3233 - change how Mu escapes strings

Thanks Sam Putman for helping think through this idea.

When you encounter a backslash, strip it out and pass through any
following run of backslashes. If we 'escaped' a single following
character like C, then the character '\' would be the same as:

  '\\' escaped once
  '\\\\' escaped twice
  '\\\\\\\\' escaped thrice (8 backslashes)

..and so on, the number of backslashes doubling each time. Instead, our
approach is to make the character '\' the same as:

  '\\' escaped once
  '\\\' escaped twice
  '\\\\' escaped thrice

..and so on, the number of backslashes merely increasing by one each
time.

This approach only works as long as backslashes aren't also overloaded
to create special characters. So Mu doesn't follow C's approach of
overloading backslashes both to escape quote characters and also as a
notation for unprintable characters like '\n'.

1 files changed, 3 insertions, 4 deletions

diff --git a/edit/011-errors.mu b/edit/011-errors.mu
index 080d5d37..774aedb1 100644
--- a/edit/011-errors.mu
+++ b/edit/011-errors.mu
@@ -377,10 +377,9 @@ scenario run-shows-unbalanced-bracket-errors [
   assume-screen 100/width, 15/height
   # recipe is incomplete (unbalanced '[')
   1:address:array:character <- new [ 
-recipe foo «
+recipe foo \\[
   x <- copy 0
 ]
-  replace 1:address:array:character, 171/«, 91  # '['
   2:address:array:character <- new [foo]
   3:address:programming-environment-data <- new-programming-environment screen:address:screen, 1:address:array:character, 2:address:array:character
   assume-console [
@@ -392,10 +391,10 @@ recipe foo «
   screen-should-contain [
     .  errors found                                                                   run (F4)           .
     .                                                  ┊foo                                              .
-    .recipe foo \\\[                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .recipe foo \\[                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
     .  x <- copy 0                                     ┊                                                 .
     .                                                  ┊                                                 .
-    .9: unbalanced '\\\[' for recipe                      ┊                                                 .
+    .9: unbalanced '\\[' for recipe                      ┊                                                 .
     .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .
     .                                                  ┊                                                 .
   ]