Hide askama_derive dependency inside askama (fixes #2)

1 files changed, 71 insertions, 2 deletions

diff --git a/askama_derive/src/lib.rs b/askama_derive/src/lib.rs
index 4b96e17..752978e 100644
--- a/askama_derive/src/lib.rs
+++ b/askama_derive/src/lib.rs
@@ -1,9 +1,78 @@
-extern crate askama;
+#[macro_use]
+extern crate nom;
 extern crate proc_macro;
 extern crate syn;
 
 use proc_macro::TokenStream;
 
+mod generator;
+mod parser;
+mod path;
+
+// Holds metadata for the template, based on the `template()` attribute.
+struct TemplateMeta {
+    path: String,
+    print: String,
+}
+
+// Returns a `TemplateMeta` based on the `template()` attribute data found
+// in the parsed struct or enum. Will panic if it does not find the required
+// template path, or if the `print` key has an unexpected value.
+fn get_template_meta(ast: &syn::DeriveInput) -> TemplateMeta {
+    let mut path = None;
+    let mut print = "none".to_string();
+    let attr = ast.attrs.iter().find(|a| a.name() == "template").unwrap();
+    if let syn::MetaItem::List(_, ref inner) = attr.value {
+        for nm_item in inner {
+            if let syn::NestedMetaItem::MetaItem(ref item) = *nm_item {
+                if let syn::MetaItem::NameValue(ref key, ref val) = *item {
+                    match key.as_ref() {
+                        "path" => if let syn::Lit::Str(ref s, _) = *val {
+                            path = Some(s.clone());
+                        } else {
+                            panic!("template path must be string literal");
+                        },
+                        "print" => if let syn::Lit::Str(ref s, _) = *val {
+                            print = s.clone();
+                        } else {
+                            panic!("print value must be string literal");
+                        },
+                        _ => { panic!("unsupported annotation key found") }
+                    }
+                }
+            }
+        }
+    }
+    if path.is_none() {
+        panic!("template path not found in struct attributes");
+    }
+    TemplateMeta { path: path.unwrap(), print: print }
+}
+
+/// Takes a `syn::DeriveInput` and generates source code for it
+///
+/// Reads the metadata from the `template()` attribute to get the template
+/// metadata, then fetches the source from the filesystem. The source is
+/// parsed, and the parse tree is fed to the code generator. Will print
+/// the parse tree and/or generated source according to the `print` key's
+/// value as passed to the `template()` attribute.
+fn build_template(ast: &syn::DeriveInput) -> String {
+    let meta = get_template_meta(ast);
+    let mut src = path::get_template_source(&meta.path);
+    if src.ends_with('\n') {
+        let _ = src.pop();
+    }
+    let nodes = parser::parse(&src);
+    if meta.print == "ast" || meta.print == "all" {
+        println!("{:?}", nodes);
+    }
+    let code = generator::generate(ast, &meta.path, nodes);
+    if meta.print == "code" || meta.print == "all" {
+        println!("{}", code);
+    }
+    code
+}
+
 #[proc_macro_derive(Template, attributes(template))]
 pub fn derive_template(input: TokenStream) -> TokenStream {
     let ast = syn::parse_derive_input(&input.to_string()).unwrap();
@@ -11,5 +80,5 @@ pub fn derive_template(input: TokenStream) -> TokenStream {
         syn::Body::Struct(ref data) => data,
         _ => panic!("#[derive(Template)] can only be used with structs"),
     };
-    askama::build_template(&ast).parse().unwrap()
+    build_template(&ast).parse().unwrap()
 }