[librsvg] xml: make steal_result return a Result

[Federico Mena Quintero <federico src gnome org>]

commit 39e121469820a42acdb78fbc053805d64297cb3b
Author: Paolo Borelli <pborelli gnome org>
Date:   Sun Jan 13 12:18:42 2019 +0100

    xml: make steal_result return a Result
    
    This is not only cleaner, but also safer since callers do not
    have to remember to call validate_tree manually.

 rsvg_internals/src/handle.rs |  6 +-----
 rsvg_internals/src/svg.rs    |  4 +---
 rsvg_internals/src/xml.rs    | 24 +++++++++---------------
 3 files changed, 11 insertions(+), 23 deletions(-)
---
diff --git a/rsvg_internals/src/handle.rs b/rsvg_internals/src/handle.rs
index b6d1bd77..fa26b27b 100644
--- a/rsvg_internals/src/handle.rs
+++ b/rsvg_internals/src/handle.rs
@@ -274,12 +274,8 @@ impl Handle {
     fn close_internal(&mut self) -> Result<(), LoadingError> {
         let mut r = self.load.borrow_mut();
         let mut load = r.take().unwrap();
-
         let mut xml = load.close()?;
-
-        xml.validate_tree()?;
-
-        *self.svg.borrow_mut() = Some(Rc::new(xml.steal_result()));
+        *self.svg.borrow_mut() = Some(Rc::new(xml.steal_result()?));
         Ok(())
     }
 
diff --git a/rsvg_internals/src/svg.rs b/rsvg_internals/src/svg.rs
index 4866392f..848700f6 100644
--- a/rsvg_internals/src/svg.rs
+++ b/rsvg_internals/src/svg.rs
@@ -51,9 +51,7 @@ impl Svg {
 
         xml_state_load_from_possibly_compressed_stream(&mut xml, load_flags, stream, cancellable)?;
 
-        xml.validate_tree()?;
-
-        Ok(xml.steal_result())
+        xml.steal_result()
     }
 
     pub fn lookup(&self, fragment: &Fragment) -> Option<RsvgNode> {
diff --git a/rsvg_internals/src/xml.rs b/rsvg_internals/src/xml.rs
index fd1d8a5a..d02a92c6 100644
--- a/rsvg_internals/src/xml.rs
+++ b/rsvg_internals/src/xml.rs
@@ -113,26 +113,20 @@ impl XmlState {
         self.tree = Some(Tree::new(root));
     }
 
-    pub fn validate_tree(&self) -> Result<(), LoadingError> {
-        if let Some(ref tree) = self.tree {
-            if tree.root_is_svg() {
-                Ok(())
-            } else {
+    pub fn steal_result(&mut self) -> Result<Svg, LoadingError> {
+        match self.tree {
+            None => Err(LoadingError::SvgHasNoElements),
+            Some(ref tree) if !tree.root_is_svg() => {
                 Err(LoadingError::RootElementIsNotSvg)
             }
-        } else {
-            Err(LoadingError::SvgHasNoElements)
+            _ => Ok(Svg::new(
+                self.tree.take().unwrap(),
+                self.ids.take().unwrap(),
+                self.load_options.clone(),
+            )),
         }
     }
 
-    pub fn steal_result(&mut self) -> Svg {
-        Svg::new(
-            self.tree.take().unwrap(),
-            self.ids.take().unwrap(),
-            self.load_options.clone(),
-        )
-    }
-
     fn context(&self) -> Context {
         // We can unwrap since the stack is never empty
         self.context_stack.last().unwrap().clone()