From cc66a7ff20d0c8626661fe6f53daab265537425f Mon Sep 17 00:00:00 2001 From: David Tolnay Date: Tue, 18 Jan 2022 19:59:36 -0800 Subject: Eliminate eof token state --- compiler/rustc_ast_pretty/src/pp.rs | 51 +++++++++++++-------------- compiler/rustc_ast_pretty/src/pp/ring.rs | 15 ++++---- compiler/rustc_ast_pretty/src/pprust/state.rs | 20 ++++++----- 3 files changed, 44 insertions(+), 42 deletions(-) diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs index b9b2f77431e..0c9d4ef0e95 100644 --- a/compiler/rustc_ast_pretty/src/pp.rs +++ b/compiler/rustc_ast_pretty/src/pp.rs @@ -167,14 +167,9 @@ pub enum Token { Break(BreakToken), Begin(BeginToken), End, - Eof, } impl Token { - crate fn is_eof(&self) -> bool { - matches!(self, Token::Eof) - } - pub fn is_hardbreak_tok(&self) -> bool { matches!(self, Token::Break(BreakToken { offset: 0, blank_space: SIZE_INFINITY })) } @@ -187,7 +182,6 @@ impl fmt::Display for Token { Token::Break(_) => f.write_str("BREAK"), Token::Begin(_) => f.write_str("BEGIN"), Token::End => f.write_str("END"), - Token::Eof => f.write_str("EOF"), } } } @@ -233,6 +227,9 @@ pub struct Printer { print_stack: Vec, /// Buffered indentation to avoid writing trailing whitespace pending_indentation: isize, + /// The token most recently popped from the left boundary of the + /// ring-buffer for printing + last_printed: Option, } #[derive(Clone)] @@ -241,39 +238,36 @@ struct BufEntry { size: isize, } -impl Default for BufEntry { - fn default() -> Self { - BufEntry { token: Token::Eof, size: 0 } - } -} - impl Printer { pub fn new() -> Self { let linewidth = 78; - let mut buf = RingBuffer::new(); - buf.advance_right(); Printer { out: String::new(), margin: linewidth as isize, space: linewidth as isize, left: 0, right: 0, - buf, + buf: RingBuffer::new(), left_total: 0, right_total: 0, scan_stack: VecDeque::new(), print_stack: Vec::new(), pending_indentation: 0, + last_printed: None, } } - pub fn last_token(&self) -> Token { - self.buf[self.right].token.clone() + pub fn last_token(&self) -> Option<&Token> { + self.last_token_still_buffered().or_else(|| self.last_printed.as_ref()) + } + + pub fn last_token_still_buffered(&self) -> Option<&Token> { + self.buf.last().map(|last| &last.token) } /// Be very careful with this! - pub fn replace_last_token(&mut self, t: Token) { - self.buf[self.right].token = t; + pub fn replace_last_token_still_buffered(&mut self, t: Token) { + self.buf.last_mut().unwrap().token = t; } fn scan_eof(&mut self) { @@ -323,7 +317,7 @@ impl Printer { fn scan_string(&mut self, s: Cow<'static, str>) { if self.scan_stack.is_empty() { - self.print_string(s); + self.print_string(&s); } else { self.right += 1; let len = s.len() as isize; @@ -459,7 +453,7 @@ impl Printer { } } - fn print_string(&mut self, s: Cow<'static, str>) { + fn print_string(&mut self, s: &str) { let len = s.len() as isize; // assert!(len <= space); self.space -= len; @@ -473,21 +467,21 @@ impl Printer { self.out.reserve(self.pending_indentation as usize); self.out.extend(std::iter::repeat(' ').take(self.pending_indentation as usize)); self.pending_indentation = 0; - self.out.push_str(&s); + self.out.push_str(s); } fn print(&mut self, token: Token, l: isize) { - match token { - Token::Begin(b) => self.print_begin(b, l), + match &token { + Token::Begin(b) => self.print_begin(*b, l), Token::End => self.print_end(), - Token::Break(b) => self.print_break(b, l), + Token::Break(b) => self.print_break(*b, l), Token::String(s) => { let len = s.len() as isize; assert_eq!(len, l); self.print_string(s); } - Token::Eof => panic!(), // Eof should never get here. } + self.last_printed = Some(token); } // Convenience functions to talk to the printer. @@ -542,7 +536,10 @@ impl Printer { } pub fn is_beginning_of_line(&self) -> bool { - self.last_token().is_eof() || self.last_token().is_hardbreak_tok() + match self.last_token() { + Some(last_token) => last_token.is_hardbreak_tok(), + None => true, + } } pub fn hardbreak_tok_offset(off: isize) -> Token { diff --git a/compiler/rustc_ast_pretty/src/pp/ring.rs b/compiler/rustc_ast_pretty/src/pp/ring.rs index 62900ddfa2d..86b87614c19 100644 --- a/compiler/rustc_ast_pretty/src/pp/ring.rs +++ b/compiler/rustc_ast_pretty/src/pp/ring.rs @@ -26,13 +26,6 @@ impl RingBuffer { self.data.push_back(value); } - pub fn advance_right(&mut self) - where - T: Default, - { - self.data.push_back(T::default()); - } - pub fn advance_left(&mut self) { self.data.pop_front().unwrap(); self.offset += 1; @@ -41,6 +34,14 @@ impl RingBuffer { pub fn clear(&mut self) { self.data.clear(); } + + pub fn last(&self) -> Option<&T> { + self.data.back() + } + + pub fn last_mut(&mut self) -> Option<&mut T> { + self.data.back_mut() + } } impl Index for RingBuffer { diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs index 17941058ed6..044f6b228dc 100644 --- a/compiler/rustc_ast_pretty/src/pprust/state.rs +++ b/compiler/rustc_ast_pretty/src/pprust/state.rs @@ -329,9 +329,9 @@ pub trait PrintState<'a>: std::ops::Deref + std::ops::Dere CommentStyle::BlankLine => { // We need to do at least one, possibly two hardbreaks. let twice = match self.last_token() { - pp::Token::String(s) => ";" == s, - pp::Token::Begin(_) => true, - pp::Token::End => true, + Some(pp::Token::String(s)) => ";" == s, + Some(pp::Token::Begin(_)) => true, + Some(pp::Token::End) => true, _ => false, }; if twice { @@ -687,11 +687,15 @@ pub trait PrintState<'a>: std::ops::Deref + std::ops::Dere fn break_offset_if_not_bol(&mut self, n: usize, off: isize) { if !self.is_beginning_of_line() { self.break_offset(n, off) - } else if off != 0 && self.last_token().is_hardbreak_tok() { - // We do something pretty sketchy here: tuck the nonzero - // offset-adjustment we were going to deposit along with the - // break into the previous hardbreak. - self.replace_last_token(pp::Printer::hardbreak_tok_offset(off)); + } else if off != 0 { + if let Some(last_token) = self.last_token_still_buffered() { + if last_token.is_hardbreak_tok() { + // We do something pretty sketchy here: tuck the nonzero + // offset-adjustment we were going to deposit along with the + // break into the previous hardbreak. + self.replace_last_token_still_buffered(pp::Printer::hardbreak_tok_offset(off)); + } + } } } -- cgit v1.2.1