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Rollup merge of rust-lang#33309 - birkenfeld:pp, r=nrc
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Make libsyntax::print::pp more idiomatic

Minor cleanup, and using VecDeque as a ring buffer instead of a vector.
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@Manishearth
Manishearth committed May 3, 2016
2 parents 40199f6 + 4186169 commit 308f10c
Showing 1 changed file with 44 additions and 85 deletions.
129 changes: 44 additions & 85 deletions src/libsyntax/print/pp.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,8 +61,9 @@
//! line (which it can't) and so naturally place the content on its own line to
//! avoid combining it with other lines and making matters even worse.

use std::collections::VecDeque;
use std::fmt;
use std::io;
use std::string;

#[derive(Clone, Copy, PartialEq)]
pub enum Breaks {
Expand Down Expand Up @@ -112,35 +113,30 @@ impl Token {
}
}

pub fn tok_str(token: &Token) -> String {
match *token {
Token::String(ref s, len) => format!("STR({},{})", s, len),
Token::Break(_) => "BREAK".to_string(),
Token::Begin(_) => "BEGIN".to_string(),
Token::End => "END".to_string(),
Token::Eof => "EOF".to_string()
impl fmt::Display for Token {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Token::String(ref s, len) => write!(f, "STR({},{})", s, len),
Token::Break(_) => f.write_str("BREAK"),
Token::Begin(_) => f.write_str("BEGIN"),
Token::End => f.write_str("END"),
Token::Eof => f.write_str("EOF"),
}
}
}

pub fn buf_str(toks: &[Token],
szs: &[isize],
left: usize,
right: usize,
lim: usize)
-> String {
fn buf_str(toks: &[Token], szs: &[isize], left: usize, right: usize, lim: usize) -> String {
let n = toks.len();
assert_eq!(n, szs.len());
let mut i = left;
let mut l = lim;
let mut s = string::String::from("[");
let mut s = String::from("[");
while i != right && l != 0 {
l -= 1;
if i != left {
s.push_str(", ");
}
s.push_str(&format!("{}={}",
szs[i],
tok_str(&toks[i])));
s.push_str(&format!("{}={}", szs[i], &toks[i]));
i += 1;
i %= n;
}
Expand Down Expand Up @@ -169,7 +165,7 @@ pub fn mk_printer<'a>(out: Box<io::Write+'a>, linewidth: usize) -> Printer<'a> {
debug!("mk_printer {}", linewidth);
let token = vec![Token::Eof; n];
let size = vec![0; n];
let scan_stack = vec![0; n];
let scan_stack = VecDeque::with_capacity(n);
Printer {
out: out,
buf_len: n,
Expand All @@ -182,9 +178,6 @@ pub fn mk_printer<'a>(out: Box<io::Write+'a>, linewidth: usize) -> Printer<'a> {
left_total: 0,
right_total: 0,
scan_stack: scan_stack,
scan_stack_empty: true,
top: 0,
bottom: 0,
print_stack: Vec::new(),
pending_indentation: 0
}
Expand Down Expand Up @@ -246,9 +239,8 @@ pub fn mk_printer<'a>(out: Box<io::Write+'a>, linewidth: usize) -> Printer<'a> {
/// approximation for purposes of line breaking).
///
/// The "input side" of the printer is managed as an abstract process called
/// SCAN, which uses 'scan_stack', 'scan_stack_empty', 'top' and 'bottom', to
/// manage calculating 'size'. SCAN is, in other words, the process of
/// calculating 'size' entries.
/// SCAN, which uses 'scan_stack', to manage calculating 'size'. SCAN is, in
/// other words, the process of calculating 'size' entries.
///
/// The "output side" of the printer is managed by an abstract process called
/// PRINT, which uses 'print_stack', 'margin' and 'space' to figure out what to
Expand Down Expand Up @@ -291,13 +283,7 @@ 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: Vec<usize> ,
/// Top==bottom disambiguator
scan_stack_empty: bool,
/// Index of top of scan_stack
top: usize,
/// Index of bottom of scan_stack
bottom: 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
Expand All @@ -316,15 +302,15 @@ impl<'a> Printer<'a> {
debug!("pp Vec<{},{}>", self.left, self.right);
match token {
Token::Eof => {
if !self.scan_stack_empty {
if !self.scan_stack.is_empty() {
self.check_stack(0);
self.advance_left()?;
}
self.indent(0);
Ok(())
}
Token::Begin(b) => {
if self.scan_stack_empty {
if self.scan_stack.is_empty() {
self.left_total = 1;
self.right_total = 1;
self.left = 0;
Expand All @@ -339,7 +325,7 @@ impl<'a> Printer<'a> {
Ok(())
}
Token::End => {
if self.scan_stack_empty {
if self.scan_stack.is_empty() {
debug!("pp End/print Vec<{},{}>", self.left, self.right);
self.print(token, 0)
} else {
Expand All @@ -353,7 +339,7 @@ impl<'a> Printer<'a> {
}
}
Token::Break(b) => {
if self.scan_stack_empty {
if self.scan_stack.is_empty() {
self.left_total = 1;
self.right_total = 1;
self.left = 0;
Expand All @@ -370,7 +356,7 @@ impl<'a> Printer<'a> {
Ok(())
}
Token::String(s, len) => {
if self.scan_stack_empty {
if self.scan_stack.is_empty() {
debug!("pp String('{}')/print Vec<{},{}>",
s, self.left, self.right);
self.print(Token::String(s, len), len)
Expand All @@ -392,12 +378,10 @@ impl<'a> Printer<'a> {
if self.right_total - self.left_total > self.space {
debug!("scan window is {}, longer than space on line ({})",
self.right_total - self.left_total, self.space);
if !self.scan_stack_empty {
if self.left == self.scan_stack[self.bottom] {
debug!("setting {} to infinity and popping", self.left);
let scanned = self.scan_pop_bottom();
self.size[scanned] = SIZE_INFINITY;
}
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.advance_left()?;
if self.left != self.right {
Expand All @@ -408,43 +392,21 @@ impl<'a> Printer<'a> {
}
pub fn scan_push(&mut self, x: usize) {
debug!("scan_push {}", x);
if self.scan_stack_empty {
self.scan_stack_empty = false;
} else {
self.top += 1;
self.top %= self.buf_len;
assert!((self.top != self.bottom));
}
self.scan_stack[self.top] = x;
self.scan_stack.push_front(x);
}
pub fn scan_pop(&mut self) -> usize {
assert!((!self.scan_stack_empty));
let x = self.scan_stack[self.top];
if self.top == self.bottom {
self.scan_stack_empty = true;
} else {
self.top += self.buf_len - 1; self.top %= self.buf_len;
}
return x;
self.scan_stack.pop_front().unwrap()
}
pub fn scan_top(&mut self) -> usize {
assert!((!self.scan_stack_empty));
return self.scan_stack[self.top];
*self.scan_stack.front().unwrap()
}
pub fn scan_pop_bottom(&mut self) -> usize {
assert!((!self.scan_stack_empty));
let x = self.scan_stack[self.bottom];
if self.top == self.bottom {
self.scan_stack_empty = true;
} else {
self.bottom += 1; self.bottom %= self.buf_len;
}
return x;
self.scan_stack.pop_back().unwrap()
}
pub fn advance_right(&mut self) {
self.right += 1;
self.right %= self.buf_len;
assert!((self.right != self.left));
assert!(self.right != self.left);
}
pub fn advance_left(&mut self) -> io::Result<()> {
debug!("advance_left Vec<{},{}>, sizeof({})={}", self.left, self.right,
Expand Down Expand Up @@ -481,7 +443,7 @@ impl<'a> Printer<'a> {
Ok(())
}
pub fn check_stack(&mut self, k: isize) {
if !self.scan_stack_empty {
if !self.scan_stack.is_empty() {
let x = self.scan_top();
match self.token[x] {
Token::Begin(_) => {
Expand Down Expand Up @@ -512,19 +474,16 @@ impl<'a> Printer<'a> {
let ret = write!(self.out, "\n");
self.pending_indentation = 0;
self.indent(amount);
return ret;
ret
}
pub fn indent(&mut self, amount: isize) {
debug!("INDENT {}", amount);
self.pending_indentation += amount;
}
pub fn get_top(&mut self) -> PrintStackElem {
let print_stack = &mut self.print_stack;
let n = print_stack.len();
if n != 0 {
(*print_stack)[n - 1]
} else {
PrintStackElem {
match self.print_stack.last() {
Some(el) => *el,
None => PrintStackElem {
offset: 0,
pbreak: PrintStackBreak::Broken(Breaks::Inconsistent)
}
Expand All @@ -538,7 +497,7 @@ impl<'a> Printer<'a> {
write!(self.out, "{}", s)
}
pub fn print(&mut self, token: Token, l: isize) -> io::Result<()> {
debug!("print {} {} (remaining line space={})", tok_str(&token), l,
debug!("print {} {} (remaining line space={})", token, l,
self.space);
debug!("{}", buf_str(&self.token,
&self.size,
Expand Down Expand Up @@ -566,7 +525,7 @@ impl<'a> Printer<'a> {
Token::End => {
debug!("print End -> pop End");
let print_stack = &mut self.print_stack;
assert!((!print_stack.is_empty()));
assert!(!print_stack.is_empty());
print_stack.pop().unwrap();
Ok(())
}
Expand Down Expand Up @@ -603,12 +562,12 @@ impl<'a> Printer<'a> {
}
}
}
Token::String(s, len) => {
Token::String(ref s, len) => {
debug!("print String({})", s);
assert_eq!(l, len);
// assert!(l <= space);
self.space -= len;
self.print_str(&s[..])
self.print_str(s)
}
Token::Eof => {
// Eof should never get here.
Expand Down Expand Up @@ -652,15 +611,15 @@ pub fn eof(p: &mut Printer) -> io::Result<()> {
}

pub fn word(p: &mut Printer, wrd: &str) -> io::Result<()> {
p.pretty_print(Token::String(/* bad */ wrd.to_string(), wrd.len() as isize))
p.pretty_print(Token::String(wrd.to_string(), wrd.len() as isize))
}

pub fn huge_word(p: &mut Printer, wrd: &str) -> io::Result<()> {
p.pretty_print(Token::String(/* bad */ wrd.to_string(), SIZE_INFINITY))
p.pretty_print(Token::String(wrd.to_string(), SIZE_INFINITY))
}

pub fn zero_word(p: &mut Printer, wrd: &str) -> io::Result<()> {
p.pretty_print(Token::String(/* bad */ wrd.to_string(), 0))
p.pretty_print(Token::String(wrd.to_string(), 0))
}

pub fn spaces(p: &mut Printer, n: usize) -> io::Result<()> {
Expand Down

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