Encapsulate FunctionsLib to hold script-defined functions.

src/optimize.rs

@@ -180,16 +180,15 @@ fn optimize_stmt<'a>(stmt: Stmt, state: &mut State<'a>, preserve_result: bool) -
             // Optimize each statement in the block
             let mut result: Vec<_> = block
                 .into_iter()
-                .map(|stmt| {
-                    if let Stmt::Const(name, value, pos) = stmt {
-                        // Add constant into the state
+                .map(|stmt| match stmt {
+                    // Add constant into the state
+                    Stmt::Const(name, value, pos) => {
                         state.push_constant(&name, *value);
                         state.set_dirty();
                         Stmt::Noop(pos) // No need to keep constants
-                    } else {
-                        // Optimize the statement
-                        optimize_stmt(stmt, state, preserve_result)
                     }
+                    // Optimize the statement
+                    _ => optimize_stmt(stmt, state, preserve_result),
                 })
                 .collect();
 
@@ -445,7 +444,7 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
                 && args.iter().all(|expr| expr.is_constant()) // all arguments are constants
         => {
             // First search in script-defined functions (can override built-in)
-            if state.engine.script_functions.binary_search_by(|f| f.compare(&id, args.len())).is_ok() {
+            if state.engine.fn_lib.has_function(&id, args.len()) {
                 // A script-defined function overrides the built-in function - do not make the call
                 return Expr::FunctionCall(id, args.into_iter().map(|a| optimize_expr(a, state)).collect(), def_value, pos);
             }