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400: Rewrite the filter parser and add a lot of tests r=irevoire a=irevoire
This PR is a complete rewrite of #358, which was reverted in #403.
You can already try this PR in Meilisearch here https://github.com/meilisearch/MeiliSearch/pull/1880.
Since writing a parser is quite complicated, I moved all the logic to another workspace called `filter_parser`.
In this workspace, we don't know anything about milli, the filterable fields / field ID or anything.
As you can see in its `cargo.toml`, it has only three dependencies entirely focused on the parsing part:
```
nom = "7.0.0"
nom_locate = "4.0.0"
```
But introducing this new workspace made some changes necessary on the “AST”. Now the parser only returns `Tokens` (a simple `&str` with a bit of context). Everything is interpreted when we execute the filter later in milli.
This crate provides a new error type for all filter related errors.
---------
## Errors
Currently, we have multiple kinds of errors. Sometimes we are generating errors looking like that: (for `name = truc`)
```
Attribute `name` is not filterable. Available filterable attributes are: ``.
```
While sometimes pest was generating errors looking like that:
```
Invalid syntax for the filter parameter: ` --> 1:7
|
1 | name =
| ^---
|
= expected word`.
```
Which most people were seeing like that: (for `name =`)
```
Invalid syntax for the filter parameter: ` --> 1:7\n |\n1 | name =\n | ^---\n |\n = expected word`.
```
-----------
With this PR, the error format is unified between all errors.
All errors follow this more straightforward format:
```
The error message.
[from char]:[to char] filter
```
This should be way easier to read when embedded in the JSON for a human. And it should also allow us to parse the errors easily and provide highlighting or something with a frontend playground.
Here is an example of the two previous errors with the new format:
For `name = truc`:
```
Attribute `name` is not filterable. Available filterable attributes are: ``.
1:4 name = truc
```
Or in one line:
```
Attribute `name` is not filterable. Available filterable attributes are: ``.\n1:4 name = truc
```
And for `name =`:
```
Was expecting a value but instead got nothing.
7:7 name =
```
Or in one line:
```
Was expecting a value but instead got nothing.\n7:7 name =
```
Also, since we now have control over the parser, we can generate more explicit error messages so a lot of new errors have been created. I tried to be as helpful as possible for the user; here is a little overview of the new error message you can get when misusing a filter:
```
Expression `"truc` is missing the following closing delimiter: `"`.
8:13 name = "truc
```
The `_geoRadius` filter is an operation and can't be used as a value.
8:30 name = _geoRadius(12, 13, 14)
```
etc
## Tests
A lot of tests have been written in the `filter_parser` crate. I think there is a unit test for every part of the syntax.
But since we can never be sure we covered all the cases, I also fuzzed the new parser A LOT (for ±8 hours on 20 threads). And the code to fuzz the parser is included in the workspace, so if one day we need to change something to the syntax, we'll be able to re-use it by simply running:
```
cargo fuzz run --release parse
```
## Milli
I renamed the type and module `filter_condition.rs` / `FilterCondition` to `filter.rs` / `Filter`.
Co-authored-by: Tamo <tamo@meilisearch.com>
