An Edit with an unclosed { is refused, not run

Edit ,x/area_of/{ answered ok and did nothing: the group ran out of text and ran what it had. sam reads on for the }; an Edit has nothing more to read, so it now fails with unmatched `{', in the words sam uses for the other side.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 11 insertions, 1 deletions

diff --git a/src/sam_edit.zig b/src/sam_edit.zig
index 40221628..e8e90b67 100644
--- a/src/sam_edit.zig
+++ b/src/sam_edit.zig
@@ -95,6 +95,8 @@ const Parser = struct {
     i: usize = 0,
     /// The last pattern given, for an empty one (edit.c:562, getregexp).
     lastpat: []const u8 = "",
+    /// The last `parse` that answered null met a `}`, not the end.
+    braced: bool = false,
     why: *Why,
 
     fn getch(ps: *Parser) ?u8 {
@@ -326,12 +328,18 @@ const Parser = struct {
                 var last: ?*Cmd = null;
                 while (true) {
                     if (ps.skipbl() == '\n') ps.i += 1;
-                    const next = (try ps.parse(nest + 1)) orelse break;
+                    ps.braced = false;
+                    const next = (try ps.parse(nest + 1)) orelse {
+                        // sam reads on for the `}`; an Edit has no more to read.
+                        if (!ps.braced) return fail(ps.why, "unmatched `{{'", .{});
+                        break;
+                    };
                     if (last) |l| l.next = next else cmd.sub = next;
                     last = next;
                 }
             },
             '}' => {
+                ps.braced = true;
                 try ps.atnl();
                 if (nest == 0) return fail(ps.why, "right brace with no left brace", .{});
                 return null;
@@ -655,6 +663,8 @@ test "an Edit that fails halfway changes nothing, and says why in acme's words"
         .{ "k", "unknown command k" },
         .{ ",x/a/{\na/1/\ni/2/\n}", "changes out of sequence" },
         .{ "}", "right brace with no left brace" },
+        .{ ",x/foo/{", "unmatched `{'" },
+        .{ ",x/foo/{\nd", "unmatched `{'" },
         .{ "w /tmp/x", "w is not supported in pardes" },
         .{ ",s/(a)/\\1/", "no \\1: mvzr keeps no submatches" },
         .{ "1 m 1,2", "move overlaps itself" },