Add enumerate helperenumerate-result

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

2 files changed, 109 insertions, 0 deletions

diff --git a/src/enumerate.rs b/src/enumerate.rs
new file mode 100644
index 0000000..1b20677
--- /dev/null
+++ b/src/enumerate.rs
@@ -0,0 +1,107 @@
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum EnumOkConfig {
+    /// Ignore Err(_) when counting
+    IgnoreErr,
+
+    /// Increase counter on Err(_)
+    CountErr,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum EnumErrConfig {
+    /// Ignore Ok(_) when counting
+    IgnoreOk,
+
+    /// Increase counter on Ok(_)
+    CountOk,
+}
+
+pub trait EnumerateResult<T, E>
+    where Self: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized,
+{
+    fn enumerate_ok(self, config: EnumOkConfig) -> EnumerateOkImpl<Self, T, E>;
+    fn enumerate_err(self, config: EnumErrConfig) -> EnumerateErrImpl<Self, T, E>;
+}
+
+impl<I, T, E> EnumerateResult<T, E> for I
+    where I: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized
+{
+    fn enumerate_ok(self, config: EnumOkConfig) -> EnumerateOkImpl<Self, T, E> {
+        EnumerateOkImpl(self, 0, config)
+    }
+
+    fn enumerate_err(self, config: EnumErrConfig) -> EnumerateErrImpl<Self, T, E> {
+        EnumerateErrImpl(self, 0, config)
+    }
+}
+
+
+pub struct EnumerateOkImpl<I, T, E>(I, usize, EnumOkConfig)
+    where I: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized;
+
+impl<I, T, E> Iterator for EnumerateOkImpl<I, T, E>
+    where I: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized,
+{
+    type Item = Result<(usize, T), E>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next().map(|o| match o {
+            Err(e) => {
+                if self.2 == EnumOkConfig::CountErr {
+                    self.1 += 1;
+                }
+                Err(e)
+            },
+
+            Ok(t) => {
+                self.1 += 1;
+                Ok((self.1, t))
+            }
+        })
+    }
+}
+
+
+pub struct EnumerateErrImpl<I, T, E>(I, usize, EnumErrConfig)
+    where I: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized;
+
+impl<I, T, E> Iterator for EnumerateErrImpl<I, T, E>
+    where I: Iterator<Item = Result<T, E>> + Sized,
+          T: Sized,
+          E: Sized,
+{
+    type Item = Result<T, (usize, E)>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next().map(|o| match o {
+            Ok(t) => {
+                if self.2 == EnumErrConfig::CountOk {
+                    self.1 += 1;
+                }
+                Ok(t)
+            },
+
+            Err(e) => {
+                self.1 += 1;
+                Err((self.1, e))
+            }
+        })
+    }
+}
+
diff --git a/src/lib.rs b/src/lib.rs
index e9ba2f3..7ec4ce2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -195,6 +195,7 @@
 //!
 
 pub mod and_then;
+pub mod enumerate;
 pub mod errors;
 pub mod filter;
 pub mod filter_map;
@@ -211,6 +212,7 @@ mod util;
 pub mod while_ok;
 
 pub use and_then::AndThen;
+pub use enumerate::*;
 pub use errors::GetErrors;
 pub use filter::Filter;
 pub use filter_map::FilterMap;