Merge pull request #421 from dmizuk/value-take

Add `Value::take` method

src/value/mod.rs

@@ -109,6 +109,7 @@
 
 use std::fmt::{self, Debug};
 use std::i64;
+use std::mem;
 use std::str;
 
 use serde::ser::Serialize;
@@ -850,7 +851,6 @@ impl Value {
     /// extern crate serde_json;
     ///
     /// use serde_json::Value;
-    /// use std::mem;
     ///
     /// fn main() {
     ///     let s = r#"{"x": 1.0, "y": 2.0}"#;
@@ -864,7 +864,7 @@ impl Value {
     ///     assert_eq!(value.pointer("/x"), Some(&1.5.into()));
     ///
     ///     // "Steal" ownership of a value. Can replace with any valid Value.
-    ///     let old_x = value.pointer_mut("/x").map(|x| mem::replace(x, Value::Null)).unwrap();
+    ///     let old_x = value.pointer_mut("/x").map(Value::take).unwrap();
     ///     assert_eq!(old_x, 1.5);
     ///     assert_eq!(value.pointer("/x").unwrap(), &Value::Null);
     /// }
@@ -901,6 +901,22 @@ impl Value {
         }
         Some(target)
     }
+
+    /// Takes the value out of the `Value`, leaving a `Null` in its place.
+    ///
+    /// ```rust
+    /// # #[macro_use]
+    /// # extern crate serde_json;
+    /// #
+    /// # fn main() {
+    /// let mut v = json!({ "x": "y" });
+    /// assert_eq!(v["x"].take(), json!("y"));
+    /// assert_eq!(v, json!({ "x": null }));
+    /// # }
+    /// ```
+    pub fn take(&mut self) -> Value {
+        mem::replace(self, Value::Null)
+    }
 }
 
 /// The default value is `Value::Null`.