update navigation buttons state

src/app/browser/window/tab/item/page/search/form.rs

@@ -64,7 +64,7 @@ impl Form {
                     match_case.is_active(),
                 );
                 input.update(!matches.is_empty());
-                navigation.update(matches);
+                navigation.renew(matches);
                 if !this.text().is_empty() {
                     result.update(navigation.position(), navigation.total());
                     result.label.set_visible(true);
@@ -109,7 +109,7 @@ impl Form {
                     this.is_active(),
                 );
                 input.update(!matches.is_empty());
-                navigation.update(matches);
+                navigation.renew(matches);
                 if !input.entry.text().is_empty() {
                     result.update(navigation.position(), navigation.total());
                     result.label.set_visible(true);
@@ -129,6 +129,7 @@ impl Form {
                 Some(subject) => {
                     match navigation.back(subject) {
                         Some((mut start, _)) => {
+                            navigation.update();
                             result.update(navigation.position(), navigation.total());
                             scroll_to_iter(&subject.text_view, &mut start)
                         }
@@ -146,6 +147,7 @@ impl Form {
             move |_| match subject.borrow().as_ref() {
                 Some(subject) => match navigation.forward(subject) {
                     Some((mut start, _)) => {
+                        navigation.update();
                         result.update(navigation.position(), navigation.total());
                         scroll_to_iter(&subject.text_view, &mut start)
                     }

src/app/browser/window/tab/item/page/search/form/navigation.rs

@@ -53,11 +53,17 @@ impl Navigation {
 
     // Actions
 
-    /// Update widget state, including child components
-    pub fn update(&self, matches: Vec<(TextIter, TextIter)>) {
-        self.back.update(!matches.is_empty());
-        self.forward.update(!matches.is_empty());
+    /// Update navigation model
+    pub fn renew(&self, matches: Vec<(TextIter, TextIter)>) {
         self.model.replace(Model::new(matches));
+        self.update();
+    }
+
+    /// Update widget including child components
+    pub fn update(&self) {
+        let model = self.model.borrow();
+        self.back.update(model.is_back());
+        self.forward.update(model.is_next());
     }
 
     /// Navigate back in matches, apply tags to the buffer

src/app/browser/window/tab/item/page/search/form/navigation/model.rs

@@ -7,13 +7,16 @@ pub struct Model<T> {
 }
 
 impl<T> Model<T> {
+    // Constructors
     pub fn new(vector: Vec<T>) -> Self {
         Self {
             cursor: Cursor::new(vector.len()),
             vector,
         }
     }
 
+    // Actions
+
     pub fn back(&mut self) -> Option<&T> {
         self.cursor.back();
         self.vector.get(self.cursor.as_index())
@@ -24,11 +27,21 @@ impl<T> Model<T> {
         self.vector.get(self.cursor.as_index())
     }
 
+    // Getters
+
     pub fn position(&self) -> Option<usize> {
         self.cursor.as_position()
     }
 
     pub fn total(&self) -> usize {
         self.vector.len()
     }
+
+    pub fn is_back(&self) -> bool {
+        self.cursor.is_back()
+    }
+
+    pub fn is_next(&self) -> bool {
+        self.cursor.is_next()
+    }
 }

src/app/browser/window/tab/item/page/search/form/navigation/model/cursor.rs

@@ -4,13 +4,17 @@ pub struct Cursor {
 }
 
 impl Cursor {
+    // Constructors
+
     pub fn new(len: usize) -> Self {
         Self {
             current: 0,
             last: len,
         }
     }
 
+    // Actions
+
     pub fn back(&mut self) {
         self.current = if self.current > 0 {
             self.current - 1
@@ -27,6 +31,8 @@ impl Cursor {
         }
     }
 
+    // Getters
+
     pub fn as_index(&self) -> usize {
         if self.current > 0 {
             self.current - 1
@@ -42,4 +48,12 @@ impl Cursor {
             None
         }
     }
+
+    pub fn is_back(&self) -> bool {
+        self.current > 0
+    }
+
+    pub fn is_next(&self) -> bool {
+        self.current < self.last
+    }
 }