From e3d08c72bc2a7c34243208e68158b6f919701082 Mon Sep 17 00:00:00 2001
From: Dirkjan Ochtman <dirkjan@ochtman.nl>
Date: Tue, 8 Aug 2017 12:35:15 +0200
Subject: Implement Deref<Parent> for inheriting templates (fixes #28)
---
askama_derive/src/generator.rs | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
(limited to 'askama_derive')
diff --git a/askama_derive/src/generator.rs b/askama_derive/src/generator.rs
index a3363b4..fd2fb5b 100644
--- a/askama_derive/src/generator.rs
+++ b/askama_derive/src/generator.rs
@@ -379,6 +379,18 @@ impl<'a> Generator<'a> {
self.writeln("}");
}
+ // Implement `Deref<Parent>` for an inheriting context struct.
+ fn deref_to_parent(&mut self, ast: &syn::DeriveInput, parent_type: &syn::Ty) {
+ self.write_header(ast, "::std::ops::Deref");
+ let mut tokens = Tokens::new();
+ parent_type.to_tokens(&mut tokens);
+ self.writeln(&format!("type Target = {};", tokens.as_str()));
+ self.writeln("fn deref(&self) -> &Self::Target {");
+ self.writeln("&self._parent");
+ self.writeln("}");
+ self.writeln("}");
+ }
+
// Implement `TraitFromPathName` for the given context struct.
fn impl_trait(&mut self, ast: &syn::DeriveInput, trait_name: &str,
blocks: &'a [Node], nodes: Option<&'a [Node]>) {
@@ -461,6 +473,23 @@ fn trait_name_for_path(base: &Option<Expr>, path: &str) -> String {
res
}
+fn get_parent_type(ast: &syn::DeriveInput) -> Option<&syn::Ty> {
+ match ast.body {
+ syn::Body::Struct(ref data) => {
+ data.fields().iter().filter_map(|f| {
+ f.ident.as_ref().and_then(|name| {
+ if name.as_ref() == "_parent" {
+ Some(&f.ty)
+ } else {
+ None
+ }
+ })
+ })
+ },
+ _ => panic!("derive(Template) only works for struct items"),
+ }.next()
+}
+
pub fn generate(ast: &syn::DeriveInput, path: &str, mut nodes: Vec<Node>) -> String {
let mut base: Option<Expr> = None;
let mut blocks = Vec::new();
@@ -489,6 +518,8 @@ pub fn generate(ast: &syn::DeriveInput, path: &str, mut nodes: Vec<Node>) -> Str
let trait_name = trait_name_for_path(&base, path);
if base.is_none() {
gen.define_trait(&trait_name, &block_names);
+ } else {
+ gen.deref_to_parent(ast, &get_parent_type(ast).unwrap());
}
let trait_nodes = if base.is_none() { Some(&content[..]) } else { None };
--
cgit