From 11a058c8df9729c6d3787cfe796faf21d5d61c98 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Wed, 4 Sep 2019 13:15:22 -0400
Subject: [PATCH] Improve number highlighting logic

---
 src/editor.rs | 44 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 39 insertions(+), 5 deletions(-)

diff --git a/src/editor.rs b/src/editor.rs
index 4ff8d31..3f57959 100644
--- a/src/editor.rs
+++ b/src/editor.rs
@@ -309,14 +309,45 @@ impl Editor {
     // Syntax Highlighting
     // ------------------------------------------------------------------------
 
+    fn is_separator(c: char) -> bool {
+        let separator_chars = ",.()+-/*=~%<>[];";
+
+        for ch in separator_chars.chars() {
+            if c == ch {
+                return true;
+            }
+        }
+
+        c.is_ascii_whitespace() || c == '\0'
+    }
+
     fn update_syntax(&mut self, index: usize) {
         let row = &mut self.rows[index];
         row.highlight = vec![Highlight::Normal; row.render.len()];
 
-        for (x, ch) in row.render.char_indices() {
-            if ch.is_ascii_digit() {
-                row.highlight[x] = Highlight::Number;
+        let mut prev_separator = false;
+
+        let mut i = 0;
+        let bytes = row.render.clone().into_bytes();
+        while i < row.render.len() {
+            let c = bytes[i] as char;
+            let prev_highlight = if i > 0 {
+                row.highlight[i - 1]
+            } else {
+                Highlight::Normal
+            };
+
+            if (c.is_ascii_digit() && (prev_separator || prev_highlight == Highlight::Number))
+                || (c == '.' && prev_highlight == Highlight::Number)
+            {
+                row.highlight[i as usize] = Highlight::Number;
+                i += 1;
+                prev_separator = false;
+                continue;
             }
+
+            prev_separator = Self::is_separator(c);
+            i += 1;
         }
     }
 
@@ -325,7 +356,7 @@ impl Editor {
 
         match syntax_type {
             Normal => 37,
-            Number => 31, // Red
+            Number => 31,      // Red
             SearchMatch => 34, // Blue
         }
     }
@@ -1039,7 +1070,10 @@ impl Editor {
         let saved_coloff = self.col_offset;
         let saved_rowoff = self.row_offset;
 
-        let query = self.prompt("Search (Use ESC/Arrows/Enter):", Some(&mut Self::find_callback));
+        let query = self.prompt(
+            "Search (Use ESC/Arrows/Enter):",
+            Some(&mut Self::find_callback),
+        );
 
         if query.is_empty() {
             self.cursor_x = saved_cx;