class Ripper
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.
Usage¶ ↑
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
.
Resources¶ ↑
Requirements¶ ↑
-
ruby 1.9 (support CVS HEAD only)
-
bison 1.28 or later (Other yaccs do not work)
License¶ ↑
Ruby License. Minero Aoki aamine@loveruby.net http://i.loveruby.net
Constants
- EVENTS
This array contains name of all ripper events.
- PARSER_EVENTS
This array contains name of parser events.
- SCANNER_EVENTS
This array contains name of scanner events.
Public Class Methods
Tokenizes the Ruby program and returns an array of an array, which is
formatted like [[lineno, column], type, token]
.
require 'ripper' require 'pp' pp Ripper.lex("def m(a) nil end") #=> [[[1, 0], :on_kw, "def"], [[1, 3], :on_sp, " " ], [[1, 4], :on_ident, "m" ], [[1, 5], :on_lparen, "(" ], [[1, 6], :on_ident, "a" ], [[1, 7], :on_rparen, ")" ], [[1, 8], :on_sp, " " ], [[1, 9], :on_kw, "nil"], [[1, 12], :on_sp, " " ], [[1, 13], :on_kw, "end"]]
# File ext/ripper/lib/ripper/lexer.rb, line 42 def Ripper.lex(src, filename = '-', lineno = 1) Lexer.new(src, filename, lineno).lex end
- EXPERIMENTAL
-
Parses
src
and create S-exp tree. Returns more readable tree rather than ::sexp_raw. This method is mainly for developer use.require 'ripper' require 'pp' pp Ripper.sexp("def m(a) nil end") #=> [:program, [[:def, [:@ident, "m", [1, 4]], [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil, nil]], [:bodystmt, [[:var_ref, [:@kw, "nil", [1, 9]]]], nil, nil, nil]]]]
# File ext/ripper/lib/ripper/sexp.rb, line 30 def Ripper.sexp(src, filename = '-', lineno = 1) SexpBuilderPP.new(src, filename, lineno).parse end
- EXPERIMENTAL
-
Parses
src
and create S-exp tree. This method is mainly for developer use.require 'ripper' require 'pp' pp Ripper.sexp_raw("def m(a) nil end") #=> [:program, [:stmts_add, [:stmts_new], [:def, [:@ident, "m", [1, 4]], [:paren, [:params, [[:@ident, "a", [1, 6]]], nil, nil, nil]], [:bodystmt, [:stmts_add, [:stmts_new], [:var_ref, [:@kw, "nil", [1, 9]]]], nil, nil, nil]]]]
# File ext/ripper/lib/ripper/sexp.rb, line 54 def Ripper.sexp_raw(src, filename = '-', lineno = 1) SexpBuilder.new(src, filename, lineno).parse end
- EXPERIMENTAL
-
Parses
src
and return a string which was matched topattern
.pattern
should be described as Regexp.require 'ripper' p Ripper.slice('def m(a) nil end', 'ident') #=> "m" p Ripper.slice('def m(a) nil end', '[ident lparen rparen]+') #=> "m(a)" p Ripper.slice("<<EOS\nstring\nEOS", 'heredoc_beg nl $(tstring_content*) heredoc_end', 1) #=> "string\n"
# File ext/ripper/lib/ripper/lexer.rb, line 84 def Ripper.slice(src, pattern, n = 0) if m = token_match(src, pattern) then m.string(n) else nil end end
Tokenizes the Ruby program and returns an array of strings.
p Ripper.tokenize("def m(a) nil end") # => ["def", " ", "m", "(", "a", ")", " ", "nil", " ", "end"]
# File ext/ripper/lib/ripper/lexer.rb, line 20 def Ripper.tokenize(src, filename = '-', lineno = 1) Lexer.new(src, filename, lineno).tokenize end
Private Instance Methods
This method is called when the parser found syntax error.
# File ext/ripper/lib/ripper/core.rb, line 55 def compile_error(msg) end
This method is called when weak warning is produced by the parser.
fmt
and args
is printf style.
# File ext/ripper/lib/ripper/core.rb, line 46 def warn(fmt, *args) end
This method is called when strong warning is produced by the parser.
fmt
and args
is printf style.
# File ext/ripper/lib/ripper/core.rb, line 51 def warning(fmt, *args) end