Support rename symbols

[faustinoaq]

Crystal compiler doesn't support rename symbols yet, see discussion here by @asterite

Would be possible to implement basic rename symbols on scry without crystal tool support? WDYT?

Nice comment by @RX14 :

Personally, local variable renaming, and small refactors such as "extract this subexpression to a variable" would be my 99% usecase for a refactoring tool.

See: Rename feature on LSP specification

[faustinoaq]

/cc @crystal-lang-tools/scry

[faustinoaq]

Interesting, I just got a rename proof of concept using transformer_example.cr. Similar to autocorrect on crystal-ameba/ameba#34 by @veelenga

require "compiler/crystal/syntax"

class Charify < Crystal::Transformer
  def transform(node : Crystal::Var)
    if node.name == "a"
      return Crystal::Var.new("c")
    end
    node
  end
end

nodes = Crystal::Parser.parse("a = 1; b = a")
puts nodes.transform(Charify.new) # => "c = 1; b = c"

https://carc.in/#/r/40jp