support filtering by tags

cli/src/invocation/filter.rs

@@ -1,10 +1,28 @@
-use crate::argparse::{Filter, TaskId, Universe};
+use crate::argparse::{Condition, Filter, TaskId, Universe};
 use failure::Fallible;
 use std::collections::HashSet;
-use taskchampion::{Replica, Task};
+use std::convert::TryInto;
+use taskchampion::{Replica, Tag, Task};
 
-fn match_task(_filter: &Filter, _task: &Task) -> bool {
-    // TODO: at the moment, only filtering by Universe is supported
+fn match_task(filter: &Filter, task: &Task) -> bool {
+    for cond in &filter.conditions {
+        match cond {
+            Condition::HasTag(ref tag) => {
+                // see #111 for the unwrap
+                let tag: Tag = tag.try_into().unwrap();
+                if !task.has_tag(&tag) {
+                    return false;
+                }
+            }
+            Condition::NoTag(ref tag) => {
+                // see #111 for the unwrap
+                let tag: Tag = tag.try_into().unwrap();
+                if task.has_tag(&tag) {
+                    return false;
+                }
+            }
+        }
+    }
     true
 }
 
@@ -186,6 +204,68 @@ mod test {
         );
     }
 
+    #[test]
+    fn tag_filtering() -> Fallible<()> {
+        let mut replica = test_replica();
+        let yes: Tag = "yes".try_into()?;
+        let no: Tag = "no".try_into()?;
+
+        let mut t1 = replica
+            .new_task(Status::Pending, "A".to_owned())?
+            .into_mut(&mut replica);
+        t1.add_tag(&yes)?;
+        let mut t2 = replica
+            .new_task(Status::Pending, "B".to_owned())?
+            .into_mut(&mut replica);
+        t2.add_tag(&yes)?;
+        t2.add_tag(&no)?;
+        let mut t3 = replica
+            .new_task(Status::Pending, "C".to_owned())?
+            .into_mut(&mut replica);
+        t3.add_tag(&no)?;
+        let _t4 = replica.new_task(Status::Pending, "D".to_owned())?;
+
+        // look for just "yes" (A and B)
+        let filter = Filter {
+            universe: Universe::AllTasks,
+            conditions: vec![Condition::HasTag("yes".to_owned())],
+            ..Default::default()
+        };
+        let mut filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
+            .map(|t| t.get_description().to_owned())
+            .collect();
+        filtered.sort();
+        assert_eq!(vec!["A".to_owned(), "B".to_owned()], filtered);
+
+        // look for tags without "no" (A, D)
+        let filter = Filter {
+            universe: Universe::AllTasks,
+            conditions: vec![Condition::NoTag("no".to_owned())],
+            ..Default::default()
+        };
+        let mut filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
+            .map(|t| t.get_description().to_owned())
+            .collect();
+        filtered.sort();
+        assert_eq!(vec!["A".to_owned(), "D".to_owned()], filtered);
+
+        // look for tags with "yes" and "no" (B)
+        let filter = Filter {
+            universe: Universe::AllTasks,
+            conditions: vec![
+                Condition::HasTag("yes".to_owned()),
+                Condition::HasTag("no".to_owned()),
+            ],
+            ..Default::default()
+        };
+        let filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
+            .map(|t| t.get_description().to_owned())
+            .collect();
+        assert_eq!(vec!["B".to_owned()], filtered);
+
+        Ok(())
+    }
+
     #[test]
     fn pending_tasks() {
         let mut replica = test_replica();

cli/src/invocation/modify.rs

@@ -34,14 +34,12 @@ pub(super) fn apply_modification<W: WriteColor>(
     }
 
     for tag in modification.add_tags.iter() {
-        // note that the parser should have already ensured that this tag was valid
-        let tag = tag.try_into()?;
+        let tag = tag.try_into()?; // see #111
         task.add_tag(&tag)?;
     }
 
     for tag in modification.remove_tags.iter() {
-        // note that the parser should have already ensured that this tag was valid
-        let tag = tag.try_into()?;
+        let tag = tag.try_into()?; // see #111
         task.remove_tag(&tag)?;
     }