1 files changed, 106 insertions, 0 deletions
diff --git a/servo/components/style/values/specified/easing.rs b/servo/components/style/values/specified/easing.rs
new file mode 100644
index 0000000000..26b921ebdc
--- /dev/null
+++ b/servo/components/style/values/specified/easing.rs
@@ -0,0 +1,106 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Specified types for CSS Easing functions.
+
+use crate::parser::{Parse, ParserContext};
+use crate::values::computed::easing::TimingFunction as ComputedTimingFunction;
+use crate::values::generics::easing::TimingFunction as GenericTimingFunction;
+use crate::values::generics::easing::{StepPosition, TimingKeyword};
+use crate::values::specified::{Integer, Number};
+use cssparser::Parser;
+use selectors::parser::SelectorParseErrorKind;
+use style_traits::{ParseError, StyleParseErrorKind};
+
+/// A specified timing function.
+pub type TimingFunction = GenericTimingFunction<Integer, Number>;
+
+impl Parse for TimingFunction {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        if let Ok(keyword) = input.try_parse(TimingKeyword::parse) {
+            return Ok(GenericTimingFunction::Keyword(keyword));
+        }
+        if let Ok(ident) = input.try_parse(|i| i.expect_ident_cloned()) {
+            let position = match_ignore_ascii_case! { &ident,
+                "step-start" => StepPosition::Start,
+                "step-end" => StepPosition::End,
+                _ => {
+                    return Err(input.new_custom_error(
+                        SelectorParseErrorKind::UnexpectedIdent(ident.clone())
+                    ));
+                },
+            };
+            return Ok(GenericTimingFunction::Steps(Integer::new(1), position));
+        }
+        let location = input.current_source_location();
+        let function = input.expect_function()?.clone();
+        input.parse_nested_block(move |i| {
+            (match_ignore_ascii_case! { &function,
+                "cubic-bezier" => {
+                    let x1 = Number::parse(context, i)?;
+                    i.expect_comma()?;
+                    let y1 = Number::parse(context, i)?;
+                    i.expect_comma()?;
+                    let x2 = Number::parse(context, i)?;
+                    i.expect_comma()?;
+                    let y2 = Number::parse(context, i)?;
+
+                    if x1.get() < 0.0 || x1.get() > 1.0 || x2.get() < 0.0 || x2.get() > 1.0 {
+                        return Err(i.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+                    }
+
+                    Ok(GenericTimingFunction::CubicBezier { x1, y1, x2, y2 })
+                },
+                "steps" => {
+                    let steps = Integer::parse_positive(context, i)?;
+                    let position = i.try_parse(|i| {
+                        i.expect_comma()?;
+                        StepPosition::parse(context, i)
+                    }).unwrap_or(StepPosition::End);
+
+                    // jump-none accepts a positive integer greater than 1.
+                    // FIXME(emilio): The spec asks us to avoid rejecting it at parse
+                    // time except until computed value time.
+                    //
+                    // It's not totally clear it's worth it though, and no other browser
+                    // does this.
+                    if position == StepPosition::JumpNone && 2 > steps.value() {
+                        return Err(i.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+                    }
+                    Ok(GenericTimingFunction::Steps(steps, position))
+                },
+                _ => Err(()),
+            })
+            .map_err(|()| {
+                location.new_custom_error(StyleParseErrorKind::UnexpectedFunction(function.clone()))
+            })
+        })
+    }
+}
+
+// We need this for converting the specified TimingFunction into computed TimingFunction without
+// Context (for some FFIs in glue.rs). In fact, we don't really need Context to get the computed
+// value of TimingFunction.
+impl TimingFunction {
+    /// Generate the ComputedTimingFunction without Context.
+    pub fn to_computed_value_without_context(&self) -> ComputedTimingFunction {
+        match *self {
+            GenericTimingFunction::Steps(steps, pos) => {
+                GenericTimingFunction::Steps(steps.value(), pos)
+            },
+            GenericTimingFunction::CubicBezier { x1, y1, x2, y2 } => {
+                GenericTimingFunction::CubicBezier {
+                    x1: x1.get(),
+                    y1: y1.get(),
+                    x2: x2.get(),
+                    y2: y2.get(),
+                }
+            },
+            GenericTimingFunction::Keyword(keyword) => GenericTimingFunction::Keyword(keyword),
+        }
+    }
+}