23 files changed, 84 insertions, 18 deletions

diff --git a/crates/ra_parser/Cargo.toml b/crates/ra_parser/Cargo.toml
new file mode 100644
index 000000000..b110e2bc6
--- /dev/null
+++ b/crates/ra_parser/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+edition = "2018"
+name = "ra_parser"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+publish = false
+
+[dependencies]
+drop_bomb = "0.1.4"
diff --git a/crates/ra_syntax/src/parsing/event.rs b/crates/ra_parser/src/event.rs
index d6cbdffe0..d6e8454d4 100644
--- a/crates/ra_syntax/src/parsing/event.rs
+++ b/crates/ra_parser/src/event.rs
@@ -10,8 +10,8 @@
 use std::mem;
 
 use crate::{
+    ParseError, TreeSink,
     SyntaxKind::{self, *},
-    parsing::{ParseError, TreeSink},
 };
 
 /// `Parser` produces a flat list of `Event`s.
@@ -84,7 +84,7 @@ impl Event {
 }
 
 /// Generate the syntax tree with the control of events.
-pub(super) fn process(sink: &mut impl TreeSink, mut events: Vec<Event>) {
+pub(super) fn process(sink: &mut dyn TreeSink, mut events: Vec<Event>) {
     let mut forward_parents = Vec::new();
 
     for i in 0..events.len() {
diff --git a/crates/ra_syntax/src/parsing/grammar.rs b/crates/ra_parser/src/grammar.rs
index 800d5a4a2..15aab6c6f 100644
--- a/crates/ra_syntax/src/parsing/grammar.rs
+++ b/crates/ra_parser/src/grammar.rs
@@ -38,20 +38,18 @@ mod types;
 
 use crate::{
     SyntaxKind::{self, *},
-    parsing::{
-        token_set::TokenSet,
-        parser::{CompletedMarker, Marker, Parser}
-    },
+    TokenSet,
+    parser::{CompletedMarker, Marker, Parser},
 };
 
-pub(super) fn root(p: &mut Parser) {
+pub(crate) fn root(p: &mut Parser) {
     let m = p.start();
     p.eat(SHEBANG);
     items::mod_contents(p, false);
     m.complete(p, SOURCE_FILE);
 }
 
-pub(super) fn reparser(
+pub(crate) fn reparser(
     node: SyntaxKind,
     first_child: Option<SyntaxKind>,
     parent: Option<SyntaxKind>,
diff --git a/crates/ra_syntax/src/parsing/grammar/attributes.rs b/crates/ra_parser/src/grammar/attributes.rs
index cd30e8a45..cd30e8a45 100644
--- a/crates/ra_syntax/src/parsing/grammar/attributes.rs
+++ b/crates/ra_parser/src/grammar/attributes.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index d5a4f4d7b..d5a4f4d7b 100644
--- a/crates/ra_syntax/src/parsing/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index e74305b6a..e74305b6a 100644
--- a/crates/ra_syntax/src/parsing/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index 4b962c1f3..4b962c1f3 100644
--- a/crates/ra_syntax/src/parsing/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/items/consts.rs b/crates/ra_parser/src/grammar/items/consts.rs
index 5a5852f83..5a5852f83 100644
--- a/crates/ra_syntax/src/parsing/grammar/items/consts.rs
+++ b/crates/ra_parser/src/grammar/items/consts.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/items/nominal.rs b/crates/ra_parser/src/grammar/items/nominal.rs
index ff9b38f9c..ff9b38f9c 100644
--- a/crates/ra_syntax/src/parsing/grammar/items/nominal.rs
+++ b/crates/ra_parser/src/grammar/items/nominal.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/items/traits.rs b/crates/ra_parser/src/grammar/items/traits.rs
index d5a8ccd98..d5a8ccd98 100644
--- a/crates/ra_syntax/src/parsing/grammar/items/traits.rs
+++ b/crates/ra_parser/src/grammar/items/traits.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/items/use_item.rs b/crates/ra_parser/src/grammar/items/use_item.rs
index 5111d37eb..5111d37eb 100644
--- a/crates/ra_syntax/src/parsing/grammar/items/use_item.rs
+++ b/crates/ra_parser/src/grammar/items/use_item.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/params.rs b/crates/ra_parser/src/grammar/params.rs
index 185386569..185386569 100644
--- a/crates/ra_syntax/src/parsing/grammar/params.rs
+++ b/crates/ra_parser/src/grammar/params.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/paths.rs b/crates/ra_parser/src/grammar/paths.rs
index 33a11886c..33a11886c 100644
--- a/crates/ra_syntax/src/parsing/grammar/paths.rs
+++ b/crates/ra_parser/src/grammar/paths.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/patterns.rs b/crates/ra_parser/src/grammar/patterns.rs
index 9d7da639d..9d7da639d 100644
--- a/crates/ra_syntax/src/parsing/grammar/patterns.rs
+++ b/crates/ra_parser/src/grammar/patterns.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/type_args.rs b/crates/ra_parser/src/grammar/type_args.rs
index f889419c5..f889419c5 100644
--- a/crates/ra_syntax/src/parsing/grammar/type_args.rs
+++ b/crates/ra_parser/src/grammar/type_args.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/type_params.rs b/crates/ra_parser/src/grammar/type_params.rs
index 40f998682..40f998682 100644
--- a/crates/ra_syntax/src/parsing/grammar/type_params.rs
+++ b/crates/ra_parser/src/grammar/type_params.rs
diff --git a/crates/ra_syntax/src/parsing/grammar/types.rs b/crates/ra_parser/src/grammar/types.rs
index adc189a29..adc189a29 100644
--- a/crates/ra_syntax/src/parsing/grammar/types.rs
+++ b/crates/ra_parser/src/grammar/types.rs
diff --git a/crates/ra_parser/src/lib.rs b/crates/ra_parser/src/lib.rs
new file mode 100644
index 000000000..fbbac4c69
--- /dev/null
+++ b/crates/ra_parser/src/lib.rs
@@ -0,0 +1,64 @@
+#[macro_use]
+mod token_set;
+mod syntax_kind;
+mod event;
+mod parser;
+mod grammar;
+
+pub(crate) use token_set::TokenSet;
+
+pub use syntax_kind::SyntaxKind;
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ParseError(pub String);
+
+/// `TreeSink` abstracts details of a particular syntax tree implementation.
+pub trait TreeSink {
+    /// Adds new leaf to the current branch.
+    fn leaf(&mut self, kind: SyntaxKind, n_tokens: u8);
+
+    /// Start new branch and make it current.
+    fn start_branch(&mut self, kind: SyntaxKind, root: bool);
+
+    /// Finish current branch and restore previous
+    /// branch as current.
+    fn finish_branch(&mut self, root: bool);
+
+    fn error(&mut self, error: ParseError);
+}
+
+/// `TokenSource` abstracts the source of the tokens parser operates one.
+///
+/// Hopefully this will allow us to treat text and token trees in the same way!
+pub trait TokenSource {
+    fn token_kind(&self, pos: usize) -> SyntaxKind;
+    fn is_token_joint_to_next(&self, pos: usize) -> bool;
+    fn is_keyword(&self, pos: usize, kw: &str) -> bool;
+}
+
+pub fn parse(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    let mut p = parser::Parser::new(token_source);
+    grammar::root(&mut p);
+    let events = p.finish();
+    event::process(tree_sink, events);
+}
+
+pub struct Reparser(fn(&mut parser::Parser));
+
+impl Reparser {
+    pub fn for_node(
+        node: SyntaxKind,
+        first_child: Option<SyntaxKind>,
+        parent: Option<SyntaxKind>,
+    ) -> Option<Reparser> {
+        grammar::reparser(node, first_child, parent).map(Reparser)
+    }
+}
+
+pub fn reparse(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink, reparser: Reparser) {
+    let Reparser(r) = reparser;
+    let mut p = parser::Parser::new(token_source);
+    r(&mut p);
+    let events = p.finish();
+    event::process(tree_sink, events);
+}
diff --git a/crates/ra_syntax/src/parsing/parser.rs b/crates/ra_parser/src/parser.rs
index 923b0f2b2..a18458148 100644
--- a/crates/ra_syntax/src/parsing/parser.rs
+++ b/crates/ra_parser/src/parser.rs
@@ -4,11 +4,8 @@ use drop_bomb::DropBomb;
 
 use crate::{
     SyntaxKind::{self, ERROR, EOF, TOMBSTONE},
-    parsing::{
-        TokenSource, ParseError,
-        token_set::TokenSet,
-        event::Event,
-    },
+    TokenSource, ParseError, TokenSet,
+    event::Event,
 };
 
 /// `Parser` struct provides the low-level API for
diff --git a/crates/ra_syntax/src/syntax_kinds.rs b/crates/ra_parser/src/syntax_kind.rs
index c1118c5ab..a2353317f 100644
--- a/crates/ra_syntax/src/syntax_kinds.rs
+++ b/crates/ra_parser/src/syntax_kind.rs
@@ -2,8 +2,6 @@ mod generated;
 
 use std::fmt;
 
-use crate::SyntaxKind::*;
-
 pub use self::generated::SyntaxKind;
 
 impl fmt::Debug for SyntaxKind {
@@ -20,7 +18,7 @@ pub(crate) struct SyntaxInfo {
 impl SyntaxKind {
     pub fn is_trivia(self) -> bool {
         match self {
-            WHITESPACE | COMMENT => true,
+            SyntaxKind::WHITESPACE | SyntaxKind::COMMENT => true,
             _ => false,
         }
     }
diff --git a/crates/ra_syntax/src/syntax_kinds/generated.rs b/crates/ra_parser/src/syntax_kind/generated.rs
index 266b95bbb..1d8f988ae 100644
--- a/crates/ra_syntax/src/syntax_kinds/generated.rs
+++ b/crates/ra_parser/src/syntax_kind/generated.rs
@@ -568,7 +568,7 @@ impl SyntaxKind {
             EOF => &SyntaxInfo { name: "EOF" },
         }
     }
-    pub(crate) fn from_keyword(ident: &str) -> Option<SyntaxKind> {
+    pub fn from_keyword(ident: &str) -> Option<SyntaxKind> {
         let kw = match ident {
             "use" => USE_KW,
             "fn" => FN_KW,
@@ -610,7 +610,7 @@ impl SyntaxKind {
         Some(kw)
     }
 
-    pub(crate) fn from_char(c: char) -> Option<SyntaxKind> {
+    pub fn from_char(c: char) -> Option<SyntaxKind> {
         let tok = match c {
             ';' => SEMI,
             ',' => COMMA,
diff --git a/crates/ra_syntax/src/syntax_kinds/generated.rs.tera b/crates/ra_parser/src/syntax_kind/generated.rs.tera
index 837437136..837437136 100644
--- a/crates/ra_syntax/src/syntax_kinds/generated.rs.tera
+++ b/crates/ra_parser/src/syntax_kind/generated.rs.tera
diff --git a/crates/ra_syntax/src/parsing/token_set.rs b/crates/ra_parser/src/token_set.rs
index 24152a38a..24152a38a 100644
--- a/crates/ra_syntax/src/parsing/token_set.rs
+++ b/crates/ra_parser/src/token_set.rs