Returns a copy of str with leading and trailing whitespace removed.
Whitespace is defined as any of the following characters: null, horizontal tab, line feed, vertical tab, form feed, carriage return, space.
" hello ".strip #=> "hello" "\tgoodbye\r\n".strip #=> "goodbye" "\x00\t\n\v\f\r ".strip #=> ""
Method
contributed by Henrik Martensson
A String
object holds and manipulates an arbitrary sequence of bytes, typically representing characters. String objects may be created using String::new
or as literals.
Because of aliasing issues, users of strings should be aware of the methods that modify the contents of a String
object. Typically, methods with names ending in “!” modify their receiver, while those without a “!” return a new String
. However, there are exceptions, such as String#[]=
.
Pseudo I/O on String object.
Commonly used to simulate ‘$stdio` or `$stderr`
require 'stringio' io = StringIO.new io.puts "Hello World" io.string #=> "Hello World\n"
StringScanner
provides for lexical scanning operations on a String. Here is an example of its usage:
s = StringScanner.new('This is an example string') s.eos? # -> false p s.scan(/\w+/) # -> "This" p s.scan(/\w+/) # -> nil p s.scan(/\s+/) # -> " " p s.scan(/\s+/) # -> nil p s.scan(/\w+/) # -> "is" s.eos? # -> false p s.scan(/\s+/) # -> " " p s.scan(/\w+/) # -> "an" p s.scan(/\s+/) # -> " " p s.scan(/\w+/) # -> "example" p s.scan(/\s+/) # -> " " p s.scan(/\w+/) # -> "string" s.eos? # -> true p s.scan(/\s+/) # -> nil p s.scan(/\w+/) # -> nil
Scanning a string means remembering the position of a scan pointer, which is just an index. The point of scanning is to move forward a bit at a time, so matches are sought after the scan pointer; usually immediately after it.
Given the string “test string”, here are the pertinent scan pointer positions:
t e s t s t r i n g 0 1 2 ... 1 0
When you scan
for a pattern (a regular expression), the match must occur at the character after the scan pointer. If you use scan_until
, then the match can occur anywhere after the scan pointer. In both cases, the scan pointer moves just beyond the last character of the match, ready to scan again from the next character onwards. This is demonstrated by the example above.
Method
Categories There are other methods besides the plain scanners. You can look ahead in the string without actually scanning. You can access the most recent match. You can modify the string being scanned, reset or terminate the scanner, find out or change the position of the scan pointer, skip ahead, and so on.
beginning_of_line?
(bol?)
Data
There are aliases to several of the methods.
ScriptError
is the superclass for errors raised when a script can not be executed because of a LoadError
, NotImplementedError
or a SyntaxError
. Note these type of ScriptErrors
are not StandardError
and will not be rescued unless it is specified explicitly (or its ancestor Exception
).
A Struct
is a convenient way to bundle a number of attributes together, using accessor methods, without having to write an explicit class.
The Struct
class generates new subclasses that hold a set of members and their values. For each member a reader and writer method is created similar to Module#attr_accessor
.
Customer = Struct.new(:name, :address) do def greeting "Hello #{name}!" end end dave = Customer.new("Dave", "123 Main") dave.name #=> "Dave" dave.greeting #=> "Hello Dave!"
See Struct::new
for further examples of creating struct subclasses and instances.
In the method descriptions that follow, a “member” parameter refers to a struct member which is either a quoted string ("name"
) or a Symbol
(:name
).
An OpenStruct
is a data structure, similar to a Hash
, that allows the definition of arbitrary attributes with their accompanying values. This is accomplished by using Ruby’s metaprogramming to define methods on the class itself.
require "ostruct" person = OpenStruct.new person.name = "John Smith" person.age = 70 person.name # => "John Smith" person.age # => 70 person.address # => nil
An OpenStruct
employs a Hash
internally to store the attributes and values and can even be initialized with one:
australia = OpenStruct.new(:country => "Australia", :capital => "Canberra") # => #<OpenStruct country="Australia", capital="Canberra">
Hash
keys with spaces or characters that could normally not be used for method calls (e.g. ()[]*
) will not be immediately available on the OpenStruct
object as a method for retrieval or assignment, but can still be reached through the Object#send
method.
measurements = OpenStruct.new("length (in inches)" => 24) measurements.send("length (in inches)") # => 24 message = OpenStruct.new(:queued? => true) message.queued? # => true message.send("queued?=", false) message.queued? # => false
Removing the presence of an attribute requires the execution of the delete_field
method as setting the property value to nil
will not remove the attribute.
first_pet = OpenStruct.new(:name => "Rowdy", :owner => "John Smith") second_pet = OpenStruct.new(:name => "Rowdy") first_pet.owner = nil first_pet # => #<OpenStruct name="Rowdy", owner=nil> first_pet == second_pet # => false first_pet.delete_field(:owner) first_pet # => #<OpenStruct name="Rowdy"> first_pet == second_pet # => true
An OpenStruct
utilizes Ruby’s method lookup structure to find and define the necessary methods for properties. This is accomplished through the methods method_missing and define_singleton_method.
This should be a consideration if there is a concern about the performance of the objects that are created, as there is much more overhead in the setting of these properties compared to using a Hash
or a Struct
.
Ripper
is a Ruby script parser.
You can get information from the parser with event-based style. Information such as abstract syntax trees or simple lexical analysis of the Ruby program.
Ripper
provides an easy interface for parsing your program into a symbolic expression tree (or S-expression).
Understanding the output of the parser may come as a challenge, it’s recommended you use PP
to format the output for legibility.
require 'ripper' require 'pp' pp Ripper.sexp('def hello(world) "Hello, #{world}!"; end') #=> [:program, [[:def, [:@ident, "hello", [1, 4]], [:paren, [:params, [[:@ident, "world", [1, 10]]], nil, nil, nil, nil, nil, nil]], [:bodystmt, [[:string_literal, [:string_content, [:@tstring_content, "Hello, ", [1, 18]], [:string_embexpr, [[:var_ref, [:@ident, "world", [1, 27]]]]], [:@tstring_content, "!", [1, 33]]]]], nil, nil, nil]]]]
You can see in the example above, the expression starts with :program
.
From here, a method definition at :def
, followed by the method’s identifier :@ident
. After the method’s identifier comes the parentheses :paren
and the method parameters under :params
.
Next is the method body, starting at :bodystmt
(stmt
meaning statement), which contains the full definition of the method.
In our case, we’re simply returning a String, so next we have the :string_literal
expression.
Within our :string_literal
you’ll notice two @tstring_content
, this is the literal part for Hello,
and !
. Between the two @tstring_content
statements is a :string_embexpr
, where embexpr is an embedded expression. Our expression consists of a local variable, or var_ref
, with the identifier (@ident
) of world
.
ruby 1.9 (support CVS HEAD only)
bison 1.28 or later (Other yaccs do not work)
Ruby License.
Minero Aoki
aamine@loveruby.net
The Matrix
class represents a mathematical matrix. It provides methods for creating matrices, operating on them arithmetically and algebraically, and determining their mathematical properties such as trace, rank, inverse, determinant, or eigensystem.
Raised in case of a stack overflow.
def me_myself_and_i me_myself_and_i end me_myself_and_i
raises the exception:
SystemStackError: stack level too deep
A custom InputMethod class used by XMP
for evaluating string io.
A template for stream parser listeners. Note that the declarations (attlistdecl, elementdecl, etc) are trivially processed; REXML
doesn’t yet handle doctype entity declarations, so you have to parse them out yourself.
C struct shell
A C struct wrapper
Psych::Stream
is a streaming YAML emitter. It will not buffer your YAML, but send it straight to an IO
.
Here is an example use:
stream = Psych::Stream.new($stdout) stream.start stream.push({:foo => 'bar'}) stream.finish
YAML will be immediately emitted to $stdout with no buffering.
Psych::Stream#start
will take a block and ensure that Psych::Stream#finish
is called, so you can do this form:
stream = Psych::Stream.new($stdout) stream.start do |em| em.push(:foo => 'bar') end
Subclass of Zlib::Error
When zlib returns a Z_STREAM_END is return if the end of the compressed data has been reached and all uncompressed out put has been produced.
Subclass of Zlib::Error
When zlib returns a Z_STREAM_ERROR, usually if the stream state was inconsistent.
Zlib::ZStream
is the abstract class for the stream which handles the compressed data. The operations are defined in the subclasses: Zlib::Deflate
for compression, and Zlib::Inflate
for decompression.
An instance of Zlib::ZStream
has one stream (struct zstream in the source) and two variable-length buffers which associated to the input (next_in) of the stream and the output (next_out) of the stream. In this document, “input buffer” means the buffer for input, and “output buffer” means the buffer for output.
Data
input into an instance of Zlib::ZStream
are temporally stored into the end of input buffer, and then data in input buffer are processed from the beginning of the buffer until no more output from the stream is produced (i.e. until avail_out
> 0 after processing). During processing, output buffer is allocated and expanded automatically to hold all output data.
Some particular instance methods consume the data in output buffer and return them as a String.
Here is an ascii art for describing above:
+================ an instance of Zlib::ZStream ================+ || || || +--------+ +-------+ +--------+ || || +--| output |<---------|zstream|<---------| input |<--+ || || | | buffer | next_out+-------+next_in | buffer | | || || | +--------+ +--------+ | || || | | || +===|======================================================|===+ | | v | "output data" "input data"
If an error occurs during processing input buffer, an exception which is a subclass of Zlib::Error
is raised. At that time, both input and output buffer keep their conditions at the time when the error occurs.
Method
Catalogue Many of the methods in this class are fairly low-level and unlikely to be of interest to users. In fact, users are unlikely to use this class directly; rather they will be interested in Zlib::Inflate
and Zlib::Deflate
.
The higher level methods are listed below.
Zlib::GzipWriter
is a class for writing gzipped files. GzipWriter
should be used with an instance of IO
, or IO-like, object.
Following two example generate the same result.
Zlib::GzipWriter.open('hoge.gz') do |gz| gz.write 'jugemu jugemu gokou no surikire...' end File.open('hoge.gz', 'w') do |f| gz = Zlib::GzipWriter.new(f) gz.write 'jugemu jugemu gokou no surikire...' gz.close end
To make like gzip(1) does, run following:
orig = 'hoge.txt' Zlib::GzipWriter.open('hoge.gz') do |gz| gz.mtime = File.mtime(orig) gz.orig_name = orig gz.write IO.binread(orig) end
NOTE: Due to the limitation of Ruby’s finalizer, you must explicitly close GzipWriter
objects by Zlib::GzipWriter#close
etc. Otherwise, GzipWriter
will be not able to write the gzip footer and will generate a broken gzip file.
The InstructionSequence
class represents a compiled sequence of instructions for the Ruby Virtual Machine.
With it, you can get a handle to the instructions that make up a method or a proc, compile strings of Ruby code down to VM instructions, and disassemble instruction sequences to strings for easy inspection. It is mostly useful if you want to learn how the Ruby VM works, but it also lets you control various settings for the Ruby iseq compiler.
You can find the source for the VM instructions in insns.def
in the Ruby source.
The instruction sequence results will almost certainly change as Ruby changes, so example output in this documentation may be different from what you see.
HTTPGenericRequest
is the parent of the HTTPRequest class. Do not use this directly; use a subclass of HTTPRequest.
Mixes in the HTTPHeader module to provide easier access to HTTP headers.