From 44744d9e67c0cf1dafd2ed712b8094d4b2b21ebb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Lecrenier?= <loic@meilisearch.com>
Date: Tue, 14 Jun 2022 15:15:05 +0200
Subject: [PATCH] Implement the simplified NOT operator

---
 filter-parser/src/lib.rs         | 23 ++++-------------------
 milli/src/search/facet/filter.rs | 10 ++++++++++
 2 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/filter-parser/src/lib.rs b/filter-parser/src/lib.rs
index 8da3da35f..49eba1c61 100644
--- a/filter-parser/src/lib.rs
+++ b/filter-parser/src/lib.rs
@@ -112,6 +112,7 @@ impl<'a> From<Span<'a>> for Token<'a> {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum FilterCondition<'a> {
+    Not(Box<Self>),
     Condition { fid: Token<'a>, op: Condition<'a> },
     Or(Vec<Self>),
     And(Vec<Self>),
@@ -148,24 +149,6 @@ impl<'a> FilterCondition<'a> {
         }
     }
 
-    pub fn negate(self) -> FilterCondition<'a> {
-        use FilterCondition::*;
-
-        match self {
-            Condition { fid, op } => match op.negate() {
-                (op, None) => Condition { fid, op },
-                (a, Some(b)) => Or(vec![
-                    Condition { fid: fid.clone(), op: a }.into(),
-                    Condition { fid, op: b }.into(),
-                ]),
-            },
-            Or(subfilters) => And(subfilters.into_iter().map(|x| x.negate().into()).collect()),
-            And(subfilters) => Or(subfilters.into_iter().map(|x| x.negate().into()).collect()),
-            GeoLowerThan { point, radius } => GeoGreaterThan { point, radius },
-            GeoGreaterThan { point, radius } => GeoLowerThan { point, radius },
-        }
-    }
-
     pub fn parse(input: &'a str) -> Result<Option<Self>, Error> {
         if input.trim().is_empty() {
             return Ok(None);
@@ -219,7 +202,9 @@ fn parse_and(input: Span) -> IResult<FilterCondition> {
 /// If we parse a `NOT` we MUST parse something behind.
 fn parse_not(input: Span) -> IResult<FilterCondition> {
     alt((
-        map(preceded(ws(tuple((tag("NOT"), multispace1))), cut(parse_not)), |e| e.negate()),
+        map(preceded(ws(tuple((tag("NOT"), multispace1))), cut(parse_not)), |e| {
+            FilterCondition::Not(Box::new(e))
+        }),
         parse_primary,
     ))(input)
 }
diff --git a/milli/src/search/facet/filter.rs b/milli/src/search/facet/filter.rs
index 371cf975e..23917e4aa 100644
--- a/milli/src/search/facet/filter.rs
+++ b/milli/src/search/facet/filter.rs
@@ -360,6 +360,16 @@ impl<'a> Filter<'a> {
         filterable_fields: &HashSet<String>,
     ) -> Result<RoaringBitmap> {
         match &self.condition {
+            FilterCondition::Not(f) => {
+                let all_ids = index.documents_ids(rtxn)?;
+                let selected = Self::inner_evaluate(
+                    &(f.as_ref().clone()).into(),
+                    rtxn,
+                    index,
+                    filterable_fields,
+                )?;
+                return Ok(all_ids - selected);
+            }
             FilterCondition::Condition { fid, op } => {
                 if crate::is_faceted(fid.value(), filterable_fields) {
                     let field_ids_map = index.fields_ids_map(rtxn)?;