Merge #719

719: Add more members of `filter_parser` to `milli::` & `From<&str>` implementation for `Token` r=Kerollmops a=GregoryConrad

## What does this PR do?
The current `milli::Filter` and `milli::FilterCondition` APIs require working with some members of `filter_parser` directly that `milli::` does *not* re-export to its users (at least when not parsing input using `parse`). Also, using `filter_parser` does not make sense when using milli from an embedded context where there is no query to parse.

Instead of reworking `milli::Filter` and `milli::FilterCondition`, this PR adds two non-breaking changes that ease the use of milli:
- Re-exports more members of the dependent version of `filter_parser` in `milli`
- Implements `From<&str>` for `filter_parser::Token`
  - This will also allow some basic tests that need to create a `Token` from a string to avoid some boilerplate.

In conjunction, both of these will allow milli users to easily create a `Token` from a `&str` without needing to add `filter_parser` as an extra dependency.

Note: I wanted to use `FromStr` for the `From` implementation; however, it requires returning a `Result` which is not needed for the conversion. Thus, I just left it as `From<&str>`.

Co-authored-by: Gregory Conrad <gregorysconrad@gmail.com>

filter-parser/src/lib.rs

@@ -115,6 +115,13 @@ impl<'a> From<Span<'a>> for Token<'a> {
     }
 }
 
+/// Allow [Token] to be constructed from &[str]
+impl<'a> From<&'a str> for Token<'a> {
+    fn from(s: &'a str) -> Self {
+        Token::from(Span::new_extra(s, s))
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum FilterCondition<'a> {
     Not(Box<Self>),
@@ -664,6 +671,13 @@ pub mod tests {
         assert!(filter.token_at_depth(2).is_some());
         assert!(filter.token_at_depth(3).is_none());
     }
+
+    #[test]
+    fn token_from_str() {
+        let s = "test string that should not be parsed";
+        let token: Token = s.into();
+        assert_eq!(token.value(), s);
+    }
 }
 
 impl<'a> std::fmt::Display for FilterCondition<'a> {

milli/src/lib.rs

@@ -22,7 +22,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::convert::{TryFrom, TryInto};
 use std::hash::BuildHasherDefault;
 
-pub use filter_parser::{Condition, FilterCondition};
+pub use filter_parser::{Condition, FilterCondition, Span, Token};
 use fxhash::{FxHasher32, FxHasher64};
 pub use grenad::CompressionType;
 use serde_json::Value;