cli: Continue on new line when missing closing group symbol

cli/src/repl.rs

@@ -192,7 +192,22 @@ impl Hinter for RLHelper {
 
 impl Validator for RLHelper {
     fn validate(&self, ctx: &mut ValidationContext) -> Result<ValidationResult, ReadlineError> {
-        self.validator.validate(ctx)
+        let mut group_symbol_count = vec![0i32, 0i32, 0i32];
+
+        for c in ctx.input().chars() {
+            match c {
+                '⌈' | '⌉' => group_symbol_count[0] += 1,
+                '⌊' | '⌋' => group_symbol_count[1] += 1,
+                '|' => group_symbol_count[2] += 1,
+                _ => (),
+            }
+        }
+
+        if !group_symbol_count.into_iter().all(|x| x % 2 == 0) {
+            Ok(ValidationResult::Incomplete)
+        } else {
+            self.validator.validate(ctx)
+        }
     }
 
     fn validate_while_typing(&self) -> bool {

kalk/src/parser.rs

@@ -569,7 +569,6 @@ fn parse_group_fn(context: &mut Context) -> Result<Expr, CalcError> {
     };
 
     let expr = parse_expr(context)?;
-    advance(context);
 
     if peek(context).kind == TokenKind::EOF {
         return Err(CalcError::Expected(String::from(
@@ -577,6 +576,8 @@ fn parse_group_fn(context: &mut Context) -> Result<Expr, CalcError> {
         )));
     }
 
+    advance(context);
+
     Ok(Expr::FnCall(Identifier::from_full_name(name), vec![expr]))
 }