From ec946a275fe78fa231140c252e4ee0df80941829 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Tue, 11 Dec 2018 22:10:05 -0800
Subject: [PATCH] enum done

---
 xenomorph/xenomorph/redo/enum.rkt           | 32 ++++++++++++++++++
 xenomorph/xenomorph/redo/test/enum-test.rkt | 36 +++++++++++++++++++++
 xenomorph/xenomorph/redo/test/main.rkt      |  2 +-
 3 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 xenomorph/xenomorph/redo/enum.rkt
 create mode 100644 xenomorph/xenomorph/redo/test/enum-test.rkt

diff --git a/xenomorph/xenomorph/redo/enum.rkt b/xenomorph/xenomorph/redo/enum.rkt
new file mode 100644
index 00000000..4568e915
--- /dev/null
+++ b/xenomorph/xenomorph/redo/enum.rkt
@@ -0,0 +1,32 @@
+#lang racket/base
+(require "helper.rkt" racket/list)
+(provide (all-defined-out))
+
+#|
+approximates
+https://github.com/mbutterick/restructure/blob/master/src/Enum.coffee
+|#
+
+(define (xenum-decode xe [port-arg (current-input-port)] #:parent [parent #f])
+  (define port (->input-port port-arg))
+  (define index (decode (xenum-type xe) port))
+  (or (list-ref (xenum-options xe) index) index))
+
+(define (xenum-size xe [val #f] [parent #f]) (size (xenum-type xe)))
+
+(define (xenum-encode xe val [port-arg (current-output-port)] #:parent [parent #f])
+  (define port (if (output-port? port-arg) port-arg (open-output-bytes)))
+  (define index (index-of (xenum-options xe) val))
+  (unless index
+    (raise-argument-error 'Enum:encode "valid option" val))
+  (encode (xenum-type xe) index port)
+  (unless port-arg (get-output-bytes port)))
+
+(struct xenum (type options) #:transparent
+  #:methods gen:xenomorphic
+  [(define decode xenum-decode)
+   (define encode xenum-encode)
+   (define size xenum-size)])
+
+(define (+xenum type [options null])
+  (xenum type options))
\ No newline at end of file
diff --git a/xenomorph/xenomorph/redo/test/enum-test.rkt b/xenomorph/xenomorph/redo/test/enum-test.rkt
new file mode 100644
index 00000000..02a232dd
--- /dev/null
+++ b/xenomorph/xenomorph/redo/test/enum-test.rkt
@@ -0,0 +1,36 @@
+#lang racket/base
+(require rackunit
+         sugar/unstable/dict
+         "../helper.rkt"
+         "../number.rkt"
+         "../enum.rkt")
+
+#|
+approximates
+https://github.com/mbutterick/restructure/blob/master/test/Enum.coffee
+|#
+
+(define e (+xenum uint8 '("foo" "bar" "baz")))
+
+(test-case
+ "should have the right size"
+ (check-equal? (size e) 1))
+
+(test-case
+ "decode should decode"
+ (parameterize ([current-input-port (open-input-bytes (bytes 1 2 0))])
+   (check-equal? (decode e) "bar")
+   (check-equal? (decode e) "baz")
+   (check-equal? (decode e) "foo")))
+
+(test-case
+ "encode should encode"
+ (parameterize ([current-output-port (open-output-bytes)])
+   (encode e "bar")
+   (encode e "baz")
+   (encode e "foo")
+   (check-equal? (dump (current-output-port)) (bytes 1 2 0))))
+
+(test-case
+ "should throw on unknown option"
+ (check-exn exn:fail:contract? (λ () (encode e "unknown" (open-output-bytes)))))
\ No newline at end of file
diff --git a/xenomorph/xenomorph/redo/test/main.rkt b/xenomorph/xenomorph/redo/test/main.rkt
index e2dd57ff..6791a71f 100644
--- a/xenomorph/xenomorph/redo/test/main.rkt
+++ b/xenomorph/xenomorph/redo/test/main.rkt
@@ -3,7 +3,7 @@
 (require "array-test.rkt"
          "bitfield-test.rkt"
          "buffer-test.rkt"
-         ;"enum-test.rkt"
+         "enum-test.rkt"
          ;"lazy-array-test.rkt"
          "number-test.rkt"
          ;"optional-test.rkt"