Introduce the new Sort criterion and AscDesc enum

milli/src/criterion.rs

@@ -12,6 +12,9 @@ pub enum Criterion {
     Words,
     /// Sorted by increasing number of typos.
     Typo,
+    /// Dynamically sort at query time the documents. None, one or multiple Asc/Desc sortable
+    /// attributes can be used in place of this criterion at query time.
+    Sort,
     /// Sorted by increasing distance between matched query terms.
     Proximity,
     /// Documents with quey words contained in more important
@@ -38,26 +41,46 @@ impl Criterion {
 impl FromStr for Criterion {
     type Err = Error;
 
-    fn from_str(txt: &str) -> Result<Criterion, Self::Err> {
-        match txt {
+    fn from_str(text: &str) -> Result<Criterion, Self::Err> {
+        match text {
             "words" => Ok(Criterion::Words),
             "typo" => Ok(Criterion::Typo),
+            "sort" => Ok(Criterion::Sort),
             "proximity" => Ok(Criterion::Proximity),
             "attribute" => Ok(Criterion::Attribute),
             "exactness" => Ok(Criterion::Exactness),
-            text => match text.rsplit_once(':') {
-                Some((field_name, "asc")) => Ok(Criterion::Asc(field_name.to_string())),
-                Some((field_name, "desc")) => Ok(Criterion::Desc(field_name.to_string())),
-                _ => Err(UserError::InvalidCriterionName { name: text.to_string() }.into()),
+            text => match AscDesc::from_str(text) {
+                Ok(AscDesc::Asc(field)) => Ok(Criterion::Asc(field)),
+                Ok(AscDesc::Desc(field)) => Ok(Criterion::Desc(field)),
+                Err(error) => Err(error.into()),
             },
         }
     }
 }
 
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
+pub enum AscDesc {
+    Asc(String),
+    Desc(String),
+}
+
+impl FromStr for AscDesc {
+    type Err = UserError;
+
+    fn from_str(text: &str) -> Result<AscDesc, Self::Err> {
+        match text.rsplit_once(':') {
+            Some((field_name, "asc")) => Ok(AscDesc::Asc(field_name.to_string())),
+            Some((field_name, "desc")) => Ok(AscDesc::Desc(field_name.to_string())),
+            _ => Err(UserError::InvalidCriterionName { name: text.to_string() }),
+        }
+    }
+}
+
 pub fn default_criteria() -> Vec<Criterion> {
     vec![
         Criterion::Words,
         Criterion::Typo,
+        Criterion::Sort,
         Criterion::Proximity,
         Criterion::Attribute,
         Criterion::Exactness,
@@ -71,6 +94,7 @@ impl fmt::Display for Criterion {
         match self {
             Words => f.write_str("words"),
             Typo => f.write_str("typo"),
+            Sort => f.write_str("sort"),
             Proximity => f.write_str("proximity"),
             Attribute => f.write_str("attribute"),
             Exactness => f.write_str("exactness"),