diff --git a/examples/serve-console.rs b/examples/serve-console.rs
index 5ef119013..21def0676 100644
--- a/examples/serve-console.rs
+++ b/examples/serve-console.rs
@@ -6,7 +6,8 @@ use std::path::PathBuf;
 use fst::Streamer;
 use elapsed::measure_time;
 use rocksdb::{DB, DBOptions, IngestExternalFileOptions};
-use raptor::{automaton, Metadata, RankedStream, CommonWords};
+use raptor::{automaton, Metadata, CommonWords};
+use raptor::rank;
 
 #[derive(Debug, StructOpt)]
 pub struct CommandConsole {
@@ -69,14 +70,21 @@ fn search(metadata: &Metadata, database: &DB, common_words: &CommonWords, query:
         automatons.push(lev);
     }
 
-    let mut stream = RankedStream::new(&metadata, automatons, 20);
+    let config = rank::Config {
+        criteria: rank::criterion::default(),
+        metadata: &metadata,
+        automatons: automatons,
+        limit: 20,
+    };
+
+    let mut stream = rank::RankedStream::new(config);
     while let Some(document) = stream.next() {
-        let id_key = format!("{}-id", document.document_id);
+        let id_key = format!("{}-id", document.id);
         let id = database.get(id_key.as_bytes()).unwrap().unwrap();
         let id = unsafe { from_utf8_unchecked(&id) };
         print!("{} ", id);
 
-        let title_key = format!("{}-title", document.document_id);
+        let title_key = format!("{}-title", document.id);
         let title = database.get(title_key.as_bytes()).unwrap().unwrap();
         let title = unsafe { from_utf8_unchecked(&title) };
         println!("{:?}", title);
diff --git a/examples/serve-http.rs b/examples/serve-http.rs
index 7bad1dd99..4581f512b 100644
--- a/examples/serve-http.rs
+++ b/examples/serve-http.rs
@@ -7,7 +7,7 @@ use std::path::PathBuf;
 use std::error::Error;
 use std::sync::Arc;
 
-use raptor::rank::RankedStream;
+use raptor::rank;
 use raptor::{automaton, Metadata, CommonWords};
 use rocksdb::{DB, DBOptions, IngestExternalFileOptions};
 use fst::Streamer;
@@ -100,26 +100,33 @@ where M: AsRef<Metadata>,
         automatons.push(lev);
     }
 
-    let mut stream = RankedStream::new(metadata.as_ref(), automatons, 20);
+    let config = rank::Config {
+        criteria: rank::criterion::default(),
+        metadata: metadata.as_ref(),
+        automatons: automatons,
+        limit: 20,
+    };
+
+    let mut stream = rank::RankedStream::new(config);
     let mut body = Vec::new();
     write!(&mut body, "[")?;
 
     let mut first = true;
     while let Some(document) = stream.next() {
-        let title_key = format!("{}-title", document.document_id);
+        let title_key = format!("{}-title", document.id);
         let title = database.as_ref().get(title_key.as_bytes()).unwrap().unwrap();
         let title = unsafe { from_utf8_unchecked(&title) };
 
-        let description_key = format!("{}-description", document.document_id);
+        let description_key = format!("{}-description", document.id);
         let description = database.as_ref().get(description_key.as_bytes()).unwrap().unwrap();
         let description = unsafe { from_utf8_unchecked(&description) };
 
-        let image_key = format!("{}-image", document.document_id);
+        let image_key = format!("{}-image", document.id);
         let image = database.as_ref().get(image_key.as_bytes()).unwrap().unwrap();
         let image = unsafe { from_utf8_unchecked(&image) };
 
         let document = Document {
-            id: document.document_id,
+            id: document.id,
             title: title,
             description: description,
             image: image,
diff --git a/src/lib.rs b/src/lib.rs
index 84b325077..ab4597301 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,7 +8,6 @@ pub mod tokenizer;
 mod common_words;
 
 pub use self::metadata::{Metadata, MetadataBuilder};
-pub use self::rank::RankedStream;
 pub use self::tokenizer::Tokenizer;
 pub use self::common_words::CommonWords;
 
diff --git a/src/rank/exact.rs b/src/rank/criterion/exact.rs
similarity index 100%
rename from src/rank/exact.rs
rename to src/rank/criterion/exact.rs
diff --git a/src/rank/criterion/mod.rs b/src/rank/criterion/mod.rs
new file mode 100644
index 000000000..31b188d63
--- /dev/null
+++ b/src/rank/criterion/mod.rs
@@ -0,0 +1,71 @@
+mod sum_of_typos;
+mod number_of_words;
+mod words_proximity;
+mod sum_of_words_attribute;
+mod sum_of_words_position;
+mod exact;
+
+use std::vec;
+use std::cmp::Ordering;
+use crate::rank::Document;
+
+pub use self::{
+    sum_of_typos::sum_of_typos,
+    number_of_words::number_of_words,
+    words_proximity::words_proximity,
+    sum_of_words_attribute::sum_of_words_attribute,
+    sum_of_words_position::sum_of_words_position,
+    exact::exact,
+};
+
+#[inline]
+pub fn document_id(lhs: &Document, rhs: &Document) -> Ordering {
+    lhs.id.cmp(&rhs.id)
+}
+
+#[derive(Debug)]
+pub struct Criteria<F>(Vec<F>);
+
+impl<F> Criteria<F> {
+    pub fn new() -> Self {
+        Criteria(Vec::new())
+    }
+
+    pub fn with_capacity(cap: usize) -> Self {
+        Criteria(Vec::with_capacity(cap))
+    }
+
+    pub fn push(&mut self, criterion: F) {
+        self.0.push(criterion)
+    }
+
+    pub fn add(mut self, criterion: F) -> Self {
+        self.push(criterion);
+        self
+    }
+}
+
+impl<F> IntoIterator for Criteria<F> {
+    type Item = F;
+    type IntoIter = vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
+pub fn default() -> Criteria<impl Fn(&Document, &Document) -> Ordering + Copy> {
+    let functions = &[
+        sum_of_typos,
+        number_of_words,
+        words_proximity,
+        sum_of_words_attribute,
+        sum_of_words_position,
+        exact,
+        document_id,
+    ];
+
+    let mut criteria = Criteria::with_capacity(functions.len());
+    for f in functions { criteria.push(f) }
+    criteria
+}
diff --git a/src/rank/number_of_words.rs b/src/rank/criterion/number_of_words.rs
similarity index 100%
rename from src/rank/number_of_words.rs
rename to src/rank/criterion/number_of_words.rs
diff --git a/src/rank/sum_of_typos.rs b/src/rank/criterion/sum_of_typos.rs
similarity index 100%
rename from src/rank/sum_of_typos.rs
rename to src/rank/criterion/sum_of_typos.rs
diff --git a/src/rank/sum_of_words_attribute.rs b/src/rank/criterion/sum_of_words_attribute.rs
similarity index 100%
rename from src/rank/sum_of_words_attribute.rs
rename to src/rank/criterion/sum_of_words_attribute.rs
diff --git a/src/rank/sum_of_words_position.rs b/src/rank/criterion/sum_of_words_position.rs
similarity index 100%
rename from src/rank/sum_of_words_position.rs
rename to src/rank/criterion/sum_of_words_position.rs
diff --git a/src/rank/words_proximity.rs b/src/rank/criterion/words_proximity.rs
similarity index 100%
rename from src/rank/words_proximity.rs
rename to src/rank/criterion/words_proximity.rs
diff --git a/src/rank/mod.rs b/src/rank/mod.rs
index e7a50003d..0fe544ae1 100644
--- a/src/rank/mod.rs
+++ b/src/rank/mod.rs
@@ -1,29 +1,9 @@
-mod sum_of_typos;
-mod number_of_words;
-mod words_proximity;
-mod sum_of_words_attribute;
-mod sum_of_words_position;
-mod exact;
+pub mod criterion;
+mod ranked_stream;
 
-use std::cmp::Ordering;
-use std::rc::Rc;
-use std::{mem, vec};
-use fst::Streamer;
-use fnv::FnvHashMap;
-use group_by::GroupByMut;
-use crate::automaton::{DfaExt, AutomatonExt};
-use crate::metadata::Metadata;
-use crate::metadata::ops::{OpBuilder, Union};
 use crate::{Match, DocumentId};
 
-use self::{
-    sum_of_typos::sum_of_typos,
-    number_of_words::number_of_words,
-    words_proximity::words_proximity,
-    sum_of_words_attribute::sum_of_words_attribute,
-    sum_of_words_position::sum_of_words_position,
-    exact::exact,
-};
+pub use self::ranked_stream::{RankedStream, Config};
 
 #[inline]
 fn match_query_index(a: &Match, b: &Match) -> bool {
@@ -32,7 +12,7 @@ fn match_query_index(a: &Match, b: &Match) -> bool {
 
 #[derive(Debug, Clone)]
 pub struct Document {
-    pub document_id: DocumentId,
+    pub id: DocumentId,
     pub matches: Vec<Match>,
 }
 
@@ -41,129 +21,7 @@ impl Document {
         Self::from_sorted_matches(doc, vec![match_])
     }
 
-    pub fn from_sorted_matches(doc: DocumentId, matches: Vec<Match>) -> Self {
-        Self {
-            document_id: doc,
-            matches: matches,
-        }
-    }
-}
-
-fn matches_into_iter(matches: FnvHashMap<DocumentId, Vec<Match>>, limit: usize) -> vec::IntoIter<Document> {
-    let mut documents: Vec<_> = matches.into_iter().map(|(id, mut matches)| {
-        matches.sort_unstable();
-        Document::from_sorted_matches(id, matches)
-    }).collect();
-
-    let sorts = &[
-        sum_of_typos,
-        number_of_words,
-        words_proximity,
-        sum_of_words_attribute,
-        sum_of_words_position,
-        exact,
-    ];
-
-    let mut groups = vec![documents.as_mut_slice()];
-
-    for sort in sorts {
-        let temp = mem::replace(&mut groups, Vec::new());
-        let mut computed = 0;
-
-        'grp: for group in temp {
-            group.sort_unstable_by(sort);
-            for group in GroupByMut::new(group, |a, b| sort(a, b) == Ordering::Equal) {
-                computed += group.len();
-                groups.push(group);
-                if computed >= limit { break 'grp }
-            }
-        }
-    }
-
-    documents.truncate(limit);
-    documents.into_iter()
-}
-
-pub struct RankedStream<'m>(RankedStreamInner<'m>);
-
-impl<'m> RankedStream<'m> {
-    pub fn new(metadata: &'m Metadata, automatons: Vec<DfaExt>, limit: usize) -> Self {
-        let automatons: Vec<_> = automatons.into_iter().map(Rc::new).collect();
-        let mut builder = OpBuilder::with_automatons(automatons.clone());
-        builder.push(metadata);
-
-        let inner = RankedStreamInner::Fed {
-            inner: builder.union(),
-            automatons: automatons,
-            limit: limit,
-            matches: FnvHashMap::default(),
-        };
-
-        RankedStream(inner)
-    }
-}
-
-impl<'m, 'a> fst::Streamer<'a> for RankedStream<'m> {
-    type Item = Document;
-
-    fn next(&'a mut self) -> Option<Self::Item> {
-        self.0.next()
-    }
-}
-
-enum RankedStreamInner<'m> {
-    Fed {
-        inner: Union<'m>,
-        automatons: Vec<Rc<DfaExt>>,
-        limit: usize,
-        matches: FnvHashMap<DocumentId, Vec<Match>>,
-    },
-    Pours {
-        inner: vec::IntoIter<Document>,
-    },
-}
-
-impl<'m, 'a> fst::Streamer<'a> for RankedStreamInner<'m> {
-    type Item = Document;
-
-    fn next(&'a mut self) -> Option<Self::Item> {
-        loop {
-            match self {
-                RankedStreamInner::Fed { inner, automatons, limit, matches } => {
-                    match inner.next() {
-                        Some((string, indexed_values)) => {
-                            for iv in indexed_values {
-
-                                let automaton = &automatons[iv.index];
-                                let distance = automaton.eval(string).to_u8();
-                                let same_length = string.len() == automaton.query_len();
-
-                                for di in iv.doc_indexes.as_slice() {
-                                    let match_ = Match {
-                                        query_index: iv.index as u32,
-                                        distance: distance,
-                                        attribute: di.attribute,
-                                        attribute_index: di.attribute_index,
-                                        is_exact: distance == 0 && same_length,
-                                    };
-                                    matches.entry(di.document)
-                                           .or_insert_with(Vec::new)
-                                           .push(match_);
-                                }
-                            }
-                        },
-                        None => {
-                            let matches = mem::replace(matches, FnvHashMap::default());
-                            *self = RankedStreamInner::Pours {
-                                inner: matches_into_iter(matches, *limit).into_iter()
-                            };
-                        },
-                    }
-                },
-                RankedStreamInner::Pours { inner } => {
-                    return inner.next()
-                },
-            }
-        }
+    pub fn from_sorted_matches(id: DocumentId, matches: Vec<Match>) -> Self {
+        Self { id, matches }
     }
 }
diff --git a/src/rank/ranked_stream.rs b/src/rank/ranked_stream.rs
new file mode 100644
index 000000000..e395eb4a9
--- /dev/null
+++ b/src/rank/ranked_stream.rs
@@ -0,0 +1,141 @@
+use std::cmp::Ordering;
+use std::rc::Rc;
+use std::{mem, vec};
+
+use fnv::FnvHashMap;
+use fst::Streamer;
+use group_by::GroupByMut;
+
+use crate::automaton::{DfaExt, AutomatonExt};
+use crate::metadata::Metadata;
+use crate::metadata::ops::{OpBuilder, Union};
+use crate::rank::criterion::Criteria;
+use crate::rank::Document;
+use crate::{Match, DocumentId};
+
+pub struct Config<'m, F> {
+    pub criteria: Criteria<F>,
+    pub metadata: &'m Metadata,
+    pub automatons: Vec<DfaExt>,
+    pub limit: usize,
+}
+
+pub struct RankedStream<'m, F>(RankedStreamInner<'m, F>);
+
+impl<'m, F> RankedStream<'m, F> {
+    pub fn new(config: Config<'m, F>) -> Self {
+        let automatons: Vec<_> = config.automatons.into_iter().map(Rc::new).collect();
+        let mut builder = OpBuilder::with_automatons(automatons.clone());
+        builder.push(config.metadata);
+
+        let inner = RankedStreamInner::Fed {
+            inner: builder.union(),
+            automatons: automatons,
+            criteria: config.criteria,
+            limit: config.limit,
+            matches: FnvHashMap::default(),
+        };
+
+        RankedStream(inner)
+    }
+}
+
+impl<'m, 'a, F> fst::Streamer<'a> for RankedStream<'m, F>
+where F: Fn(&Document, &Document) -> Ordering + Copy,
+{
+    type Item = Document;
+
+    fn next(&'a mut self) -> Option<Self::Item> {
+        self.0.next()
+    }
+}
+
+enum RankedStreamInner<'m, F> {
+    Fed {
+        inner: Union<'m>,
+        automatons: Vec<Rc<DfaExt>>,
+        criteria: Criteria<F>,
+        limit: usize,
+        matches: FnvHashMap<DocumentId, Vec<Match>>,
+    },
+    Pours {
+        inner: vec::IntoIter<Document>,
+    },
+}
+
+impl<'m, 'a, F> fst::Streamer<'a> for RankedStreamInner<'m, F>
+where F: Fn(&Document, &Document) -> Ordering + Copy,
+{
+    type Item = Document;
+
+    fn next(&'a mut self) -> Option<Self::Item> {
+        loop {
+            match self {
+                RankedStreamInner::Fed { inner, automatons, criteria, limit, matches } => {
+                    match inner.next() {
+                        Some((string, indexed_values)) => {
+                            for iv in indexed_values {
+                                let automaton = &automatons[iv.index];
+                                let distance = automaton.eval(string).to_u8();
+                                let same_length = string.len() == automaton.query_len();
+
+                                for di in iv.doc_indexes.as_slice() {
+                                    let match_ = Match {
+                                        query_index: iv.index as u32,
+                                        distance: distance,
+                                        attribute: di.attribute,
+                                        attribute_index: di.attribute_index,
+                                        is_exact: distance == 0 && same_length,
+                                    };
+                                    matches.entry(di.document)
+                                           .or_insert_with(Vec::new)
+                                           .push(match_);
+                                }
+                            }
+                        },
+                        None => {
+                            let matches = mem::replace(matches, FnvHashMap::default());
+                            let criteria = mem::replace(criteria, Criteria::new());
+                            *self = RankedStreamInner::Pours {
+                                inner: matches_into_iter(matches, criteria, *limit).into_iter()
+                            };
+                        },
+                    }
+                },
+                RankedStreamInner::Pours { inner } => {
+                    return inner.next()
+                },
+            }
+        }
+    }
+}
+
+fn matches_into_iter<F>(matches: FnvHashMap<DocumentId, Vec<Match>>,
+                        criteria: Criteria<F>,
+                        limit: usize) -> vec::IntoIter<Document>
+where F: Fn(&Document, &Document) -> Ordering + Copy,
+{
+    let mut documents: Vec<_> = matches.into_iter().map(|(id, mut matches)| {
+        matches.sort_unstable();
+        Document::from_sorted_matches(id, matches)
+    }).collect();
+
+    let mut groups = vec![documents.as_mut_slice()];
+
+    for sort in criteria {
+        let temp = mem::replace(&mut groups, Vec::new());
+        let mut computed = 0;
+
+        'grp: for group in temp {
+            group.sort_unstable_by(sort);
+            for group in GroupByMut::new(group, |a, b| sort(a, b) == Ordering::Equal) {
+                computed += group.len();
+                groups.push(group);
+                if computed >= limit { break 'grp }
+            }
+        }
+    }
+
+    documents.truncate(limit);
+    documents.into_iter()
+}