implement bf as a module, with a real parser

.gitignore

@@ -1,2 +1,4 @@
 **/compiled/**
-*~
+*~
+*.zo
+*.dep

bf/atsign.rkt

@@ -0,0 +1,4 @@
+#lang reader "bf-reader.rkt"
+Greatest language ever!
+++++-+++-++-++[>++++-+++-++-++<-]>.
+

bf/bf-expander.rkt

@@ -0,0 +1,40 @@
+#lang br/quicklang
+
+(define-macro (bf-module-begin PARSE-TREE)
+  #'(#%module-begin PARSE-TREE))
+
+(provide (rename-out [bf-module-begin #%module-begin]))
+
+(define-macro (bf-program OP-OR-LOOP-ARG ...)
+  #'(void OP-OR-LOOP-ARG ...))
+(provide bf-program)
+
+(define-macro (bf-loop "[" OP-OR-LOOP-ARG ... "]")
+  #'(until (zero? (current-byte))
+      OP-OR-LOOP-ARG ...))
+(provide bf-loop)
+
+(define-macro-cases bf-op
+  [(bf-op ">") #'(gt)]
+  [(bf-op "<") #'(lt)]
+  [(bf-op "+") #'(plus)]
+  [(bf-op "-") #'(minus)]
+  [(bf-op ".") #'(period)]
+  [(bf-op ",") #'(comma)]
+  )
+(provide bf-op)
+
+(define arr (make-vector 30000 0))
+(define ptr 0)
+
+(define (current-byte) (vector-ref arr ptr))
+(define (set-current-byte! val) (vector-set! arr ptr val))
+
+(define (gt) (set! ptr (add1 ptr)))
+(define (lt) (set! ptr (sub1 ptr)))
+
+(define (plus) (set-current-byte! (add1 (current-byte))))
+(define (minus) (set-current-byte! (sub1 (current-byte))))
+
+(define (period) (write-byte (current-byte)))
+(define (comma) (set-current-byte! (read-byte)))

bf/bf-parser.rkt

@@ -0,0 +1,4 @@
+#lang brag
+bf-program : (bf-op|bf-loop)*
+bf-op      : ">" | "<" | "+" | "-" | "." | ","
+bf-loop    : "[" (bf-op|bf-loop)* "]"

bf/bf-reader.rkt

@@ -0,0 +1,18 @@
+#lang br/quicklang
+
+(require "bf-parser.rkt")
+(define (read-syntax path port)
+  (define parse-tree (parse path (make-tokenizer port)))
+  (define module-datum `(module bf-mod bf/bf-expander ,parse-tree))
+  (datum->syntax #f module-datum))
+(provide read-syntax)
+
+(require brag/support)
+(define (make-tokenizer port)
+  (define (next-token)
+    (define bf-lexer
+      (lexer
+       [(char-set "><-.,+[]") lexeme]
+       [any-char (next-token)]))
+    (bf-lexer port))
+  next-token)

bf/main.rkt

@@ -0,0 +1,4 @@
+#lang br/quicklang
+(module reader br
+  (require "bf-reader.rkt")
+  (provide read-syntax))

bf/parser-test.rkt

@@ -0,0 +1,3 @@
+#lang br
+(require "bf-parser.rkt")
+(parse-to-datum "+++--[[+>]<,]++.")