update

lib/kernel/rewriter/rewrite_template.ml

@@ -103,9 +103,11 @@ module Make (Metasyntax : Matchers.Metasyntax.S) = struct
   let hole_prefixes =
     List.map Metasyntax.syntax ~f:(function
         | Hole (_, Delimited (Some left, _))
-        | Regex (left, _, _) -> Some left
+        | Regex (left, _, _) -> Some [left]
+        | Hole (_, Reserved_identifiers l) -> Some l
         | _ -> None)
     |> List.filter_opt
+    |> List.concat
 
   (** Not smart enough: only looks for hole prefix to stop scanning constant,
       because there isn't a good 'not' parser *)

test/common/test_parse_rewrite_template.ml

@@ -34,4 +34,35 @@ let%expect_test "interpret_incomplete_hole_as_constant_metasyntax" =
   in
   parse metasyntax template |> print_string;
   [%expect_exact {|((Constant $) (Constant ":x ") (Hole ((variable B) (pattern "$B:x ")))
- (Constant " ") (Hole ((variable A) (pattern $A))))|}];
+ (Constant " ") (Hole ((variable A) (pattern $A))))|}]
+
+let%expect_test "interpret_incomplete_hole_as_constant_metasyntax" =
+  let template = "(  , ,  )" in
+  let metasyntax =
+    Matchers.Metasyntax.{
+      syntax =
+        [ Hole (Everything, Delimited (Some "NOTHING", None))
+        ; Hole (Everything, Reserved_identifiers ["  "; " "])
+        ]
+    ; identifier = "AB"
+    }
+  in
+  parse metasyntax template |> print_string;
+  [%expect_exact {|((Constant "(") (Hole ((variable "  ") (pattern "  "))) (Constant ,)
+ (Hole ((variable " ") (pattern " "))) (Constant ,)
+ (Hole ((variable "  ") (pattern "  "))) (Constant ")"))|}]
+
+let%expect_test "interpret_incomplete_hole_as_constant_metasyntax" =
+  let template = "(..,.)" in
+  let metasyntax =
+    Matchers.Metasyntax.{
+      syntax =
+        [ Hole (Everything, Delimited (Some "NOTHING", None))
+        ; Hole (Everything, Reserved_identifiers [".."; "."])
+        ]
+    ; identifier = "AB"
+    }
+  in
+  parse metasyntax template |> print_string;
+  [%expect_exact {|((Constant "(") (Hole ((variable ..) (pattern ..))) (Constant ,)
+ (Hole ((variable .) (pattern .))) (Constant ")"))|}]

test/example/metasyntax/dangling.json

@@ -0,0 +1,11 @@
+{
+  "syntax": [
+   [ "Hole", [ "Everything" ], [ "Delimited", ")", null ] ],
+   [ "Hole", [ "Expression" ], [ "Delimited", "))", null ] ]
+  ],
+  "identifier":
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+}
+//  echo 'swap(x, y)' | \
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/dangling.json \
+//  'swap()1, ))2)' 'swap()2, )1)'

test/example/metasyntax/emoji.json

@@ -0,0 +1,24 @@
+{
+  "syntax": [
+    [ "Hole", [ "Everything" ], [ "Delimited", "place-holder", null ] ],
+    [ "Hole", [ "Everything" ],
+        [ "Reserved_identifiers",
+            [ "❤️", "💙", "💚", "💜", "💛", "🧡" ]
+        ]
+    ],
+    [ "Hole", [ "Expression" ],
+        [ "Reserved_identifiers",
+            [ "😂", "🚡", "😃", "😬", "😈", "🐵", "✋", "😻", "🍌" ]
+        ]
+    ]
+  ],
+  "identifier":
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+}
+//  echo 'swap(x, y)' | \
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/emoji.json \
+//  'swap(🐵, 🍌)' 'swap(🍌, 🐵)'
+
+//  echo 'add(x, x)' | \                                                    [17:25:08]
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/emoji.json \ 
+//  'add(😂, 😂)' 'multiply(2, 😂)'

test/example/metasyntax/inverted-parens.json

@@ -0,0 +1,11 @@
+{
+  "syntax": [
+   [ "Hole", [ "Everything" ], [ "Delimited", ")", "(" ] ],
+   [ "Hole", [ "Expression" ], [ "Delimited", "))", "((" ] ]
+  ],
+  "identifier":
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+}
+//  echo 'swap(x, y)' | \
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/inverted-parens.json \
+//  'swap()1(, )2()' 'swap()2(, )1()'

test/example/metasyntax/lambda.json

@@ -0,0 +1,25 @@
+{
+  "syntax": [
+    [ "Hole", [ "Everything" ], [ "Delimited", "place-holder", null ] ],
+    [ "Hole", [ "Everything" ],
+        [ "Reserved_identifiers",
+            [ "Γ", "Δ", "Θ", "Λ", "Ξ", "Π", "Σ", "Φ", "Ψ", "Ω" ]
+        ]
+    ],
+    [ "Hole", [ "Expression" ],
+        [ "Reserved_identifiers",
+            [
+                "α", "β", "γ", "δ", "ε", "ζ", "η", "θ", "ι", "κ", "λ",
+                "μ", "ξ", "π", "ρ", "ς", "σ", "τ", "υ", "φ", "χ", "ψ",
+                "ω"
+            ]
+        ]
+    ]
+  ],
+  "identifier":
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+}
+//  echo 'swap(x, y)' | \
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/lambda.json \
+//  'λ(α, β)' 'λ(β, α)'
+

test/example/metasyntax/wutspace.json

@@ -0,0 +1,17 @@
+{
+  "syntax": [
+    // Currently a placeholder is needed if we only care about Reserved_idenitifersl to avoid trickery.
+    // Order is significant.
+    [ "Hole", [ "Everything" ], [ "Delimited", "place-holder", null ] ],
+    [ "Hole", [ "Everything" ],
+        [ "Reserved_identifiers",
+            [ "  ", " " ]
+        ]
+    ]
+  ],
+  "identifier":
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"
+}
+//  echo 'swap(x,y)' | \
+//  ./comby -stdin -custom-metasyntax test/example/metasyntax/wutspace.json \
+//  'swap( ,  )' 'swap(  , )'