Add support for Index operation (see #95)

2 files changed, 25 insertions, 1 deletions

diff --git a/askama_derive/src/generator.rs b/askama_derive/src/generator.rs
index 59d8134..0e86a27 100644
--- a/askama_derive/src/generator.rs
+++ b/askama_derive/src/generator.rs
@@ -594,6 +594,7 @@ impl<'a> Generator<'a> {
             Expr::Path(ref path) => self.visit_path(path, code),
             Expr::Array(ref elements) => self.visit_array(elements, code),
             Expr::Attr(ref obj, name) => self.visit_attr(obj, name, code),
+            Expr::Index(ref obj, ref key) => self.visit_index(obj, key, code),
             Expr::Filter(name, ref args) => self.visit_filter(name, args, code),
             Expr::Unary(op, ref inner) => self.visit_unary(op, inner, code),
             Expr::BinOp(op, ref left, ref right) => self.visit_binop(op, left, right, code),
@@ -728,6 +729,14 @@ impl<'a> Generator<'a> {
         DisplayWrap::Unwrapped
     }
 
+    fn visit_index(&mut self, obj: &Expr, key: &Expr, code: &mut String) -> DisplayWrap {
+        self.visit_expr(obj, code);
+        code.push_str("[");
+        self.visit_expr(key, code);
+        code.push_str("]");
+        DisplayWrap::Unwrapped
+    }
+
     fn visit_method_call(
         &mut self,
         obj: &Expr,
diff --git a/askama_derive/src/parser.rs b/askama_derive/src/parser.rs
index 96e0f09..c8bbb96 100644
--- a/askama_derive/src/parser.rs
+++ b/askama_derive/src/parser.rs
@@ -12,6 +12,7 @@ pub enum Expr<'a> {
     Path(Vec<&'a str>),
     Array(Vec<Expr<'a>>),
     Attr(Box<Expr<'a>>, &'a str),
+    Index(Box<Expr<'a>>, Box<Expr<'a>>),
     Filter(&'a str, Vec<Expr<'a>>),
     Unary(&'a str, Box<Expr<'a>>),
     BinOp(&'a str, Box<Expr<'a>>, Box<Expr<'a>>),
@@ -347,6 +348,20 @@ named!(expr_attr<Input, Expr>, do_parse!(
     })
 ));
 
+named!(expr_index<Input, Expr>, do_parse!(
+    obj: expr_attr >>
+    key: opt!(do_parse!(
+        ws!(tag_s!("[")) >>
+        key: expr_any >>
+        ws!(tag_s!("]")) >>
+        (key)
+    )) >>
+    (match key {
+        Some(key) => Expr::Index(Box::new(obj), Box::new(key)),
+        None => obj,
+    })
+));
+
 named!(filter<Input, (&str, Option<Vec<Expr>>)>, do_parse!(
     tag_s!("|") >>
     fname: identifier >>
@@ -355,7 +370,7 @@ named!(filter<Input, (&str, Option<Vec<Expr>>)>, do_parse!(
 ));
 
 named!(expr_filtered<Input, Expr>, do_parse!(
-    obj: expr_attr >>
+    obj: expr_index >>
     filters: many0!(filter) >>
     ({
        let mut res = obj;