Merge pull request #712 from dtolnay/remove_entry

Add Map::remove_entry

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [beta, stable, 1.36.0, 1.31.0]
+        rust: [beta, stable, 1.45.0, 1.40.0, 1.36.0, 1.31.0]
         os: [ubuntu]
         include:
           - rust: stable

Cargo.toml

@@ -14,7 +14,7 @@ edition = "2018"
 
 [dependencies]
 serde = { version = "1.0.100", default-features = false }
-indexmap = { version = "1.2", optional = true }
+indexmap = { version = "1.5", optional = true }
 itoa = { version = "0.4.3", default-features = false }
 ryu = "1.0"
 

build.rs

@@ -1,4 +1,6 @@
 use std::env;
+use std::process::Command;
+use std::str::{self, FromStr};
 
 fn main() {
     // Decide ideal limb width for arithmetic in the float parser. Refer to
@@ -12,4 +14,33 @@ fn main() {
             println!("cargo:rustc-cfg=limb_width_32");
         }
     }
+
+    let minor = match rustc_minor_version() {
+        Some(minor) => minor,
+        None => return,
+    };
+
+    // BTreeMap::get_key_value
+    // https://blog.rust-lang.org/2019/12/19/Rust-1.40.0.html#additions-to-the-standard-library
+    if minor < 40 {
+        println!("cargo:rustc-cfg=no_btreemap_get_key_value");
+    }
+
+    // BTreeMap::remove_entry
+    // https://blog.rust-lang.org/2020/07/16/Rust-1.45.0.html#library-changes
+    if minor < 45 {
+        println!("cargo:rustc-cfg=no_btreemap_remove_entry");
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    let next = pieces.next()?;
+    u32::from_str(next).ok()
 }

src/lib.rs

@@ -371,6 +371,7 @@ mod lib {
         pub use std::*;
     }
 
+    pub use self::core::ops::{Bound, RangeBounds};
     pub use self::core::cell::{Cell, RefCell};
     pub use self::core::clone::{self, Clone};
     pub use self::core::convert::{self, From, Into};

src/map.rs

@@ -122,6 +122,54 @@ impl Map<String, Value> {
         return self.map.remove(key);
     }
 
+    /// Removes a key from the map, returning the stored key and value if the
+    /// key was previously in the map.
+    ///
+    /// The key may be any borrowed form of the map's key type, but the ordering
+    /// on the borrowed form *must* match the ordering on the key type.
+    pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(String, Value)>
+    where
+        String: Borrow<Q>,
+        Q: ?Sized + Ord + Eq + Hash,
+    {
+        #[cfg(any(feature = "preserve_order", not(no_btreemap_remove_entry)))]
+        return self.map.remove_entry(key);
+        #[cfg(all(
+            not(feature = "preserve_order"),
+            no_btreemap_remove_entry,
+            not(no_btreemap_get_key_value),
+        ))]
+        {
+            let (key, _value) = self.map.get_key_value(key)?;
+            let key = key.clone();
+            let value = self.map.remove::<String>(&key)?;
+            Some((key, value))
+        }
+        #[cfg(all(
+            not(feature = "preserve_order"),
+            no_btreemap_remove_entry,
+            no_btreemap_get_key_value,
+        ))]
+        {
+            struct Key<'a, Q: ?Sized>(&'a Q);
+
+            impl<'a, Q: ?Sized> RangeBounds<Q> for Key<'a, Q> {
+                fn start_bound(&self) -> Bound<&Q> {
+                    Bound::Included(self.0)
+                }
+                fn end_bound(&self) -> Bound<&Q> {
+                    Bound::Included(self.0)
+                }
+            }
+
+            let mut range = self.map.range(Key(key));
+            let (key, _value) = range.next()?;
+            let key = key.clone();
+            let value = self.map.remove::<String>(&key)?;
+            Some((key, value))
+        }
+    }
+
     /// Moves all elements from other into Self, leaving other empty.
     #[inline]
     pub fn append(&mut self, other: &mut Self) {