From ac029f68c8a15078664095272abe3c942bcfc3d4 Mon Sep 17 00:00:00 2001
From: "Jorge C. Leitao" <jorgecarleitao@gmail.com>
Date: Tue, 19 Jan 2021 07:30:02 +0100
Subject: [PATCH] Fixed size_hint.

---
 rust/arrow/src/array/iterator.rs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/rust/arrow/src/array/iterator.rs b/rust/arrow/src/array/iterator.rs
index 356ae545fa8..463eb031ce6 100644
--- a/rust/arrow/src/array/iterator.rs
+++ b/rust/arrow/src/array/iterator.rs
@@ -59,7 +59,10 @@ impl<'a, T: ArrowPrimitiveType> std::iter::Iterator for PrimitiveIter<'a, T> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.array.len(), Some(self.array.len()))
+        (
+            self.array.len() - self.current,
+            Some(self.array.len() - self.current),
+        )
     }
 }
 
@@ -118,7 +121,10 @@ impl<'a> std::iter::Iterator for BooleanIter<'a> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.array.len(), Some(self.array.len()))
+        (
+            self.array.len() - self.current,
+            Some(self.array.len() - self.current),
+        )
     }
 }
 
@@ -179,7 +185,7 @@ impl<'a, T: StringOffsetSizeTrait> std::iter::Iterator for GenericStringIter<'a,
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.len, Some(self.len))
+        (self.len - self.i, Some(self.len - self.i))
     }
 }
 
@@ -228,7 +234,7 @@ impl<'a, T: BinaryOffsetSizeTrait> std::iter::Iterator for GenericBinaryIter<'a,
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.len, Some(self.len))
+        (self.len - self.i, Some(self.len - self.i))
     }
 }