Add support for range operators (see #95)

2 files changed, 39 insertions, 1 deletions

diff --git a/askama_derive/src/generator.rs b/askama_derive/src/generator.rs
index 0e86a27..5ec2238 100644
--- a/askama_derive/src/generator.rs
+++ b/askama_derive/src/generator.rs
@@ -598,6 +598,7 @@ impl<'a> Generator<'a> {
             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),
+            Expr::Range(op, ref left, ref right) => self.visit_range(op, left, right, code),
             Expr::Group(ref inner) => self.visit_group(inner, code),
             Expr::MethodCall(ref obj, method, ref args) => {
                 self.visit_method_call(obj, method, args, code)
@@ -762,6 +763,23 @@ impl<'a> Generator<'a> {
         DisplayWrap::Unwrapped
     }
 
+    fn visit_range(
+        &mut self,
+        op: &str,
+        left: &Option<Box<Expr>>,
+        right: &Option<Box<Expr>>,
+        code: &mut String,
+    ) -> DisplayWrap {
+        if let Some(left) = left {
+            self.visit_expr(left, code);
+        }
+        code.push_str(op);
+        if let Some(right) = right {
+            self.visit_expr(right, code);
+        }
+        DisplayWrap::Unwrapped
+    }
+
     fn visit_binop(
         &mut self,
         op: &str,
diff --git a/askama_derive/src/parser.rs b/askama_derive/src/parser.rs
index c8bbb96..5694d4e 100644
--- a/askama_derive/src/parser.rs
+++ b/askama_derive/src/parser.rs
@@ -16,6 +16,7 @@ pub enum Expr<'a> {
     Filter(&'a str, Vec<Expr<'a>>),
     Unary(&'a str, Box<Expr<'a>>),
     BinOp(&'a str, Box<Expr<'a>>, Box<Expr<'a>>),
+    Range(&'a str, Option<Box<Expr<'a>>>, Option<Box<Expr<'a>>>),
     Group(Box<Expr<'a>>),
     MethodCall(Box<Expr<'a>>, &'a str, Vec<Expr<'a>>),
 }
@@ -422,7 +423,26 @@ expr_prec_layer!(expr_compare, expr_bor,
     "==", "!=", ">=", ">", "<=", "<"
 );
 expr_prec_layer!(expr_and, expr_compare, "&&");
-expr_prec_layer!(expr_any, expr_and, "||");
+expr_prec_layer!(expr_or, expr_and, "||");
+
+named!(range_right<Input, Expr>, do_parse!(
+    ws!(tag_s!("..")) >>
+    incl: opt!(ws!(tag_s!("="))) >>
+    right: opt!(expr_or) >>
+    (Expr::Range(if incl.is_some() { "..=" } else { ".." }, None, right.map(|v| Box::new(v))))
+));
+
+named!(expr_any<Input, Expr>, alt!(
+    range_right |
+    do_parse!(
+        left: expr_or >>
+        rest: range_right >> (match rest {
+            Expr::Range(op, _, right) => Expr::Range(op, Some(Box::new(left)), right),
+            _ => unreachable!(),
+        })
+    ) |
+    expr_or
+));
 
 named!(expr_node<Input, Node>, do_parse!(
     tag_s!("{{") >>