Sourceror 0.8.0 is out 
This one is a bit small, just bug fixes and the addition of Sourceror.patch_string/2 which allows you to modify just some parts of a string, instead of having to print the whole tree. It receives the original string and a list of patches to be applied.
A patch is just a map with a :range pointing to the start and end positions to be replaced, and a :change that can be either a string, in which case the range will be replaced with it, or a function that accepts the original code in that range, and returns the string that replaces it.
This allows you to perform more fine grained changes to the source code, as you can use Sourceror.get_range/1 in combination with a traversal to generate the patches.
Also, now Sourceror.to_string/2 can receive a format: :splicing option that makes it easier to print elements of a keyword list without having to string the brackets yourself.
To illustrate these changes, here’s how a transformation for the Surface converter that renames the slot props: ... to args: ... would look like (from a discussion in the issue tracker):
Mix.install([{:sourceror, "~> 0.8"}])
code = """
defmodule Card do
use Surface.Component
slot footer
slot header, props: [:item]
slot default, required: true, props: [:item]
end
"""
{_, patches} =
code
|> Sourceror.parse_string!()
|> Sourceror.postwalk([], fn
{:slot, _, args} = quoted, state ->
opts_node = Enum.at(args, 1, [])
props_node = Enum.find(opts_node, &match?({{:__block__, _, [:props]}, _}, &1))
if props_node do
range = Sourceror.get_range(props_node)
{{:__block__, meta, [:props]}, body} = props_node
args_node = {{:__block__, meta, [:args]}, body}
new_code = Sourceror.to_string([args_node], format: :splicing)
patch = %{change: new_code, range: range}
{quoted, %{state | acc: [patch | state.acc]}}
else
{quoted, state}
end
quoted, state ->
{quoted, state}
end)
code
|> Sourceror.patch_string(patches)
|> IO.puts
The next versions will be focused on exploring ways to make it easier to create the patches, and to make the apis more stable
Changelog:
1. Enhancements
- [Sourceror] Added
Sourceror.patch_string/2
- [Sourceror] Added the
format: :splicing option to Sourceror.to_string/2
2. Bug fixes
- [Sourceror] Now
Sourceror.to_string/2 won’t produce invalid Elixir code when a keyword list element is at the beginning of a non-keyword list.
- [Sourceror] Now
Sourceror.get_range/1 will take the leading comments into account when calculating the range.
