Part 1: Push ValueRc and friends into edn crate.

This is a pre-requisite for moving the existing `combine`-based parser
to use `rust-peg` -- part of the push to use `rust-peg` for all parsing
started in https://github.com/mozilla/mentat/pull/681.  We need the
types for the parsed structure "very early", and the `edn` crate is
the earliest such crate.

This is an unfortunate destruction of boundaries between parts of the
system, but it's the best way we have to achieve this right now.

core/src/lib.rs

@@ -38,10 +38,13 @@ pub use chrono::{
 };
 
 pub use edn::{
+    Cloned,
     FromMicros,
+    FromRc,
     Keyword,
     ToMicros,
     Utc,
+    ValueRc,
 };
 
 pub use cache::{
@@ -56,15 +59,12 @@ mod sql_types;
 
 pub use types::{
     Binding,
-    Cloned,
     Entid,
-    FromRc,
     KnownEntid,
     StructuredMap,
     TypedValue,
     ValueType,
     ValueTypeTag,
-    ValueRc,
     now,
 };
 

core/src/types.rs

@@ -39,103 +39,16 @@ use ::indexmap::{
 
 use ::edn::{
     self,
+    Cloned,
     FromMicros,
+    FromRc,
     Keyword,
     Utc,
+    ValueRc,
 };
 
 use values;
 
-pub trait FromRc<T> {
-    fn from_rc(val: Rc<T>) -> Self;
-    fn from_arc(val: Arc<T>) -> Self;
-}
-
-impl<T> FromRc<T> for Rc<T> where T: Sized + Clone {
-    fn from_rc(val: Rc<T>) -> Self {
-        val.clone()
-    }
-
-    fn from_arc(val: Arc<T>) -> Self {
-        match ::std::sync::Arc::<T>::try_unwrap(val) {
-            Ok(v) => Self::new(v),
-            Err(r) => Self::new(r.cloned()),
-        }
-    }
-}
-
-impl<T> FromRc<T> for Arc<T> where T: Sized + Clone {
-    fn from_rc(val: Rc<T>) -> Self {
-        match ::std::rc::Rc::<T>::try_unwrap(val) {
-            Ok(v) => Self::new(v),
-            Err(r) => Self::new(r.cloned()),
-        }
-    }
-
-    fn from_arc(val: Arc<T>) -> Self {
-        val.clone()
-    }
-}
-
-impl<T> FromRc<T> for Box<T> where T: Sized + Clone {
-    fn from_rc(val: Rc<T>) -> Self {
-        match ::std::rc::Rc::<T>::try_unwrap(val) {
-            Ok(v) => Self::new(v),
-            Err(r) => Self::new(r.cloned()),
-        }
-    }
-
-    fn from_arc(val: Arc<T>) -> Self {
-        match ::std::sync::Arc::<T>::try_unwrap(val) {
-            Ok(v) => Self::new(v),
-            Err(r) => Self::new(r.cloned()),
-        }
-    }
-}
-
-// We do this a lot for errors.
-pub trait Cloned<T> {
-    fn cloned(&self) -> T;
-    fn to_value_rc(&self) -> ValueRc<T>;
-}
-
-impl<T: Clone> Cloned<T> for Rc<T> where T: Sized + Clone {
-    fn cloned(&self) -> T {
-        (*self.as_ref()).clone()
-    }
-
-    fn to_value_rc(&self) -> ValueRc<T> {
-        ValueRc::from_rc(self.clone())
-    }
-}
-
-impl<T: Clone> Cloned<T> for Arc<T> where T: Sized + Clone {
-    fn cloned(&self) -> T {
-        (*self.as_ref()).clone()
-    }
-
-    fn to_value_rc(&self) -> ValueRc<T> {
-        ValueRc::from_arc(self.clone())
-    }
-}
-
-impl<T: Clone> Cloned<T> for Box<T> where T: Sized + Clone {
-    fn cloned(&self) -> T {
-        self.as_ref().clone()
-    }
-
-    fn to_value_rc(&self) -> ValueRc<T> {
-        ValueRc::new(self.cloned())
-    }
-}
-
-///
-/// This type alias exists to allow us to use different boxing mechanisms for values.
-/// This type must implement `FromRc` and `Cloned`, and a `From` implementation must exist for
-/// `TypedValue`.
-///
-pub type ValueRc<T> = Arc<T>;
-
 /// Represents one entid in the entid space.
 ///
 /// Per https://www.sqlite.org/datatype3.html (see also http://stackoverflow.com/a/8499544), SQLite

edn/src/lib.rs

@@ -30,6 +30,12 @@ pub mod types;
 pub mod pretty_print;
 pub mod utils;
 pub mod matcher;
+pub mod value_rc;
+pub use value_rc::{
+    Cloned,
+    FromRc,
+    ValueRc,
+};
 
 pub mod parse {
     include!(concat!(env!("OUT_DIR"), "/edn.rs"));

edn/src/value_rc.rs

@@ -0,0 +1,107 @@
+// Copyright 2018 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+use ::std::rc::{
+    Rc,
+};
+
+use ::std::sync::{
+    Arc,
+};
+
+pub trait FromRc<T> {
+    fn from_rc(val: Rc<T>) -> Self;
+    fn from_arc(val: Arc<T>) -> Self;
+}
+
+impl<T> FromRc<T> for Rc<T> where T: Sized + Clone {
+    fn from_rc(val: Rc<T>) -> Self {
+        val.clone()
+    }
+
+    fn from_arc(val: Arc<T>) -> Self {
+        match ::std::sync::Arc::<T>::try_unwrap(val) {
+            Ok(v) => Self::new(v),
+            Err(r) => Self::new(r.cloned()),
+        }
+    }
+}
+
+impl<T> FromRc<T> for Arc<T> where T: Sized + Clone {
+    fn from_rc(val: Rc<T>) -> Self {
+        match ::std::rc::Rc::<T>::try_unwrap(val) {
+            Ok(v) => Self::new(v),
+            Err(r) => Self::new(r.cloned()),
+        }
+    }
+
+    fn from_arc(val: Arc<T>) -> Self {
+        val.clone()
+    }
+}
+
+impl<T> FromRc<T> for Box<T> where T: Sized + Clone {
+    fn from_rc(val: Rc<T>) -> Self {
+        match ::std::rc::Rc::<T>::try_unwrap(val) {
+            Ok(v) => Self::new(v),
+            Err(r) => Self::new(r.cloned()),
+        }
+    }
+
+    fn from_arc(val: Arc<T>) -> Self {
+        match ::std::sync::Arc::<T>::try_unwrap(val) {
+            Ok(v) => Self::new(v),
+            Err(r) => Self::new(r.cloned()),
+        }
+    }
+}
+
+// We do this a lot for errors.
+pub trait Cloned<T> {
+    fn cloned(&self) -> T;
+    fn to_value_rc(&self) -> ValueRc<T>;
+}
+
+impl<T: Clone> Cloned<T> for Rc<T> where T: Sized + Clone {
+    fn cloned(&self) -> T {
+        (*self.as_ref()).clone()
+    }
+
+    fn to_value_rc(&self) -> ValueRc<T> {
+        ValueRc::from_rc(self.clone())
+    }
+}
+
+impl<T: Clone> Cloned<T> for Arc<T> where T: Sized + Clone {
+    fn cloned(&self) -> T {
+        (*self.as_ref()).clone()
+    }
+
+    fn to_value_rc(&self) -> ValueRc<T> {
+        ValueRc::from_arc(self.clone())
+    }
+}
+
+impl<T: Clone> Cloned<T> for Box<T> where T: Sized + Clone {
+    fn cloned(&self) -> T {
+        self.as_ref().clone()
+    }
+
+    fn to_value_rc(&self) -> ValueRc<T> {
+        ValueRc::new(self.cloned())
+    }
+}
+
+///
+/// This type alias exists to allow us to use different boxing mechanisms for values.
+/// This type must implement `FromRc` and `Cloned`, and a `From` implementation must exist for
+/// `TypedValue`.
+///
+pub type ValueRc<T> = Arc<T>;