[elpa] externals/triples 09a78f5b80 6/7: Add `triples-mode-subject', for renaming a subject.

[ELPA Syncer]

branch: externals/triples
commit 09a78f5b80af54032055df028a16a4eed45b7747
Author: Andrew Hyatt <ahyatt@gmail.com>
Commit: Andrew Hyatt <ahyatt@gmail.com>

    Add `triples-mode-subject', for renaming a subject.
    
    This method not only renames the subject, but also any objects that point 
to the
    subject.
---
 CHANGELOG.org   |  1 +
 triples-test.el | 15 +++++++++++++++
 triples.el      | 26 ++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/CHANGELOG.org b/CHANGELOG.org
index 90aebd5c20..66d4677898 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -3,6 +3,7 @@ TITLE: Changelog for the triples module for GNU Emacs.
 * 0.2
 - Create a default database to encourage a shared triple database.  Add 
information on why this is an interesting idea in the README.
 - Add support for backups of databases via =triples-backup=, and a simple way 
to have a sane and shared backups created with the new =triples-backups= module.
+- Add =triples-move-subject= which will move both a subject as well as 
reference to it.
 * 0.1.2
 - Bugfix release to remove backward compatibility with pre-Emacs 29 versions.  
 * 0.1.1
diff --git a/triples-test.el b/triples-test.el
index 44d92ab2da..3442a3b626 100644
--- a/triples-test.el
+++ b/triples-test.el
@@ -345,6 +345,21 @@ easily debug into it.")
                    (sqlite-select db "SELECT COUNT(*) FROM triples WHERE 
subject = ? AND predicate = 'base/type' AND object = 'marker'"
                                   (list (triples-standardize-val "foo")))))))
 
+(ert-deftest triples-move-subject ()
+  (triples-test-with-temp-db
+   (triples-add-schema db 'named '(name))
+   (triples-add-schema db 'friend '(id))
+   (triples-set-subject db 123 '(named :name "Ada Lovelace"))
+   (triples-set-subject db 456 '(named :name "Michael Faraday")
+                        '(friend :id 123))
+   (triples-set-subject db 987 '(named :name "To Be Deleted"))
+   (should-error (triples-move-subject db 123 987))
+   (triples-delete-subject db 987)
+   (triples-move-subject db 123 987)
+   (should-not (triples-get-subject db 123))
+   (should (equal "Ada Lovelace" (plist-get (triples-get-subject db 987) 
:named/name)))
+   (should (equal 987 (plist-get (triples-get-subject db 456) :friend/id)))))
+
 (ert-deftest triples-readme ()
   (triples-test-with-temp-db
    (triples-add-schema db 'person
diff --git a/triples.el b/triples.el
index ebc59982f0..7d688896d0 100644
--- a/triples.el
+++ b/triples.el
@@ -300,6 +300,32 @@ object, properties to retrieve or nil for *."
                                  (when properties `((= properties ,(intern 
(format "$s%d" (cl-incf n)))))))))))
               (seq-filter #'identity (list subject predicate object 
properties)))))))
 
+(defun triples-move-subject (db old-subject new-subject)
+  "Replace all instance in DB of OLD-SUBJECT to NEW-SUBJECT.
+Any references to OLD-SUBJECT as an object are also replaced.
+This will throw an error if there is an existing subject
+NEW-SUBJECT with at least one equal property (such as type
+markers). But if there are no commonalities, the OLD-SUBJECT is
+merged into NEW-SUBJECT."
+  (pcase triples-sqlite-interface
+    ('builtin
+     (condition-case err
+         (progn
+           (sqlite-transaction db)
+           (sqlite-execute db "UPDATE triples SET subject = ? WHERE subject = 
?"
+                           (list (triples-standardize-val new-subject) 
(triples-standardize-val old-subject)))
+           (sqlite-execute db "UPDATE triples SET object = ? WHERE object = ?"
+                           (list (triples-standardize-val new-subject) 
(triples-standardize-val old-subject)))
+           (sqlite-commit db))
+       (error (sqlite-rollback db)
+              (signal 'error err))))
+    ('emacsql
+     (emacsql-with-transaction db
+         (emacsql db [:update triples :set (= subject $s1) :where (= subject 
$s2)]
+                  new-subject old-subject)
+         (emacsql db [:update triples :set (= object $s1) :where (= object 
$s2)]
+                  new-subject old-subject)))))
+
 ;; Code after this point should not call sqlite or emacsql directly. If any 
more
 ;; calls are needed, put them in a defun, make it work for sqlite and emacsql,
 ;; and put them above.