support filtering by tags

cli/src/argparse/filter.rs

@@ -1,6 +1,6 @@
-use super::args::{arg_matching, id_list, TaskId};
+use super::args::{arg_matching, id_list, minus_tag, plus_tag, TaskId};
 use super::ArgList;
-use nom::{combinator::*, multi::fold_many0, IResult};
+use nom::{branch::alt, combinator::*, multi::fold_many0, IResult};
 
 /// A filter represents a selection of a particular set of tasks.
 ///
@@ -9,8 +9,12 @@ use nom::{combinator::*, multi::fold_many0, IResult};
 /// pending tasks, or all tasks.
 #[derive(Debug, PartialEq, Default, Clone)]
 pub(crate) struct Filter {
-    /// A list of numeric IDs or prefixes of UUIDs
+    /// The universe of tasks from which this filter can select
     pub(crate) universe: Universe,
+
+    /// A set of filter conditions, all of which must match a task in order for that task to be
+    /// selected.
+    pub(crate) conditions: Vec<Condition>,
 }
 
 /// The universe of tasks over which a filter should be applied.
@@ -39,15 +43,26 @@ impl Default for Universe {
     }
 }
 
+/// A condition which tasks must match to be accepted by the filter.
+#[derive(Debug, PartialEq, Clone)]
+pub(crate) enum Condition {
+    /// Task has the given tag
+    HasTag(String),
+
+    /// Task does not have the given tag
+    NoTag(String),
+}
+
 /// Internal struct representing a parsed filter argument
 enum FilterArg {
     IdList(Vec<TaskId>),
+    Condition(Condition),
 }
 
 impl Filter {
     pub(super) fn parse(input: ArgList) -> IResult<ArgList, Filter> {
         fold_many0(
-            Self::id_list,
+            alt((Self::id_list, Self::plus_tag, Self::minus_tag)),
             Filter {
                 ..Default::default()
             },
@@ -68,6 +83,9 @@ impl Filter {
                     acc.universe = Universe::IdList(id_list);
                 }
             }
+            FilterArg::Condition(cond) => {
+                acc.conditions.push(cond);
+            }
         }
         acc
     }
@@ -78,6 +96,20 @@ impl Filter {
         }
         map_res(arg_matching(id_list), to_filterarg)(input)
     }
+
+    fn plus_tag(input: ArgList) -> IResult<ArgList, FilterArg> {
+        fn to_filterarg(input: &str) -> Result<FilterArg, ()> {
+            Ok(FilterArg::Condition(Condition::HasTag(input.to_owned())))
+        }
+        map_res(arg_matching(plus_tag), to_filterarg)(input)
+    }
+
+    fn minus_tag(input: ArgList) -> IResult<ArgList, FilterArg> {
+        fn to_filterarg(input: &str) -> Result<FilterArg, ()> {
+            Ok(FilterArg::Condition(Condition::NoTag(input.to_owned())))
+        }
+        map_res(arg_matching(minus_tag), to_filterarg)(input)
+    }
 }
 
 #[cfg(test)]
@@ -159,4 +191,21 @@ mod test {
             }
         );
     }
+
+    #[test]
+    fn test_tags() {
+        let (input, filter) = Filter::parse(argv!["1", "+yes", "-no"]).unwrap();
+        assert_eq!(input.len(), 0);
+        assert_eq!(
+            filter,
+            Filter {
+                universe: Universe::IdList(vec![TaskId::WorkingSetId(1),]),
+                conditions: vec![
+                    Condition::HasTag("yes".into()),
+                    Condition::NoTag("no".into()),
+                ],
+                ..Default::default()
+            }
+        );
+    }
 }

cli/src/argparse/mod.rs

@@ -20,7 +20,7 @@ mod subcommand;
 
 pub(crate) use args::TaskId;
 pub(crate) use command::Command;
-pub(crate) use filter::{Filter, Universe};
+pub(crate) use filter::{Condition, Filter, Universe};
 pub(crate) use modification::{DescriptionMod, Modification};
 pub(crate) use report::Report;
 pub(crate) use subcommand::Subcommand;

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)?;
     }