introduce convenience string conversion functions (#287)

lib/kernel/comby_kernel.mli

@@ -335,9 +335,17 @@ module Matchers : sig
     type kind =
       | Value
       | Length
+      | Type
       | FileName
       | FilePath
-      | Type
+      | Lowercase
+      | Uppercase
+      | Capitalize
+      | Uncapitalize
+      | UpperCamelCase
+      | LowerCamelCase
+      | UpperSnakeCase
+      | LowerSnakeCase
 
     type syntax =
       { variable : string

lib/kernel/matchers/template.ml

@@ -76,10 +76,35 @@ module Make (Metasyntax : Types.Metasyntax.S) = struct
     | "type" -> Type
     | "file.name" -> FileName
     | "file.path" -> FilePath
+    | "lowercase" -> Lowercase
+    | "UPPERCASE" -> Uppercase
+    | "capitalize" -> Capitalize
+    | "uncapitalize" -> Uncapitalize
+    | "UpperCamelCase" -> UpperCamelCase
+    | "lowerCamelCase" -> LowerCamelCase
+    | "UPPER_SNAKE_CASE" -> UpperSnakeCase
+    | "lower_snake_case" -> LowerSnakeCase
     | _ -> failwith "invalid attribute"
 
   let attribute_access () =
-    char '.' *> choice [ string "length"; string "type" ] <* not_followed_by (Omega_parser_helper.alphanum)
+    char '.' *> choice
+      [ string "value"
+      ; string "length"
+      (*
+      ; string "type"
+      ; string "file.name"
+      ; string "file.path"
+      *)
+      ; string "lowercase"
+      ; string "UPPERCASE"
+      ; string "Capitalize"
+      ; string "uncapitalize"
+      ; string "UpperCamelCase"
+      ; string "lowerCamelCase"
+      ; string "UPPER_SNALE_CASE"
+      ; string "lowers_nake_case"
+      ]
+    <* not_followed_by (Omega_parser_helper.alphanum)
 
   (** Folds left to respect order of definitions in custom metasyntax for
       matching, where we attempt to parse in order. Note this is significant if a
@@ -146,15 +171,57 @@ module Make (Metasyntax : Types.Metasyntax.S) = struct
         | Hole { pattern; _ } -> Buffer.add_string buf pattern);
     Buffer.contents buf
 
+  let camel_to_snake s =
+    let rec aux i = function
+      | [] -> []
+      | ('A'..'Z' as c)::tl when i = 0 -> (Char.lowercase c)::aux (i+1) tl
+      | ('A'..'Z' as c)::tl when i <> 0 -> '_'::(Char.lowercase c)::aux (i+1) tl
+      | c::tl -> c::aux (i+1) tl
+    in
+    aux 0 (String.to_list s)
+    |> String.of_char_list
+
   let substitute_kind { variable; kind; _ } env =
     let open Option in
     let length_to_string n = Format.sprintf "%d" (String.length n) in
     match kind with
     | Value -> Environment.lookup env variable
     | Length -> Environment.lookup env variable >>| length_to_string
+    | Type -> failwith "unimplemented"
     | FileName -> failwith "unimplemented"
     | FilePath -> failwith "unimplemented"
-    | Type -> failwith "unimplemented"
+    | Lowercase ->
+      Environment.lookup env variable
+      >>| String.lowercase
+    | Uppercase ->
+      Environment.lookup env variable
+      >>| String.uppercase
+    | Capitalize ->
+      Environment.lookup env variable
+      >>| String.capitalize
+    | Uncapitalize ->
+      Environment.lookup env variable
+      >>| String.uncapitalize
+    | UpperCamelCase ->
+      Environment.lookup env variable
+      >>| String.split ~on:'_'
+      >>| List.map ~f:String.capitalize
+      >>| String.concat
+      >>| String.capitalize
+    | LowerCamelCase ->
+      Environment.lookup env variable
+      >>| String.split ~on:'_'
+      >>| List.map ~f:String.capitalize
+      >>| String.concat
+      >>| String.uncapitalize
+    | UpperSnakeCase ->
+      Environment.lookup env variable
+      >>| camel_to_snake
+      >>| String.uppercase
+    | LowerSnakeCase ->
+      Environment.lookup env variable
+      >>| camel_to_snake
+      >>| String.lowercase
 
   let substitute template environment =
     let replacement_content, environment', _ =

lib/kernel/matchers/types.ml

@@ -117,9 +117,17 @@ module Template = struct
   type kind =
     | Value
     | Length
+    | Type
     | FileName
     | FilePath
-    | Type
+    | Lowercase
+    | Uppercase
+    | Capitalize
+    | Uncapitalize
+    | UpperCamelCase
+    | LowerCamelCase
+    | UpperSnakeCase
+    | LowerSnakeCase
   [@@deriving sexp]
 
   type syntax =

test/common/dune

@@ -35,6 +35,7 @@
   test_regex_holes
   test_template_constraints
   test_custom_metasyntax
+  test_rewrite_attributes
   )
  (inline_tests)
  (preprocess (pps ppx_expect ppx_sexp_message ppx_deriving_yojson))

test/common/test_rewrite_attributes.ml

@@ -0,0 +1,48 @@
+open Core
+
+open Comby_kernel
+open Test_helpers
+
+let%expect_test "strings" =
+  let source = {|
+    LOWERCASE
+    uppercase
+    capitalize
+    Uncapitalize
+    upper_camel_case
+    Lower_camel_Case
+    upperSnakeCase
+    lowerSnakeCase
+|}
+  in
+  run (module Matchers.Alpha.Generic) source
+    {|
+       :[[a]]
+       :[[b]]
+       :[[c]]
+       :[[d]]
+       :[[e]]
+       :[[f]]
+       :[[g]]
+       :[[h]]
+    |}
+    {|
+       :[[a]].lowercase
+       :[[b]].UPPERCASE
+       :[[c]].Capitalize
+       :[[d]].uncapitalize
+       :[[e]].UpperCamelCase
+       :[[f]].lowerCamelCase
+       :[[g]].UPPER_SNAKE_CASE
+       :[[h]].lower_snake_case
+    |};
+  [%expect_exact {|
+       lowercase
+       UPPERCASE
+       Capitalize
+       uncapitalize
+       UpperCamelCase
+       lowerCamelCase
+       UPPER_SNAKE_CASE
+       lower_snake_case
+    |}];