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Module: RubyVM::AbstractSyntaxTree

Relationships & Source Files
Namespace Children
Classes:
Node
Defined in: ast.rb,
ast.c

Overview

AbstractSyntaxTree provides methods to parse Ruby code into abstract syntax trees. The nodes in the tree are instances of Node.

This module is MRI specific as it exposes implementation details of the MRI abstract syntax tree.

This module is experimental and its API is not stable, therefore it might change without notice. As examples, the order of children nodes is not guaranteed, the number of children nodes might change, there is no way to access children nodes by name, etc.

If you are looking for a stable API or an API working under multiple Ruby implementations, consider using the parser gem or Ripper. If you would like to make AbstractSyntaxTree stable, please join the discussion at bugs.ruby-lang.org/issues/14844.

Class Method Summary

Class Method Details

.node_id_for_backtrace_location(backtrace_location) ⇒ Integer

Returns the node id for the given backtrace location.

begin
  raise
rescue =>  e
  loc = e.backtrace_locations.first
  RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(loc)
end # => 0
[ GitHub ] 

  


# File 'ast.rb', line 111



def self.node_id_for_backtrace_location backtrace_location
  Primitive.node_id_for_backtrace_location backtrace_location
end


  








  

    

      .of(proc, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false)  ⇒ AbstractSyntaxTree 
      .of(method, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false)  ⇒ AbstractSyntaxTree 
    

  



  

    

Returns AST nodes of the given proc or method.



RubyVM::AbstractSyntaxTree.of(proc {1 + 2})
# => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:35-1:42>

def hello
  puts "hello, world"
end

RubyVM::AbstractSyntaxTree.of(method(:hello))
# => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-3:3>



See .parse for explanation of keyword argument meaning and usage.


  





  


  [ GitHub ]


  

  


# File 'ast.rb', line 96



def self.of body, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
  Primitive.ast_s_of body, keep_script_lines, error_tolerant, keep_tokens
end


  








  

    .parse(string, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false)  ⇒ AbstractSyntaxTree   



  

    

Parses the given string into an abstract syntax tree, returning the root node of that tree.



RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
# => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-1:9>



If keep_script_lines: true option is provided, the text of the parsed source is associated with nodes and is available via Node#script_lines.



If keep_tokens: true option is provided, Node#tokens are populated.



::SyntaxError is raised if the given string is invalid syntax. To overwrite this behavior, error_tolerant: true can be provided. In this case, the parser will produce a tree where expressions with syntax errors would be represented by AbstractSyntaxTree::Node with type=:ERROR.



root = RubyVM::AbstractSyntaxTree.parse("x = 1; p(x; y=2")
# <internal:ast>:33:in `parse': syntax error, unexpected ';', expecting ')' (SyntaxError)
# x = 1; p(x; y=2
#           ^

root = RubyVM::AbstractSyntaxTree.parse("x = 1; p(x; y=2", error_tolerant: true)
# (SCOPE@1:0-1:15
#  tbl: [:x, :y]
#  args: nil
#  body: (BLOCK@1:0-1:15 (LASGN@1:0-1:5 :x (LIT@1:4-1:5 1)) (ERROR@1:7-1:11) (LASGN@1:12-1:15 :y (LIT@1:14-1:15 2))))
root.children.last.children
# [(LASGN@1:0-1:5 :x (LIT@1:4-1:5 1)),
#  (ERROR@1:7-1:11),
#  (LASGN@1:12-1:15 :y (LIT@1:14-1:15 2))]



Note that parsing continues even after the errored expression.


  



  [ GitHub ]


  

  


# File 'ast.rb', line 58



def self.parse string, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
  Primitive.ast_s_parse string, keep_script_lines, error_tolerant, keep_tokens
end


  








  

    .parse_file(pathname, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false)  ⇒ AbstractSyntaxTree   



  

    

Reads the file from pathname, then parses it like .parse, returning the root node of the abstract syntax tree.



::SyntaxError is raised if pathname’s contents are not valid Ruby syntax.



RubyVM::AbstractSyntaxTree.parse_file("my-app/app.rb")
# => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-31:3>



See .parse for explanation of keyword argument meaning and usage.


  



  [ GitHub ]


  

  


# File 'ast.rb', line 75



def self.parse_file pathname, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
  Primitive.ast_s_parse_file pathname, keep_script_lines, error_tolerant, keep_tokens
end