Implement the rules for parsing integers as defined by HTML, and use them for canvas.

2 files changed, 64 insertions, 4 deletions

diff --git a/src/components/script/dom/htmlcanvaselement.rs b/src/components/script/dom/htmlcanvaselement.rs
index 50198b197ee..5d6f09badce 100644
--- a/src/components/script/dom/htmlcanvaselement.rs
+++ b/src/components/script/dom/htmlcanvaselement.rs
@@ -19,12 +19,11 @@ use dom::node::{Node, ElementNodeTypeId, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 
 use servo_util::atom::Atom;
-use servo_util::str::DOMString;
+use servo_util::str::{DOMString, parse_unsigned_integer};
 
 use geom::size::Size2D;
 
 use std::cell::Cell;
-use std::num;
 
 static DefaultWidth: u32 = 300;
 static DefaultHeight: u32 = 150;
@@ -134,11 +133,11 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLCanvasElement> {
 
         let recreate = match name.as_slice() {
             "width" => {
-                self.width.set(num::from_str_radix(value.as_slice(), 10).unwrap());
+                self.width.set(parse_unsigned_integer(value.as_slice().chars()).unwrap());
                 true
             }
             "height" => {
-                self.height.set(num::from_str_radix(value.as_slice(), 10).unwrap());
+                self.height.set(parse_unsigned_integer(value.as_slice().chars()).unwrap());
                 true
             }
             _ => false,
diff --git a/src/components/util/str.rs b/src/components/util/str.rs
index 69e50a78e59..8f698ac3271 100644
--- a/src/components/util/str.rs
+++ b/src/components/util/str.rs
@@ -46,3 +46,64 @@ pub static HTML_SPACE_CHARACTERS: StaticCharVec = &[
 pub fn split_html_space_chars<'a>(s: &'a str) -> Filter<'a, &'a str, CharSplits<'a, StaticCharVec>> {
     s.split(HTML_SPACE_CHARACTERS).filter(|&split| !split.is_empty())
 }
+
+/// Shared implementation to parse an integer according to
+/// <http://www.whatwg.org/html/#rules-for-parsing-integers> or
+/// <http://www.whatwg.org/html/#rules-for-parsing-non-negative-integers>.
+fn do_parse_integer<T: Iterator<char>>(input: T) -> Option<i64> {
+    fn as_ascii_digit(c: char) -> Option<i64> {
+        match c {
+            '0'..'9' => Some(c as i64 - '0' as i64),
+            _ => None,
+        }
+    }
+
+
+    let mut input = input.skip_while(|c| {
+        HTML_SPACE_CHARACTERS.iter().any(|s| s == c)
+    }).peekable();
+
+    let sign = match input.peek() {
+        None => return None,
+        Some(&'-') => {
+            input.next();
+            -1
+        },
+        Some(&'+') => {
+            input.next();
+            1
+        },
+        Some(_) => 1,
+    };
+
+    match input.peek() {
+        Some(&c) if as_ascii_digit(c).is_some() => (),
+        _ => return None,
+    }
+
+    let value = input.filter_map(as_ascii_digit).fuse().fold(Some(0i64), |accumulator, d| {
+        accumulator.and_then(|accumulator| {
+            accumulator.checked_mul(&10)
+        }).and_then(|accumulator| {
+            accumulator.checked_add(&d)
+        })
+    });
+
+    return value.and_then(|value| value.checked_mul(&sign));
+}
+
+/// Parse an integer according to
+/// <http://www.whatwg.org/html/#rules-for-parsing-integers>.
+pub fn parse_integer<T: Iterator<char>>(input: T) -> Option<i32> {
+    do_parse_integer(input).and_then(|result| {
+        result.to_i32()
+    })
+}
+
+/// Parse an integer according to
+/// <http://www.whatwg.org/html/#rules-for-parsing-non-negative-integers>.
+pub fn parse_unsigned_integer<T: Iterator<char>>(input: T) -> Option<u32> {
+    do_parse_integer(input).and_then(|result| {
+        result.to_u32()
+    })
+}