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.smet...@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 > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to elixir-lang-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/4dbc37cc-6630-4989-acc0-c4acfd719a5b%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/4dbc37cc-6630-4989-acc0-c4acfd719a5b%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CABu8xFDcupN2SX%2Bivg%2BTJ7Q0LGbxARjAgRz-uta2ck8L%3DaTmKg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
