add report struct with methods

src/intersections.rs

@@ -1,5 +1,6 @@
 use crate::intersection::{Intersection, Intersections};
 use crate::position::Position;
+pub use crate::report::{Report, ReportFragment};
 #[allow(unused_imports)]
 use crate::string::String;
 use bitflags::bitflags;
@@ -115,13 +116,6 @@ impl Default for OverlapAmount {
     }
 }
 
-#[derive(Debug)]
-pub struct ReportFragment {
-    pub a: Option<Position>,
-    pub b: Vec<Position>,
-    pub id: usize,
-}
-
 impl Intersections {
     pub fn report(
         &self,
@@ -131,7 +125,7 @@ impl Intersections {
         b_part: &IntersectionPart,
         a_requirements: &OverlapAmount,
         b_requirements: &OverlapAmount,
-    ) -> Vec<ReportFragment> {
+    ) -> Report {
         // usually the result is [query, [[b1-part, b1-part2, ...], [b2-part, ...]]]],
         // in fact, usually, there's only a single b and a single interval from b, so it's:
         // [query, [[b1-part]]]
@@ -197,7 +191,7 @@ impl Intersections {
             }
         }
 
-        result
+        Report::new(result)
     }
 
     fn satisfies_requirements(

src/lib.rs

@@ -12,6 +12,9 @@ pub mod position;
 // Interval type
 pub mod interval;
 
+/// Reports from intersections.
+pub mod report;
+
 /// a std::String::String unless other string features are enabled.
 pub mod string;
 

src/report.rs

@@ -0,0 +1,38 @@
+use crate::position::Position;
+
+#[derive(Debug)]
+pub struct ReportFragment {
+    pub a: Option<Position>,
+    pub b: Vec<Position>,
+    pub id: usize,
+}
+
+#[derive(Debug)]
+pub struct Report(Vec<ReportFragment>);
+
+/// implement Indexing for Report to get each fragment
+impl std::ops::Index<usize> for Report {
+    type Output = ReportFragment;
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.0[index]
+    }
+}
+
+impl Report {
+    pub fn new(frags: Vec<ReportFragment>) -> Self {
+        Self(frags)
+    }
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+    pub fn count_overlaps_by_id(&self) -> Vec<u64> {
+        let mut result = Vec::new();
+        self.0.iter().for_each(|frag| {
+            if frag.id >= result.len() {
+                result.resize(frag.id + 1, 0);
+            }
+            result[frag.id] += frag.b.len() as u64;
+        });
+        result
+    }
+}