2 files changed, 67 insertions, 11 deletions

diff --git a/askama_shared/src/generator.rs b/askama_shared/src/generator.rs
index 6fca3fb..0c8b1e2 100644
--- a/askama_shared/src/generator.rs
+++ b/askama_shared/src/generator.rs
@@ -1,6 +1,6 @@
 use filters;
 use input::TemplateInput;
-use parser::{self, Cond, Expr, Macro, Node, Target, When, WS};
+use parser::{self, Cond, Expr, Macro, MatchParameter, Node, Target, When, WS};
 use path;
 
 use quote::{Tokens, ToTokens};
@@ -445,15 +445,20 @@ impl<'a> Generator<'a> {
         for arm in arms {
             let &(ref ws, ref variant, ref params, ref body) = arm;
             self.locals.push();
-            self.write(variant);
+            match *variant {
+                Some(ref param) => { self.visit_match_param(param); },
+                None => self.write("_"),
+            };
             if params.len() > 0 {
                 self.write("(");
                 for (i, param) in params.iter().enumerate() {
-                    self.locals.insert(param);
+                    if let MatchParameter::Name(ref p) = *param {
+                        self.locals.insert(p);
+                    }
                     if i > 0 {
                         self.write(", ");
                     }
-                    self.write(param);
+                    self.visit_match_param(param);
                 }
                 self.write(")");
             }
@@ -624,6 +629,17 @@ impl<'a> Generator<'a> {
         }
     }
 
+    fn visit_match_param(&mut self, param: &MatchParameter) -> DisplayWrap {
+        match *param {
+            MatchParameter::NumLit(s) => self.visit_num_lit(s),
+            MatchParameter::StrLit(s) => self.visit_str_lit(s),
+            MatchParameter::Name(s) => {
+                self.write(s);
+                DisplayWrap::Unwrapped
+            }
+        }
+    }
+
     fn visit_filter(&mut self, name: &str, args: &[Expr]) -> DisplayWrap {
         if name == "format" {
             self._visit_format_filter(args);
diff --git a/askama_shared/src/parser.rs b/askama_shared/src/parser.rs
index 6ea5ffd..76125ef 100644
--- a/askama_shared/src/parser.rs
+++ b/askama_shared/src/parser.rs
@@ -16,6 +16,13 @@ pub enum Expr<'a> {
 }
 
 #[derive(Debug)]
+pub enum MatchParameter<'a> {
+    Name(&'a str),
+    NumLit(&'a str),
+    StrLit(&'a str),
+}
+
+#[derive(Debug)]
 pub enum Target<'a> {
     Name(&'a str),
 }
@@ -50,7 +57,7 @@ pub enum Node<'a> {
 }
 
 pub type Cond<'a> = (WS, Option<Expr<'a>>, Vec<Node<'a>>);
-pub type When<'a> = (WS, &'a str, Vec<&'a str>, Vec<Node<'a>>);
+pub type When<'a> = (WS, Option<MatchParameter<'a>>, Vec<MatchParameter<'a>>, Vec<Node<'a>>);
 
 fn split_ws_parts(s: &[u8]) -> Node {
     if s.is_empty() {
@@ -147,11 +154,20 @@ named!(expr_array_lit<Expr>, do_parse!(
     })
 ));
 
+named!(param_num_lit<MatchParameter>, map!(num_lit,
+    |s| MatchParameter::NumLit(s)
+));
+
 named!(expr_str_lit<Expr>, map!(
     delimited!(char!('"'), take_until!("\""), char!('"')),
     |s| Expr::StrLit(str::from_utf8(s).unwrap())
 ));
 
+named!(param_str_lit<MatchParameter>, map!(
+    delimited!(char!('"'), is_not!("\""), char!('"')),
+    |s| MatchParameter::StrLit(str::from_utf8(s).unwrap())
+));
+
 named!(expr_var<Expr>, map!(identifier,
     |s| Expr::Var(s))
 );
@@ -174,6 +190,10 @@ named!(target_single<Target>, map!(identifier,
     |s| Target::Name(s)
 ));
 
+named!(param_name<MatchParameter>, map!(identifier,
+    |s| MatchParameter::Name(s)
+));
+
 named!(arguments<Vec<Expr>>, do_parse!(
     tag_s!("(") >>
     args: opt!(do_parse!(
@@ -212,10 +232,24 @@ named!(parameters<Vec<&'a str>>, do_parse!(
     (vals.unwrap_or_default())
 ));
 
-named!(with_parameters<Vec<&'a str>>, do_parse!(
+named!(with_parameters<Vec<MatchParameter>>, do_parse!(
     tag_s!("with") >>
-    params: ws!(parameters) >>
-    (params)
+    ws!(tag_s!("(")) >>
+    vals: opt!(do_parse!(
+        arg0: ws!(match_parameter) >>
+        args: many0!(do_parse!(
+            tag_s!(",") >>
+            argn: ws!(match_parameter) >>
+            (argn)
+        )) >>
+        ({
+            let mut res = vec![arg0];
+            res.extend(args);
+            res
+        })
+    )) >>
+    tag_s!(")") >>
+    (vals.unwrap_or_default())
 ));
 
 named!(expr_group<Expr>, map!(
@@ -232,6 +266,12 @@ named!(expr_single<Expr>, alt!(
     expr_group
 ));
 
+named!(match_parameter<MatchParameter>, alt!(
+    param_name |
+    param_num_lit |
+    param_str_lit
+));
+
 named!(attr<(&str, Option<Vec<Expr>>)>, do_parse!(
     tag_s!(".") >>
     attr: alt!(num_lit | identifier) >>
@@ -374,19 +414,19 @@ named!(match_else_block<When>, do_parse!(
     nws: opt!(tag_s!("-")) >>
     tag_s!("%}") >>
     block: parse_template >>
-    (WS(pws.is_some(), nws.is_some()), "_", vec![], block)
+    (WS(pws.is_some(), nws.is_some()), None, vec![], block)
 ));
 
 named!(when_block<When>, do_parse!(
     tag_s!("{%") >>
     pws: opt!(tag_s!("-")) >>
     ws!(tag_s!("when")) >>
-    variant: ws!(identifier) >>
+    variant: ws!(match_parameter) >>
     params: opt!(ws!(with_parameters)) >>
     nws: opt!(tag_s!("-")) >>
     tag_s!("%}") >>
     block: parse_template >>
-    (WS(pws.is_some(), nws.is_some()), variant, params.unwrap_or_default(), block)
+    (WS(pws.is_some(), nws.is_some()), Some(variant), params.unwrap_or_default(), block)
 ));
 
 named!(block_match<Node>, do_parse!(