Syntax tree nodes

parse(source) answers an Array of nodes, one for each top-level statement in source, and body on the method get_source returns answers the method's statements the same way. A node is a Hash with a "type" key and the keys its type lists below. A child node is a Hash of the same kind, and a list of children is an Array. Code as objects shows them in use.

node = parse("total = items.sum(:price) if ready").first
p node["type"]
p node["condition"]

assignment = node["then_branch"].first
p assignment["target"]["name"]
p assignment["value"]["method"]
p assignment["value"]["arguments"]
p node["else_branch"]

p parse("case size when 1 then :one end").first

"If"
{"type" => "Identifier", "name" => "ready"}
"total"
"sum"
[{"type" => "Symbol", "value" => "price"}]
nil
{"type" => "Unknown"}

A statement or expression with no type below answers {"type" => "Unknown"}, as the case above does. Method definitions are among them.

Values#

Type	Keys
IntLiteral	value, an Integer
FloatLiteral	value, a Float
StringLiteral	value, a String. A string whose interpolations are all literals is folded into one StringLiteral.
InterpolatedString	none
BoolLiteral	value, true or false
NilLiteral	none
Symbol	value, the name as a String
Array	elements, an Array of nodes
Dictionary	entries, an Array of Hashes with key and value nodes
Lambda	parameters, an Array of names, and body, an Array of nodes

Names#

Type	Keys
Identifier	name
InstanceVariable	name
ClassVariable	name
GlobalVariable	name
Self	none
ScopeResolution	namespace, a node, and name, as in Foo::Bar

Operations and calls#

Type	Keys
BinaryOp	op, left, and right
UnaryOp	op, which is - or !, and operand
Grouped	expression, the node inside the parentheses
Call	callee, a node, and arguments, an Array of nodes, for a call with no receiver
MethodCall	receiver, a node, method, a String, and arguments, an Array of nodes
Index	array and index, as in list[0]

op in a BinaryOp is one of +, -, *, /, %, **, ==, ===, !=, <, >, <=, >=, <=>, &, |, ^, &&, ||, =, +=, -=, *=, and /=.

Statements#

Type	Keys
Assignment	target and value, both nodes. @count += 1 is an Assignment too.
If	condition, then_branch, an Array of nodes, and else_branch, an Array of nodes or nil
While	condition and body
For	variable, a name, iterable, a node, and body
Return	value, a node or nil
Raise	exception, a node or nil
Break	none
Continue	none, for next

The sample on this page is tests/_examples/site/docs_nodes.rb in the metorex repository, where the test suite checks its output.