6814 - tile: backspace deletes char or word

3 files changed, 58 insertions, 0 deletions

diff --git a/apps/tile/environment.mu b/apps/tile/environment.mu
index 275b87df..caa8c720 100644
--- a/apps/tile/environment.mu
+++ b/apps/tile/environment.mu
@@ -93,9 +93,36 @@ $process:body: {
       }
       break $process:body
     }
+    compare key, 0x7f  # del (backspace on Macs)
+    {
+      break-if-!=
+      var cursor-word-ah/edi: (addr handle word) <- get self, cursor-word
+      var _cursor-word/eax: (addr word) <- lookup *cursor-word-ah
+      var cursor-word/ecx: (addr word) <- copy _cursor-word
+      # if not at start of some word, delete grapheme before cursor within current word
+      var at-start?/eax: boolean <- cursor-at-start? cursor-word
+      compare at-start?, 0  # false
+      {
+        break-if-=
+        delete-before-cursor cursor-word
+        break $process:body
+      }
+      # otherwise delete current word and move to end of prev word
+      var prev-word-ah/esi: (addr handle word) <- get cursor-word, prev
+      var prev-word/eax: (addr word) <- lookup *prev-word-ah
+      {
+        compare prev-word, 0
+        break-if-=
+        copy-object prev-word-ah, cursor-word-ah
+        cursor-to-end prev-word
+        delete-next prev-word
+      }
+      break $process:body
+    }
     compare key, 0x20  # space
     {
       break-if-!=
+      # insert new word
       var cursor-word-ah/edx: (addr handle word) <- get self, cursor-word
       append-word cursor-word-ah
       var cursor-word/eax: (addr word) <- lookup *cursor-word-ah
@@ -103,6 +130,7 @@ $process:body: {
       copy-object next-word-ah, cursor-word-ah
       break $process:body
     }
+    # otherwise insert key within current word
     var g/edx: grapheme <- copy key
     var print?/eax: boolean <- real-grapheme? key
     {
diff --git a/apps/tile/gap-buffer.mu b/apps/tile/gap-buffer.mu
index 8a57fc5b..3d001cf6 100644
--- a/apps/tile/gap-buffer.mu
+++ b/apps/tile/gap-buffer.mu
@@ -169,6 +169,12 @@ fn gap-index _self: (addr gap-buffer) -> result/eax: int {
   result <- copy *top-addr
 }
 
+fn delete-before-gap _self: (addr gap-buffer) {
+  var self/eax: (addr gap-buffer) <- copy _self
+  var left/eax: (addr grapheme-stack) <- get self, left
+  var dummy/eax: grapheme <- pop-grapheme-stack left
+}
+
 fn gap-buffer-equal? _self: (addr gap-buffer), s: (addr array byte) -> result/eax: boolean {
 $gap-buffer-equal?:body: {
   var self/esi: (addr gap-buffer) <- copy _self
diff --git a/apps/tile/word.mu b/apps/tile/word.mu
index cbc3c90d..9145f1d5 100644
--- a/apps/tile/word.mu
+++ b/apps/tile/word.mu
@@ -140,6 +140,30 @@ fn cursor-index _self: (addr word) -> result/eax: int {
   result <- gap-index data
 }
 
+fn delete-before-cursor _self: (addr word) {
+  var self/esi: (addr word) <- copy _self
+  var data/eax: (addr gap-buffer) <- get self, data
+  delete-before-gap data
+}
+
+fn delete-next _self: (addr word) {
+$delete-next:body: {
+  var self/esi: (addr word) <- copy _self
+  var next-ah/edi: (addr handle word) <- get self, next
+  var next/eax: (addr word) <- lookup *next-ah
+  compare next, 0
+  break-if-= $delete-next:body
+  var next-next-ah/ecx: (addr handle word) <- get next, next
+  var self-ah/esi: (addr handle word) <- get next, prev
+  copy-object next-next-ah, next-ah
+  var new-next/eax: (addr word) <- lookup *next-next-ah
+  compare new-next, 0
+  break-if-= $delete-next:body
+  var dest/eax: (addr handle word) <- get new-next, prev
+  copy-object self-ah, dest
+}
+}
+
 fn print-word screen: (addr screen), _self: (addr word) {
   var self/esi: (addr word) <- copy _self
   var data/eax: (addr gap-buffer) <- get self, data