Fix operator preference at loop.first

askama_derive/src/generator.rs

@@ -747,14 +747,14 @@ impl<'a> Generator<'a> {
     fn visit_attr(&mut self, buf: &mut Buffer, obj: &Expr, attr: &str) -> DisplayWrap {
         if let Expr::Var(name) = *obj {
             if name == "loop" {
-                buf.write("_loop_index");
                 if attr == "index" {
-                    buf.write(" + 1");
+                    buf.write("_loop_index + 1");
                     return DisplayWrap::Unwrapped;
                 } else if attr == "index0" {
+                    buf.write("_loop_index");
                     return DisplayWrap::Unwrapped;
                 } else if attr == "first" {
-                    buf.write(" == 0");
+                    buf.write("(_loop_index == 0)");
                     return DisplayWrap::Unwrapped;
                 } else {
                     panic!("unknown loop variable");

testing/templates/precedence-for.html

@@ -0,0 +1,3 @@
+{% for s in strings %}
+    {{- loop.index0 }}. {{ s }}{% if !loop.first %}{% else %} (first){% endif %}
+{% endfor %}

testing/tests/loops.rs

@@ -32,3 +32,17 @@ fn test_nested_for() {
     };
     assert_eq!(s.render().unwrap(), "1\n  0a1b2c2\n  0one1two");
 }
+
+#[derive(Template)]
+#[template(path = "precedence-for.html")]
+struct PrecedenceTemplate<'a> {
+    strings: Vec<&'a str>,
+}
+
+#[test]
+fn test_precedence_for() {
+    let s = PrecedenceTemplate {
+        strings: vec!["A", "alfa", "1"],
+    };
+    assert_eq!(s.render().unwrap(), "0. A (first)\n1. alfa\n2. 1\n");
+}