module RubyVM::AbstractSyntaxTree
AbstractSyntaxTree provides methods to parse Ruby code into abstract syntax trees. The nodes in the tree are instances of RubyVM::AbstractSyntaxTree::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 prism gem, which is the official Ruby API to parse Ruby code.
Public Class Methods
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
# File ast.rb, line 110 def self.node_id_for_backtrace_location backtrace_location Primitive.node_id_for_backtrace_location backtrace_location end
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.
# File ast.rb, line 95 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
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 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.
# File ast.rb, line 57 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
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.
# File ast.rb, line 74 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