added a preliminary reader mode, so

#lang planet me mylanguage.plt 3 4

gets the named planet package, gets lang/reader.ss, and uses it as the reader.

svn: r7778

collects/planet/lang/reader.ss

@@ -0,0 +1,30 @@
+#lang scheme/base
+
+(provide (rename-out [planet-read read]
+                     [planet-read-syntax read-syntax]))
+
+(define (planet-read-fn in spec->read-data)
+  (let* ([spec (read-line in)]
+         [pkgname (regexp-match #rx"^[ ]*([^ ]+)[ ]*([^ ]+)[ ]*([^ ]*)[ ]*([^ ]*)[ ]*$" spec)])
+    (unless pkgname
+      (raise-syntax-error 'read "bad syntax, oops"))
+    (let-values ([(_ owner pkgname majstr minstr) (apply values pkgname)])
+      (let ([maj (string->number majstr)]
+            [min (string->number minstr)])
+        (unless (or maj (string=? majstr ""))
+          (raise-syntax-error 'read "bad maj"))
+        (unless (or min (string=? minstr ""))
+          (raise-syntax-error 'read "bad min"))
+        (unless (or maj (not min))
+          (raise-syntax-error 'read "bad version number pair"))
+        (spec->read-data
+         `(planet "lang/reader.ss"
+                  (,owner
+                   ,pkgname
+                   ,@(if maj `(,maj) '())
+                   ,@(if min `(,min) '()))))))))
+         
+(define (planet-read in) 
+  (planet-read-fn in (λ (spec) ((dynamic-require spec 'read) in)))) 
+(define (planet-read-syntax srcname in) 
+  (planet-read-fn in (λ (spec) ((dynamic-require spec 'read-syntax) srcname in))))