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author | Tom Willemse | 2022-03-03 01:08:16 -0800 |
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committer | Tom Willemse | 2022-03-03 01:08:16 -0800 |
commit | c12a766e1920e726129dfd1161a2ef15471f89e8 (patch) | |
tree | da1347e2ee4330fe46fb04dc14134e9c1e32ba65 /mpd.scm | |
parent | 5c371433b9ba76da6fde27849775e5bf9c4c7db4 (diff) | |
download | mpd-random-albums-c12a766e1920e726129dfd1161a2ef15471f89e8.tar.gz mpd-random-albums-c12a766e1920e726129dfd1161a2ef15471f89e8.zip |
Write a small DSL for converting a simple lisp expression to an MPD query
format. This turns, for example:
(and (= artist "Katatonia") (= album "Last Fair Deal Gone Down"))
Into:
((artist == "Katatonia") AND (album == "Last Fair Deal Gone Down"))
The expressions inside ‘query’ are quasi-quoted, so that variable substitution
is possible.
Diffstat (limited to 'mpd.scm')
-rw-r--r-- | mpd.scm | 22 |
1 files changed, 22 insertions, 0 deletions
@@ -0,0 +1,22 @@ +(define-structure mpd (export query) + (open scheme-with-scsh) + (begin + (define-syntax query + (syntax-rules () + ((_ a) + (mpd-query-1 `a)))) + + (define (mpd-query-equals params) + (apply format #f "~s == ~s" params)) + + (define (mpd-query-and params) + (format #f "~a AND ~a" + (mpd-query-1 (car params)) + (mpd-query-1 (cadr params)))) + + (define (mpd-query-1 query) + (format #f "(~a)" + (let ((op (car query))) + (case op + ('= (mpd-query-equals (cdr query))) + ('and (mpd-query-and (cdr query))))))))) |