Add internal plugin for creating Reflectable implementations

components/plugins/utils.rs

@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use syntax::ptr::P;
+use syntax::ast::{TyPath, Path, AngleBracketedParameters, PathSegment, Ty};
+
+/// Matches a type with a provided string, and returns its type parameters if successful
+pub fn match_ty_unwrap<'a>(ty: &'a Ty, segments: &[&str]) -> Option<&'a [P<Ty>]> {
+    match ty.node {
+        TyPath(Path {segments: ref seg, ..}, _, _) => {
+            // So ast::Path isn't the full path, just the tokens that were provided.
+            // I could muck around with the maps and find the full path
+            // however the more efficient way is to simply reverse the iterators and zip them
+            // which will compare them in reverse until one of them runs out of segments
+            if seg.iter().rev().zip(segments.iter().rev()).all(|(a,b)| a.identifier.as_str() == *b) {
+                match seg.as_slice().last() {
+                    Some(&PathSegment {parameters: AngleBracketedParameters(ref a), ..}) => {
+                        Some(a.types.as_slice())
+                    }
+                    _ => None
+                }
+            } else {
+                None
+            }
+        },
+        _ => None
+    }
+}