644 - backspacing out from within strings/comments

I'd worried last night that I'd have to track the points where
comments/strings begin, but at least so far this is elegant. Might run
into problems when I try to backspace over strings after ending them.

And backspacing over comments after terminating them is a whole
different ball of wax. We still can't backspace over newlines because we
can't move the cursor across lines because we can't tell where our
cursor currently is. And even if we could tell we'd need to track how
long each line is. A new data structure is needed..

1 files changed, 23 insertions, 12 deletions

diff --git a/color-repl.mu b/color-repl.mu
index d733b8f8..d95d48d9 100644
--- a/color-repl.mu
+++ b/color-repl.mu
@@ -30,7 +30,7 @@
       (comment?:boolean <- equal c:character ((#\; literal)))
       (break-unless comment?:boolean)
       ($print-key-to-host c:character 4:literal/fg/blue)
-      (skip-comment)
+      (skip-comment result:buffer-address)
       ; comment slurps newline, so check if we should return
       (end-sexp?:boolean <- lesser-or-equal open-parens:integer 0:literal)
       (break-if end-sexp?:boolean 2:blocks)
@@ -86,8 +86,11 @@
 
 (function skip-comment [
   (default-space:space-address <- new space:literal 30:literal)
+  (result:buffer-address <- next-input)
+  (orig-len:integer <- get result:buffer-address/deref length:offset)
   ; test: ; abc<enter>
   { begin
+    next-key-in-comment
     (c:character <- $wait-for-key-from-host)
     ($print-key-to-host c:character 4:literal/fg/blue)
     ; handle backspace
@@ -96,17 +99,25 @@
     { begin
       (backspace?:boolean <- equal c:character ((#\backspace literal)))
       (break-unless backspace?:boolean)
-      (loop 2:blocks)
+      (len:integer-address <- get-address result:buffer-address/deref length:offset)
+      ; buffer has to have at least the semi-colon so can't be empty
+      (len:integer-address/deref <- subtract len:integer-address/deref 1:literal)
+      ; if we erase start of comment, return
+      (comment-deleted?:boolean <- lesser-or-equal len:integer-address/deref orig-len:integer)
+      (jump-unless comment-deleted?:boolean end:offset)
+      (jump next-key-in-comment:offset)
     }
+    (result:buffer-address <- append result:buffer-address c:character)
     (newline?:boolean <- equal c:character ((#\newline literal)))
-    (break-if newline?:boolean)
-    (loop)
+    (jump-unless newline?:boolean next-key-in-comment:offset)
   }
+  end
 ])
 
 (function slurp-string [
   (default-space:space-address <- new space:literal 30:literal)
   (result:buffer-address <- next-input)
+  (orig-len:integer <- get result:buffer-address/deref length:offset)
   ; test: "abc"
   { begin
     next-key-in-string
@@ -119,14 +130,12 @@
       (backspace?:boolean <- equal c:character ((#\backspace literal)))
       (break-unless backspace?:boolean)
       (len:integer-address <- get-address result:buffer-address/deref length:offset)
-      ; but only if we need to
-      ; test: "<backspace>abc"
-      ; unnecessary?!
-      { begin
-        (zero?:boolean <- lesser-or-equal len:integer-address/deref 0:literal)
-        (break-if zero?:boolean)
-        (len:integer-address/deref <- subtract len:integer-address/deref 1:literal)
-      }
+      ; typed a quote before calling slurp-string, so can't be empty
+      (len:integer-address/deref <- subtract len:integer-address/deref 1:literal)
+      ; if we erase start of string, return
+      ; test: "<backspace>34
+      (string-deleted?:boolean <- lesser-or-equal len:integer-address/deref orig-len:integer)
+      (jump-unless string-deleted?:boolean end:offset)
       (jump next-key-in-string:offset)
     }
     (result:buffer-address <- append result:buffer-address c:character)
@@ -145,6 +154,7 @@
           (backspace?:boolean <- equal c2:character ((#\backspace literal)))
           (break-unless backspace?:boolean)
           (len:integer-address <- get-address result:buffer-address/deref length:offset)
+          ; just typed a backslash, so buffer can't be empty
           (len:integer-address/deref <- subtract len:integer-address/deref 1:literal)
           (jump next-key-in-string:offset)
         }
@@ -157,6 +167,7 @@
     (end-quote?:boolean <- equal c:character ((#\" literal)))  ; for vim: "
     (jump-unless end-quote?:boolean next-key-in-string:offset)
   }
+  end
 ])
 
 (function main [