From 5e0dc6b60a4991d7574e611bcd13a0511482673a Mon Sep 17 00:00:00 2001
From: favonia <favonia@gmail.com>
Date: Sun, 27 Oct 2024 16:39:49 -0500
Subject: [PATCH] feat(SourceMarker): display EOL and EOF points as "EOL" and
 "EOF"

---
 src/MarkedSource.ml     |  9 ++++++++-
 src/MarkedSourceData.ml |  7 ++++++-
 src/SourceMarker.ml     | 13 +++++++++++--
 src/tty/Tty.ml          | 10 +++++++---
 4 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/src/MarkedSource.ml b/src/MarkedSource.ml
index d52d4fa..044e5f4 100644
--- a/src/MarkedSource.ml
+++ b/src/MarkedSource.ml
@@ -6,10 +6,17 @@ let dump_marker dump_tag fmt =
   | RangeEnd tag -> Format.fprintf fmt {|@[<2>RangeEnd@ @[%a@]@]|} dump_tag tag
   | Point tag -> Format.fprintf fmt {|@[<2>Point@ @[%a@]@]|} dump_tag tag
 
+let dump_special_position fmt =
+  function
+  | End_of_line -> Format.fprintf fmt {|End_of_line|}
+  | End_of_file -> Format.fprintf fmt {|End_of_file|}
+
 let dump_token dump_tag fmt =
   function
   | String str -> Format.fprintf fmt {|@[<2>String@ "%s"@]|} (String.escaped str)
-  | Marker m -> Format.fprintf fmt {|@[<2>Marker@ @[<1>(%a)@]@]|} (dump_marker dump_tag) m
+  | Marker (p, m) ->
+    Format.fprintf fmt {|@[<2>Marker@ @[<1>(@[%a@],@ @[%a@])@]@]|}
+      (Utils.dump_option dump_special_position) p (dump_marker dump_tag) m
 
 let dump_line dump_tag fmt {markers; tokens} =
   Format.fprintf fmt {|@[<1>{@[<2>markers=@,@[%a@]@];@ @[<2>tokens=@ @[%a@]@]}@]|}
diff --git a/src/MarkedSourceData.ml b/src/MarkedSourceData.ml
index 98f47e6..a807f66 100644
--- a/src/MarkedSourceData.ml
+++ b/src/MarkedSourceData.ml
@@ -1,3 +1,8 @@
+(** Special positions. *)
+type special_position =
+  | End_of_line
+  | End_of_file
+
 (** A marker is a delimiter of a range or a specific point. *)
 type 'tag marker =
   | RangeBegin of 'tag
@@ -7,7 +12,7 @@ type 'tag marker =
 (** A token is either a string or a marker. *)
 type 'tag token =
   | String of string
-  | Marker of 'tag marker
+  | Marker of special_position option * 'tag marker
 
 (** A line is a list of {!type:segment}s along with tags. *)
 type 'tag line =
diff --git a/src/SourceMarker.ml b/src/SourceMarker.ml
index 7ea8254..f8e75fc 100644
--- a/src/SourceMarker.ml
+++ b/src/SourceMarker.ml
@@ -83,11 +83,20 @@ module Make (Tag : Tag) = struct
         | (loc, marker) :: markers when state.cursor.line_num = loc.line_num (* on the same line *) ->
           if loc.offset > eof then invalid_arg "Asai.SourceMarker.mark: position beyond EOF; use the debug mode";
           if loc.offset > state.eol then invalid_arg "Asai.SourceMarker.mark: unexpected newline; use the debug mode";
+          let special_position =
+            if loc.offset = state.eol then
+              if loc.offset = eof then
+                Some End_of_file
+              else
+                Some End_of_line
+            else
+              None
+          in
           let tokens =
             if loc.offset = state.cursor.offset then
-              state.tokens <: Marker marker
+              state.tokens <: Marker (special_position, marker)
             else
-              state.tokens <: String (read_between ~source state.cursor.offset loc.offset) <: Marker marker
+              state.tokens <: String (read_between ~source state.cursor.offset loc.offset) <: Marker (special_position, marker)
           in
           go { state with tokens; cursor = loc } markers
         | markers ->
diff --git a/src/tty/Tty.ml b/src/tty/Tty.ml
index 614e706..b3b3b2c 100644
--- a/src/tty/Tty.ml
+++ b/src/tty/Tty.ml
@@ -111,11 +111,15 @@ struct
       function
       | MarkedSource.String s ->
         render_styled_segment ~param fmt (TtyTagSet.prioritized set) s; set
-      | MarkedSource.Marker RangeEnd t ->
+      | MarkedSource.Marker (_, RangeEnd t) ->
         TtyTagSet.remove t set
-      | MarkedSource.Marker Point t ->
+      | MarkedSource.Marker (Some End_of_file, Point t) ->
+        render_styled_segment ~param fmt (Some t) "‹EOF›"; set
+      | MarkedSource.Marker (Some End_of_line, Point t) ->
+        render_styled_segment ~param fmt (Some t) "‹EOL›"; set
+      | MarkedSource.Marker (None, Point t) ->
         render_styled_segment ~param fmt (Some t) "‹POS›"; set
-      | MarkedSource.Marker RangeBegin t ->
+      | MarkedSource.Marker (_, RangeBegin t) ->
         TtyTagSet.add t set
     in
     Format.fprintf fmt (" " ^^ highlight "%*d |" ^^ " ")