From 077b227f03709a97a31dcc3ec6b3d29bef6c90d1 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Sun, 28 Apr 2019 17:14:51 -0700
Subject: [PATCH] fly the flag

---
 xenomorph/xenomorph/scribblings/xenomorph.scrbl | 12 ++++++------
 xenomorph/xenomorph/string.rkt                  |  6 +++---
 xenomorph/xenomorph/symbol.rkt                  |  6 +++---
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/xenomorph/xenomorph/scribblings/xenomorph.scrbl b/xenomorph/xenomorph/scribblings/xenomorph.scrbl
index b43e8760..753ae1f3 100644
--- a/xenomorph/xenomorph/scribblings/xenomorph.scrbl
+++ b/xenomorph/xenomorph/scribblings/xenomorph.scrbl
@@ -509,7 +509,7 @@ Base class for string formats. Use @racket[x:string] to conveniently instantiate
 
 @defconstructor[
 ([len length-resolvable?]
-[encoding supported-encoding?])]{
+[encoding (or/c procedure? supported-encoding?)])]{
 Create class instance that represents a string format of length @racket[len]. If @racket[len] is an integer,  the string is fixed at that length, otherwise it can be any length.
 }
 
@@ -544,9 +544,9 @@ Whether @racket[x] is an object of type @racket[x:string%].
 @defproc[
 (x:string
 [len-arg (or/c length-resolvable? #false) #false]
-[enc-arg (or/c supported-encoding? #false) #false]
+[enc-arg (or/c procedure? supported-encoding? #false) #false]
 [#:length len-kw (or/c length-resolvable? #false) #false]
-[#:encoding enc-kw (or/c supported-encoding? #false) #false]
+[#:encoding enc-kw (or/c procedure? supported-encoding? #false) #false]
 [#:pre-encode pre-encode-proc (or/c (any/c . -> . any/c) #false) #false]
 [#:post-decode post-decode-proc (or/c (any/c . -> . any/c) #false) #false]
 [#:base-class base-class (λ (c) (subclass? c x:string%)) x:string%]
@@ -574,7 +574,7 @@ Base class for symbol formats. Use @racket[x:symbol] to conveniently instantiate
 
 @defconstructor[
 ([len length-resolvable?]
-[encoding supported-encoding?])]{
+[encoding (or/c procedure? supported-encoding?)])]{
 Create class instance that represents a symbol format of length @racket[len]. If @racket[len] is an integer,  the symbol is fixed at that length, otherwise it can be any length.
 }
 
@@ -609,9 +609,9 @@ Whether @racket[x] is an object of type @racket[x:symbol%].
 @defproc[
 (x:symbol
 [len-arg (or/c length-resolvable? #false) #false]
-[enc-arg (or/c supported-encoding? #false) #false]
+[enc-arg (or/c procedure? supported-encoding? #false) #false]
 [#:length len-kw (or/c length-resolvable? #false) #false]
-[#:encoding enc-kw (or/c supported-encoding? #false) #false]
+[#:encoding enc-kw (or/c procedure? supported-encoding? #false) #false]
 [#:pre-encode pre-encode-proc (or/c (any/c . -> . any/c) #false) #false]
 [#:post-decode post-decode-proc (or/c (any/c . -> . any/c) #false) #false]
 [#:base-class base-class (λ (c) (subclass? c x:symbol%)) x:symbol%]
diff --git a/xenomorph/xenomorph/string.rkt b/xenomorph/xenomorph/string.rkt
index 83849152..4966995e 100644
--- a/xenomorph/xenomorph/string.rkt
+++ b/xenomorph/xenomorph/string.rkt
@@ -101,9 +101,9 @@ https://github.com/mbutterick/restructure/blob/master/src/String.coffee
                   #:base-class [base-class x:string%])
   (()
    ((or/c length-resolvable? #false)
-    (or/c supported-encoding? #false)
+    (or/c procedure? supported-encoding? #false)
     #:length (or/c length-resolvable? #false)
-    #:encoding (or/c supported-encoding? #false)
+    #:encoding (or/c procedure? supported-encoding? #false)
     #:pre-encode (or/c (any/c . -> . any/c) #false)
     #:post-decode (or/c (any/c . -> . any/c) #false)
     #:base-class (λ (c) (subclass? c x:string%)))
@@ -113,7 +113,7 @@ https://github.com/mbutterick/restructure/blob/master/src/String.coffee
   (unless (length-resolvable? len)
     (raise-argument-error 'x:string "resolvable length" len))
   (define encoding (or enc-arg enc-kwarg 'ascii))
-  (unless (supported-encoding? encoding)
+  (unless (or (supported-encoding? encoding) (procedure? encoding))
     (raise-argument-error 'x:string "valid encoding value" encoding))
   (new (generate-subclass base-class pre-proc post-proc)
        [len len]
diff --git a/xenomorph/xenomorph/symbol.rkt b/xenomorph/xenomorph/symbol.rkt
index 36505c52..a75e01d5 100644
--- a/xenomorph/xenomorph/symbol.rkt
+++ b/xenomorph/xenomorph/symbol.rkt
@@ -30,9 +30,9 @@
                   #:base-class [base-class x:symbol%])
   (()
    ((or/c length-resolvable? #false)
-    (or/c supported-encoding? #false)
+    (or/c procedure? supported-encoding? #false)
     #:length (or/c length-resolvable? #false)
-    #:encoding (or/c supported-encoding? #false)
+    #:encoding (or/c procedure? supported-encoding? #false)
     #:pre-encode (or/c (any/c . -> . any/c) #false)
     #:post-decode (or/c (any/c . -> . any/c) #false)
     #:base-class (λ (c) (subclass? c x:symbol%)))
@@ -42,7 +42,7 @@
   (unless (length-resolvable? len)
     (raise-argument-error 'x:symbol "resolvable length" len))
   (define encoding (or enc-arg enc-kwarg 'utf8))
-  (unless (supported-encoding? encoding)
+  (unless (or (supported-encoding? encoding) (procedure? encoding))
     (raise-argument-error 'x:symbol "valid encoding value" encoding))
   (new (generate-subclass base-class pre-proc post-proc)
        [len len]