utils: Add find-definition-insertion-location procedure.

* guix/utils.scm (find-definition-insertion-location): Add and export
procedure.
* tests/utils.scm ("find-definition-insertion-location"): Add test.

Change-Id: Ie17e1b4a94790f58518ce121411a38d357f49feb
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/guix/utils.scm b/guix/utils.scm
index 94b4d753d0..29ad09d9f7 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -148,6 +148,7 @@
             edit-expression
             delete-expression
             insert-expression
+            find-definition-insertion-location
 
             filtered-port
             decompressed-port
@@ -513,6 +514,24 @@ SOURCE-PROPERTIES."
                    (string-append expr "\n\n" str))))
     (edit-expression source-properties insert)))
 
+(define (find-definition-insertion-location file term)
+  "Search in FILE for a top-level public definition whose defined term
+alphabetically succeeds TERM. Return the location if found, or #f
+otherwise."
+  (let ((search-term (symbol->string term)))
+    (call-with-input-file file
+      (lambda (port)
+        (do ((syntax (read-syntax port)
+                     (read-syntax port)))
+          ((match (syntax->datum syntax)
+             (('define-public current-term _ ...)
+              (string> (symbol->string current-term)
+                       search-term))
+             ((? eof-object?) #t)
+             (_ #f))
+           (and (not (eof-object? syntax))
+                (syntax-source syntax))))))))
+
 
 ;;;
 ;;; Keyword arguments.