Merge pull request #32 from regexident/split-up-lib-rs

Split-up lib.rs

Author: ecstatic-morse

src/iteration.rs

@@ -0,0 +1,65 @@
+use std::io::Write;
+
+use crate::variable::{Variable, VariableTrait};
+
+/// An iterative context for recursive evaluation.
+///
+/// An `Iteration` tracks monotonic variables, and monitors their progress.
+/// It can inform the user if they have ceased changing, at which point the
+/// computation should be done.
+#[derive(Default)]
+pub struct Iteration {
+    variables: Vec<Box<dyn VariableTrait>>,
+    round: u32,
+    debug_stats: Option<Box<dyn Write>>,
+}
+
+impl Iteration {
+    /// Create a new iterative context.
+    pub fn new() -> Self {
+        Self::default()
+    }
+    /// Reports whether any of the monitored variables have changed since
+    /// the most recent call.
+    pub fn changed(&mut self) -> bool {
+        self.round += 1;
+
+        let mut result = false;
+        for variable in self.variables.iter_mut() {
+            if variable.changed() {
+                result = true;
+            }
+
+            if let Some(ref mut stats_writer) = self.debug_stats {
+                variable.dump_stats(self.round, stats_writer);
+            }
+        }
+        result
+    }
+    /// Creates a new named variable associated with the iterative context.
+    pub fn variable<Tuple: Ord + 'static>(&mut self, name: &str) -> Variable<Tuple> {
+        let variable = Variable::new(name);
+        self.variables.push(Box::new(variable.clone()));
+        variable
+    }
+    /// Creates a new named variable associated with the iterative context.
+    ///
+    /// This variable will not be maintained distinctly, and may advertise tuples as
+    /// recent multiple times (perhaps unboundedly many times).
+    pub fn variable_indistinct<Tuple: Ord + 'static>(&mut self, name: &str) -> Variable<Tuple> {
+        let mut variable = Variable::new(name);
+        variable.distinct = false;
+        self.variables.push(Box::new(variable.clone()));
+        variable
+    }
+
+    /// Set up this Iteration to write debug statistics about each variable,
+    /// for each round of the computation.
+    pub fn record_stats_to(&mut self, mut w: Box<dyn Write>) {
+        // print column names header
+        writeln!(w, "Variable,Round,Stable count,Recent count")
+            .expect("Couldn't write debug stats CSV header");
+
+        self.debug_stats = Some(w);
+    }
+}