diagnostic formatting: respect tab characters

ltcc/src/diagnostic.rs

@@ -28,7 +28,6 @@ pub fn print_diagnostic(
 
     println!("\n{}:", path.green());
     for (i, l) in lines.enumerate() {
-
         line_region.end += l.chars().count();
 
         last_lines.push((i+1, l.clone()));
@@ -44,12 +43,27 @@ pub fn print_diagnostic(
             let column_begin = region.begin - line_region.begin;
             let column_end   = region.end   - line_region.begin;
 
+
+            let tab_width = 4;
+
+            let column_begin_c = column_begin + (tab_width-1)*l.chars().take(column_begin).filter(|&c|c=='\t').count();
+            let column_end_c = column_end + (tab_width-1)*l.chars().filter(|&c|c=='\t').count();
+
             // display the source line
             for (j,ll) in last_lines.iter() {
                 print!("{}\t{}{}",
                     format!("{}",j).to_string().bright_black(),
                     "|".bright_black().bold(),
-                    ll.bright_white());
+                    ll.chars().map(|c| {
+                        if c == '\t' {
+                            std::iter::repeat(' ').take(tab_width)
+                        } else {
+                            std::iter::repeat(c).take(1)
+                        }
+                    })
+                    .flatten()
+                    .collect::<String>()
+                    .bright_white());
             }
 
             print!("\t{}", "|".bright_magenta());