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https://github.com/ctron/sikula

A simple query language
https://github.com/ctron/sikula

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A simple query language

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# SiKuLa

[![CI](https://github.com/ctron/sikula/workflows/CI/badge.svg)](https://github.com/ctron/sikula/actions?query=workflow%3A%22CI%22)
[![GitHub release (latest SemVer)](https://img.shields.io/github/v/tag/ctron/sikula?sort=semver)](https://github.com/ctron/sikula/releases)
[![crates.io](https://img.shields.io/crates/v/sikula.svg)](https://crates.io/crates/sikula)
[![docs.rs](https://docs.rs/sikula/badge.svg)](https://docs.rs/sikula)

Simple Query Language - [ˈziːˈkuːˈlaː]

## Rationale

_Another query language, are you serious?_

Actually it isn't that new. But naming it "Query language similar to GitHub's search syntax" (QLSTGHSS)
wasn't a real option.

Think of it more as an implementation of a familiar syntax.

_What's the difference then?_

They are subtle. But I don't want to spoil the surprise. Or maybe I am just too lazy documenting it. 🤷

## Example

Assuming you have an enum defined for searching e-mails:

```rust
use sikula::prelude::*;

#[derive(Search, Clone, Debug, PartialEq, Eq)]
enum DeriveResource<'a> {
/// Standard qualifier: `author:someone`.
#[search(sort, scope)]
Author(&'a str),
/// Default primary: `warranty`.
#[search(default)]
Subject(Primary<'a>),
/// Non-default primary: `warranty in:message`, to search in both: `warranty in:message in:subject`.
#[search(scope)]
Message(Primary<'a>),

/// Predicate: `is:read`.
Read,

/// Numeric qualifier example:
/// * `size:100` (equals)
/// * `size:>=100` (size greater than or equals 100)
/// * `size:100..200` (size between 100 inclusive and 200 exclusive)
/// * `size:*..200` (size up to 200 exclusive)
#[search(sort)]
Size(Ordered),

#[search(sort)]
Sent(Ordered),

Label(Qualified<'a, &'a str>),
}
```

The `Search` derive provides the trait implementation. The `#[search(default)]` attribute flags the variant `Subject`
as default scopes for the primary search terms, marking `Subject` as the default if none was selected.

In general, there are three types of terms: Primary, Qualifiers, Predicates. Predicates are simple "is this condition
true" style of filters. If an enum variant doesn't have any value, it is a predicate.

Qualifiers are additional matching criteria, which depend on the type of the value.

With the `#[search(sort)]` flag, a field can be used for sorting the result.

Now, you can do the following queries:

| Query | Retrieves all entries… |
|---------------------------------------------------|-------------------------------------------------------------------------------------------------------|
| `foo` | … containing "foo" in the "subject" |
| `foo in:subject in:message` | … containing "foo" in either "subject" or "message" |
| `foo in:subject in:message is:read` | … containing "foo" in either "subject" or "message" being "read" |
| `foo bar` | … containing "foo" and "bar" in the "subject" |
| `size:>10000` | … having the "size" greater than 10000 |
| `size:100..200` | … having the "size" between 100 (inclusive) and 200 (exclusive) |
| `-is:read` | … being "not read" |
| `foo sort:sent` | … containing "foo" in the "subject", sorted by "sent" ascending |
| `foo -sort:sent` | … containing "foo" in the "subject", sorted by "sent" descending |
| `author:"Max Mustermann"` | … having the "author" of `Max Mustermann` |
| `author:"Max Mustermann" author:"Eva Mustermann"` | … having the "author" of `Max Mustermann` and `Eva Mustermann` (most likely no results will be found) |
| `author:"Max Mustermann","Eva Mustermann"` | … having the "author" of `Max Mustermann` or `Eva Mustermann` |
| `foo OR bar` | … containing "foo" or "bar" in the "subject" |
| `foo AND bar` | … containing "foo" and "bar" in the "subject" |
| `foo OR bar AND baz` | … containing either "foo" or ( "bar" and "baz" ) in the "subject" |
| `(foo OR bar) AND baz` | … containing ( "foo" or "bar" ) and "baz" in the "subject" |
| `foo OR bar baz` | … containing ( "foo" or "bar" ) and "baz" in the "subject" |

For testing more examples with the resource above, you can run the `cli` example:

```shell
cargo run --example cli --features time -- -is:read AND foo
```

Which will give you a structured output of the parsed query:

```
Input: '-is:read AND foo'

MIR:
Query {
term: And {
scopes: [],
terms: [
Not(
Match {
qualifier: Qualifier(
[
"read",
],
),
expression: Predicate,
},
),
Match {
qualifier: Qualifier(
[],
),
expression: Simple(
"foo",
),
},
],
},
sorting: [],
}

LIR:
Query {
terms: And(
[
Not(
Match(
Read,
),
),
Match(
Subject(
Partial(
"foo",
),
),
),
],
),
sorting: [],
}
```