switch to dynamic dispatch for TokenSource

Benchmarks show no difference. This is probably because we are
bottlenecked on memory allocations, and we should fix that, but we are
not optimizing for performance just yet.

changes. Lines starting # with '#' will be ignored, and an empty
message aborts the commit. # # On branch token-source # Changes to be
committed: # modified: crates/ra_syntax/src/parsing/parser_api.rs #
modified: crates/ra_syntax/src/parsing/parser_impl.rs #

2 files changed, 7 insertions, 9 deletions

diff --git a/crates/ra_syntax/src/parsing/parser_api.rs b/crates/ra_syntax/src/parsing/parser_api.rs
index 813ae494c..aed23a6a4 100644
--- a/crates/ra_syntax/src/parsing/parser_api.rs
+++ b/crates/ra_syntax/src/parsing/parser_api.rs
@@ -4,7 +4,7 @@ use crate::{
     SyntaxKind::{self, ERROR},
     parsing::{
         token_set::TokenSet,
-        parser_impl::ParserImpl
+        parser_impl::ParserImpl,
     },
 };
 
@@ -17,9 +17,7 @@ use crate::{
 /// tree, but rather a flat stream of events of the form
 /// "start expression, consume number literal,
 /// finish expression". See `Event` docs for more.
-pub(crate) struct Parser<'t>(
-    pub(super) ParserImpl<crate::parsing::parser_impl::input::ParserInput<'t>>,
-);
+pub(crate) struct Parser<'t>(pub(super) ParserImpl<'t>);
 
 impl<'t> Parser<'t> {
     /// Returns the kind of the current token.
diff --git a/crates/ra_syntax/src/parsing/parser_impl.rs b/crates/ra_syntax/src/parsing/parser_impl.rs
index c0d2b6ec1..96de32fc2 100644
--- a/crates/ra_syntax/src/parsing/parser_impl.rs
+++ b/crates/ra_syntax/src/parsing/parser_impl.rs
@@ -54,7 +54,7 @@ pub(super) fn parse_with<S: TreeSink>(
 ) -> S::Tree {
     let mut events = {
         let input = input::ParserInput::new(text, tokens);
-        let parser_impl = ParserImpl::new(input);
+        let parser_impl = ParserImpl::new(&input);
         let mut parser_api = Parser(parser_impl);
         parser(&mut parser_api);
         parser_api.0.into_events()
@@ -65,15 +65,15 @@ pub(super) fn parse_with<S: TreeSink>(
 /// Implementation details of `Parser`, extracted
 /// to a separate struct in order not to pollute
 /// the public API of the `Parser`.
-pub(super) struct ParserImpl<S> {
-    token_source: S,
+pub(super) struct ParserImpl<'a> {
+    token_source: &'a dyn TokenSource,
     pos: InputPosition,
     events: Vec<Event>,
     steps: Cell<u32>,
 }
 
-impl<S: TokenSource> ParserImpl<S> {
-    fn new(token_source: S) -> ParserImpl<S> {
+impl<'a> ParserImpl<'a> {
+    fn new(token_source: &'a dyn TokenSource) -> ParserImpl<'a> {
         ParserImpl {
             token_source,
             pos: InputPosition::new(),