From eb675b44bc62fbe2984c8a2831b14a7feb7e2d18 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sun, 1 Mar 2020 18:03:04 +0100
Subject: Add iterator extension for reporting from iterator

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
---
 lib/core/libimagrt/src/runtime.rs | 56 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/lib/core/libimagrt/src/runtime.rs b/lib/core/libimagrt/src/runtime.rs
index 4522a1f0..c29a2846 100644
--- a/lib/core/libimagrt/src/runtime.rs
+++ b/lib/core/libimagrt/src/runtime.rs
@@ -577,6 +577,62 @@ impl<'a> Runtime<'a> {
     }
 }
 
+pub trait IntoTouchIterator<E, F>
+    where Self: Iterator<Item = E> + Sized,
+          E: Sized,
+          F: Fn(&E) -> Option<StoreId>
+{
+    fn report_entries_touched<'a>(self, rt: &'a Runtime<'a>, func: F) -> TouchIterator<'a, Self, E, F> {
+        TouchIterator {
+            inner: self,
+            rt,
+            func
+        }
+    }
+}
+
+impl<I, E, F> IntoTouchIterator<E, F> for I
+    where I: Iterator<Item = E>,
+          E: Sized,
+          F: Fn(&E) -> Option<StoreId>
+{
+    // default implementation
+}
+
+pub struct TouchIterator<'a, I, E, F>
+    where I: Iterator<Item = E>,
+          E: Sized,
+          F: Fn(&E) -> Option<StoreId>
+{
+    inner: I,
+    rt: &'a Runtime<'a>,
+    func: F
+}
+
+impl<'a, I, E, F> Iterator for TouchIterator<'a, I, E, F>
+    where I: Iterator<Item = E>,
+          E: Sized,
+          F: Fn(&E) -> Option<StoreId>
+{
+    type Item = Result<E>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        while let Some(next) = self.inner.next() {
+            match (self.func)(&next) {
+                Some(id) => if let Err(e) = self.rt.report_touched(&id) {
+                    return Some(Err(e))
+                } else {
+                    return Some(Ok(next))
+                },
+
+                None => continue,
+            }
+        }
+
+        None
+    }
+}
+
 /// A trait for providing ids from clap argument matches
 ///
 /// This trait can be implement on a type so that it can provide IDs when given a ArgMatches
-- 
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