From 43c94d34457965ae221947a2986a265c428dfff2 Mon Sep 17 00:00:00 2001
From: tigercosmos <phy.tiger@gmail.com>
Date: Fri, 22 Dec 2017 16:21:32 +0800
Subject: [PATCH] pretty print tree

---
 components/gfx_traits/print_tree.rs | 34 ++++++++++++++++++++++++-----
 components/layout/block.rs          |  2 +-
 components/layout/flow.rs           | 13 ++++++-----
 components/layout/fragment.rs       |  8 +++----
 4 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/components/gfx_traits/print_tree.rs b/components/gfx_traits/print_tree.rs
index a842193e03f3..e347c82bed99 100644
--- a/components/gfx_traits/print_tree.rs
+++ b/components/gfx_traits/print_tree.rs
@@ -22,12 +22,21 @@ impl PrintTree {
         }
     }
 
-    /// Descend one level in the tree with the given title.
-    pub fn new_level(&mut self, title: String) {
+    /// Descend one level in the tree with the given title string.
+    pub fn new_level(&mut self, queued_title: String) {
         self.flush_queued_item("\u{251C}\u{2500}");
 
         self.print_level_prefix();
-        println!("\u{251C}\u{2500} {}", title);
+
+        let items: Vec<&str> = queued_title.split("\n").collect();
+        println!("\u{251C}\u{2500} {}", items[0]);
+        for i in 1..items.len() {
+            self.print_level_child_indentation();
+            print!("{}", items[i]);
+            if i < items.len() {
+                print!("\n");
+            }
+        }
 
         self.level = self.level + 1;
     }
@@ -35,7 +44,7 @@ impl PrintTree {
     /// Ascend one level in the tree.
     pub fn end_level(&mut self) {
         self.flush_queued_item("\u{2514}\u{2500}");
-        self.level = self.level - 1;
+        self.level -= 1;
     }
 
     /// Add an item to the current level in the tree.
@@ -50,10 +59,25 @@ impl PrintTree {
         }
     }
 
+    fn print_level_child_indentation(&self) {
+        for _ in 0..(self.level + 1) {
+            print!("\u{2502}  ");
+        }
+        print!("{}", " ".repeat(7));
+    }
+
     fn flush_queued_item(&mut self, prefix: &str) {
         if let Some(queued_item) = self.queued_item.take() {
             self.print_level_prefix();
-            println!("{} {}", prefix, queued_item);
+            let items: Vec<&str> = queued_item.split("\n").collect();
+            println!("{} {}", prefix, items[0]);
+            for i in 1..items.len() {
+                self.print_level_child_indentation();
+                print!("{}", items[i]);
+                if i < items.len() {
+                    print!("\n");
+                }
+            }
         }
     }
 }
diff --git a/components/layout/block.rs b/components/layout/block.rs
index f615c5aa4698..1f01327a160f 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -2191,7 +2191,7 @@ impl Flow for BlockFlow {
     }
 
     fn print_extra_flow_children(&self, print_tree: &mut PrintTree) {
-        print_tree.add_item(format!("↑↑ Fragment for block: {:?}", self.fragment));
+        print_tree.add_item(format!("↑↑ Fragment for block:{:?}", self.fragment));
     }
 }
 
diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index c706516933b8..e4b19e20b0c1 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -925,26 +925,29 @@ impl fmt::Debug for BaseFlow {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let child_count = self.parallel.children_count.load(Ordering::SeqCst);
         let child_count_string = if child_count > 0 {
-            format!(" children={}", child_count)
+            format!("\nchildren={}", child_count)
         } else {
             "".to_owned()
         };
 
         let absolute_descendants_string = if self.abs_descendants.len() > 0 {
-            format!(" abs-descendents={}", self.abs_descendants.len())
+            format!("\nabs-descendents={}", self.abs_descendants.len())
         } else {
             "".to_owned()
         };
 
         let damage_string = if self.restyle_damage != RestyleDamage::empty() {
-            format!(" damage={:?}", self.restyle_damage)
+            format!("\ndamage={:?}", self.restyle_damage)
         } else {
             "".to_owned()
         };
 
         write!(f,
-               "sc={:?} pos={:?}, {}{} floatspec-in={:?}, floatspec-out={:?}, \
-                overflow={:?}{}{}{}",
+               "\nsc={:?}\
+                \npos={:?}{}{}\
+                \nfloatspec-in={:?}\
+                \nfloatspec-out={:?}\
+                \noverflow={:?}{}{}{}",
                self.stacking_context_id,
                self.position,
                if self.flags.contains(FlowFlags::FLOATS_LEFT) { "FL" } else { "" },
diff --git a/components/layout/fragment.rs b/components/layout/fragment.rs
index b2a627347da7..0b78fb86475f 100644
--- a/components/layout/fragment.rs
+++ b/components/layout/fragment.rs
@@ -2958,24 +2958,24 @@ impl Fragment {
 impl fmt::Debug for Fragment {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let border_padding_string = if !self.border_padding.is_zero() {
-            format!(" border_padding={:?}", self.border_padding)
+            format!("\nborder_padding={:?}", self.border_padding)
         } else {
             "".to_owned()
         };
 
         let margin_string = if !self.margin.is_zero() {
-            format!(" margin={:?}", self.margin)
+            format!("\nmargin={:?}", self.margin)
         } else {
             "".to_owned()
         };
 
         let damage_string = if self.restyle_damage != RestyleDamage::empty() {
-            format!(" damage={:?}", self.restyle_damage)
+            format!("\ndamage={:?}", self.restyle_damage)
         } else {
             "".to_owned()
         };
 
-        write!(f, "{}({}) [{:?}] border_box={:?}{}{}{}",
+        write!(f, "\n{}({}) [{:?}]\nborder_box={:?}{}{}{}",
             self.specific.get_type(),
             self.debug_id,
             self.specific,