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, itâs 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 methodâs identifier :@ident. After the methodâs 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, weâre simply returning a String, so next we have the :string_literal expression.
Within our :string_literal youâll 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.
def Ripper.lex(src, filename = '-', lineno = 1, **kw) Lexer.new(src, filename, lineno).lex(**kw) end
Tokenizes the Ruby program and returns an array of an array, which is formatted like [[lineno, column], type, token, state]. The filename argument is mostly ignored. By default, this method does not handle syntax errors in src, use the raise_errors keyword to raise a SyntaxError for an error in src.
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 ]]
Source
def Ripper.parse(src, filename = '(ripper)', lineno = 1) new(src, filename, lineno).parse end
Parses the given Ruby program read from src. src must be a String or an IO or a object with a gets method.
def Ripper.sexp(src, filename = '-', lineno = 1, raise_errors: false)
builder = SexpBuilderPP.new(src, filename, lineno)
sexp = builder.parse
if builder.error?
if raise_errors
raise SyntaxError, builder.error
end
else
sexp
end
end
Parses src and create S-exp tree. Returns more readable tree rather than Ripper.sexp_raw. This method is mainly for developer use. The filename argument is mostly ignored. By default, this method does not handle syntax errors in src, returning nil in such cases. Use the raise_errors keyword to raise a SyntaxError for an error in src.
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]]]]
def Ripper.sexp_raw(src, filename = '-', lineno = 1, raise_errors: false)
builder = SexpBuilder.new(src, filename, lineno)
sexp = builder.parse
if builder.error?
if raise_errors
raise SyntaxError, builder.error
end
else
sexp
end
end
Parses src and create S-exp tree. This method is mainly for developer use. The filename argument is mostly ignored. By default, this method does not handle syntax errors in src, returning nil in such cases. Use the raise_errors keyword to raise a SyntaxError for an error in src.
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]]]]
def Ripper.slice(src, pattern, n = 0) if m = token_match(src, pattern) then m.string(n) else nil end 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')
p Ripper.slice('def m(a) nil end', '[ident lparen rparen]+')
p Ripper.slice("<<EOS\nstring\nEOS",
'heredoc_beg nl $(tstring_content*) heredoc_end', 1)
def Ripper.tokenize(src, filename = '-', lineno = 1, **kw) Lexer.new(src, filename, lineno).tokenize(**kw) end
Tokenizes the Ruby program and returns an array of strings. The filename and lineno arguments are mostly ignored, since the return value is just the tokenized input. By default, this method does not handle syntax errors in src, use the raise_errors keyword to raise a SyntaxError for an error in src.
p Ripper.tokenize("def m(a) nil end")
Private Instance Methods
Source
def compile_error(msg) end
This method is called when the parser found syntax error.
SourceThis method is called when weak warning is produced by the parser. fmt and args is printf style.
def warning(fmt, *args) end
This method is called when strong warning is produced by the parser. fmt and args is printf style.
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