Record cleanup (#11726)

# Description
Does a little cleanup in `record.rs`:
- Makes the `record!` macro more hygienic.
- Converts regular comments to doc comments from #11718.
- Converts the `Record` iterators to new types.

crates/nu-protocol/src/value/mod.rs

@@ -4,10 +4,11 @@ mod from_value;
 mod lazy_record;
 mod path;
 mod range;
-mod record;
 mod stream;
 mod unit;
 
+pub mod record;
+
 use crate::ast::{Bits, Boolean, CellPath, Comparison, PathMember};
 use crate::ast::{Math, Operator};
 use crate::engine::{Closure, EngineState};

crates/nu-protocol/src/value/record.rs

@@ -26,25 +26,25 @@ impl Record {
         }
     }
 
-    // Constructor that checks that `cols` and `vals` are of the same length.
-    //
-    // WARNING! Panics with assertion failure if cols and vals have different length!
-    // Should be used only when the same lengths are guaranteed!
-    //
-    // For perf reasons does not validate the rest of the record assumptions.
-    // - unique keys
+    /// Constructor that checks that `cols` and `vals` are of the same length.
+    ///
+    /// WARNING! Panics with assertion failure if cols and vals have different length!
+    /// Should be used only when the same lengths are guaranteed!
+    ///
+    /// For perf reasons does not validate the rest of the record assumptions.
+    /// - unique keys
     pub fn from_raw_cols_vals_unchecked(cols: Vec<String>, vals: Vec<Value>) -> Self {
         assert_eq!(cols.len(), vals.len());
 
         Self { cols, vals }
     }
 
-    // Constructor that checks that `cols` and `vals` are of the same length.
-    //
-    // Returns None if cols and vals have different length.
-    //
-    // For perf reasons does not validate the rest of the record assumptions.
-    // - unique keys
+    /// Constructor that checks that `cols` and `vals` are of the same length.
+    ///
+    /// Returns None if cols and vals have different length.
+    ///
+    /// For perf reasons does not validate the rest of the record assumptions.
+    /// - unique keys
     pub fn from_raw_cols_vals(
         cols: Vec<String>,
         vals: Vec<Value>,
@@ -314,6 +314,7 @@ impl Record {
 impl FromIterator<(String, Value)> for Record {
     fn from_iter<T: IntoIterator<Item = (String, Value)>>(iter: T) -> Self {
         let (cols, vals) = iter.into_iter().unzip();
+        // TODO: should this check for duplicate keys/columns?
         Self { cols, vals }
     }
 }
@@ -328,7 +329,29 @@ impl Extend<(String, Value)> for Record {
     }
 }
 
-pub type IntoIter = std::iter::Zip<std::vec::IntoIter<String>, std::vec::IntoIter<Value>>;
+pub struct IntoIter {
+    iter: std::iter::Zip<std::vec::IntoIter<String>, std::vec::IntoIter<Value>>,
+}
+
+impl Iterator for IntoIter {
+    type Item = (String, Value);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next()
+    }
+}
+
+impl DoubleEndedIterator for IntoIter {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.iter.next_back()
+    }
+}
+
+impl ExactSizeIterator for IntoIter {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
 
 impl IntoIterator for Record {
     type Item = (String, Value);
@@ -336,11 +359,35 @@ impl IntoIterator for Record {
     type IntoIter = IntoIter;
 
     fn into_iter(self) -> Self::IntoIter {
-        self.cols.into_iter().zip(self.vals)
+        IntoIter {
+            iter: self.cols.into_iter().zip(self.vals),
+        }
     }
 }
 
-pub type Iter<'a> = std::iter::Zip<std::slice::Iter<'a, String>, std::slice::Iter<'a, Value>>;
+pub struct Iter<'a> {
+    iter: std::iter::Zip<std::slice::Iter<'a, String>, std::slice::Iter<'a, Value>>,
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = (&'a String, &'a Value);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next()
+    }
+}
+
+impl<'a> DoubleEndedIterator for Iter<'a> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.iter.next_back()
+    }
+}
+
+impl<'a> ExactSizeIterator for Iter<'a> {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
 
 impl<'a> IntoIterator for &'a Record {
     type Item = (&'a String, &'a Value);
@@ -348,11 +395,35 @@ impl<'a> IntoIterator for &'a Record {
     type IntoIter = Iter<'a>;
 
     fn into_iter(self) -> Self::IntoIter {
-        self.cols.iter().zip(&self.vals)
+        Iter {
+            iter: self.cols.iter().zip(&self.vals),
+        }
     }
 }
 
-pub type IterMut<'a> = std::iter::Zip<std::slice::Iter<'a, String>, std::slice::IterMut<'a, Value>>;
+pub struct IterMut<'a> {
+    iter: std::iter::Zip<std::slice::Iter<'a, String>, std::slice::IterMut<'a, Value>>,
+}
+
+impl<'a> Iterator for IterMut<'a> {
+    type Item = (&'a String, &'a mut Value);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next()
+    }
+}
+
+impl<'a> DoubleEndedIterator for IterMut<'a> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.iter.next_back()
+    }
+}
+
+impl<'a> ExactSizeIterator for IterMut<'a> {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
 
 impl<'a> IntoIterator for &'a mut Record {
     type Item = (&'a String, &'a mut Value);
@@ -360,7 +431,9 @@ impl<'a> IntoIterator for &'a mut Record {
     type IntoIter = IterMut<'a>;
 
     fn into_iter(self) -> Self::IntoIter {
-        self.cols.iter().zip(&mut self.vals)
+        IterMut {
+            iter: self.cols.iter().zip(&mut self.vals),
+        }
     }
 }
 
@@ -480,9 +553,9 @@ impl ExactSizeIterator for Drain<'_> {
 #[macro_export]
 macro_rules! record {
     {$($col:expr => $val:expr),+ $(,)?} => {
-        $crate::Record::from_raw_cols_vals_unchecked (
-            vec![$($col.into(),)+],
-            vec![$($val,)+]
+        $crate::Record::from_raw_cols_vals_unchecked(
+            ::std::vec![$($col.into(),)+],
+            ::std::vec![$($val,)+]
         )
     };
     {} => {