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# frozen_string_literal: true
module Parser
##
# {Parser::TreeRewriter} offers a basic API that makes it easy to rewrite
# existing ASTs. It's built on top of {Parser::AST::Processor} and
# {Parser::Source::TreeRewriter}
#
# For example, assume you want to remove `do` tokens from a while statement.
# You can do this as following:
#
# require 'parser/current'
#
# class RemoveDo < Parser::TreeRewriter
# def on_while(node)
# # Check if the statement starts with "do"
# if node.location.begin.is?('do')
# remove(node.location.begin)
# end
# end
# end
#
# code = <<-EOF
# while true do
# puts 'hello'
# end
# EOF
#
# ast = Parser::CurrentRuby.parse code
# buffer = Parser::Source::Buffer.new('(example)', source: code)
# rewriter = RemoveDo.new
#
# # Rewrite the AST, returns a String with the new form.
# puts rewriter.rewrite(buffer, ast)
#
# This would result in the following Ruby code:
#
# while true
# puts 'hello'
# end
#
# Keep in mind that {Parser::TreeRewriter} does not take care of indentation when
# inserting/replacing code so you'll have to do this yourself.
#
# See also [a blog entry](http://whitequark.org/blog/2013/04/26/lets-play-with-ruby-code/)
# describing rewriters in greater detail.
#
# @api public
#
class TreeRewriter < Parser::AST::Processor
##
# Rewrites the AST/source buffer and returns a String containing the new
# version.
#
# @param [Parser::Source::Buffer] source_buffer
# @param [Parser::AST::Node] ast
# @param [Symbol] crossing_deletions:, different_replacements:, swallowed_insertions:
# policy arguments for TreeRewriter (optional)
# @return [String]
#
def rewrite(source_buffer,
ast,
**policy)
@source_rewriter = Parser::Source::TreeRewriter.new(source_buffer, **policy)
process(ast)
@source_rewriter.process
end
##
# Returns `true` if the specified node is an assignment node, returns false
# otherwise.
#
# @param [Parser::AST::Node] node
# @return [Boolean]
#
def assignment?(node)
[:lvasgn, :ivasgn, :gvasgn, :cvasgn, :casgn].include?(node.type)
end
##
# Removes the source range.
#
# @param [Parser::Source::Range] range
#
def remove(range)
@source_rewriter.remove(range)
end
##
# Wraps the given source range with the given values.
#
# @param [Parser::Source::Range] range
# @param [String] content
#
def wrap(range, before, after)
@source_rewriter.wrap(range, before, after)
end
##
# Inserts new code before the given source range.
#
# @param [Parser::Source::Range] range
# @param [String] content
#
def insert_before(range, content)
@source_rewriter.insert_before(range, content)
end
##
# Inserts new code after the given source range.
#
# @param [Parser::Source::Range] range
# @param [String] content
#
def insert_after(range, content)
@source_rewriter.insert_after(range, content)
end
##
# Replaces the code of the source range `range` with `content`.
#
# @param [Parser::Source::Range] range
# @param [String] content
#
def replace(range, content)
@source_rewriter.replace(range, content)
end
end
end
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