Add utility to print debugging information while mapping

libimagutil/src/debug_result.rs

@@ -0,0 +1,28 @@
+pub trait DebugResult<T, E> : Sized {
+
+    fn map_dbg<F: FnOnce(&T) -> String>(self, f: F) -> Self;
+
+    fn map_dbg_str(self, s: &str) -> Self {
+        self.map_dbg(|_| format!("{}", s))
+    }
+
+    fn map_dbg_err<F: FnOnce(&E) -> String>(self, f: F) -> Self;
+
+    fn map_dbg_err_str(self, s: &str) -> Self {
+        self.map_dbg_err(|_| format!("{}", s))
+    }
+
+}
+
+impl<T, E> DebugResult<T, E> for Result<T, E> {
+
+    fn map_dbg<F: FnOnce(&T) -> String>(self, f: F) -> Self {
+        self.map(|t| { debug!("{}", f(&t)); t })
+    }
+
+    fn map_dbg_err<F: FnOnce(&E) -> String>(self, f: F) -> Self {
+        self.map_err(|e| { debug!("{}", f(&e)); e })
+    }
+
+}
+

libimagutil/src/lib.rs

@@ -17,6 +17,7 @@
 #[macro_use] extern crate log;
 extern crate regex;
 
+pub mod debug_result;
 pub mod ismatch;
 pub mod iter;
 pub mod key_value_split;