1 files changed, 181 insertions, 0 deletions
diff --git a/servo/components/style/str.rs b/servo/components/style/str.rs
new file mode 100644
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+++ b/servo/components/style/str.rs
@@ -0,0 +1,181 @@
+/* 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/. */
+
+//! String utils for attributes and similar stuff.
+
+#![deny(missing_docs)]
+
+use num_traits::ToPrimitive;
+use std::borrow::Cow;
+use std::convert::AsRef;
+use std::iter::{Filter, Peekable};
+use std::str::Split;
+
+/// A static slice of characters.
+pub type StaticCharVec = &'static [char];
+
+/// A static slice of `str`s.
+pub type StaticStringVec = &'static [&'static str];
+
+/// A "space character" according to:
+///
+/// <https://html.spec.whatwg.org/multipage/#space-character>
+pub static HTML_SPACE_CHARACTERS: StaticCharVec =
+    &['\u{0020}', '\u{0009}', '\u{000a}', '\u{000c}', '\u{000d}'];
+
+/// Whether a character is a HTML whitespace character.
+#[inline]
+pub fn char_is_whitespace(c: char) -> bool {
+    HTML_SPACE_CHARACTERS.contains(&c)
+}
+
+/// Whether all the string is HTML whitespace.
+#[inline]
+pub fn is_whitespace(s: &str) -> bool {
+    s.chars().all(char_is_whitespace)
+}
+
+#[inline]
+fn not_empty(&split: &&str) -> bool {
+    !split.is_empty()
+}
+
+/// Split a string on HTML whitespace.
+#[inline]
+pub fn split_html_space_chars<'a>(
+    s: &'a str,
+) -> Filter<Split<'a, StaticCharVec>, fn(&&str) -> bool> {
+    s.split(HTML_SPACE_CHARACTERS)
+        .filter(not_empty as fn(&&str) -> bool)
+}
+
+/// Split a string on commas.
+#[inline]
+pub fn split_commas<'a>(s: &'a str) -> Filter<Split<'a, char>, fn(&&str) -> bool> {
+    s.split(',').filter(not_empty as fn(&&str) -> bool)
+}
+
+/// Character is ascii digit
+pub fn is_ascii_digit(c: &char) -> bool {
+    match *c {
+        '0'..='9' => true,
+        _ => false,
+    }
+}
+
+fn is_decimal_point(c: char) -> bool {
+    c == '.'
+}
+
+fn is_exponent_char(c: char) -> bool {
+    match c {
+        'e' | 'E' => true,
+        _ => false,
+    }
+}
+
+/// Read a set of ascii digits and read them into a number.
+pub fn read_numbers<I: Iterator<Item = char>>(mut iter: Peekable<I>) -> (Option<i64>, usize) {
+    match iter.peek() {
+        Some(c) if is_ascii_digit(c) => (),
+        _ => return (None, 0),
+    }
+
+    iter.take_while(is_ascii_digit)
+        .map(|d| d as i64 - '0' as i64)
+        .fold((Some(0i64), 0), |accumulator, d| {
+            let digits = accumulator
+                .0
+                .and_then(|accumulator| accumulator.checked_mul(10))
+                .and_then(|accumulator| accumulator.checked_add(d));
+            (digits, accumulator.1 + 1)
+        })
+}
+
+/// Read a decimal fraction.
+pub fn read_fraction<I: Iterator<Item = char>>(
+    mut iter: Peekable<I>,
+    mut divisor: f64,
+    value: f64,
+) -> (f64, usize) {
+    match iter.peek() {
+        Some(c) if is_decimal_point(*c) => (),
+        _ => return (value, 0),
+    }
+    iter.next();
+
+    iter.take_while(is_ascii_digit)
+        .map(|d| d as i64 - '0' as i64)
+        .fold((value, 1), |accumulator, d| {
+            divisor *= 10f64;
+            (accumulator.0 + d as f64 / divisor, accumulator.1 + 1)
+        })
+}
+
+/// Reads an exponent from an iterator over chars, for example `e100`.
+pub fn read_exponent<I: Iterator<Item = char>>(mut iter: Peekable<I>) -> Option<i32> {
+    match iter.peek() {
+        Some(c) if is_exponent_char(*c) => (),
+        _ => return None,
+    }
+    iter.next();
+
+    match iter.peek() {
+        None => None,
+        Some(&'-') => {
+            iter.next();
+            read_numbers(iter).0.map(|exp| -exp.to_i32().unwrap_or(0))
+        },
+        Some(&'+') => {
+            iter.next();
+            read_numbers(iter).0.map(|exp| exp.to_i32().unwrap_or(0))
+        },
+        Some(_) => read_numbers(iter).0.map(|exp| exp.to_i32().unwrap_or(0)),
+    }
+}
+
+/// Join a set of strings with a given delimiter `join`.
+pub fn str_join<I, T>(strs: I, join: &str) -> String
+where
+    I: IntoIterator<Item = T>,
+    T: AsRef<str>,
+{
+    strs.into_iter()
+        .enumerate()
+        .fold(String::new(), |mut acc, (i, s)| {
+            if i > 0 {
+                acc.push_str(join);
+            }
+            acc.push_str(s.as_ref());
+            acc
+        })
+}
+
+/// Returns true if a given string has a given prefix with case-insensitive match.
+pub fn starts_with_ignore_ascii_case(string: &str, prefix: &str) -> bool {
+    string.len() >= prefix.len() &&
+        string.as_bytes()[0..prefix.len()].eq_ignore_ascii_case(prefix.as_bytes())
+}
+
+/// Returns an ascii lowercase version of a string, only allocating if needed.
+pub fn string_as_ascii_lowercase<'a>(input: &'a str) -> Cow<'a, str> {
+    if input.bytes().any(|c| matches!(c, b'A'..=b'Z')) {
+        input.to_ascii_lowercase().into()
+    } else {
+        // Already ascii lowercase.
+        Cow::Borrowed(input)
+    }
+}
+
+/// To avoid accidentally instantiating multiple monomorphizations of large
+/// serialization routines, we define explicit concrete types and require
+/// them in those routines. This avoids accidental mixing of String and
+/// nsACString arguments in Gecko, which would cause code size to blow up.
+#[cfg(feature = "gecko")]
+pub type CssStringWriter = ::nsstring::nsACString;
+
+/// String type that coerces to CssStringWriter, used when serialization code
+/// needs to allocate a temporary string.
+#[cfg(feature = "gecko")]
+pub type CssString = ::nsstring::nsCString;