Fix panic on huge integers, closes #139

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "json"
-version = "0.11.12"
+version = "0.11.13"
 authors = ["Maciej Hirsz <maciej.hirsz@gmail.com>"]
 description = "JSON implementation in Rust"
 repository = "https://github.com/maciejhirsz/json-rust"

src/parser.rs

@@ -578,7 +578,7 @@ impl<'a> Parser<'a> {
                         num.checked_add((ch - b'0') as u64)
                     }) {
                         Some(result) => num = result,
-                        None         => e += 1 ,
+                        None         => e = e.checked_add(1).ok_or_else(|| Error::ExceededDepthLimit)?,
                     }
                 },
                 b'.' => {

tests/parse.rs

@@ -367,3 +367,14 @@ fn does_not_panic_on_single_zero() {
 
     parse(source).unwrap();
 }
+
+#[test]
+fn does_not_panic_on_huge_numbers() {
+    let mut string = String::from("8");
+
+    for _ in 1..32787 {
+        string.push('0');
+    }
+
+    let _ = json::parse(&string);
+}