[nongnu] elpa/emacsql 672963ae53 191/427: Add DISTINCT option to :select.

[ELPA Syncer]

branch: elpa/emacsql
commit 672963ae533cb30f57774ab80ae20567cb26f89b
Author: Christopher Wellons <wellons@nullprogram.com>
Commit: Christopher Wellons <wellons@nullprogram.com>

    Add DISTINCT option to :select.
---
 README.md           |  3 ++-
 emacsql-compiler.el | 14 +++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 885aa8380c..dd81a92cf6 100644
--- a/README.md
+++ b/README.md
@@ -191,7 +191,7 @@ Provides `DROP TABLE`.
 [:drop-table employees]
 ```
 
-#### :select `<column-spec>`
+#### :select `<column-spec>|(:distinct <column-spec>)`
 
 Provides `SELECT`. `column-spec` can be a `*` symbol or a vector of
 column identifiers, optionally as expressions.
@@ -199,6 +199,7 @@ column identifiers, optionally as expressions.
 ```el
 [:select [name (/ salary 52)] ...]
 [:select [(as name n) (as age a)] ...]
+[:select (:distinct [name age id]) ...]
 ```
 
 #### :from `<table>`
diff --git a/emacsql-compiler.el b/emacsql-compiler.el
index db24fbb9f0..0d21aa7554 100644
--- a/emacsql-compiler.el
+++ b/emacsql-compiler.el
@@ -374,9 +374,17 @@ definitions for return from a `emacsql-defexpander'."
 (emacsql-defexpander :select (arg)
   "Expands to the SELECT keyword."
   (emacsql-with-vars "SELECT "
-    (if (eq '* arg)
-        "*"
-      (idents arg))))
+    (cond ((eq '* arg)
+           "*")
+          ((listp arg)
+           (cl-case (length arg)
+             (1 (idents (car arg)))
+             (2 (cl-case (car arg)
+                  (:distinct (concat "DISTINCT " (idents (cadr arg))))
+                  (:all (concat "ALL " (idents (cadr arg))))
+                  (otherwise (emacsql-error "Invalid SELECT: %S" (car arg)))))
+             (otherwise (emacsql-error "Invalid SELECT idents: %S" arg))))
+          ((idents arg)))))
 
 (emacsql-defexpander :from (sources)
   "Expands to the FROM keyword."