Add JsonValue::Null to json example

examples/json.rs

@@ -16,6 +16,7 @@ use std::str;
 
 #[derive(Debug, PartialEq)]
 pub enum JsonValue {
+  Null,
   Str(String),
   Boolean(bool),
   Num(f64),
@@ -75,6 +76,10 @@ fn boolean<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, bool,
   alt((parse_true, parse_false))(input)
 }
 
+fn null<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, (), E> {
+  value((), tag("null"))(input)
+}
+
 /// this parser combines the previous `parse_str` parser, that recognizes the
 /// interior of a string, with a parse to recognize the double quote character,
 /// before the string (using `preceded`) and after the string (using `terminated`).
@@ -159,6 +164,7 @@ fn json_value<'a, E: ParseError<&'a str> + ContextError<&'a str>>(
       map(string, |s| JsonValue::Str(String::from(s))),
       map(double, JsonValue::Num),
       map(boolean, JsonValue::Boolean),
+      map(null, |_| JsonValue::Null),
     )),
   )(i)
 }
@@ -169,7 +175,11 @@ fn root<'a, E: ParseError<&'a str> + ContextError<&'a str>>(
 ) -> IResult<&'a str, JsonValue, E> {
   delimited(
     sp,
-    alt((map(hash, JsonValue::Object), map(array, JsonValue::Array))),
+    alt((
+      map(hash, JsonValue::Object),
+      map(array, JsonValue::Array),
+      map(null, |_| JsonValue::Null),
+    )),
     opt(sp),
   )(i)
 }
@@ -315,4 +325,6 @@ fn main() {
     }
     _ => {}
   }
+
+  assert!(root::<(&str, ErrorKind)>("null").is_ok());
 }