more expand boilerplate

diff --git a/crates/ra_macros/Cargo.toml b/crates/ra_macros/Cargo.toml
index b4fdbfd184fae9102187df8495ed9f37c8aa422a..21c128442dcda98a21b74e379cf36c274aa43be9 100644 (file)
--- a/crates/ra_macros/Cargo.toml
+++ b/crates/ra_macros/Cargo.toml
@@ -5,4 +5,5 @@ version = "0.1.0"
 authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]
 
 [dependencies]
+rustc_hash = "1.0.0"
 smol_str = "0.1.9"

diff --git a/crates/ra_macros/src/mbe_expander.rs b/crates/ra_macros/src/mbe_expander.rs
index 42622965951ff7e52a751377e9876a4ec1c23cdd..9436baa2837c106d89db744d0f16d43fd8f3b3e0 100644 (file)
--- a/crates/ra_macros/src/mbe_expander.rs
+++ b/crates/ra_macros/src/mbe_expander.rs
@@ -1,5 +1,26 @@
+use rustc_hash::FxHashMap;
+use smol_str::SmolStr;
+
 use crate::{mbe, tt};
 
-pub fn exapnd(rules: &mbe::MacroRules, input: tt::Subtree) -> Option<tt::Subtree> {
-    Some(input)
+pub fn exapnd(rules: &mbe::MacroRules, input: &tt::Subtree) -> Option<tt::Subtree> {
+    rules.rules.iter().find_map(|it| expand_rule(it, input))
+}
+
+fn expand_rule(rule: &mbe::Rule, input: &tt::Subtree) -> Option<tt::Subtree> {
+    let bidings = match_lhs(&rule.lhs, input)?;
+    expand_rhs(&rule.rhs, &bindings)
+}
+
+#[derive(Debug, Default)]
+struct Bindings {
+    inner: FxHashMap<SmolStr, tt::TokenTree>,
+}
+
+fn match_lhs(pattern: &mbe::TokenTree, input: &tt::Subtree) -> Option<Bindings> {
+    Some(Bindings::default())
+}
+
+fn expand_rhs(template: &mbe::TokenTree, bindings: &Bindings) -> Option<tt::Subtree> {
+    None
 }