# Description
Compatible with `Vec::truncate` and `indexmap::IndexMap::truncate`
Found useful in #10903 for `drop column`
# Tests + Formatting
Doctest with the relevant edge-cases
Matches the general behavior of `Vec::drain` or
`indexmap::IndexMap::drain`:
- Drop the remaining elements (implementing the unstable `keep_rest()`
would not be compatible with something like `indexmap`)
- No `AsRef<[T]>` or `Drain::as_slice()` behavior as this would make
layout assumptions.
- `Drain: DoubleEndedIterator`
Found useful in #10903
# Description
Replaces the `Vec::remove` in `Record::retain_mut` with some swaps which
should eliminate the `O(n^2)` complexity due to repeated shifting of
elements.
# Description
While we have now a few ways to add items or iterate over the
collection, we don't have a way to cleanly remove items from `Record`.
This PR fixes that:
- Add `Record.remove()` to remove by key
- makes the assumption that keys are unique, so can not be used
universally, yet (see #10875 for an important example)
- Add naive `Record.retain()` for inplace removal
- This follows the two separate `retain`/`retain_mut` in the Rust std
library types, compared to the value-mutating `retain` in `indexmap`
- Add `Record.retain_mut()` for one-pass pruning
Continuation of #10841
# User-Facing Changes
None yet.
# Tests + Formatting
Doctests for the `retain`ing fun
# Description
> Our `Record` looks like a map, quacks like a map, so let's treat it
with the API for a map
Implement common methods found on e.g. `std::collections::HashMap` or
the insertion-ordered [indexmap](https://docs.rs/indexmap).
This allows contributors to not have to worry about how to get to the
relevant items and not mess up the assumptions of a Nushell record.
## Record assumptions
- `cols` and `vals` are of equal length
- for all practical purposes, keys/columns should be unique
## End goal
The end goal of the upcoming series of PR's is to allow us to make
`cols` and `vals` private.
Then it would be possible to exchange the backing datastructure to best
fit the expected workload.
This could be statically (by finding the best balance) or dynamically by
using an `enum` of potential representations.
## Parts
- Add validating explicit part constructor
`Record::from_raw_cols_vals()`
- Add `Record.columns()` iterator
- Add `Record.values()` iterator
- Add consuming `Record.into_values()` iterator
- Add `Record.contains()` helper
- Add `Record.insert()` that respects existing keys
- Add key-based `.get()`/`.get_mut()` to `Record`
- Add `Record.get_index()` for index-based access
- Implement `Extend` for `Record` naively
- Use checked constructor in `record!` macro
- Add `Record.index_of()` to get index by key
# User-Facing Changes
None directly
# Developer facing changes
You don't have to roll your own record handling and can use a familiar
API
# Tests + Formatting
No explicit unit tests yet. Wouldn't be too tricky to validate core
properties directly.
Will be exercised by the following PRs using the new
methods/traits/iterators.
# Description
This PR creates a new `Record` type to reduce duplicate code and
possibly bugs as well. (This is an edited version of #9648.)
- `Record` implements `FromIterator` and `IntoIterator` and so can be
iterated over or collected into. For example, this helps with
conversions to and from (hash)maps. (Also, no more
`cols.iter().zip(vals)`!)
- `Record` has a `push(col, val)` function to help insure that the
number of columns is equal to the number of values. I caught a few
potential bugs thanks to this (e.g. in the `ls` command).
- Finally, this PR also adds a `record!` macro that helps simplify
record creation. It is used like so:
```rust
record! {
"key1" => some_value,
"key2" => Value::string("text", span),
"key3" => Value::int(optional_int.unwrap_or(0), span),
"key4" => Value::bool(config.setting, span),
}
```
Since macros hinder formatting, etc., the right hand side values should
be relatively short and sweet like the examples above.
Where possible, prefer `record!` or `.collect()` on an iterator instead
of multiple `Record::push`s, since the first two automatically set the
record capacity and do less work overall.
# User-Facing Changes
Besides the changes in `nu-protocol` the only other breaking changes are
to `nu-table::{ExpandedTable::build_map, JustTable::kv_table}`.
