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Don't emit trivia tokens
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@matklad
matklad committed Sep 1, 2020
1 parent 445f34b commit 8f24c2e
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Showing 2 changed files with 56 additions and 73 deletions.
113 changes: 53 additions & 60 deletions compiler/rustc_parse/src/lexer/mod.rs
View file
@@ -1,5 +1,6 @@
use rustc_ast::ast::AttrStyle;
use rustc_ast::token::{self, CommentKind, Token, TokenKind};
use rustc_ast::tokenstream::IsJoint;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{error_code, Applicability, DiagnosticBuilder, FatalError};
use rustc_lexer::Base;
Expand Down Expand Up @@ -65,42 +66,46 @@ impl<'a> StringReader<'a> {
self.override_span.unwrap_or_else(|| Span::with_root_ctxt(lo, hi))
}

/// Returns the next token, including trivia like whitespace or comments.
fn next_token(&mut self) -> Token {
/// Returns the next token, and info about preceding whitespace, if any.
fn next_token(&mut self) -> (IsJoint, Token) {
let mut is_joint = IsJoint::Joint;

// Skip `#!` at the start of the file
let start_src_index = self.src_index(self.pos);
let text: &str = &self.src[start_src_index..self.end_src_index];

if text.is_empty() {
let span = self.mk_sp(self.pos, self.pos);
return Token::new(token::Eof, span);
let is_beginning_of_file = self.pos == self.start_pos;
if is_beginning_of_file {
if let Some(shebang_len) = rustc_lexer::strip_shebang(text) {
self.pos = self.pos + BytePos::from_usize(shebang_len);
is_joint = IsJoint::NonJoint;
}
}

{
let is_beginning_of_file = self.pos == self.start_pos;
if is_beginning_of_file {
if let Some(shebang_len) = rustc_lexer::strip_shebang(text) {
let start = self.pos;
self.pos = self.pos + BytePos::from_usize(shebang_len);
// Skip trivial (whitespace & comments) tokens
loop {
let start_src_index = self.src_index(self.pos);
let text: &str = &self.src[start_src_index..self.end_src_index];

let sym = self.symbol_from(start + BytePos::from_usize("#!".len()));
let kind = token::Shebang(sym);

let span = self.mk_sp(start, self.pos);
return Token::new(kind, span);
}
if text.is_empty() {
let span = self.mk_sp(self.pos, self.pos);
return (is_joint, Token::new(token::Eof, span));
}
}

let token = rustc_lexer::first_token(text);
let token = rustc_lexer::first_token(text);

let start = self.pos;
self.pos = self.pos + BytePos::from_usize(token.len);
let start = self.pos;
self.pos = self.pos + BytePos::from_usize(token.len);

debug!("try_next_token: {:?}({:?})", token.kind, self.str_from(start));
debug!("next_token: {:?}({:?})", token.kind, self.str_from(start));

let kind = self.cook_lexer_token(token.kind, start);
let span = self.mk_sp(start, self.pos);
Token::new(kind, span)
match self.cook_lexer_token(token.kind, start) {
Some(kind) => {
let span = self.mk_sp(start, self.pos);
return (is_joint, Token::new(kind, span));
}
None => is_joint = IsJoint::NonJoint,
}
}
}

/// Report a fatal lexical error with a given span.
Expand Down Expand Up @@ -140,19 +145,16 @@ impl<'a> StringReader<'a> {
/// Turns simple `rustc_lexer::TokenKind` enum into a rich
/// `librustc_ast::TokenKind`. This turns strings into interned
/// symbols and runs additional validation.
fn cook_lexer_token(&self, token: rustc_lexer::TokenKind, start: BytePos) -> TokenKind {
match token {
fn cook_lexer_token(&self, token: rustc_lexer::TokenKind, start: BytePos) -> Option<TokenKind> {
Some(match token {
rustc_lexer::TokenKind::LineComment { doc_style } => {
match doc_style {
Some(doc_style) => {
// Opening delimiter of the length 3 is not included into the symbol.
let content_start = start + BytePos(3);
let content = self.str_from(content_start);
// Skip non-doc comments
let doc_style = doc_style?;

self.cook_doc_comment(content_start, content, CommentKind::Line, doc_style)
}
None => token::Comment,
}
// Opening delimiter of the length 3 is not included into the symbol.
let content_start = start + BytePos(3);
let content = self.str_from(content_start);
self.cook_doc_comment(content_start, content, CommentKind::Line, doc_style)
}
rustc_lexer::TokenKind::BlockComment { doc_style, terminated } => {
if !terminated {
Expand All @@ -171,20 +173,18 @@ impl<'a> StringReader<'a> {
.emit();
FatalError.raise();
}
match doc_style {
Some(doc_style) => {
// Opening delimiter of the length 3 and closing delimiter of the length 2
// are not included into the symbol.
let content_start = start + BytePos(3);
let content_end = self.pos - BytePos(if terminated { 2 } else { 0 });
let content = self.str_from_to(content_start, content_end);

self.cook_doc_comment(content_start, content, CommentKind::Block, doc_style)
}
None => token::Comment,
}

// Skip non-doc comments
let doc_style = doc_style?;

// Opening delimiter of the length 3 and closing delimiter of the length 2
// are not included into the symbol.
let content_start = start + BytePos(3);
let content_end = self.pos - BytePos(if terminated { 2 } else { 0 });
let content = self.str_from_to(content_start, content_end);
self.cook_doc_comment(content_start, content, CommentKind::Block, doc_style)
}
rustc_lexer::TokenKind::Whitespace => token::Whitespace,
rustc_lexer::TokenKind::Whitespace => return None,
rustc_lexer::TokenKind::Ident | rustc_lexer::TokenKind::RawIdent => {
let is_raw_ident = token == rustc_lexer::TokenKind::RawIdent;
let mut ident_start = start;
Expand Down Expand Up @@ -282,12 +282,11 @@ impl<'a> StringReader<'a> {
// this should be inside `rustc_lexer`. However, we should first remove compound
// tokens like `<<` from `rustc_lexer`, and then add fancier error recovery to it,
// as there will be less overall work to do this way.
let token = unicode_chars::check_for_substitution(self, start, c, &mut err)
.unwrap_or_else(|| token::Unknown(self.symbol_from(start)));
let token = unicode_chars::check_for_substitution(self, start, c, &mut err);
err.emit();
token
token?
}
}
})
}

fn cook_doc_comment(
Expand Down Expand Up @@ -450,12 +449,6 @@ impl<'a> StringReader<'a> {
self.str_from_to(start, self.pos)
}

/// Creates a Symbol from a given offset to the current offset.
fn symbol_from(&self, start: BytePos) -> Symbol {
debug!("taking an ident from {:?} to {:?}", start, self.pos);
Symbol::intern(self.str_from(start))
}

/// As symbol_from, with an explicit endpoint.
fn symbol_from_to(&self, start: BytePos, end: BytePos) -> Symbol {
debug!("taking an ident from {:?} to {:?}", start, end);
Expand Down
16 changes: 3 additions & 13 deletions compiler/rustc_parse/src/lexer/tokentrees.rs
View file
Expand Up @@ -272,19 +272,9 @@ impl<'a> TokenTreesReader<'a> {
}

fn real_token(&mut self) {
self.joint_to_prev = Joint;
loop {
let token = self.string_reader.next_token();
match token.kind {
token::Whitespace | token::Comment | token::Shebang(_) | token::Unknown(_) => {
self.joint_to_prev = NonJoint;
}
_ => {
self.token = token;
return;
}
}
}
let (joint_to_prev, token) = self.string_reader.next_token();
self.joint_to_prev = joint_to_prev;
self.token = token;
}
}

Expand Down

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