Add support for simple variable definition statements

2 files changed, 27 insertions, 0 deletions

diff --git a/askama_derive/src/generator.rs b/askama_derive/src/generator.rs
index 3c97845..faf4e48 100644
--- a/askama_derive/src/generator.rs
+++ b/askama_derive/src/generator.rs
@@ -312,6 +312,20 @@ impl<'a> Generator<'a> {
         self.writeln("))?;");
     }
 
+    fn write_let(&mut self, ws: &WS, var: &'a Target, val: &Expr) {
+        self.handle_ws(ws);
+        self.write("let ");
+        match *var {
+            Target::Name(name) => {
+                self.locals.insert(name);
+                self.write(name);
+            },
+        }
+        self.write(" = ");
+        self.visit_expr(val);
+        self.writeln(";");
+    }
+
     fn write_cond(&mut self, conds: &'a [Cond], ws: &WS) {
         for (i, &(ref cws, ref cond, ref nodes)) in conds.iter().enumerate() {
             self.handle_ws(cws);
@@ -403,6 +417,7 @@ impl<'a> Generator<'a> {
                 Node::Lit(lws, val, rws) => { self.write_lit(lws, val, rws); }
                 Node::Comment() => {},
                 Node::Expr(ref ws, ref val) => { self.write_expr(ws, val); },
+                Node::Let(ref ws, ref var, ref val) => { self.write_let(ws, var, val); },
                 Node::Cond(ref conds, ref ws) => {
                     self.write_cond(conds, ws);
                 },
diff --git a/askama_derive/src/parser.rs b/askama_derive/src/parser.rs
index b07d8eb..2a6a602 100644
--- a/askama_derive/src/parser.rs
+++ b/askama_derive/src/parser.rs
@@ -26,6 +26,7 @@ pub enum Node<'a> {
     Lit(&'a str, &'a str, &'a str),
     Comment(),
     Expr(WS, Expr<'a>),
+    Let(WS, Target<'a>, Expr<'a>),
     Cond(Vec<(WS, Option<Expr<'a>>, Vec<Node<'a>>)>, WS),
     Loop(WS, Target<'a>, Expr<'a>, Vec<Node<'a>>, WS),
     Extends(Expr<'a>),
@@ -277,6 +278,16 @@ named!(block_if<Node>, do_parse!(
     })
 ));
 
+named!(block_let<Node>, do_parse!(
+    pws: opt!(tag_s!("-")) >>
+    ws!(tag_s!("let")) >>
+    var: ws!(target_single) >>
+    ws!(tag_s!("=")) >>
+    val: ws!(expr_any) >>
+    nws: opt!(tag_s!("-")) >>
+    (Node::Let(WS(pws.is_some(), nws.is_some()), var, val))
+));
+
 named!(block_for<Node>, do_parse!(
     pws1: opt!(tag_s!("-")) >>
     ws!(tag_s!("for")) >>
@@ -331,6 +342,7 @@ named!(block_include<Node>, do_parse!(
 named!(block_node<Node>, do_parse!(
     tag_s!("{%") >>
     contents: alt!(
+        block_let |
         block_if |
         block_for |
         block_extends |