Start refactoring how interpreter options are split up

TODO.md

@@ -7,7 +7,7 @@
 
 
 * change 'trait' to 'interface'
-  -think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids)
+  -think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
 
 * Share state between programming languages
 

schala-repl/src/language.rs

@@ -170,4 +170,10 @@ pub trait ProgrammingLanguageInterface {
   }
   fn get_language_name(&self) -> String;
   fn get_source_file_suffix(&self) -> String;
+  fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
+    None
+  }
+  fn custom_interpreter_directives_help(&self) -> String {
+    format!(">> No custom interpreter directives specified <<")
+  }
 }

schala-repl/src/lib.rs

@@ -214,6 +214,74 @@ impl Repl {
     interpreter_output.to_repl()
   }
 
+  fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
+    let mut iter = input.chars();
+    iter.next();
+    let commands: Vec<&str> = iter
+      .as_str()
+      .split_whitespace()
+      .collect();
+
+    let cmd: &str = match commands.get(0).clone() {
+      None => return None,
+      Some(s) => s
+    };
+
+    match cmd {
+      "exit" | "quit"  => {
+        self.save_options();
+        exit(0)
+      },
+      "lang" | "language" => match commands.get(1) {
+        Some(&"show") => {
+          let mut buf = String::new();
+          for (i, lang) in self.languages.iter().enumerate() {
+            write!(buf, "{}{}\n", if i == self.current_language_index { "* "} else { "" }, lang.get_language_name()).unwrap();
+          }
+          Some(buf)
+        },
+        Some(&"go") => match commands.get(2) {
+          None => Some(format!("Must specify a language name")),
+          Some(&desired_name) => {
+            for (i, _) in self.languages.iter().enumerate() {
+              let lang_name = self.languages[i].get_language_name();
+              if lang_name.to_lowercase() == desired_name.to_lowercase() {
+                self.current_language_index = i;
+                return Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()));
+              }
+            }
+            Some(format!("Language {} not found", desired_name))
+          }
+        },
+        Some(&"next") | Some(&"n") => {
+          self.current_language_index = (self.current_language_index + 1) % self.languages.len();
+          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
+        },
+        Some(&"previous") | Some(&"p") | Some(&"prev") => { 
+          self.current_language_index = if self.current_language_index == 0 { self.languages.len() - 1 } else { self.current_language_index - 1 };
+          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
+        },
+        Some(e) => Some(format!("Bad `lang(uage)` argument: {}", e)),
+        None => Some(format!("Valid arguments for `lang(uage)` are `show`, `next`|`n`, `previous`|`prev`|`n`"))
+      },
+      "help" =>  {
+        let mut buf = String::new();
+        let ref lang = self.languages[self.current_language_index];
+
+        writeln!(buf, "MetaInterpreter options").unwrap();
+        writeln!(buf, "-----------------------").unwrap();
+        writeln!(buf, "exit | quit - exit the REPL").unwrap();
+        writeln!(buf, "lang [prev|next|go <name> |show] - toggle to previous or next language, go to a specific language by name, or show all languages").unwrap();
+        writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
+        writeln!(buf, "-----------------------").unwrap();
+        writeln!(buf, "{}", lang.custom_interpreter_directives_help()).unwrap();
+        Some(buf)
+      },
+      _ => self.languages[self.current_language_index].handle_custom_interpreter_directives(&commands),
+    }
+  }
+
+  /*
   fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
     let mut iter = input.chars();
     iter.next();
@@ -309,6 +377,7 @@ tokens: {}, parse: {}, ast: {}, symbols: {}"#, tokens, parse_tree, ast, symbol_t
       e => Some(format!("Unknown command: {}", e))
     }
   }
+  */
 }
 
 /*