From 54ea6ee880f52c23279bf58262ca245b531d04b0 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Thu, 22 Aug 2019 13:03:52 +0100
Subject: [PATCH] src/module-parse.lisp (code): Allow setting constraints
 without a fragment.

Add new syntax for adding constraints to the output sequencer without
actually producing any output at all.
---
 doc/syntax.tex         |  2 ++
 src/module-output.lisp | 13 +++++++------
 src/module-parse.lisp  |  8 +++++++-
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/doc/syntax.tex b/doc/syntax.tex
index 0b415d2..8c66487 100644
--- a/doc/syntax.tex
+++ b/doc/syntax.tex
@@ -672,6 +672,8 @@ declarations instead.
 <code-definition> ::=
   "code" <reason> ":" <item-name> @[<constraints>@]
   "{" <c-fragment> "}"
+\alt
+  "code" <reason> ":" <constraints> ";"
 
 <reason> ::= <identifier>
 
diff --git a/src/module-output.lisp b/src/module-output.lisp
index f9eb3a4..7895176 100644
--- a/src/module-output.lisp
+++ b/src/module-output.lisp
@@ -114,12 +114,13 @@
   (when (eq reason (code-fragment-reason frag))
     (dolist (constraint (code-fragment-constraints frag))
       (add-sequencer-constraint sequencer constraint))
-    (add-sequencer-item-function sequencer (code-fragment-name frag)
-				 (lambda (stream)
-				   (write (code-fragment frag)
-					  :stream stream
-					  :pretty nil
-					  :escape nil)))))
+    (awhen (code-fragment-name frag)
+      (add-sequencer-item-function sequencer it
+				   (lambda (stream)
+				     (write (code-fragment frag)
+					    :stream stream
+					    :pretty nil
+					    :escape nil))))))
 
 (defmethod hook-output progn ((module module) (reason (eql :h)) sequencer)
   (sequence-output (stream sequencer)
diff --git a/src/module-parse.lisp b/src/module-parse.lisp
index f025e37..8344281 100644
--- a/src/module-parse.lisp
+++ b/src/module-parse.lisp
@@ -52,6 +52,7 @@
 
 (define-pluggable-parser module code (scanner pset)
   ;; `code' id `:' item-name [constraints] `{' c-fragment `}'
+  ;; `code' id `:' constraints `;'
   ;;
   ;; constraints ::= `[' list[constraint] `]'
   ;; constraint ::= item-name+
@@ -80,7 +81,12 @@
       (parse (seq ("code"
 		   (reason (must (kw)))
 		   (nil (must #\:))
-		   (item (or (seq ((name (must (item)))
+		   (item (or (seq ((constraints (constraints))
+				   (nil (must #\;)))
+			       (make-instance 'code-fragment-item
+					      :reason reason
+					      :constraints constraints))
+			     (seq ((name (must (item)))
 				   (constraints (? (constraints)))
 				   (fragment (fragment)))
 			       (and name
-- 
2.11.0