Extend parser and generator to handle else blocks

2 files changed, 40 insertions, 13 deletions

diff --git a/askama/src/generator.rs b/askama/src/generator.rs
index adfa278..95e4dcb 100644
--- a/askama/src/generator.rs
+++ b/askama/src/generator.rs
@@ -1,4 +1,4 @@
-use parser::{Expr, Node};
+use parser::{Conds, Expr, Node};
 use std::str;
 
 struct Generator {
@@ -79,13 +79,24 @@ impl Generator {
         self.writeln(")).unwrap();");
     }
 
-    fn write_cond(&mut self, cond: &Expr, nodes: &Vec<Node>) {
-        self.write("if ");
-        self.visit_expr(cond);
-        self.writeln(" {");
-        self.indent();
-        self.handle(nodes);
-        self.dedent();
+    fn write_cond(&mut self, conds: &Conds) {
+        for (i, &(ref cond, ref nodes)) in conds.iter().enumerate() {
+            match cond {
+                &Some(ref expr) => {
+                    if i == 0 {
+                        self.write("if ");
+                    } else {
+                        self.write("} else if ");
+                    }
+                    self.visit_expr(expr);
+                },
+                &None => { self.writeln("} else"); },
+            }
+            self.writeln(" {");
+            self.indent();
+            self.handle(nodes);
+            self.dedent();
+        }
         self.writeln("}");
     }
 
@@ -94,9 +105,7 @@ impl Generator {
             match n {
                 &Node::Lit(val) => { self.write_lit(val); },
                 &Node::Expr(ref val) => { self.write_expr(&val); },
-                &Node::Cond(ref cond, ref nodes) => {
-                    self.write_cond(&cond, &nodes);
-                },
+                &Node::Cond(ref conds) => { self.write_cond(&conds); },
             }
         }
     }
diff --git a/askama/src/parser.rs b/askama/src/parser.rs
index 48bcf15..4759472 100644
--- a/askama/src/parser.rs
+++ b/askama/src/parser.rs
@@ -9,9 +9,12 @@ pub enum Expr<'a> {
 pub enum Node<'a> {
     Lit(&'a [u8]),
     Expr(Expr<'a>),
-    Cond(Expr<'a>, Vec<Node<'a>>),
+    Cond(Vec<(Option<Expr<'a>>, Vec<Node<'a>>)>),
 }
 
+pub type Nodes<'a> = Vec<Node<'a>>;
+pub type Conds<'a> = Vec<(Option<Expr<'a>>, Nodes<'a>)>;
+
 fn take_content(i: &[u8]) -> IResult<&[u8], Node> {
     if i.len() < 1 || i[0] == b'{' {
         return IResult::Error(error_position!(nom::ErrorKind::TakeUntil, i));
@@ -59,16 +62,31 @@ named!(expr_node<Node>, map!(
     delimited!(tag_s!("{{"), ws!(expr_filtered), tag_s!("}}")),
     Node::Expr));
 
+named!(cond_blocks<Conds>, do_parse!(
+    tag_s!("{%") >>
+    ws!(tag_s!("else")) >>
+    tag_s!("%}") >>
+    block: parse_template >>
+    (vec![(None, block)])));
+
 named!(block_if<Node>, do_parse!(
     tag_s!("{%") >>
     ws!(tag_s!("if")) >>
     cond: ws!(expr_filtered) >>
     tag_s!("%}") >>
     block: parse_template >>
+    rest: opt!(cond_blocks) >>
     tag_s!("{%") >>
     ws!(tag_s!("endif")) >>
     tag_s!("%}") >>
-    (Node::Cond(cond, block))));
+    ({
+        let mut res = Vec::new();
+        res.push((Some(cond), block));
+        if let Some(blocks) = rest {
+            res.extend(blocks);
+        }
+        Node::Cond(res)
+    })));
 
 named!(parse_template< Vec<Node> >, many1!(alt!(
     take_content |