Convert query-pull/ to failure.

query-pull/Cargo.toml

@@ -4,7 +4,8 @@ version = "0.0.1"
 workspace = ".."
 
 [dependencies]
-error-chain = { git = "https://github.com/rnewman/error-chain", branch = "rnewman/sync" }
+failure = "0.1.1"
+failure_derive = "0.1.1"
 
 [dependencies.rusqlite]
 version = "0.13"

query-pull/src/errors.rs

@@ -8,28 +8,23 @@
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
 
+use std; // To refer to std::result::Result.
+
 use mentat_core::{
     Entid,
 };
 
-error_chain! {
-    types {
-        Error, ErrorKind, ResultExt, Result;
-    }
+use failure::{
+    Error,
+};
 
-    errors {
-        UnnamedAttribute(id: Entid) {
-            description("unnamed attribute")
-            display("attribute {:?} has no name", id)
-        }
+pub type Result<T> = std::result::Result<T, Error>;
 
-        RepeatedDbId {
-            description(":db/id repeated")
-            display(":db/id repeated")
-        }
-    }
+#[derive(Debug, Fail)]
+pub enum PullError {
+    #[fail(display = "attribute {:?} has no name", _0)]
+    UnnamedAttribute(Entid),
 
-    links {
-        DbError(::mentat_db::Error, ::mentat_db::ErrorKind);
-    }
+    #[fail(display = ":db/id repeated")]
+    RepeatedDbId,
 }

query-pull/src/lib.rs

@@ -57,8 +57,10 @@
 ///      [*]))
 ///! ```
 
+extern crate failure;
+
 #[macro_use]
-extern crate error_chain;
+extern crate failure_derive;
 
 extern crate rusqlite;
 
@@ -101,7 +103,7 @@ use mentat_query::{
 pub mod errors;
 
 use errors::{
-    ErrorKind,
+    PullError,
     Result,
 };
 
@@ -163,7 +165,7 @@ impl Puller {
             // In the unlikely event that we have an attribute with no name, we bail.
             schema.get_ident(*i)
                     .map(|ident| ValueRc::new(ident.clone()))
-                    .ok_or_else(|| ErrorKind::UnnamedAttribute(*i))
+                    .ok_or_else(|| PullError::UnnamedAttribute(*i))
         };
 
         let mut names: BTreeMap<Entid, ValueRc<Keyword>> = Default::default();
@@ -192,7 +194,7 @@ impl Puller {
                         &PullConcreteAttribute::Ident(ref i) if i.as_ref() == db_id.as_ref() => {
                             // We only allow :db/id once.
                             if db_id_alias.is_some() {
-                                bail!(ErrorKind::RepeatedDbId);
+                                Err(PullError::RepeatedDbId)?
                             }
                             db_id_alias = Some(alias.unwrap_or_else(|| db_id.to_value_rc()));
                         },