mentat/tx-parser/src/errors.rs
Nick Alexander d1ac752de6 Parse without copying; parse keyword maps using macros.
This is a big commit, but it breaks into two conceptual pieces.  The
first is to "parse without copying".  We replace a stream of an owned
collection of edn::ValueAndSpan and instead have a stream of a
borrowed collection of &edn::ValueAndSpan references.  (Generally,
this is represented as an iterator over a slice, but it can be over
other things too.)  Cloning such iterators is constant time, which
improves on cloning an owned collection of edn::ValueAndSpan, which is
linear time in the length of the collection and additional time
depending on the complexity of the EDN values.

The second conceptual piece is to parse keyword maps using a special
parser and a macro to build the parser implementations.  Before, we
created a new edn::ValueAndSpan::Map to represent a keyword map in
vector form; since we're working with &edn::ValueAndSpan references
now, we can't create an &edn::ValueAndSpan reference with an
appropriate lifetime.  Therefore we generalize the concept of
iteration slightly and turn keyword maps in map form into linear
iterators by flattening the value maps.  This is a potentially
obscuring transformation, so we have to take care to protect against
some failure cases.  (See the comments and the tests in the code.)

After these changes, parsing using `combine` is linear time (and
reasonably fast).
2017-05-18 10:17:13 -07:00

31 lines
1.1 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 mentat_parser_utils::ValueParseError;
error_chain! {
types {
Error, ErrorKind, ResultExt, Result;
}
errors {
ParseError(parse_error: ValueParseError) {
description("error parsing edn values")
display("error parsing edn values:\n{}", parse_error)
}
DbIdError {
description("bad :db/id in map notation")
display("bad :db/id in map notation: must either be not present or be an entid, an ident, or a tempid")
}
}
}