all: split reusable components into workspace crates

criteria/src/crit_matchers/critm_exactly.rs

@@ -0,0 +1,61 @@
+use {
+    crate::crit_graph::{CritMiddleCriterion, CritTarget, CritUpstreamNode},
+    std::{marker::PhantomData, rc::Rc},
+};
+
+pub struct CritMatchExactly<Target> {
+    total: usize,
+    num: usize,
+    not: bool,
+    _phantom: PhantomData<fn(&Target)>,
+}
+
+impl<Target> CritMatchExactly<Target> {
+    pub fn new(upstream: &[Rc<dyn CritUpstreamNode<Target>>], num: usize) -> Self {
+        Self {
+            total: upstream.len(),
+            num,
+            not: false,
+            _phantom: Default::default(),
+        }
+    }
+}
+
+impl<Target> CritMiddleCriterion<Target> for CritMatchExactly<Target>
+where
+    Target: CritTarget,
+{
+    type Data = usize;
+    type Not = Self;
+
+    fn update_matched(&self, _data: &Target, node: &mut usize, matched: bool) -> bool {
+        if matched {
+            *node += 1;
+        } else {
+            *node -= 1;
+        }
+        (*node == self.num) ^ self.not
+    }
+
+    fn pull(&self, upstream: &[Rc<dyn CritUpstreamNode<Target>>], node: &Target) -> bool {
+        let mut n = 0;
+        for upstream in upstream {
+            if upstream.pull(node) {
+                n += 1;
+            }
+        }
+        (n == self.num) ^ self.not
+    }
+
+    fn not(&self) -> Self
+    where
+        Self: Sized,
+    {
+        Self {
+            total: self.total,
+            num: self.total - self.num,
+            not: !self.not,
+            _phantom: Default::default(),
+        }
+    }
+}