[librsvg] CoordUnits: use a cssparser

[Federico Mena Quintero <federico src gnome org>]

commit ee38b6c6b3e8e49e21dd9befbe5e346f2c4e9877
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Jun 12 18:12:20 2018 -0500

    CoordUnits: use a cssparser
    
    We'll refactor the Parse trait later.

 rsvg_internals/src/coord_units.rs | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)
---
diff --git a/rsvg_internals/src/coord_units.rs b/rsvg_internals/src/coord_units.rs
index 60f2700d..5f9931aa 100644
--- a/rsvg_internals/src/coord_units.rs
+++ b/rsvg_internals/src/coord_units.rs
@@ -1,3 +1,5 @@
+use cssparser::{CowRcStr, Parser, ParserInput, Token};
+
 use error::AttributeError;
 use parsers::{Parse, ParseError};
 
@@ -18,13 +20,26 @@ impl Parse for CoordUnits {
     type Err = AttributeError;
 
     fn parse(s: &str, _: ()) -> Result<CoordUnits, AttributeError> {
-        match s {
-            "userSpaceOnUse" => Ok(CoordUnits::UserSpaceOnUse),
-            "objectBoundingBox" => Ok(CoordUnits::ObjectBoundingBox),
-            _ => Err(AttributeError::Parse(ParseError::new(
-                "expected 'userSpaceOnUse' or 'objectBoundingBox'",
-            ))),
-        }
+        let mut input = ParserInput::new(s);
+        let mut parser = Parser::new(&mut input);
+        let loc = parser.current_source_location();
+
+        parser
+            .expect_ident()
+            .and_then(|cow| match cow.as_ref() {
+                "userSpaceOnUse" => Ok(CoordUnits::UserSpaceOnUse),
+                "objectBoundingBox" => Ok(CoordUnits::ObjectBoundingBox),
+                _ => Err(
+                    loc.new_basic_unexpected_token_error(Token::Ident(CowRcStr::from(
+                        cow.as_ref().to_string(),
+                    ))),
+                ),
+            })
+            .map_err(|_| {
+                AttributeError::Parse(ParseError::new(
+                    "expected 'userSpaceOnUse' or 'objectBoundingBox'",
+                ))
+            })
     }
 }