Thread ParseError return values through CSS parsing.

components/style_traits/lib.rs

@@ -18,8 +18,12 @@ extern crate app_units;
 extern crate euclid;
 #[cfg(feature = "servo")] extern crate heapsize;
 #[cfg(feature = "servo")] #[macro_use] extern crate heapsize_derive;
+extern crate selectors;
 #[cfg(feature = "servo")] #[macro_use] extern crate serde_derive;
 
+use selectors::parser::SelectorParseError;
+use std::borrow::Cow;
+
 /// Opaque type stored in type-unsafe work queues for parallel layout.
 /// Must be transmutable to and from `TNode`.
 pub type UnsafeNode = (usize, usize);
@@ -68,3 +72,71 @@ pub mod viewport;
 
 pub use values::{ToCss, OneOrMoreCommaSeparated};
 pub use viewport::HasViewportPercentage;
+
+/// The error type for all CSS parsing routines.
+pub type ParseError<'i> = cssparser::ParseError<'i, SelectorParseError<'i, StyleParseError<'i>>>;
+
+#[derive(Clone, Debug, PartialEq)]
+/// Errors that can be encountered while parsing CSS values.
+pub enum StyleParseError<'i> {
+    /// A bad URL token in a DVB.
+    BadUrlInDeclarationValueBlock,
+    /// A bad string token in a DVB.
+    BadStringInDeclarationValueBlock,
+    /// Unexpected closing parenthesis in a DVB.
+    UnbalancedCloseParenthesisInDeclarationValueBlock,
+    /// Unexpected closing bracket in a DVB.
+    UnbalancedCloseSquareBracketInDeclarationValueBlock,
+    /// Unexpected closing curly bracket in a DVB.
+    UnbalancedCloseCurlyBracketInDeclarationValueBlock,
+    /// A property declaration parsing error.
+    PropertyDeclaration(PropertyDeclarationParseError),
+    /// A property declaration value had input remaining after successfully parsing.
+    PropertyDeclarationValueNotExhausted,
+    /// An unexpected dimension token was encountered.
+    UnexpectedDimension(Cow<'i, str>),
+    /// A media query using a ranged expression with no value was encountered.
+    RangedExpressionWithNoValue,
+    /// A function was encountered that was not expected.
+    UnexpectedFunction(Cow<'i, str>),
+    /// @namespace must be before any rule but @charset and @import
+    UnexpectedNamespaceRule,
+    /// @import must be before any rule but @charset
+    UnexpectedImportRule,
+    /// Unexpected @charset rule encountered.
+    UnexpectedCharsetRule,
+    /// Unsupported @ rule
+    UnsupportedAtRule(Cow<'i, str>),
+    /// A placeholder for many sources of errors that require more specific variants.
+    UnspecifiedError,
+}
+
+/// The result of parsing a property declaration.
+#[derive(Eq, PartialEq, Copy, Clone, Debug)]
+pub enum PropertyDeclarationParseError {
+    /// The property declaration was for an unknown property.
+    UnknownProperty,
+    /// The property declaration was for a disabled experimental property.
+    ExperimentalProperty,
+    /// The property declaration contained an invalid value.
+    InvalidValue,
+    /// The declaration contained an animation property, and we were parsing
+    /// this as a keyframe block (so that property should be ignored).
+    ///
+    /// See: https://drafts.csswg.org/css-animations/#keyframes
+    AnimationPropertyInKeyframeBlock,
+    /// The property is not allowed within a page rule.
+    NotAllowedInPageRule,
+}
+
+impl<'a> From<StyleParseError<'a>> for ParseError<'a> {
+    fn from(this: StyleParseError<'a>) -> Self {
+        cssparser::ParseError::Custom(SelectorParseError::Custom(this))
+    }
+}
+
+impl<'a> From<PropertyDeclarationParseError> for ParseError<'a> {
+    fn from(this: PropertyDeclarationParseError) -> Self {
+        cssparser::ParseError::Custom(SelectorParseError::Custom(StyleParseError::PropertyDeclaration(this)))
+    }
+}