mentat/edn/src/utils.rs
Nick Alexander 81af295948 Start installing SQL schema. (#171) r=rnewman
* Start installing the SQLite store and bootstrapping the datom store.

* Review comment: Decomplect V2_IDENTS.

* Review comment: Decomplect V2_PARTS.

* Review comment: Pre: Expose Clojure's merge on Value instances.

* Review comment: Decomplect V2_SYMBOLIC_SCHEMA.

* Review comment: Decomplect V1_STATEMENTS.

* Review comment: Prefer ? to try!.

* Review comment: Fix typos; format; add TODOs.

* Review comment: Assert that Mentat `Schema` is valid upon creation.

* Review comment: Improve conversion to and from SQL values.

This patch factors the fundamental SQL conversion maps
between (rusqlite::Value, value_type_tag) and (edn::Value, ValueType)
through a new Mentat TypedValue.  (A future patch might rename this
fundamental type mentat::Value.)

To make certain conversion functions infallible, I removed
placeholders for :db.type/{instant,uuid,uri}.  (We could panic
instead, but there's no need to do that right now.)

* Review comment: Always uses bundled SQLite in rusqlite.

This avoids (runtime) failures in Travis CI due to old SQLite
versions.  See 432966ac77.

* Review comment: Move semantics in `from_sql_value_pair`.

* Review comment: DB_EXCISE_BEFORE_T instead of ...BEFORET (no underscore).

* Review comment: Move overview notes to the Wiki.
2017-01-25 16:13:56 -08:00

31 lines
1.2 KiB
Rust

// Copyright 2016 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.
#![allow(dead_code)]
use types::Value;
/// Merge the EDN `Value::Map` instance `right` into `left`. Returns `None` if either `left` or
/// `right` is not a `Value::Map`.
///
/// Keys present in `right` overwrite keys present in `left`. See also
/// https://clojuredocs.org/clojure.core/merge.
///
/// TODO: implement `merge` for [Value], following the `concat`/`SliceConcatExt` pattern.
pub fn merge(left: &Value, right: &Value) -> Option<Value> {
match (left, right) {
(&Value::Map(ref l), &Value::Map(ref r)) => {
let mut result = l.clone();
result.extend(r.clone().into_iter());
Some(Value::Map(result))
}
_ => None
}
}