fix(dynamic string): parser issue related to incorrectly matching braces

src/dynamic_string.rs

@@ -4,6 +4,9 @@ use gtk::prelude::*;
 use std::sync::{Arc, Mutex};
 use tokio::spawn;
 
+/// A segment of a dynamic string,
+/// containing either a static string
+/// or a script.
 #[derive(Debug)]
 enum DynamicStringSegment {
     Static(String),
@@ -20,47 +23,7 @@ impl DynamicString {
     where
         F: FnMut(String) -> Continue + 'static,
     {
-        let mut segments = vec![];
-
-        let mut chars = input.chars().collect::<Vec<_>>();
-        while !chars.is_empty() {
-            let char = &chars[..=1];
-
-            let (token, skip) = if let ['{', '{'] = char {
-                const SKIP_BRACKETS: usize = 4;
-
-                let str = chars
-                    .iter()
-                    .skip(2)
-                    .enumerate()
-                    .take_while(|(i, &c)| c != '}' && chars[i + 1] != '}')
-                    .map(|(_, c)| c)
-                    .collect::<String>();
-
-                let len = str.len();
-
-                (
-                    DynamicStringSegment::Dynamic(Script::from(str.as_str())),
-                    len + SKIP_BRACKETS,
-                )
-            } else {
-                let str = chars
-                    .iter()
-                    .enumerate()
-                    .take_while(|(i, &c)| !(c == '{' && chars[i + 1] == '{'))
-                    .map(|(_, c)| c)
-                    .collect::<String>();
-
-                let len = str.len();
-
-                (DynamicStringSegment::Static(str), len)
-            };
-
-            assert_ne!(skip, 0);
-
-            segments.push(token);
-            chars.drain(..skip);
-        }
+        let segments = Self::parse_input(input);
 
         let label_parts = Arc::new(Mutex::new(Vec::new()));
         let (tx, rx) = glib::MainContext::channel(glib::PRIORITY_DEFAULT);
@@ -105,6 +68,62 @@ impl DynamicString {
 
         Self
     }
+
+    /// Parses the input string into static and dynamic segments
+    fn parse_input(input: &str) -> Vec<DynamicStringSegment> {
+        if !input.contains("{{") {
+            return vec![DynamicStringSegment::Static(input.to_string())];
+        }
+
+        let mut segments = vec![];
+
+        let mut chars = input.chars().collect::<Vec<_>>();
+        while !chars.is_empty() {
+            let char_pair = &chars[..=1];
+
+            let (token, skip) = if let ['{', '{'] = char_pair {
+                const SKIP_BRACKETS: usize = 4; // two braces either side
+
+                let str = chars
+                    .windows(2)
+                    .skip(2)
+                    .take_while(|win| win != &['}', '}'])
+                    .map(|w| w[0])
+                    .collect::<String>();
+
+                let len = str.len();
+
+                (
+                    DynamicStringSegment::Dynamic(Script::from(str.as_str())),
+                    len + SKIP_BRACKETS,
+                )
+            } else {
+                let mut str = chars
+                    .windows(2)
+                    .take_while(|win| win != &['{', '{'])
+                    .map(|w| w[0])
+                    .collect::<String>();
+
+                // if segment is at end of string, last char gets missed above due to uneven window.
+                if chars.len() == str.len() + 1 {
+                    let remaining_char = *chars.get(str.len()).expect("Failed to find last char");
+                    str.push(remaining_char);
+                }
+
+                let len = str.len();
+
+                (DynamicStringSegment::Static(str), len)
+            };
+
+            // quick runtime check to make sure the parser is working as expected
+            assert_ne!(skip, 0);
+
+            segments.push(token);
+            chars.drain(..skip);
+        }
+
+        segments
+    }
 }
 
 #[cfg(test)]