Prefer 'is_empty' over 'len' when doing existential check.

src/aabbtree.rs

@@ -280,7 +280,7 @@ impl AABBTree {
         let children = {
             let node = self.node_mut(node_index);
             if node.split_rect.intersects(rect) {
-                if node.draw_list_group_segments.len() > 0 &&
+                if !node.draw_list_group_segments.is_empty() &&
                    node.actual_rect.intersects(rect) {
                     debug_assert!(node.children.is_none());
                     node.is_visible = true;
@@ -304,7 +304,7 @@ impl AABBTree {
         for node in &mut self.nodes {
             node.is_visible = false;
         }
-        if self.nodes.len() > 0 {
+        if !self.nodes.is_empty() {
             self.check_node_visibility(NodeIndex(0), &rect);
         }
     }

src/debug_render.rs

@@ -162,9 +162,9 @@ impl DebugRenderer {
     pub fn render(&mut self,
                   device: &mut Device,
                   viewport_size: &Size2D<u32>) {
-        if self.font_indices.len() > 0 ||
-           self.line_vertices.len() > 0 ||
-           self.tri_vertices.len() > 0 {
+        if !self.font_indices.is_empty() ||
+           !self.line_vertices.is_empty() ||
+           !self.tri_vertices.is_empty() {
             gl::disable(gl::DEPTH_TEST);
             gl::enable(gl::BLEND);
             gl::blend_equation(gl::FUNC_ADD);

src/node_compiler.rs

@@ -134,7 +134,7 @@ impl NodeCompiler for AABBTreeNode {
             }
 
             let batches = builder.finalize();
-            if batches.len() > 0 {
+            if !batches.is_empty() {
                 compiled_node.batch_list.push(BatchList {
                     batches: batches,
                     draw_list_group_id: draw_list_group_segment.draw_list_group_id,

src/profiler.rs

@@ -239,7 +239,7 @@ impl ProfileGraph {
             stats.max_value = stats.max_value.max(*value);
         }
 
-        if self.values.len() > 0 {
+        if !self.values.is_empty() {
             stats.mean_value = stats.mean_value / self.values.len() as f32;
         }
 

src/render_backend.rs

@@ -295,7 +295,7 @@ impl RenderBackend {
                                      self.device_pixel_ratio);
 
         let pending_update = self.resource_cache.pending_updates();
-        if pending_update.updates.len() > 0 {
+        if !pending_update.updates.is_empty() {
             self.result_tx.send(ResultMsg::UpdateTextureCache(pending_update)).unwrap();
         }
 

src/renderer.rs

@@ -932,7 +932,7 @@ impl Renderer {
 
     fn flush_raster_batches(&mut self) {
         let batches = mem::replace(&mut self.raster_batches, vec![]);
-        if batches.len() > 0 {
+        if !batches.is_empty() {
             //println!("flushing {:?} raster batches", batches.len());
 
             gl::disable(gl::DEPTH_TEST);
@@ -1201,7 +1201,7 @@ impl Renderer {
                     self.device.bind_program(self.quad_program_id,
                                              &projection);
 
-                    if info.offset_palette.len() > 0 {
+                    if !info.offset_palette.is_empty() {
                         // TODO(gw): Avoid alloc here...
                         let mut floats = Vec::new();
                         for vec in &info.offset_palette {
@@ -1313,7 +1313,7 @@ impl Renderer {
                                 draw_call.first_instance);
                             self.device.bind_vao(vao_id);
 
-                            if draw_call.tile_params.len() > 0 {
+                            if !draw_call.tile_params.is_empty() {
                                 // TODO(gw): Avoid alloc here...
                                 let mut floats = Vec::new();
                                 for vec in &draw_call.tile_params {
@@ -1327,7 +1327,7 @@ impl Renderer {
                                                                    &floats);
                             }
 
-                            if draw_call.clip_rects.len() > 0 {
+                            if !draw_call.clip_rects.is_empty() {
                                 // TODO(gw): Avoid alloc here...
                                 let mut floats = Vec::new();
                                 for rect in &draw_call.clip_rects {