Move util::str::parse_length into 'style' component.

The function is only used in the 'style' component, so we'll move it
there alongside other relevant parse functions.

components/util/str.rs

@@ -10,7 +10,7 @@ use std::ffi::CStr;
 use std::fmt;
 use std::iter::{Filter, Peekable};
 use std::ops::{Deref, DerefMut};
-use std::str::{Bytes, CharIndices, FromStr, Split, from_utf8};
+use std::str::{Bytes, CharIndices, Split, from_utf8};
 use string_cache::Atom;
 
 #[derive(Clone, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
@@ -187,75 +187,6 @@ pub enum LengthOrPercentageOrAuto {
     Length(Au),
 }
 
-/// TODO: this function can be rewritten to return Result<LengthOrPercentage, _>
-/// Parses a dimension value per HTML5 § 2.4.4.4. If unparseable, `Auto` is
-/// returned.
-/// https://html.spec.whatwg.org/multipage/#rules-for-parsing-dimension-values
-pub fn parse_length(mut value: &str) -> LengthOrPercentageOrAuto {
-    // Steps 1 & 2 are not relevant
-
-    // Step 3
-    value = value.trim_left_matches(WHITESPACE);
-
-    // Step 4
-    if value.is_empty() {
-        return LengthOrPercentageOrAuto::Auto
-    }
-
-    // Step 5
-    if value.starts_with("+") {
-        value = &value[1..]
-    }
-
-    // Steps 6 & 7
-    match value.chars().nth(0) {
-        Some('0'...'9') => {},
-        _ => return LengthOrPercentageOrAuto::Auto,
-    }
-
-    // Steps 8 to 13
-    // We trim the string length to the minimum of:
-    // 1. the end of the string
-    // 2. the first occurence of a '%' (U+0025 PERCENT SIGN)
-    // 3. the second occurrence of a '.' (U+002E FULL STOP)
-    // 4. the occurrence of a character that is neither a digit nor '%' nor '.'
-    // Note: Step 10 is directly subsumed by FromStr::from_str
-    let mut end_index = value.len();
-    let (mut found_full_stop, mut found_percent) = (false, false);
-    for (i, ch) in value.chars().enumerate() {
-        match ch {
-            '0'...'9' => continue,
-            '%' => {
-                found_percent = true;
-                end_index = i;
-                break
-            }
-            '.' if !found_full_stop => {
-                found_full_stop = true;
-                continue
-            }
-            _ => {
-                end_index = i;
-                break
-            }
-        }
-    }
-    value = &value[..end_index];
-
-    if found_percent {
-        let result: Result<f32, _> = FromStr::from_str(value);
-        match result {
-            Ok(number) => return LengthOrPercentageOrAuto::Percentage((number as f32) / 100.0),
-            Err(_) => return LengthOrPercentageOrAuto::Auto,
-        }
-    }
-
-    match FromStr::from_str(value) {
-        Ok(number) => LengthOrPercentageOrAuto::Length(Au::from_f64_px(number)),
-        Err(_) => LengthOrPercentageOrAuto::Auto,
-    }
-}
-
 #[derive(Clone, Eq, PartialEq, Hash, Debug, Deserialize, Serialize)]
 pub struct LowercaseString {
     inner: String,