched text. +# +# Each of the examples above uses a simple string as the replacing string. +# +# +String+ +replacement+ may contain back-references to the pattern's captures: +# +# - <tt>\n</tt> (_n_ is a non-negative integer) refers to <tt>$n</tt>. +# - <tt>\k<name></tt> refers to the named capture +name+. +# +# See Regexp for details. +# +# Note that within the string +replacement+, a character combination +# such as <tt>$&</tt> is treated as ordinary text, not as +# a special match variable. +# However, you may refer to some special match variables using these +# combinations: +# +# - <tt>\&</tt> and <tt>\0</tt> correspond to <tt>$&</tt>, +# which contains the complete matched text. +# - <tt>\'</tt> corresponds to <tt>$'</tt>, +# which contains the string after the match. +# - <tt>\`</tt> corresponds to <tt>$`</tt>, +# which contains the string before the match. +# - <tt>\\+</tt> corresponds to <tt>$+</tt>, +# which contains the last capture group. +# +# See Regexp for details. +# +# Note that <tt>\\\\</tt> is interpreted as an escape, i.e., a single backslash. +# +# Note also that a string literal consumes backslashes. +# See {String Literals}[rdoc-ref:syntax/literals.rdoc@String+Literals] for details about string literals. +# +# A back-reference is typically preceded by an additional backslash. +# For example, if you want to write a back-reference <tt>\&</tt> in +# +replacement+ with a double-quoted string literal, you need to write +# <tt>"..\\\\&.."</tt>. +# +# If you want to write a non-back-reference string <tt>\&</tt> in +# +replacement+, you need to first escape the backslash to prevent +# this method from interpreting it as a back-reference, and then you +# need to escape the backslashes again to prevent a string literal from +# consuming them: <tt>"..\\\\\\\\&.."</tt>. +# +# You may want to use the block form to avoid excessive backslashes. +# +# <b>\Hash +replacement+</b> +# +# If the argument +replacement+ is a hash, and +pattern+ matches one of its keys, +# the replacing string is the value for that key: +# +# h = {'foo' => 'bar', 'baz' => 'bat'} +# 'food'.sub('foo', h) # => "bard" +# +# Note that a symbol key does not match: +# +# h = {foo: 'bar', baz: 'bat'} +# 'food'.sub('foo', h) # => "d" +# +# <b>Block</b> +# +# In the block form, the current match string is passed to the block; +# the block's return value becomes the replacing string: +# +# s = '@' +# '1234'.gsub(/\d/) { |match| s.succ! } # => "ABCD" +# +# Special match variables such as <tt>$1</tt>, <tt>$2</tt>, <tt>$`</tt>, +# <tt>$&</tt>, and <tt>$'</tt> are set appropriately. +# +# == Whitespace in Strings +# +# In the class +String+, _whitespace_ is defined as a contiguous sequence of characters +# consisting of any mixture of the following: +# +# - NL (null): <tt>"\x00"</tt>, <tt>"\u0000"</tt>. +# - HT (horizontal tab): <tt>"\x09"</tt>, <tt>"\t"</tt>. +# - LF (line feed): <tt>"\x0a"</tt>, <tt>"\n"</tt>. +# - VT (vertical tab): <tt>"\x0b"</tt>, <tt>"\v"</tt>. +# - FF (form feed): <tt>"\x0c"</tt>, <tt>"\f"</tt>. +# - CR (carriage return): <tt>"\x0d"</tt>, <tt>"\r"</tt>. +# - SP (space): <tt>"\x20"</tt>, <tt>" "</tt>. +# +# +# Whitespace is relevant for the following methods: +# +# - #lstrip, #lstrip!: Strip leading whitespace. +# - #rstrip, #rstrip!: Strip trailing whitespace. +# - #strip, #strip!: Strip leading and trailing whitespace. +# +# == What's Here +# +# First, what's elsewhere. Class +String+: +# +# - Inherits from the {Object class}[rdoc-ref:Object@What-27s+Here]. +# - Includes the {Comparable module}[rdoc-ref:Comparable@What-27s+Here]. +# +# Here, class +String+ provides methods that are useful for: +# +# - {Creating a \String}[rdoc-ref:String@Creating+a+String]. +# - {Freezing/Unfreezing a \String}[rdoc-ref:String@Freezing-2FUnfreezing]. +# - {Querying a \String}[rdoc-ref:String@Querying]. +# - {Comparing Strings}[rdoc-ref:String@Comparing]. +# - {Modifying a \String}[rdoc-ref:String@Modifying]. +# - {Converting to a new \String}[rdoc-ref:String@Converting+to+New+String]. +# - {Converting to a non-\String}[rdoc-ref:String@Converting+to+Non--5CString]. +# - {Iterating over a \String}[rdoc-ref:String@Iterating]. +# +# === Creating a \String +# +# - ::new: Returns a new string. +# - ::try_convert: Returns a new string created from a given object. +# +# === Freezing/Unfreezing +# +# - #+@: Returns a string that is not frozen: +self+ if not frozen; +# +self.dup+ otherwise. +# - #-@ (aliased as #dedup): Returns a string that is frozen: +self+ if already frozen; +# +self.freeze+ otherwise. +# - #freeze: Freezes +self+ if not already frozen; returns +self+. +# +# === Querying +# +# _Counts_ +# +# - #bytesize: Returns the count of bytes. +# - #count: Returns the count of substrings matching given strings. +# - #empty?: Returns whether the length of +self+ is zero. +# - #length (aliased as #size): Returns the count of characters (not bytes). +# +# _Substrings_ +# +# - #=~: Returns the index of the first substring that matches a given +# Regexp or other object; returns +nil+ if no match is found. +# - #byteindex: Returns the byte index of the first occurrence of a given substring. +# - #byterindex: Returns the byte index of the last occurrence of a given substring. +# - #index: Returns the index of the _first_ occurrence of a given substring; +# returns +nil+ if none found. +# - #rindex: Returns the index of the _last_ occurrence of a given substring; +# returns +nil+ if none found. +# - #include?: Returns +true+ if the string contains a given substring; +false+ otherwise. +# - #match: Returns a MatchData object if the string matches a given Regexp; +nil+ otherwise. +# - #match?: Returns +true+ if the string matches a given Regexp; +false+ otherwise. +# - #start_with?: Returns +true+ if the string begins with any of the given substrings. +# - #end_with?: Returns +true+ if the string ends with any of the given substrings. +# +# _Encodings_ +# +# - #encoding\: Returns the Encoding object that represents the encoding of the string. +# - #unicode_normalized?: Returns +true+ if the string is in Unicode normalized form; +false+ otherwise. +# - #valid_encoding?: Returns +true+ if the string contains only characters that are valid +# for its encoding. +# - #ascii_only?: Returns +true+ if the string has only ASCII characters; +false+ otherwise. +# +# _Other_ +# +# - #sum: Returns a basic checksum for the string: the sum of each byte. +# - #hash: Returns the integer hash code. +# +# === Comparing +# +# - #== (aliased as #===): Returns +true+ if a given other string has the same content as +self+. +# - #eql?: Returns +true+ if the content is the same as the given other string. +# - #<=>: Returns -1, 0, or 1 as a given other string is smaller than, +# equal to, or larger than +self+. +# - #casecmp: Ignoring case, returns -1, 0, or 1 as +# +self+ is smaller than, equal to, or larger than a given other string. +# - #casecmp?: Ignoring case, returns whether a given other string is equal to +self+. +# +# === Modifying +# +# Each of these methods modifies +self+. +# +# _Insertion_ +# +# - #insert: Returns +self+ with a given string inserted at a specified offset. +# - #<<: Returns +self+ concatenated with a given string or integer. +# - #append_as_bytes: Returns +self+ concatenated with strings without performing any +# encoding validation or conversion. +# - #prepend: Prefixes to +self+ the concatenation of given other strings. +# +# _Substitution_ +# +# - #bytesplice: Replaces bytes of +self+ with bytes from a given string; returns +self+. +# - #sub!: Replaces the first substring that matches a given pattern with a given replacement string; +# returns +self+ if any changes, +nil+ otherwise. +# - #gsub!: Replaces each substring that matches a given pattern with a given replacement string; +# returns +self+ if any changes, +nil+ otherwise. +# - #succ! (aliased as #next!): Returns +self+ modified to become its own successor. +# - #replace: Returns +self+ with its entire content replaced by a given string. +# - #reverse!: Returns +self+ with its characters in reverse order. +# - #setbyte: Sets the byte at a given integer offset to a given value; returns the argument. +# - #tr!: Replaces specified characters in +self+ with specified replacement characters; +# returns +self+ if any changes, +nil+ otherwise. +# - #tr_s!: Replaces specified characters in +self+ with specified replacement characters, +# removing duplicates from the substrings that were modified; +# returns +self+ if any changes, +nil+ otherwise. +# +# _Casing_ +# +# - #capitalize!: Upcases the initial character and downcases all others; +# returns +self+ if any changes, +nil+ otherwise. +# - #downcase!: Downcases all characters; returns +self+ if any changes, +nil+ otherwise. +# - #upcase!: Upcases all characters; returns +self+ if any changes, +nil+ otherwise. +# - #swapcase!: Upcases each downcase character and downcases each upcase character; +# returns +self+ if any changes, +nil+ otherwise. +# +# _Encoding_ +# +# - #encode!: Returns +self+ with all characters transcoded from one encoding to another. +# - #unicode_normalize!: Unicode-normalizes +self+; returns +self+. +# - #scrub!: Replaces each invalid byte with a given character; returns +self+. +# - #force_encoding: Changes the encoding to a given encoding; returns +self+. +# +# _Deletion_ +# +# - #clear: Removes all content, so that +self+ is empty; returns +self+. +# - #slice!, #[]=: Removes a substring determined by a given index, start/length, range, regexp, or substring. +# - #squeeze!: Removes contiguous duplicate characters; returns +self+. +# - #delete!: Removes characters as determined by the intersection of substring arguments. +# - #delete_prefix!: Removes leading prefix; returns +self+ if any changes, +nil+ otherwise. +# - #delete_suffix!: Removes trailing suffix; returns +self+ if any changes, +nil+ otherwise. +# - #lstrip!: Removes leading whitespace; returns +self+ if any changes, +nil+ otherwise. +# - #rstrip!: Removes trailing whitespace; returns +self+ if any changes, +nil+ otherwise. +# - #strip!: Removes leading and trailing whitespace; returns +self+ if any changes, +nil+ otherwise. +# - #chomp!: Removes the trailing record separator, if found; returns +self+ if any changes, +nil+ otherwise. +# - #chop!: Removes trailing newline characters if found; otherwise removes the last character; +# returns +self+ if any changes, +nil+ otherwise. +# +# === Converting to New \String +# +# Each of these methods returns a new +String+ based on +self+, +# often just a modified copy of +self+. +# +# _Extension_ +# +# - #*: Returns the concatenation of multiple copies of +self+. +# - #+: Returns the concatenation of +self+ and a given other string. +# - #center: Returns a copy of +self+, centered by specified padding. +# - #concat: Returns the concatenation of +self+ with given other strings. +# - #ljust: Returns a copy of +self+ of a given length, right-padded with a given other string. +# - #rjust: Returns a copy of +self+ of a given length, left-padded with a given other string. +# +# _Encoding_ +# +# - #b: Returns a copy of +self+ with ASCII-8BIT encoding. +# - #scrub: Returns a copy of +self+ with each invalid byte replaced with a given character. +# - #unicode_normalize: Returns a copy of +self+ with each character Unicode-normalized. +# - #encode: Returns a copy of +self+ with all characters transcoded from one encoding to another. +# +# _Substitution_ +# +# - #dump: Returns a printable version of +self+, enclosed in double-quotes. +# - #undump: Inverse of #dump; returns a copy of +self+ with changes of the kinds made by #dump "undone." +# - #sub: Returns a copy of +self+ with the first substring matching a given pattern +# replaced with a given replacement string. +# - #gsub: Returns a copy of +self+ with each substring that matches a given pattern +# replaced with a given replacement string. +# - #succ (aliased as #next): Returns the string that is the successor to +self+. +# - #reverse: Returns a copy of +self+ with its characters in reverse order. +# - #tr: Returns a copy of +self+ with specified characters replaced with specified replacement characters. +# - #tr_s: Returns a copy of +self+ with specified characters replaced with +# specified replacement characters, +# removing duplicates from the substrings that were modified. +# - #%: Returns the string resulting from formatting a given object into +self+. +# +# _Casing_ +# +# - #capitalize: Returns a copy of +self+ with the first character upcased +# and all other characters downcased. +# - #downcase: Returns a copy of +self+ with all characters downcased. +# - #upcase: Returns a copy of +self+ with all characters upcased. +# - #swapcase: Returns a copy of +self+ with all upcase characters downcased +# and all downcase characters upcased. +# +# _Deletion_ +# +# - #delete: Returns a copy of +self+ with characters removed. +# - #delete_prefix: Returns a copy of +self+ with a given prefix removed. +# - #delete_suffix: Returns a copy of +self+ with a given suffix removed. +# - #lstrip: Returns a copy of +self+ with leading whitespace removed. +# - #rstrip: Returns a copy of +self+ with trailing whitespace removed. +# - #strip: Returns a copy of +self+ with leading and trailing whitespace removed. +# - #chomp: Returns a copy of +self+ with a trailing record separator removed, if found. +# - #chop: Returns a copy of +self+ with trailing newline characters or the last character removed. +# - #squeeze: Returns a copy of +self+ with contiguous duplicate characters removed. +# - #[] (aliased as #slice): Returns a substring determined by a given index, start/length, range, regexp, or string. +# - #byteslice: Returns a substring determined by a given index, start/length, or range. +# - #chr: Returns the first character. +# +# _Duplication_ +# +# - #to_s (aliased as #to_str): If +self+ is a subclass of +String+, returns +self+ copied into a +String+; +# otherwise, returns +self+. +# +# === Converting to Non-\String +# +# Each of these methods converts the contents of +self+ to a non-+String+. +# +# <em>Characters, Bytes, and Clusters</em> +# +# - #bytes: Returns an array of the bytes in +self+. +# - #chars: Returns an array of the characters in +self+. +# - #codepoints: Returns an array of the integer ordinals in +self+. +# - #getbyte: Returns the integer byte at the given index in +self+. +# - #grapheme_clusters: Returns an array of the grapheme clusters in +self+. +# +# _Splitting_ +# +# - #lines: Returns an array of the lines in +self+, as determined by a given record separator. +# - #partition: Returns a 3-element array determined by the first substring that matches +# a given substring or regexp. +# - #rpartition: Returns a 3-element array determined by the last substring that matches +# a given substring or regexp. +# - #split: Returns an array of substrings determined by a given delimiter -- regexp or string -- +# or, if a block is given, passes those substrings to the block. +# +# _Matching_ +# +# - #scan: Returns an array of substrings matching a given regexp or string, or, +# if a block is given, passes each matching substring to the block. +# - #unpack: Returns an array of substrings extracted from +self+ according to a given format. +# - #unpack1: Returns the first substring extracted from +self+ according to a given format. +# +# _Numerics_ +# +# - #hex: Returns the integer value of the leading characters, interpreted as hexadecimal digits. +# - #oct: Returns the integer value of the leading characters, interpreted as octal digits. +# - #ord: Returns the integer ordinal of the first character in +self+. +# - #to_c: Returns the complex value of leading characters, interpreted as a complex number. +# - #to_i: Returns the integer value of leading characters, interpreted as an integer. +# - #to_f: Returns the floating-point value of leading characters, interpreted as a floating-point number. +# - #to_r: Returns the rational value of leading characters, interpreted as a rational. +# +# <em>Strings and Symbols</em> +# +# - #inspect: Returns a copy of +self+, enclosed in double quotes, with special characters escaped. +# - #intern (aliased as #to_sym): Returns the symbol corresponding to +self+. +# +# === Iterating +# +# - #each_byte: Calls the given block with each successive byte in +self+. +# - #each_char: Calls the given block with each successive character in +self+. +# - #each_codepoint: Calls the given block with each successive integer codepoint in +self+. +# - #each_grapheme_cluster: Calls the given block with each successive grapheme cluster in +self+. +# - #each_line: Calls the given block with each successive line in +self+, +# as determined by a given record separator. +# - #upto: Calls the given block with each string value returned by successive calls to #succ. + +class String; end |