Update docs

* improve linking
* parallel construction for storage and servers
* clarify rationale for Task/TaskMut

taskchampion/src/lib.rs

@@ -3,16 +3,26 @@
 
 This crate implements the core of TaskChampion, the [replica](crate::Replica).
 
+Users of this crate can manipulate a task database using this API, including synchronizing that task database with others via a synchronization server.
+
+Example uses of this crate:
+ * user interfaces for task management, such as mobile apps, web apps, or command-line interfaces
+ * integrations for task management, such as synchronization with ticket-tracking systems or
+   request forms.
+
 # Replica
 
 A TaskChampion replica is a local copy of a user's task data.  As the name suggests, several
 replicas of the same data can exist (such as on a user's laptop and on their phone) and can
 synchronize with one another.
 
-Replicas are accessed using the [`Replica`](crate::replica) type.
+Replicas are accessed using the [`Replica`](crate::Replica) type.
 
 # Task Storage
 
+Replicas access the task database via a [storage object](crate::storage::Storage).
+Create a storage object with [`StorageConfig`](crate::storage::StorageConfig).
+
 The [`storage`](crate::storage) module supports pluggable storage for a replica's data.
 An implementation is provided, but users of this crate can provide their own implementation as well.
 

taskchampion/src/replica.rs

@@ -16,7 +16,10 @@ use uuid::Uuid;
 /// ## Tasks
 ///
 /// Tasks are uniquely identified by UUIDs.
-/// Most task modifications are performed via the [`crate::Task`] and [`crate::TaskMut`] types.
+/// Most task modifications are performed via the [`Task`](crate::Task) and
+/// [`TaskMut`](crate::TaskMut) types.  Use of two types for tasks allows easy
+/// read-only manipulation of lots of tasks, with exclusive access required only
+/// for modifications.
 ///
 /// ## Working Set
 ///

taskchampion/src/task/mod.rs

@@ -10,7 +10,7 @@ mod task;
 pub use annotation::Annotation;
 pub use priority::Priority;
 pub use status::Status;
-pub use tag::{Tag, INVALID_TAG_CHARACTERS};
+pub use tag::Tag;
 pub use task::{Task, TaskMut};
 
 pub type Timestamp = DateTime<Utc>;

taskchampion/src/task/tag.rs

@@ -5,7 +5,7 @@ use std::str::FromStr;
 /// A Tag is a descriptor for a task, that is either present or absent, and can be used for
 /// filtering.  Tags composed of all uppercase letters are reserved for synthetic tags.
 ///
-/// Valid tags must not contain whitespace or any of the characters in [`INVALID_TAG_CHARACTERS`].
+/// Valid tags must not contain whitespace or any of the characters in `+-*/(<>^! %=~`.
 /// The first characters additionally cannot be a digit, and subsequent characters cannot be `:`.
 /// This definition is based on [that of
 /// TaskWarrior](https://github.com/GothenburgBitFactory/taskwarrior/blob/663c6575ceca5bd0135ae884879339dac89d3142/src/Lexer.cpp#L146-L164).
@@ -19,6 +19,7 @@ pub(super) enum TagInner {
     Synthetic(SyntheticTag),
 }
 
+// see doc comment for Tag, above
 pub const INVALID_TAG_CHARACTERS: &str = "+-*/(<>^! %=~";
 
 impl Tag {

taskchampion/src/task/task.rs

@@ -8,6 +8,16 @@ use std::convert::AsRef;
 use std::convert::TryInto;
 use uuid::Uuid;
 
+/* The Task and TaskMut classes wrap the underlying [`TaskMap`], which is a simple key/value map.
+ * They provide semantic meaning to that TaskMap according to the TaskChampion data model.  For
+ * example, [`get_status`](Task::get_status) and [`set_status`](TaskMut::set_status) translate from
+ * strings in the TaskMap to [`Status`].
+ *
+ * The same approach applies for more complex data such as dependencies or annotations.  Users of
+ * this API should only need the [`get_taskmap`](Task::get_taskmap) method for debugging purposes,
+ * and should never need to make changes to the TaskMap directly.
+ */
+
 /// A task, as publicly exposed by this crate.
 ///
 /// Note that Task objects represent a snapshot of the task at a moment in time, and are not
@@ -15,16 +25,21 @@ use uuid::Uuid;
 /// but a Task that is cached for more than a few seconds may cause the user to see stale
 /// data.  Fetch, use, and drop Tasks quickly.
 ///
-/// This struct contains only getters for various values on the task. The `into_mut` method returns
-/// a TaskMut which can be used to modify the task.
+/// This struct contains only getters for various values on the task. The
+/// [`into_mut`](Task::into_mut) method
+/// returns a TaskMut which can be used to modify the task.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Task {
     uuid: Uuid,
     taskmap: TaskMap,
 }
 
-/// A mutable task, with setter methods.  Most methods are simple setters and not further
-/// described.  Calling a setter will update the Replica, as well as the included Task.
+/// A mutable task, with setter methods.
+///
+/// Most methods are simple setters and not further described.  Calling a setter will update the
+/// referenced Replica, as well as the included Task, immediately.
+///
+/// The [`Task`] methods are available on [`TaskMut`] via [`Deref`](std::ops::Deref).
 pub struct TaskMut<'r> {
     task: Task,
     replica: &'r mut Replica,
@@ -150,8 +165,7 @@ impl Task {
 }
 
 impl<'r> TaskMut<'r> {
-    /// Get the immutable version of this object.  Note that TaskMut [`std::ops::Deref`]s to
-    /// [`crate::task::Task`], so all of that struct's getter methods can be used on TaskMut.
+    /// Get the immutable version of this object, ending the exclusive reference to the Replica.
     pub fn into_immut(self) -> Task {
         self.task
     }