Split Rule::update in several functions

Also optimization with a static Regex

Cargo.toml

@@ -16,3 +16,4 @@ serde_yaml = "0.7"
 serde_json = "1.0"
 # Regex support
 regex = "1.3"
+lazy_static = "1.4.0"

src/lib.rs

@@ -12,6 +12,9 @@
 //! [original software](https://github.com/ceronyon/LangEvolve) which applies
 //! user-defined sound changes to words and texts based on regex expressions.
 
+#[macro_use]
+extern crate lazy_static;
+
 use std::fs::File;
 extern crate log;
 extern crate simplelog;

src/settings/rule/mod.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 extern crate serde;
 extern crate serde_json;
 extern crate serde_yaml;
@@ -31,16 +33,23 @@ impl Rule {
         }
     }
 
-    // TODO break categories in different rules
-    pub fn update(
-        &self,
-        categories: &std::collections::HashMap<String, String>,
-    ) -> std::result::Result<Rule, String> {
+    fn detect_categories(&self) -> (u8, u8) {
+        lazy_static! {
+            static ref RE : Regex = Regex::new("%([A-Z])");
+        }
+        let captures_from = match RE.captures(self.from.as_str()) {
+            None => 0 as u8,
+            Some(c) => c.len() as u8,
+        };
+        let captures_to = match RE.captures(&self.to) {
+            None => 0 as u8,
+            Some(c) => c.len() as u8,
+        };
+        (captures_from, captures_to)
+    }
+
+    fn simple_rewrite(&self, categories: &HashMap<String, String>) -> Self {
         let mut rule = self.clone();
-        let re = Regex::new("%\\D");
-        let from_match = re.is_match(&self.from.as_str());
-        let to_match = re.is_match(&self.to.as_str());
-        if from_match && !to_match {
         for (category, content) in categories {
             rule.from = Regex::new(
                 rule.from
@@ -49,10 +58,29 @@ impl Rule {
                         format!("%{}", category).as_str(),
                         format!("[{}]", content).as_str(),
                     )
-                        .as_str(),
+                    .as_str()
             );
         }
+        rule
     }
+
+    // TODO break categories in different rules
+    pub fn update(
+        &self,
+        categories: &HashMap<String, String>,
+    ) -> std::result::Result<Rule, String> {
+        let mut rule = self.clone();
+        let (from_match, to_match) = self.detect_categories();
+        // If there are only simple rewrites to make in the from String
+        if from_match > 0 && to_match == 0 {
+            rule = self.simple_rewrite(&categories);
+        }
+
+        // If there are equivalences between from and to
+        if from_match > 0 && to_match <= from_match && to_match > 0 {
+
+        }
+
         Ok(rule)
     }