I think you can reformat a part of the AST.
iex> some_ast_fragment = quote do [h|t] end
iex> some_ast_fragment |> Macro.to_string() |> Code.format_string! |>
Enum.join
"[h | t]"
Not sure if this would work for you. And the round-trip to a string might
not be necessary; I haven't had more than a cursory look at Code.Formatter.
- Martin
tis 27 feb. 2018 kl 12:32 skrev Serge Smetana <serge.smet...@gmail.com>:
> Hi,
>
> Sounds reasonable but may not work as good. This may change a lot of user
> formatted code and produce extra diffs in tests. If we could only reformat
> a part of the AST (one function call in our case) this would be ideal.
>
> Thanks,
> Serge.
>
> On Monday, February 26, 2018 at 2:31:01 PM UTC+2, Louis Pop wrote:
>
>> Hi there
>>
>> Given we have the formatter now I would be tempted to avoid editing
>> strings and instead update the AST of the file, render that to a string,
>> format it and write it back to the file. Would be more reliable.
>>
>> Cheers,
>> Louis
>>
>> On Mon, 26 Feb 2018, 12:11 Serge Smetana, <serge....@gmail.com> wrote:
>>
> Hi,
>>>
>>> I would like Elixir AST nodes to include begin and end parse character
>>> offsets.
>>> This would make it easier to write refactoring tools that modify parts of
>>> Elixir source files.
>>>
>>> Usecase:
>>>
>>> We have a library https://github.com/assert-value/assert_value_elixir
>>> that is
>>> able to create and update expected values in tests. For example, given
>>> the
>>> following:
>>>
>>> assert_value 2 + 2 == 2 + 3
>>>
>>> our code will find the location of `2 + 3` and replace it with `4`:
>>>
>>> assert_value 2 + 2 == 4
>>>
>>> Today determining the location of `2 + 3` in the source file is
>>> difficult. For
>>> now, we use a custom-made parser which processes code char by char until
>>> it gets
>>> value matching AST:
>>>
>>> https://github.com/assert-value/assert_value_elixir/blob/master/lib/assert_value/parser.ex
>>> But if we had the parse offsets it would be much easier.
>>>
>>> Proposed interface:
>>>
>>> Probably need two sets of offsets, exclusive and inclusive of children.
>>> For
>>> each probably best to store beginning offset and length. Will need
>>> reasonable
>>> handling for parentheses and other tokens that do not make it into AST.
>>>
>>> Existing implementation:
>>>
>>> Elixir AST nodes do have useful info on this already. We use the "line:"
>>> which
>>> is very helpful. We don't use "column:", it did not seem useful given our
>>> implementation. We may be missing something obvious here.
>>>
>>> Details:
>>>
>>> In Elixir 1.6 compiled code AST has only function line number in meta.
>>> Even
>>> "columns: true" in Code.string_to_quoted gives only function starting
>>> column
>>> without information about arguments.
>>>
>>> Consider the following code:
>>>
>>> Code.string_to_quoted!("(41.00 == 42.0000)", columns: true)
>>> #=> {:==, [line: 1, column: 8], [41.0, 42.0]}
>>>
>>> From the AST you don't know where to find 41.00 and 42.0000 in a code.
>>> Column information does not help. AST values of 41.0 and 42.0 don't have
>>> information about how original values were formatted.
>>>
>>> Thanks,
>>> Serge
>>>
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