Adding documentation for classical.rs, modifying compute_step with pointers

src/rsprocess/classical.rs

@@ -1,13 +1,24 @@
+//! Definitions for the 'classical' mechanism for computation.
+//!
+//! This initial part allows to define the 'classical' mechanism to compute in a
+//! Reaction System (RS) Framework.
+//! The data is held in RSset or RSreaction, in the latter the reagents,
+//! inhibitors and products are held.
+
 use super::structure::{RSset, RSreaction};
 
-pub fn compute_step<'a>(current_state: &RSset<'a>, reaction: &RSreaction<'a>) -> RSset<'a> {
+/// Computes the result of a single reaction (if enabled returns the products)
+/// otherwise returns None.
+pub fn compute_step<'a>(current_state: &RSset<'a>, reaction: &'a RSreaction<'a>) -> Option<&'a RSset<'a>> {
     if reaction.enabled(current_state) {
-	reaction.products_clone()
+	Some(reaction.products())
     } else {
-	RSset::new()
+	None
     }
 }
 
-pub fn compute_all<'a>(current_state: &RSset<'a>, reactions: Vec<&RSreaction<'a>>) -> RSset<'a> {
-    reactions.iter().fold(RSset::new(), |acc, r| acc.union(&compute_step(current_state, r)))
+/// Computes the result of a series of reactions. Returns the union of all
+/// products.
+pub fn compute_all<'a>(current_state: &RSset<'a>, reactions: Vec<&'a RSreaction<'a>>) -> RSset<'a> {
+    reactions.iter().fold(RSset::new(), |acc, r| acc.union_option(compute_step(current_state, r)))
 }