Separate parser API from implementation

7 files changed, 252 insertions, 230 deletions

diff --git a/src/parser/event.rs b/src/parser/event.rs
index 90348398e..30fe5c6d7 100644
--- a/src/parser/event.rs
+++ b/src/parser/event.rs
@@ -61,7 +61,7 @@ pub(crate) enum Event {
     },
 
     Error {
-        message: String,
+        msg: String,
     },
 }
 
@@ -140,8 +140,8 @@ pub(super) fn to_file(text: String, tokens: &[Token], events: Vec<Event>) -> Fil
                 }
                 builder.leaf(kind, len);
             }
-            &Event::Error { ref message } => builder.error(ErrorMsg {
-                message: message.clone(),
+            &Event::Error { ref msg } => builder.error(ErrorMsg {
+                msg: msg.clone(),
             }),
         }
     }
diff --git a/src/parser/grammar/mod.rs b/src/parser/grammar/mod.rs
index f5b63aaab..e29cf9b02 100644
--- a/src/parser/grammar/mod.rs
+++ b/src/parser/grammar/mod.rs
@@ -1,4 +1,5 @@
-use super::parser::{Parser, TokenSet};
+use parser::parser::{Parser};
+use parser::token_set::TokenSet;
 use SyntaxKind;
 use syntax_kinds::*;
 
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index c23ed3349..3814837e1 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -3,19 +3,20 @@ use {File, SyntaxKind, Token};
 use syntax_kinds::*;
 
 #[macro_use]
+mod token_set;
 mod parser;
 mod input;
 mod event;
 mod grammar;
-use self::event::Event;
 
 /// Parse a sequence of tokens into the representative node tree
 pub fn parse(text: String, tokens: &[Token]) -> File {
     let events = {
         let input = input::ParserInput::new(&text, tokens);
-        let mut parser = parser::Parser::new(&input);
+        let parser_impl = parser::imp::ParserImpl::new(&input);
+        let mut parser = parser::Parser(parser_impl);
         grammar::file(&mut parser);
-        parser.into_events()
+        parser.0.into_events()
     };
     event::to_file(text, tokens, events)
 }
@@ -26,33 +27,3 @@ fn is_insignificant(kind: SyntaxKind) -> bool {
         _ => false,
     }
 }
-
-impl<'p> parser::Parser<'p> {
-    fn at(&self, kind: SyntaxKind) -> bool {
-        self.current() == kind
-    }
-
-    fn err_and_bump(&mut self, message: &str) {
-        let err = self.start();
-        self.error(message);
-        self.bump();
-        err.complete(self, ERROR);
-    }
-
-    fn expect(&mut self, kind: SyntaxKind) -> bool {
-        if self.at(kind) {
-            self.bump();
-            true
-        } else {
-            self.error(format!("expected {:?}", kind));
-            false
-        }
-    }
-
-    fn eat(&mut self, kind: SyntaxKind) -> bool {
-        self.at(kind) && {
-            self.bump();
-            true
-        }
-    }
-}
diff --git a/src/parser/parser.rs b/src/parser/parser.rs
deleted file mode 100644
index 7c8e47cb6..000000000
--- a/src/parser/parser.rs
+++ /dev/null
@@ -1,193 +0,0 @@
-use super::Event;
-use super::input::{InputPosition, ParserInput};
-use SyntaxKind::{self, EOF, TOMBSTONE};
-
-pub(crate) struct Marker {
-    pos: u32,
-}
-
-impl Marker {
-    pub fn complete(self, p: &mut Parser, kind: SyntaxKind) -> CompleteMarker {
-        match self.event(p) {
-            &mut Event::Start {
-                kind: ref mut slot, ..
-            } => {
-                *slot = kind;
-            }
-            _ => unreachable!(),
-        }
-        p.event(Event::Finish);
-        let result = CompleteMarker { pos: self.pos };
-        ::std::mem::forget(self);
-        result
-    }
-
-    pub fn abandon(self, p: &mut Parser) {
-        let idx = self.pos as usize;
-        if idx == p.events.len() - 1 {
-            match p.events.pop() {
-                Some(Event::Start {
-                    kind: TOMBSTONE,
-                    forward_parent: None,
-                }) => (),
-                _ => unreachable!(),
-            }
-        }
-        ::std::mem::forget(self);
-    }
-
-    fn event<'p>(&self, p: &'p mut Parser) -> &'p mut Event {
-        &mut p.events[self.idx()]
-    }
-
-    fn idx(&self) -> usize {
-        self.pos as usize
-    }
-}
-
-impl Drop for Marker {
-    fn drop(&mut self) {
-        if !::std::thread::panicking() {
-            panic!("Each marker should be eithe completed or abandoned");
-        }
-    }
-}
-
-pub(crate) struct CompleteMarker {
-    pos: u32,
-}
-
-impl CompleteMarker {
-    pub(crate) fn precede(self, p: &mut Parser) -> Marker {
-        let m = p.start();
-        match p.events[self.pos as usize] {
-            Event::Start {
-                ref mut forward_parent,
-                ..
-            } => {
-                *forward_parent = Some(m.pos - self.pos);
-            }
-            _ => unreachable!(),
-        }
-        m
-    }
-}
-
-pub(crate) struct TokenSet {
-    pub tokens: &'static [SyntaxKind],
-}
-
-impl TokenSet {
-    pub fn contains(&self, kind: SyntaxKind) -> bool {
-        self.tokens.contains(&kind)
-    }
-}
-
-#[macro_export]
-macro_rules! token_set {
-    ($($t:ident),*) => {
-        TokenSet {
-            tokens: &[$($t),*],
-        }
-    };
-
-    ($($t:ident),* ,) => {
-        token_set!($($t),*)
-    };
-}
-
-pub(crate) struct Parser<'t> {
-    inp: &'t ParserInput<'t>,
-
-    pos: InputPosition,
-    events: Vec<Event>,
-}
-
-impl<'t> Parser<'t> {
-    pub(crate) fn new(inp: &'t ParserInput<'t>) -> Parser<'t> {
-        Parser {
-            inp,
-
-            pos: InputPosition::new(),
-            events: Vec::new(),
-        }
-    }
-
-    pub(crate) fn into_events(self) -> Vec<Event> {
-        assert_eq!(self.current(), EOF);
-        self.events
-    }
-
-    pub(crate) fn start(&mut self) -> Marker {
-        let m = Marker {
-            pos: self.events.len() as u32,
-        };
-        self.event(Event::Start {
-            kind: TOMBSTONE,
-            forward_parent: None,
-        });
-        m
-    }
-
-    pub(crate) fn error<'p, T: Into<String>>(&'p mut self, msg: T) -> ErrorBuilder<'p, 't> {
-        ErrorBuilder::new(self, msg.into())
-    }
-
-    pub(crate) fn bump(&mut self) {
-        let kind = self.current();
-        if kind == EOF {
-            return;
-        }
-        self.pos += 1;
-        self.event(Event::Token {
-            kind,
-            n_raw_tokens: 1,
-        });
-    }
-
-    pub(crate) fn bump_remap(&mut self, kind: SyntaxKind) {
-        if self.current() == EOF {
-            // TODO: panic!?
-            return;
-        }
-        self.pos += 1;
-        self.event(Event::Token {
-            kind,
-            n_raw_tokens: 1,
-        });
-    }
-
-    pub(crate) fn nth(&self, n: u32) -> SyntaxKind {
-        self.inp.kind(self.pos + n)
-    }
-
-    pub(crate) fn at_kw(&self, t: &str) -> bool {
-        self.inp.text(self.pos) == t
-    }
-
-    pub(crate) fn current(&self) -> SyntaxKind {
-        self.nth(0)
-    }
-
-    fn event(&mut self, event: Event) {
-        self.events.push(event)
-    }
-}
-
-pub(crate) struct ErrorBuilder<'p, 't: 'p> {
-    message: String,
-    parser: &'p mut Parser<'t>,
-}
-
-impl<'p, 't: 'p> Drop for ErrorBuilder<'p, 't> {
-    fn drop(&mut self) {
-        let message = ::std::mem::replace(&mut self.message, String::new());
-        self.parser.event(Event::Error { message });
-    }
-}
-
-impl<'t, 'p> ErrorBuilder<'p, 't> {
-    fn new(parser: &'p mut Parser<'t>, message: String) -> Self {
-        ErrorBuilder { message, parser }
-    }
-}
diff --git a/src/parser/parser/imp.rs b/src/parser/parser/imp.rs
new file mode 100644
index 000000000..2b16e11b9
--- /dev/null
+++ b/src/parser/parser/imp.rs
@@ -0,0 +1,118 @@
+use parser::input::{ParserInput, InputPosition};
+use parser::event::Event;
+
+use SyntaxKind;
+use syntax_kinds::{TOMBSTONE, EOF};
+
+pub(crate) struct ParserImpl<'t> {
+    inp: &'t ParserInput<'t>,
+
+    pos: InputPosition,
+    events: Vec<Event>,
+}
+
+impl<'t> ParserImpl<'t> {
+    pub(crate) fn new(inp: &'t ParserInput<'t>) -> ParserImpl<'t> {
+        ParserImpl {
+            inp,
+
+            pos: InputPosition::new(),
+            events: Vec::new(),
+        }
+    }
+
+    pub(crate) fn into_events(self) -> Vec<Event> {
+        assert_eq!(self.nth(0), EOF);
+        self.events
+    }
+
+
+    pub(super) fn nth(&self, n: u32) -> SyntaxKind {
+        self.inp.kind(self.pos + n)
+    }
+
+    pub(super) fn at_kw(&self, t: &str) -> bool {
+        self.inp.text(self.pos) == t
+    }
+
+    pub(super) fn start(&mut self) -> u32 {
+        let pos = self.events.len() as u32;
+        self.event(Event::Start {
+            kind: TOMBSTONE,
+            forward_parent: None,
+        });
+        pos
+    }
+
+    pub(super) fn bump(&mut self) {
+        let kind = self.nth(0);
+        if kind == EOF {
+            return;
+        }
+        self.do_bump(kind);
+    }
+
+    pub(super) fn bump_remap(&mut self, kind: SyntaxKind) {
+        if self.nth(0) == EOF {
+            // TODO: panic!?
+            return;
+        }
+        self.do_bump(kind);
+    }
+
+    fn do_bump(&mut self, kind: SyntaxKind) {
+        self.pos += 1;
+        self.event(Event::Token {
+            kind,
+            n_raw_tokens: 1,
+        });
+    }
+
+    pub(super) fn error(&mut self, msg: String) {
+        self.event(Event::Error { msg })
+    }
+
+    pub(super) fn complete(&mut self, pos: u32, kind: SyntaxKind) {
+        match self.events[pos as usize] {
+            Event::Start {
+                kind: ref mut slot, ..
+            } => {
+                *slot = kind;
+            }
+            _ => unreachable!(),
+        }
+        self.event(Event::Finish);
+    }
+
+    pub(super) fn abandon(&mut self, pos: u32) {
+        let idx = pos as usize;
+        if idx == self.events.len() - 1 {
+            match self.events.pop() {
+                Some(Event::Start {
+                         kind: TOMBSTONE,
+                         forward_parent: None,
+                     }) => (),
+                _ => unreachable!(),
+            }
+        }
+    }
+
+    pub(super) fn precede(&mut self, pos: u32) -> u32 {
+        let new_pos = self.start();
+        match self.events[pos as usize] {
+            Event::Start {
+                ref mut forward_parent,
+                ..
+            } => {
+                *forward_parent = Some(new_pos - pos);
+            }
+            _ => unreachable!(),
+        }
+        new_pos
+    }
+
+
+    fn event(&mut self, event: Event) {
+        self.events.push(event)
+    }
+}
diff --git a/src/parser/parser/mod.rs b/src/parser/parser/mod.rs
new file mode 100644
index 000000000..c8db20918
--- /dev/null
+++ b/src/parser/parser/mod.rs
@@ -0,0 +1,100 @@
+use SyntaxKind;
+use syntax_kinds::ERROR;
+
+pub(super) mod imp;
+use self::imp::ParserImpl;
+
+pub(crate) struct Parser<'t>(pub(super) ParserImpl<'t>);
+
+
+impl<'t> Parser<'t> {
+    pub(crate) fn current(&self) -> SyntaxKind {
+        self.nth(0)
+    }
+
+    pub(crate) fn nth(&self, n: u32) -> SyntaxKind {
+        self.0.nth(n)
+    }
+
+    pub(crate) fn at(&self, kind: SyntaxKind) -> bool {
+        self.current() == kind
+    }
+
+    pub(crate) fn at_kw(&self, t: &str) -> bool {
+        self.0.at_kw(t)
+    }
+
+    pub(crate) fn start(&mut self) -> Marker {
+        Marker(self.0.start())
+    }
+
+    pub(crate) fn bump(&mut self) {
+        self.0.bump();
+    }
+
+    pub(crate) fn bump_remap(&mut self, kind: SyntaxKind) {
+        self.0.bump_remap(kind);
+    }
+
+    pub(crate) fn error<T: Into<String>>(&mut self, message: T) {
+        self.0.error(message.into())
+    }
+
+    pub(crate) fn expect(&mut self, kind: SyntaxKind) -> bool {
+        if self.at(kind) {
+            self.bump();
+            return true;
+        }
+        self.error(format!("expected {:?}", kind));
+        false
+    }
+
+    pub(crate) fn eat(&mut self, kind: SyntaxKind) -> bool {
+        if !self.at(kind) {
+            return false;
+        }
+        self.bump();
+        true
+    }
+
+    pub(crate) fn err_and_bump(&mut self, message: &str) {
+        let m = self.start();
+        self.error(message);
+        self.bump();
+        m.complete(self, ERROR);
+    }
+}
+
+pub(crate) struct Marker(u32);
+
+impl Marker {
+    pub(crate) fn complete(self, p: &mut Parser, kind: SyntaxKind) -> CompletedMarker {
+        let pos = self.0;
+        ::std::mem::forget(self);
+        p.0.complete(pos, kind);
+        CompletedMarker(pos)
+    }
+
+    pub(crate) fn abandon(self, p: &mut Parser) {
+        let pos = self.0;
+        ::std::mem::forget(self);
+        p.0.abandon(pos);
+    }
+}
+
+impl Drop for Marker {
+    fn drop(&mut self) {
+        if !::std::thread::panicking() {
+            panic!("Marker must be either completed or abandoned");
+        }
+    }
+}
+
+
+pub(crate) struct CompletedMarker(u32);
+
+impl CompletedMarker {
+    pub(crate) fn precede(self, p: &mut Parser) -> Marker {
+        Marker(p.0.precede(self.0))
+    }
+}
diff --git a/src/parser/token_set.rs b/src/parser/token_set.rs
new file mode 100644
index 000000000..82558fa2e
--- /dev/null
+++ b/src/parser/token_set.rs
@@ -0,0 +1,25 @@
+use SyntaxKind;
+
+pub(crate) struct TokenSet {
+    pub tokens: &'static [SyntaxKind],
+}
+
+impl TokenSet {
+    pub fn contains(&self, kind: SyntaxKind) -> bool {
+        self.tokens.contains(&kind)
+    }
+}
+
+#[macro_export]
+macro_rules! token_set {
+    ($($t:ident),*) => {
+        TokenSet {
+            tokens: &[$($t),*],
+        }
+    };
+
+    ($($t:ident),* ,) => {
+        token_set!($($t),*)
+    };
+}
+