Overview
I try it.
block_source.rb (require RUBY_VERSION >= '2.6.0'
def inspector(ast:, &block)
ast.children.each do |child|
next unless child.instance_of?(RubyVM::AbstractSyntaxTree::Node)
yield child
inspector(ast: child, &block)
end
end
def find_node(ast:, type:, lineno:)
inspector(ast: ast) do |node|
return node if node.type == type && node.first_lineno == lineno
end
nil
end
def extract_source(node:, source:)
first_lineno = node.first_lineno - 1
first_column = node.first_column
last_lineno = node.last_lineno - 1
last_column = node.last_column - 1
if first_lineno == last_lineno
source[first_lineno][first_column..last_column]
else
src = ' ' * first_column + source[first_lineno][first_column..]
((first_lineno + 1)...last_lineno).each do |lineno|
src << source[lineno]
end
src << source[last_lineno][0..last_column]
end
end
module Kernel
# RUBY_VERSION >= '2.6.0'
def block_source
@file_specs ||= {}
bl = caller_locations.last
source = @file_specs.dig(bl.path, :source) || File.readlines(bl.path)
@file_specs[bl.path] ||= { source: source, ast: RubyVM::AbstractSyntaxTree.parse(source.join) }
node = find_node(
ast: @file_specs.dig(bl.path, :ast),
type: :ITER,
lineno: bl.lineno
)
extract_source(node: node.children[1], source: source) if node
end
end
Usage
require_relative 'block_source'
def foo
pp block_source
end
foo { 'hello' } #=> " { 'hello' }"
foo { |i| i * 3 } #=> " { |i| i * 3 }"
foo #=> nil
Detail
First, get a caller information by bl = caller_locations.last.
bl = caller_locations.last
Second, find ITER node. (ITER node is method call with block.)
node = find_node(
ast: @file_specs.dig(bl.path, :ast),
type: :ITER,
lineno: bl.lineno
)
find_node implement is simple. call inspector and find node which match conditions.
def find_node(ast:, type:, lineno:)
inspector(ast: ast) do |node|
return node if node.type == type && node.first_lineno == lineno
end
nil
end
Finarlly, extract block source from ITER. (ITER node has block body in a second children element.
extract_source(node: node.children[1], source: source) if node
TODO
Currently, it isn't possible to get a column number from the information of the caller_locations. so, this case not working.
foo { 'hello' }; bar { 'world' }
" { 'hello' }"
" { 'hello' }"
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