added everygrams

src/edit_distance.rs

@@ -1,3 +1,5 @@
+// sandbox, to be removed
+
 use unicode_segmentation::UnicodeSegmentation;
 
 //could also be powers of 2 that are combined using bitwise-or

src/lib.rs

@@ -1,4 +1,4 @@
-mod edit_distance;
-mod ngrams;
+mod edit_distance; // to be removed
+mod ngrams;// to be removed
 pub mod lm;
 pub mod util;

src/ngrams.rs

@@ -1,3 +1,4 @@
+// sandbox, to be removed
 use std::cmp::Ordering;
 use std::collections::BTreeMap;
 

src/util/mod.rs

@@ -64,6 +64,10 @@ pub fn trigrams<'a>(sequence: impl Iterator<Item=&'a &'a str> + 'a) -> impl Iter
     ngrams::NGramSequenceIter::new(sequence, 3)
 }
 
+pub fn everygrams<'a>(sequence: impl Iterator<Item=&'a &'a str> + 'a, n: usize) -> impl Iterator<Item=impl Iterator<Item=&'a &'a str> + 'a> + 'a {
+    ngrams::EveryGramSequenceIter::everygrams(sequence, n)
+}
+
 #[cfg(test)]
 mod tests {
     use std::slice::Iter;
@@ -154,10 +158,45 @@ mod tests {
         should_be_equal_list_of_lists(&mut bigrams, expected)
     }
 
-    fn should_be_equal_list_of_lists<'a>(bigrams: &mut impl Iterator<Item=impl Iterator<Item=&'a &'a str>>, expected: Vec<Iter<&'a str>>) {
-        for (mut left_outer, mut right_outer) in bigrams.zip(expected.into_iter()) {
-            for (left_inner, right_inner) in left_outer.zip(right_outer) {
-                assert_eq!(left_inner, right_inner);
+
+    #[test]
+    fn test_everygrams_n_eq_2() {
+        let sequence = vec!["a", "b", "c", "d"];
+        let mut bigrams = everygrams(sequence.iter(), 2);
+        let gram1 = vec!["a"];
+        let gram2 = vec!["a", "b"];
+        let gram3 = vec!["b"];
+        let gram4 = vec!["b", "c"];
+        let gram5 = vec!["c"];
+        let gram6 = vec!["c", "d"];
+        let expected = vec![gram1.iter(), gram2.iter(), gram3.iter(), gram4.iter(), gram5.iter(), gram6.iter()];
+
+        should_be_equal_list_of_lists(&mut bigrams, expected)
+    }
+
+    #[test]
+    fn test_everygrams_n_eq_3() {
+        let sequence = vec!["a", "b", "c", "d", "e"];
+        let mut bigrams = everygrams(sequence.iter(), 3);
+        let gram1 = vec!["a"];
+        let gram2 = vec!["a", "b"];
+        let gram3 = vec!["a", "b", "c"];
+        let gram4 = vec!["b"];
+        let gram5 = vec!["b", "c"];
+        let gram6 = vec!["b", "c", "d"];
+        let gram7 = vec!["c"];
+        let gram8 = vec!["c", "d"];
+        let gram9 = vec!["c", "d", "e"];
+        let expected = vec![gram1.iter(), gram2.iter(), gram3.iter(), gram4.iter(), gram5.iter(), gram6.iter(), gram7.iter(), gram8.iter(), gram9.iter()];
+
+        should_be_equal_list_of_lists(&mut bigrams, expected)
+    }
+
+    fn should_be_equal_list_of_lists<'a>(actual: &mut impl Iterator<Item=impl Iterator<Item=&'a &'a str>>, expected: Vec<Iter<&'a str>>) {
+        for (mut actual_outer, expected_outer) in actual.zip(expected.into_iter()) {
+            for (actual_inner, expected_inner) in actual_outer.zip(expected_outer) {
+                // println!("{} {}", actual_inner, expected_inner);
+                assert_eq!(actual_inner, expected_inner);
             }
         }
     }

src/util/ngrams.rs

@@ -40,3 +40,50 @@ impl<'a> Iterator for NGramSequenceIter<'a> {
         };
     }
 }
+
+pub struct EveryGramSequenceIter<'a> {
+    sequence: Box<dyn Iterator<Item=&'a &'a str> + 'a>,
+    n: usize,
+    current_ngram: Vec<&'a &'a str>,
+    current_size: usize,
+}
+
+impl<'a> EveryGramSequenceIter<'a> {
+    pub(crate) fn everygrams(sequence: impl Iterator<Item=&'a &'a str> + 'a, n: usize) -> Self {
+        Self {
+            sequence: Box::new(sequence),
+            n,
+            current_ngram: Vec::new(),
+            current_size: 0,
+        }
+    }
+}
+
+impl<'a> Iterator for EveryGramSequenceIter<'a> {
+    type Item = Box<dyn Iterator<Item=&'a &'a str> + 'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_ngram.len() == 0 {
+            for i in 0..self.n {
+                if let Some(item) = self.sequence.next() {
+                    self.current_ngram.push(item);
+                } else {
+                    return None; // n > len
+                }
+            }
+        }
+
+        self.current_size += 1;
+
+        if self.current_size > self.n {
+            self.current_size = 1;
+            self.current_ngram.remove(0);
+            let maybe_next = self.sequence.next();
+            if maybe_next.is_some() {
+                self.current_ngram.push(&maybe_next.unwrap());
+            } else { return None; }
+        }
+
+        return Some(Box::new(self.current_ngram.clone().into_iter().take(self.current_size)));
+    }
+}