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
This array contains name of all ripper events.
This array contains name of parser events.
This array contains name of scanner events.
Tokenizes the Ruby program and returns an array of an array, which is
formatted like [[lineno, column], type, token, state]
.
require 'ripper' require 'pp' pp Ripper.lex("def m(a) nil end") #=> [[[1, 0], :on_kw, "def", FNAME ], [[1, 3], :on_sp, " ", FNAME ], [[1, 4], :on_ident, "m", ENDFN ], [[1, 5], :on_lparen, "(", BEG|LABEL], [[1, 6], :on_ident, "a", ARG ], [[1, 7], :on_rparen, ")", ENDFN ], [[1, 8], :on_sp, " ", BEG ], [[1, 9], :on_kw, "nil", END ], [[1, 12], :on_sp, " ", END ], [[1, 13], :on_kw, "end", END ]]
# File ripper/lib/ripper/lexer.rb, line 44 def Ripper.lex(src, filename = '-', lineno = 1) Lexer.new(src, filename, lineno).lex end
Parses the given Ruby program read from src
. src
must be a String or an IO or a object with a gets method.
# File ripper/lib/ripper/core.rb, line 18 def Ripper.parse(src, filename = '(ripper)', lineno = 1) new(src, filename, lineno).parse end
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, nil, nil]], [:bodystmt, [[:var_ref, [:@kw, "nil", [1, 9]]]], nil, nil, nil]]]]
# File ripper/lib/ripper/sexp.rb, line 31 def Ripper.sexp(src, filename = '-', lineno = 1) builder = SexpBuilderPP.new(src, filename, lineno) sexp = builder.parse sexp unless builder.error? end
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 ripper/lib/ripper/sexp.rb, line 57 def Ripper.sexp_raw(src, filename = '-', lineno = 1) builder = SexpBuilder.new(src, filename, lineno) sexp = builder.parse sexp unless builder.error? end
Parses src
and return a string which was matched to
pattern
. 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 ripper/lib/ripper/lexer.rb, line 201 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 ripper/lib/ripper/lexer.rb, line 21 def Ripper.tokenize(src, filename = '-', lineno = 1) Lexer.new(src, filename, lineno).tokenize end