fully implement the first-nonblank-column thing for H and L

surprisingly intricate, but although it looks messy now, this approach will clean up nicely

Force-Push: yes
Change-Id: Ic9c90982787a58110ec0a189844742a1e6c2216f

1 files changed, 24 insertions, 4 deletions

diff --git a/src/main.rs b/src/main.rs
index 4b5dc5a..70bc0b4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ use crate::types::*;
 use smol::prelude::*;
 
 use smol::fs::File;
+use smol::io::Cursor;
 use smol::lock::RwLock;
 use std::path::PathBuf;
 use std::process::ExitCode;
@@ -464,12 +465,31 @@ impl Ivy {
 
   async fn first_non_blank_column(&mut self) -> Result<()> {
     let row = *self.window.read().await.cursor_row.read().await;
+    let buffer = self.buffer.write().await;
+
+    if let Some(row_span) = buffer.line_span(row).await {
+      let mut offset = 0;
+      loop {
+        let sub_span = row_span.start + offset .. row_span.end;
+        let mut contents = buffer.contents.write().await;
+        let mut cursor = Cursor::new(&mut contents[sub_span]);
+
+        if let Ok(decode) = encoding::read_utf8_char(&mut cursor).await {
+          offset += decode.skipped_bytes;
+
+          if decode.c.is_whitespace() {
+            offset += decode.found_bytes;
+          } else {
+            break;
+          }
+        } else {
+          break;
+        }
+      }
 
-    if let Some(span) = self.buffer.read().await.line_span(row).await {
-      /* TODO */
       let window = self.window.write().await;
-      *window.cursor_column.write().await = 0;
-      *window.cursor_neutral_column.write().await = 0;
+      *window.cursor_column.write().await = offset;
+      *window.cursor_neutral_column.write().await = offset;
     } else {
       let window = self.window.write().await;
       *window.cursor_column.write().await = 0;