[librsvg] Use AttributeResultExt in pattern.rs

[Federico Mena Quintero <federico src gnome org>]

commit 36dac5dd0cc40c76cda7d2f1689d431af8351c48
Author: Federico Mena Quintero <federico gnome org>
Date:   Thu Nov 29 17:55:26 2018 -0600

    Use AttributeResultExt in pattern.rs

 rsvg_internals/src/defs.rs    | 16 ++++++++++++++++
 rsvg_internals/src/pattern.rs | 16 +++++++++-------
 2 files changed, 25 insertions(+), 7 deletions(-)
---
diff --git a/rsvg_internals/src/defs.rs b/rsvg_internals/src/defs.rs
index d536b704..96651304 100644
--- a/rsvg_internals/src/defs.rs
+++ b/rsvg_internals/src/defs.rs
@@ -6,8 +6,10 @@ use std::ptr;
 use std::rc::Rc;
 
 use allowed_url::AllowedUrl;
+use error::ValueErrorKind;
 use handle::{self, RsvgHandle};
 use node::{Node, RsvgNode};
+use parsers::ParseError;
 use util::rsvg_g_warning;
 use util::utf8_cstr;
 
@@ -141,6 +143,20 @@ pub enum HrefError {
     FragmentRequired,
 }
 
+impl From<HrefError> for ValueErrorKind {
+    fn from(e: HrefError) -> ValueErrorKind {
+        match e {
+            HrefError::ParseError => ValueErrorKind::Parse(ParseError::new("url parse error")),
+            HrefError::FragmentForbidden => {
+                ValueErrorKind::Value("fragment identifier not allowed".to_string())
+            }
+            HrefError::FragmentRequired => {
+                ValueErrorKind::Value("fragment identifier required".to_string())
+            }
+        }
+    }
+}
+
 impl Href {
     /// Parses a string into an Href, or returns an error
     ///
diff --git a/rsvg_internals/src/pattern.rs b/rsvg_internals/src/pattern.rs
index c7f2b435..f599b0e0 100644
--- a/rsvg_internals/src/pattern.rs
+++ b/rsvg_internals/src/pattern.rs
@@ -9,8 +9,9 @@ use aspect_ratio::*;
 use attributes::Attribute;
 use bbox::*;
 use coord_units::CoordUnits;
+use defs::Fragment;
 use drawing_ctx::{DrawingCtx, NodeStack};
-use error::RenderingError;
+use error::{AttributeResultExt, RenderingError};
 use float_eq_cairo::ApproxEqCairo;
 use handle::RsvgHandle;
 use length::*;
@@ -36,7 +37,7 @@ pub struct Pattern {
     pub vbox: Option<Option<ViewBox>>,
     pub preserve_aspect_ratio: Option<AspectRatio>,
     pub affine: Option<cairo::Matrix>,
-    pub fallback: Option<String>,
+    pub fallback: Option<Fragment>,
     pub x: Option<Length>,
     pub y: Option<Length>,
     pub width: Option<Length>,
@@ -204,7 +205,9 @@ impl NodeTrait for NodePattern {
                     p.affine = Some(parse("patternTransform", value, ())?)
                 }
 
-                Attribute::XlinkHref => p.fallback = Some(value.to_owned()),
+                Attribute::XlinkHref => {
+                    p.fallback = Some(Fragment::parse(value).attribute(Attribute::XlinkHref)?);
+                }
 
                 Attribute::X => p.x = Some(parse("x", value, LengthDir::Horizontal)?),
 
@@ -249,10 +252,9 @@ impl PaintSource<Pattern> for NodePattern {
         let mut stack = NodeStack::new();
 
         while !result.is_resolved() {
-            if let Some(acquired) = draw_ctx.get_acquired_href_of_type(
-                result.fallback.as_ref().map(String::as_ref),
-                NodeType::Pattern,
-            ) {
+            if let Some(acquired) =
+                draw_ctx.get_acquired_node_of_type(result.fallback.as_ref(), NodeType::Pattern)
+            {
                 let node = acquired.get();
 
                 if stack.contains(node) {