Sets the current position and line number to zero; see Position and Line Number.
See IO#read.
See IO#pread.
Sets both [byte position] and [character position] to zero, and clears [match values]; returns self:
scanner = StringScanner.new('foobarbaz') scanner.exist?(/bar/) # => 6 scanner.reset # => #<StringScanner 0/9 @ "fooba..."> put_situation(scanner) # Situation: # pos: 0 # charpos: 0 # rest: "foobarbaz" # rest_size: 9 # => nil match_values_cleared?(scanner) # => true
Returns the array of [captured match values] at indexes (1..) if the most recent match attempt succeeded, or nil otherwise:
scanner = StringScanner.new('Fri Dec 12 1975 14:39') scanner.captures # => nil scanner.exist?(/(?<wday>\w+) (?<month>\w+) (?<day>\d+) /) scanner.captures # => ["Fri", "Dec", "12"] scanner.values_at(*0..4) # => ["Fri Dec 12 ", "Fri", "Dec", "12", nil] scanner.exist?(/Fri/) scanner.captures # => [] scanner.scan(/nope/) scanner.captures # => nil
Rebuilds the hash table by recomputing the hash index for each key; returns self.
The hash table becomes invalid if the hash value of a key has changed after the entry was created. See Modifying an Active Hash Key.
Returns true if there are no hash entries, false otherwise:
{}.empty? # => true
{foo: 0, bar: 1, baz: 2}.empty? # => false
Returns a new Hash object whose entries are all those from self for which the block returns false or nil:
h = {foo: 0, bar: 1, baz: 2} h1 = h.reject {|key, value| key.start_with?('b') } h1 # => {:foo=>0}
Returns a new Enumerator if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.reject # => #<Enumerator: {:foo=>0, :bar=>1, :baz=>2}:reject> h1 = e.each {|key, value| key.start_with?('b') } h1 # => {:foo=>0}
Returns self, whose remaining entries are those for which the block returns false or nil:
h = {foo: 0, bar: 1, baz: 2} h.reject! {|key, value| value < 2 } # => {:baz=>2}
Returns nil if no entries are removed.
Returns a new Enumerator if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.reject! # => #<Enumerator: {:foo=>0, :bar=>1, :baz=>2}:reject!> e.each {|key, value| key.start_with?('b') } # => {:foo=>0}
Returns a new Hash object with the each key-value pair inverted:
h = {foo: 0, bar: 1, baz: 2} h1 = h.invert h1 # => {0=>:foo, 1=>:bar, 2=>:baz}
Overwrites any repeated new keys: (see Entry Order):
h = {foo: 0, bar: 0, baz: 0} h.invert # => {0=>:baz}
Replaces the entire contents of self with the contents of other_hash; returns self:
h = {foo: 0, bar: 1, baz: 2} h.replace({bat: 3, bam: 4}) # => {:bat=>3, :bam=>4}
Returns true if key is a key in self, otherwise false.
Yields each environment variable name and its value as a 2-element Array. Returns a Hash whose items are determined by the block. When the block returns a truthy value, the name/value pair is added to the return Hash; otherwise the pair is ignored:
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') ENV.reject { |name, value| name.start_with?('b') } # => {"foo"=>"0"}
Returns an Enumerator if no block given:
e = ENV.reject e.each { |name, value| name.start_with?('b') } # => {"foo"=>"0"}
Similar to ENV.delete_if, but returns nil if no changes were made.
Yields each environment variable name and its value as a 2-element Array, deleting each environment variable for which the block returns a truthy value, and returning ENV (if any deletions) or nil (if not):
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') ENV.reject! { |name, value| name.start_with?('b') } # => ENV ENV # => {"foo"=>"0"} ENV.reject! { |name, value| name.start_with?('b') } # => nil
Returns an Enumerator if no block given:
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') e = ENV.reject! # => #<Enumerator: {"bar"=>"1", "baz"=>"2", "foo"=>"0"}:reject!> e.each { |name, value| name.start_with?('b') } # => ENV ENV # => {"foo"=>"0"} e.each { |name, value| name.start_with?('b') } # => nil
Returns a Hash whose keys are the ENV values, and whose values are the corresponding ENV names:
ENV.replace('foo' => '0', 'bar' => '1') ENV.invert # => {"1"=>"bar", "0"=>"foo"}
For a duplicate ENV value, overwrites the hash entry:
ENV.replace('foo' => '0', 'bar' => '0') ENV.invert # => {"0"=>"foo"}
Note that the order of the ENV processing is OS-dependent, which means that the order of overwriting is also OS-dependent. See About Ordering.
Replaces the entire content of the environment variables with the name/value pairs in the given hash; returns ENV.
Replaces the content of ENV with the given pairs:
ENV.replace('foo' => '0', 'bar' => '1') # => ENV ENV.to_hash # => {"bar"=>"1", "foo"=>"0"}
Raises an exception if a name or value is invalid (see Invalid Names and Values):
ENV.replace('foo' => '0', :bar => '1') # Raises TypeError (no implicit conversion of Symbol into String) ENV.replace('foo' => '0', 'bar' => 1) # Raises TypeError (no implicit conversion of Integer into String) ENV.to_hash # => {"bar"=>"1", "foo"=>"0"}
Returns true when there are no environment variables, false otherwise:
ENV.clear ENV.empty? # => true ENV['foo'] = '0' ENV.empty? # => false
Returns true if there is an environment variable with the given name:
ENV.replace('foo' => '0', 'bar' => '1') ENV.include?('foo') # => true
Returns false if name is a valid String and there is no such environment variable:
ENV.include?('baz') # => false
Returns false if name is the empty String or is a String containing character '=':
ENV.include?('') # => false ENV.include?('=') # => false
Raises an exception if name is a String containing the NUL character "\0":
ENV.include?("\0") # Raises ArgumentError (bad environment variable name: contains null byte)
Raises an exception if name has an encoding that is not ASCII-compatible:
ENV.include?("\xa1\xa1".force_encoding(Encoding::UTF_16LE)) # Raises ArgumentError (bad environment variable name: ASCII incompatible encoding: UTF-16LE)
Raises an exception if name is not a String:
ENV.include?(Object.new) # TypeError (no implicit conversion of Object into String)
Reads length bytes from ARGF. The files named on the command line are concatenated and treated as a single file by this method, so when called without arguments the contents of this pseudo file are returned in their entirety.
length must be a non-negative integer or nil.
If length is a positive integer, read tries to read length bytes without any conversion (binary mode). It returns nil if an EOF is encountered before anything can be read. Fewer than length bytes are returned if an EOF is encountered during the read. In the case of an integer length, the resulting string is always in ASCII-8BIT encoding.
If length is omitted or is nil, it reads until EOF and the encoding conversion is applied, if applicable. A string is returned even if EOF is encountered before any data is read.
If length is zero, it returns an empty string ("").
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
For example:
$ echo "small" > small.txt $ echo "large" > large.txt $ ./glark.rb small.txt large.txt ARGF.read #=> "small\nlarge" ARGF.read(200) #=> "small\nlarge" ARGF.read(2) #=> "sm" ARGF.read(0) #=> ""
Note that this method behaves like the fread() function in C. This means it retries to invoke read(2) system calls to read data with the specified length. If you need the behavior like a single read(2) system call, consider ARGF#readpartial or ARGF#read_nonblock.
Reads at most maxlen bytes from the ARGF stream.
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
It raises EOFError on end of ARGF stream. Since ARGF stream is a concatenation of multiple files, internally EOF is occur for each file. ARGF.readpartial returns empty strings for EOFs except the last one and raises EOFError for the last one.
Reads each file in ARGF in its entirety, returning an Array containing lines from the files. Lines are assumed to be separated by sep.
lines = ARGF.readlines lines[0] #=> "This is line one\n"
See IO.readlines for a full description of all options.
Returns the next line from the current file in ARGF.
By default lines are assumed to be separated by $/; to use a different character as a separator, supply it as a String for the sep argument.
The optional limit argument specifies how many characters of each line to return. By default all characters are returned.
An EOFError is raised at the end of the file.