1 files changed, 53 insertions, 13 deletions
diff --git a/src/display/crop.rs b/src/display/crop.rs
index 38a1ad0..c060739 100644
--- a/src/display/crop.rs
+++ b/src/display/crop.rs
@@ -1,22 +1,62 @@
 use {
+    super::TAB_REPLACEMENT,
     unicode_width::UnicodeWidthChar,
 };
 
-// return the counts in bytes and columns of the longest substring
-// fitting the given number of columns
-pub fn count_fitting(s: &str, columns_max: usize) -> (usize, usize) {
-    let mut count_bytes = 0;
-    let mut str_width = 0;
-    for (idx, c) in s.char_indices() {
-        let char_width = UnicodeWidthChar::width(c).unwrap_or(0);
-        let next_str_width = str_width + char_width;
-        if next_str_width > columns_max {
-            break;
+
+#[derive(Debug, Clone, Copy)]
+pub struct StrFit {
+    bytes_count: usize,
+    cols_count: usize,
+    has_tab: bool,
+}
+
+impl StrFit {
+    pub fn from(s: &str, cols_max: usize) -> Self {
+        let mut bytes_count = 0;
+        let mut cols_count = 0;
+        let mut has_tab = false;
+        for (idx, c) in s.char_indices() {
+            let char_width = if '\t' == c {
+                has_tab = true;
+                TAB_REPLACEMENT.len()
+            } else {
+                UnicodeWidthChar::width(c).unwrap_or(0)
+            };
+            let next_str_width = cols_count + char_width;
+            if next_str_width > cols_max {
+                break;
+            }
+            cols_count = next_str_width;
+            bytes_count = idx + c.len_utf8();
         }
-        str_width = next_str_width;
-        count_bytes = idx + c.len_utf8();
+        Self {
+            bytes_count,
+            cols_count,
+            has_tab,
+        }
+    }
+}
+
+/// return the counts in bytes and columns of the longest substring
+/// fitting the given number of columns
+pub fn count_fitting(s: &str, cols_max: usize) -> (usize, usize) {
+    let fit = StrFit::from(s, cols_max);
+    (fit.bytes_count, fit.cols_count)
+}
+
+/// return both the longest fitting string and the number of cols
+/// it takes on screen.
+/// We don't build a string around the whole str, which could be costly
+/// if it's very big
+pub fn make_string(s: &str, cols_max: usize) -> (String, usize) {
+    let fit = StrFit::from(s, cols_max);
+    if fit.has_tab {
+        let string = (&s[0..fit.bytes_count]).replace('\t', TAB_REPLACEMENT);
+        (string, fit.cols_count)
+    } else {
+        (s[0..fit.bytes_count].to_string(), fit.cols_count)
     }
-    (count_bytes, str_width)
 }
 
 #[cfg(test)]