From 90ede21f0cdd7ac926a3a5470240643bb7906200 Mon Sep 17 00:00:00 2001
From: Manish Goregaokar <manishsmail@gmail.com>
Date: Fri, 2 Jun 2017 17:39:18 -0700
Subject: [PATCH] Parse nth-child(-/*comment*/n+b) (fixes #153)

---
 src/css-parsing-tests/An+B.json |  2 ++
 src/nth.rs                      | 23 ++++++++++++++---------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/css-parsing-tests/An+B.json b/src/css-parsing-tests/An+B.json
index f17849ea..6ecdb83c 100644
--- a/src/css-parsing-tests/An+B.json
+++ b/src/css-parsing-tests/An+B.json
@@ -80,6 +80,8 @@
 " -n +1", [-1, 1],
 "+ n +1", null,
 "- N +1", null,
+"+/**/n +1", [1, 1],
+"-/**/N +1", [-1, 1],
 
 "3N -1", [3, -1],
 "+2n -1 ", [2, -1],
diff --git a/src/nth.rs b/src/nth.rs
index ec735bc2..b1767e32 100644
--- a/src/nth.rs
+++ b/src/nth.rs
@@ -12,7 +12,7 @@ use super::{Token, Parser};
 /// in which case the caller needs to check if the arguments’ parser is exhausted.
 /// Return `Ok((A, B))`, or `Err(())` for a syntax error.
 pub fn parse_nth(input: &mut Parser) -> Result<(i32, i32), ()> {
-    match try!(input.next()) {
+    match input.next()? {
         Token::Number(value) => Ok((0, try!(value.int_value.ok_or(())) as i32)),
         Token::Dimension(value, unit) => {
             let a = try!(value.int_value.ok_or(())) as i32;
@@ -37,15 +37,20 @@ pub fn parse_nth(input: &mut Parser) -> Result<(i32, i32), ()> {
                 }
             }
         }
-        Token::Delim('+') => match try!(input.next_including_whitespace()) {
-            Token::Ident(value) => {
-                match_ignore_ascii_case! { &value,
-                    "n" => parse_b(input, 1),
-                    "n-" => parse_signless_b(input, 1, -1),
-                    _ => Ok((1, try!(parse_n_dash_digits(&*value))))
-                }
+        Token::Delim(delim) => {
+            let val = match delim {
+                '+' => 1,
+                '-' => -1,
+                _ => return Err(()),
+            };
+            match input.next_including_whitespace()? {
+                Token::Ident(n) => match_ignore_ascii_case! { &n,
+                    "n" => parse_b(input, val),
+                    "n-" => parse_signless_b(input, val, -1),
+                    _ => Ok((1, try!(parse_n_dash_digits(&*n))))
+                },
+                _ => Err(())
             }
-            _ => Err(())
         },
         _ => Err(())
     }