[nongnu] elpa/emacsql 6d17256e1b 171/427: Add a mix-in class to reduce code duplication.

[ELPA Syncer]

branch: elpa/emacsql
commit 6d17256e1b80da18e7bbd69c880cd4f4b9cf1af8
Author: Christopher Wellons <wellons@nullprogram.com>
Commit: Christopher Wellons <wellons@nullprogram.com>

    Add a mix-in class to reduce code duplication.
---
 emacsql-psql.el   |  4 ++--
 emacsql-sqlite.el | 23 ++---------------------
 emacsql.el        | 33 +++++++++++++++++++++++++++++++--
 3 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/emacsql-psql.el b/emacsql-psql.el
index 008eb8334c..56583f6de4 100644
--- a/emacsql-psql.el
+++ b/emacsql-psql.el
@@ -26,7 +26,7 @@
                 nil)))
         (error :cannot-execute)))))
 
-(defclass emacsql-psql-connection (emacsql-connection)
+(defclass emacsql-psql-connection (emacsql-connection emacsql-simple-parser)
   ((dbname :reader emacsql-psql-dbname :initarg :dbname))
   (:documentation "A connection to a PostgreSQL database."))
 
@@ -91,7 +91,7 @@
     (emacsql-clear connection)
     (emacsql-send-string connection sql-string)
     (emacsql-psql--check-error connection)
-    (emacsql-sqlite--parse connection)))
+    (emacsql-simple-parse connection)))
 
 (provide 'emacsql-psql)
 
diff --git a/emacsql-sqlite.el b/emacsql-sqlite.el
index 6bb1f2e5c1..4708ffbaf2 100644
--- a/emacsql-sqlite.el
+++ b/emacsql-sqlite.el
@@ -26,7 +26,7 @@
                 nil)))
         (error :cannot-execute)))))
 
-(defclass emacsql-sqlite-connection (emacsql-connection)
+(defclass emacsql-sqlite-connection (emacsql-connection emacsql-simple-parser)
   ((file :initarg :file
          :type (or null string)
          :documentation "Database file name."))
@@ -71,25 +71,6 @@ buffer. This is for debugging purposes."
     (when (process-live-p process)
       (process-send-string process ".exit\n"))))
 
-(defmethod emacsql-waiting-p ((connection emacsql-sqlite-connection))
-  (with-current-buffer (emacsql-buffer connection)
-    (cond ((= (buffer-size) 1) (string= "]" (buffer-string)))
-          ((> (buffer-size) 1) (string= "\n]"
-                                        (buffer-substring
-                                         (- (point-max) 2) (point-max)))))))
-
-(defun emacsql-sqlite--parse (connection)
-  "Parse SQLite output into an s-expression."
-  (with-current-buffer (emacsql-buffer connection)
-    (let ((standard-input (current-buffer)))
-      (setf (point) (point-min))
-      (cl-loop until (looking-at "]")
-               collect (read) into row
-               when (looking-at "\n")
-               collect row into rows
-               and do (progn (forward-char 1) (setf row ()))
-               finally (cl-return rows)))))
-
 (defvar emacsql-sqlite-condition-alist
   '(("unable to open"              emacsql-access)
     ("cannot open"                 emacsql-access)
@@ -157,7 +138,7 @@ buffer. This is for debugging purposes."
     (emacsql-clear connection)
     (emacsql-send-string connection sql-string)
     (emacsql-sqlite--check-error connection)
-    (emacsql-sqlite--parse connection)))
+    (emacsql-simple-parse connection)))
 
 (provide 'emacsql-sqlite)
 
diff --git a/emacsql.el b/emacsql.el
index eb30f73ca3..17a574d56d 100644
--- a/emacsql.el
+++ b/emacsql.el
@@ -115,7 +115,7 @@ MESSAGE should not have a newline on the end."
   "Like `error', but signal an emacsql-syntax condition."
   (signal 'emacsql-syntax (list (apply #'format format args))))
 
-;;; Sending and receiving:
+;; Sending and receiving:
 
 (defmethod emacsql-send-string
   ((connection emacsql-connection) string &optional no-log)
@@ -140,6 +140,35 @@ MESSAGE should not have a newline on the end."
                 (not (emacsql-waiting-p connection)))
       (accept-process-output (emacsql-process connection) timeout))))
 
+;; Helper mix-in class:
+
+(defclass emacsql-simple-parser ()
+  ()
+  (:documentation "A mix-in for back-ends with a specific output format.")
+  :abstract t)
+
+(defmethod emacsql-waiting-p ((connection emacsql-simple-parser))
+  "The back-end must us a single \"]\" character as its prompt.
+This prompt value was chosen because it is unreadable."
+  (with-current-buffer (emacsql-buffer connection)
+    (cond ((= (buffer-size) 1) (string= "]" (buffer-string)))
+          ((> (buffer-size) 1) (string= "\n]"
+                                        (buffer-substring
+                                         (- (point-max) 2) (point-max)))))))
+
+(defmethod emacsql-simple-parse ((connection emacsql-simple-parser))
+  "Parse output into an s-expression.
+Output should have one row per line, separated by whitespace."
+  (with-current-buffer (emacsql-buffer connection)
+    (let ((standard-input (current-buffer)))
+      (setf (point) (point-min))
+      (cl-loop until (looking-at "]")
+               collect (read) into row
+               when (looking-at "\n")
+               collect row into rows
+               and do (progn (forward-char 1) (setf row ()))
+               finally (cl-return rows)))))
+
 (provide 'emacsql) ; end of generic function declarations
 
 ;; Automatic connection cleanup:
@@ -218,7 +247,7 @@ A statement can be a list, containing a statement with its 
arguments."
                else
                collect (append (list 'emacsql 'emacsql--conn) statement))))
 
-;;; Escaping:
+;; Escaping:
 
 (defun emacsql-quote (string)
   "Quote STRING for use in a SQL expression."