[util] enum printer codegen

scripts/enum.rkt

@@ -30,6 +30,9 @@
 (define (parser-file-name dsc)
   (format "~a.parser.inc" (desc-name dsc)))
 
+(define (printer-file-name dsc)
+  (format "~a.printer.inc" (desc-name dsc)))
+
 (define (write-parser dsc [port (current-output-port)])
   (match-define (desc name vals) dsc)
   (for ([v+s (in-list vals)]
@@ -43,6 +46,15 @@
     (fprintf port "} else "))
   (fprintf port "{\n  return 1;\n}\n"))
 
+(define (write-printer dsc [port (current-output-port)])
+  (match-define (desc name vals) dsc)
+  (fprintf port "switch (val) {\n")
+  (for ([v+s (in-list vals)])
+    (match-define (cons val str) v+s)
+    (fprintf port "case ~a:\n  str = ~s;\n  break;\n" val str))
+  (fprintf port "default:\n  IMPOSSIBLE(\"invalid enum value for `~a' printer\");\n}\n"
+           name))
+
 ;; -----
 
 (define (in-scan dir-path)
@@ -57,6 +69,9 @@
   (for ([dsc (in-scan scan-dir)])
     (write-parser dsc
                   (open-output-file (build-path build-dir (parser-file-name dsc))
+                                    #:exists 'replace))
+    (write-printer dsc
+                  (open-output-file (build-path build-dir (printer-file-name dsc))
                                     #:exists 'replace))))
 
 ;; -----