Implement Zip::all()

Test if every element of the iterator matches a predicate.

This is useful, for instance, to test if two matrices are elementwise
"similar" (within a given threshold) without modifying the matrices.

Author: mneumann

src/zip/mod.rs

@@ -738,6 +738,22 @@ macro_rules! map_impl {
                 })
             }
 
+            /// Tests if every element of the iterator matches a predicate.
+            ///
+            /// Returns `true` if `predicate` evaluates to `true` for all elements.
+            pub fn all<F>(mut self, mut predicate: F) -> bool
+                where F: FnMut($($p::Item),*) -> bool
+            {
+                self.apply_core(true, move |_, args| {
+                    let ($($p,)*) = args;
+                    if predicate($($p),*) {
+                        FoldWhile::Continue(true)
+                    } else {
+                        FoldWhile::Done(false)
+                    }
+                }).into_inner()
+            }
+
             expand_if!(@bool [$notlast]
 
             /// Include the producer `p` in the Zip.

tests/azip.rs

@@ -271,3 +271,19 @@ fn test_indices_split_1() {
         }
     }
 }
+
+#[test]
+fn test_zip_all() {
+    let a = Array::<f32, _>::zeros(62);
+    let b = Array::<f32, _>::ones(62);
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&x, &y| x + y == 1.0));
+    assert_eq!(false, Zip::from(&a).and(&b).all(|&x, &y| x == y));
+}
+
+#[test]
+fn test_zip_all_empty_array() {
+    let a = Array::<f32, _>::zeros(0);
+    let b = Array::<f32, _>::ones(0);
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&_x, &_y| true));
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&_x, &_y| false));
+}