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Merge Printer::token and Printer::size.
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Logically, it's a vector of pairs, so might as well represent it that
way.

The commit also changes `scan_stack` so that it is initialized with the
default size, instead of the excessive `55 * linewidth` size, which it
usually doesn't get even close to reaching.
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@nnethercote
nnethercote committed Oct 10, 2016
1 parent a5dac7a commit 67a5444
Showing 1 changed file with 31 additions and 38 deletions.
69 changes: 31 additions & 38 deletions src/libsyntax/print/pp.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -125,9 +125,8 @@ impl fmt::Display for Token {
}
}

fn buf_str(toks: &[Token], szs: &[isize], left: usize, right: usize, lim: usize) -> String {
let n = toks.len();
assert_eq!(n, szs.len());
fn buf_str(buf: &[BufEntry], left: usize, right: usize, lim: usize) -> String {
let n = buf.len();
let mut i = left;
let mut l = lim;
let mut s = String::from("[");
Expand All @@ -136,7 +135,7 @@ fn buf_str(toks: &[Token], szs: &[isize], left: usize, right: usize, lim: usize)
if i != left {
s.push_str(", ");
}
s.push_str(&format!("{}={}", szs[i], &toks[i]));
s.push_str(&format!("{}={}", buf[i].size, &buf[i].token));
i += 1;
i %= n;
}
Expand All @@ -159,25 +158,20 @@ pub struct PrintStackElem {
const SIZE_INFINITY: isize = 0xffff;

pub fn mk_printer<'a>(out: Box<io::Write+'a>, linewidth: usize) -> Printer<'a> {
// Yes 55, it makes the ring buffers big enough to never
// fall behind.
// Yes 55, it makes the ring buffers big enough to never fall behind.
let n: usize = 55 * linewidth;
debug!("mk_printer {}", linewidth);
let token = vec![Token::Eof; n];
let size = vec![0; n];
let scan_stack = VecDeque::with_capacity(n);
Printer {
out: out,
buf_len: n,
margin: linewidth as isize,
space: linewidth as isize,
left: 0,
right: 0,
token: token,
size: size,
buf: vec![BufEntry { token: Token::Eof, size: 0 }; n],
left_total: 0,
right_total: 0,
scan_stack: scan_stack,
scan_stack: VecDeque::new(),
print_stack: Vec::new(),
pending_indentation: 0
}
Expand Down Expand Up @@ -269,10 +263,8 @@ pub struct Printer<'a> {
left: usize,
/// Index of right side of input stream
right: usize,
/// Ring-buffer stream goes through
token: Vec<Token> ,
/// Ring-buffer of calculated sizes
size: Vec<isize> ,
/// Ring-buffer of tokens and calculated sizes
buf: Vec<BufEntry>,
/// Running size of stream "...left"
left_total: isize,
/// Running size of stream "...right"
Expand All @@ -283,20 +275,26 @@ pub struct Printer<'a> {
/// Begin (if there is any) on top of it. Stuff is flushed off the
/// bottom as it becomes irrelevant due to the primary ring-buffer
/// advancing.
scan_stack: VecDeque<usize> ,
scan_stack: VecDeque<usize>,
/// Stack of blocks-in-progress being flushed by print
print_stack: Vec<PrintStackElem> ,
/// Buffered indentation to avoid writing trailing whitespace
pending_indentation: isize,
}

#[derive(Clone)]
struct BufEntry {
token: Token,
size: isize,
}

impl<'a> Printer<'a> {
pub fn last_token(&mut self) -> Token {
self.token[self.right].clone()
self.buf[self.right].token.clone()
}
// be very careful with this!
pub fn replace_last_token(&mut self, t: Token) {
self.token[self.right] = t;
self.buf[self.right].token = t;
}
pub fn pretty_print(&mut self, token: Token) -> io::Result<()> {
debug!("pp Vec<{},{}>", self.left, self.right);
Expand All @@ -318,8 +316,7 @@ impl<'a> Printer<'a> {
} else { self.advance_right(); }
debug!("pp Begin({})/buffer Vec<{},{}>",
b.offset, self.left, self.right);
self.token[self.right] = token;
self.size[self.right] = -self.right_total;
self.buf[self.right] = BufEntry { token: token, size: -self.right_total };
let right = self.right;
self.scan_push(right);
Ok(())
Expand All @@ -331,8 +328,7 @@ impl<'a> Printer<'a> {
} else {
debug!("pp End/buffer Vec<{},{}>", self.left, self.right);
self.advance_right();
self.token[self.right] = token;
self.size[self.right] = -1;
self.buf[self.right] = BufEntry { token: token, size: -1 };
let right = self.right;
self.scan_push(right);
Ok(())
Expand All @@ -350,8 +346,7 @@ impl<'a> Printer<'a> {
self.check_stack(0);
let right = self.right;
self.scan_push(right);
self.token[self.right] = token;
self.size[self.right] = -self.right_total;
self.buf[self.right] = BufEntry { token: token, size: -self.right_total };
self.right_total += b.blank_space;
Ok(())
}
Expand All @@ -364,8 +359,7 @@ impl<'a> Printer<'a> {
debug!("pp String('{}')/buffer Vec<{},{}>",
s, self.left, self.right);
self.advance_right();
self.token[self.right] = Token::String(s, len);
self.size[self.right] = len;
self.buf[self.right] = BufEntry { token: Token::String(s, len), size: len };
self.right_total += len;
self.check_stream()
}
Expand All @@ -381,7 +375,7 @@ impl<'a> Printer<'a> {
if Some(&self.left) == self.scan_stack.back() {
debug!("setting {} to infinity and popping", self.left);
let scanned = self.scan_pop_bottom();
self.size[scanned] = SIZE_INFINITY;
self.buf[scanned].size = SIZE_INFINITY;
}
self.advance_left()?;
if self.left != self.right {
Expand Down Expand Up @@ -410,12 +404,12 @@ impl<'a> Printer<'a> {
}
pub fn advance_left(&mut self) -> io::Result<()> {
debug!("advance_left Vec<{},{}>, sizeof({})={}", self.left, self.right,
self.left, self.size[self.left]);
self.left, self.buf[self.left].size);

let mut left_size = self.size[self.left];
let mut left_size = self.buf[self.left].size;

while left_size >= 0 {
let left = self.token[self.left].clone();
let left = self.buf[self.left].token.clone();

let len = match left {
Token::Break(b) => b.blank_space,
Expand All @@ -437,31 +431,31 @@ impl<'a> Printer<'a> {
self.left += 1;
self.left %= self.buf_len;

left_size = self.size[self.left];
left_size = self.buf[self.left].size;
}

Ok(())
}
pub fn check_stack(&mut self, k: isize) {
if !self.scan_stack.is_empty() {
let x = self.scan_top();
match self.token[x] {
match self.buf[x].token {
Token::Begin(_) => {
if k > 0 {
let popped = self.scan_pop();
self.size[popped] = self.size[x] + self.right_total;
self.buf[popped].size = self.buf[x].size + self.right_total;
self.check_stack(k - 1);
}
}
Token::End => {
// paper says + not =, but that makes no sense.
let popped = self.scan_pop();
self.size[popped] = 1;
self.buf[popped].size = 1;
self.check_stack(k + 1);
}
_ => {
let popped = self.scan_pop();
self.size[popped] = self.size[x] + self.right_total;
self.buf[popped].size = self.buf[x].size + self.right_total;
if k > 0 {
self.check_stack(k);
}
Expand Down Expand Up @@ -499,8 +493,7 @@ impl<'a> Printer<'a> {
pub fn print(&mut self, token: Token, l: isize) -> io::Result<()> {
debug!("print {} {} (remaining line space={})", token, l,
self.space);
debug!("{}", buf_str(&self.token,
&self.size,
debug!("{}", buf_str(&self.buf,
self.left,
self.right,
6));
Expand Down

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