From df1e23c6fb5f3968b9024e6e5fead9c2176835f8 Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Mon, 11 Sep 2017 10:08:23 -0400
Subject: [PATCH] Avoid array overallocation when parsing background-image
 property.  r=SimonSapin

Part 3 of the fix for Gecko bug 1397614 <https://bugzilla.mozilla.org/show_bug.cgi?id=1397614>.
---
 Cargo.toml    | 2 +-
 src/parser.rs | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index c409bac9..7d1e6a5c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "cssparser"
-version = "0.20.1"
+version = "0.20.2"
 authors = [ "Simon Sapin <simon.sapin@exyr.org>" ]
 
 description = "Rust implementation of CSS Syntax Level 3"
diff --git a/src/parser.rs b/src/parser.rs
index 93a40a62..4887becd 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -478,7 +478,11 @@ impl<'i: 't, 't> Parser<'i, 't> {
     #[inline]
     pub fn parse_comma_separated<F, T, E>(&mut self, mut parse_one: F) -> Result<Vec<T>, ParseError<'i, E>>
     where F: for<'tt> FnMut(&mut Parser<'i, 'tt>) -> Result<T, ParseError<'i, E>> {
-        let mut values = vec![];
+        // Vec grows from 0 to 4 by default on first push().  So allocate with
+        // capacity 1, so in the somewhat common case of only one item we don't
+        // way overallocate.  Note that we always push at least one item if
+        // parsing succeeds.
+        let mut values = Vec::with_capacity(1);
         loop {
             self.skip_whitespace();  // Unnecessary for correctness, but may help try() in parse_one rewind less.
             values.push(self.parse_until_before(Delimiter::Comma, &mut parse_one)?);