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45 changes: 41 additions & 4 deletions dash-docs.el
Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,6 @@ the default except when using Emacs 27.
For more information see https://github.com/magit/ghub/issues/81
and https://debbugs.gnu.org/cgi/bugreport.cgi?bug=34341.")


(defun dash-docs-docset-path (docset)
"Return the full path of the directory for DOCSET."
(let* ((base (dash-docs-docsets-path))
Expand Down Expand Up @@ -145,9 +144,10 @@ If there are errors, print them in `dash-docs-debugging-buffer'"
(with-output-to-string
(let ((error-file (when dash-docs-enable-debugging
(make-temp-file "dash-docs-errors-file"))))
(call-process "sqlite3" nil (list standard-output error-file) nil
;; args for sqlite3:
"-list" "-init" "''" db-path sql)
(apply
'call-process "sqlite3" nil (list standard-output error-file) nil
;; args for sqlite3:
(dash-docs-get-sqlite-args db-path sql))

;; display errors, stolen from emacs' `shell-command` function
(when (and error-file (file-exists-p error-file))
Expand All @@ -165,6 +165,43 @@ If there are errors, print them in `dash-docs-debugging-buffer'"
(display-buffer (current-buffer))))
(delete-file error-file))))))

(defun dash-docs-get-sqlite-args (db-path sql)
"Return SQLite args to run the SQL command in the db at DB-PATH.

These args depend on the SQLite version.
"
;; To avoid any initialization when SQLite runs the command, use the init
;; option. For SQLite versions older than 3.34.0, you would use arguments
;; "-init ''" to do so. As of that version, SQLite reports the error that file
;; '' doesn't exist and you need to pass the null device instead. For those
;; versions, you also have to provide argument "-batch" to avoid the output of
;; status information.
(if (version< dash-docs-sqlite-version "3.34.0")
`("-list" "-init" "''" ,db-path ,sql)
`("-list" "-init" ,null-device "-batch" ,db-path ,sql)))

(defun dash-docs-extract-sqlite-version (sqlite-version-output)
"Extract the SQLite version from SQLITE-VERSION-OUTPUT.
SQLITE-VERSION-OUTPUT is the output of a call to \"sqlite3
--version\" as a list of strings. If this function cannot parse
that output, it returns \"0.0.0\", which serves as the (fake)
oldest version of SQLite."
(let ((oldest-sqlite-version "0.0.0"))
(if (>= (length sqlite-version-output) 1)
(let ((sqlite-version-string (car sqlite-version-output)))
(if (string-match
"^\\([[:digit:]]+[.][[:digit:]]+[.][[:digit:]]+\\) [[:digit:]]\\{4\\}-"
sqlite-version-string)
(match-string 1 sqlite-version-string)
oldest-sqlite-version))
oldest-sqlite-version)))

(defvar dash-docs-sqlite-version
(dash-docs-extract-sqlite-version (process-lines "sqlite3" "--version"))
"Version of available sqlite3 binary.
This version string is retrieved by executing \"sqlite3
--version\" and parsing its output.")

(defun dash-docs-parse-sql-results (sql-result-string)
"Parse SQL-RESULT-STRING splitting it by newline and '|' chars."
(mapcar (lambda (x) (split-string x "|" t))
Expand Down
27 changes: 27 additions & 0 deletions test/dash-docs-test.el
Original file line number Diff line number Diff line change
Expand Up @@ -166,4 +166,31 @@

(provide 'dash-docs-test)

;;;; dash-docs-get-sqlite-args

(ert-deftest dash-docs-sqlite-args-with-old-version-is-backward-compatible()
(let ((dash-docs-sqlite-version "3.33.0"))
(let ((actual-result (dash-docs-get-sqlite-args "/path/to/db" "SELECT ...")))
(should (equal '("-list" "-init" "''" "/path/to/db" "SELECT ...") actual-result)))))

(ert-deftest dash-docs-sqlite-args-with-newer-version-uses-different-init()
(let ((dash-docs-sqlite-version "3.34.0") (null-device "/dev/null"))
(let ((actual-result (dash-docs-get-sqlite-args "/path/to/db" "SELECT ...")))
(should (equal '("-list" "-init" "/dev/null" "-batch" "/path/to/db" "SELECT ...") actual-result)))))

(ert-deftest dash-docs-sqlite-args-with-newer-version-uses-different-init-and-null-device()
;; null-device "NUL" is used by Windows
(let ((dash-docs-sqlite-version "3.34.0") (null-device "NUL"))
(let ((actual-result (dash-docs-get-sqlite-args "/path/to/db" "SELECT ...")))
(should (equal '("-list" "-init" "NUL" "-batch" "/path/to/db" "SELECT ...") actual-result)))))

(ert-deftest dash-docs-extract-sqlite-version-using-valid-output()
(let ((dash-docs-sqlite-version "3.34.0"))
(let ((sqlite-version-output '("3.34.0 2020-12-01 16:14:00 a26b6597e3ae272231b96f9982c3bcc17ddec2f2b6eb4df06a224b91089fed5b")))
(should (equal "3.34.0" (dash-docs-extract-sqlite-version sqlite-version-output))))))

(ert-deftest dash-docs-extract-sqlite-version-using-empty-output()
(let ((sqlite-version-output ()))
(should (equal "0.0.0" (dash-docs-extract-sqlite-version sqlite-version-output)))))

;;; dash-docs-test ends here