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Auto merge of #36969 - nnethercote:rename-Parser-fields, r=eddyb
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Clarify the positions of the lexer and parser

The lexer and parser use unclear names to indicate their positions in the
source code. I propose the following renamings.

Lexer:
```
pos      -> next_pos      # it's actually the next pos!
last_pos -> pos           # it's actually the current pos!
curr     -> ch            # the current char
curr_is  -> ch_is         # tests the current char
col (unchanged)           # the current column
```
parser
```
- last_span       -> prev_span          # the previous token's span
- last_token_kind -> prev_token_kind    # the previous token's kind
- LastTokenKind   -> PrevTokenKind      # ditto (but the type)
- token (unchanged)                     # the current token
- span (unchanged)                      # the current span
```

Things to note:
- This proposal removes all uses of "last", which is an unclear word because it
  could mean (a) previous, (b) final, or (c) most recent, i.e. current.
- The "current" things (ch, col, token, span) consistently lack a prefix. The
  "previous" and "next" things consistently have a prefix.
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@bors
bors authored Oct 18, 2016
2 parents 1d3dfa5 + 94b3659 commit 3543a0f
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Showing 9 changed files with 414 additions and 415 deletions.
2 changes: 1 addition & 1 deletion src/librustc_metadata/creader.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -582,7 +582,7 @@ impl<'a> CrateReader<'a> {
unreachable!();
}
};
let local_span = mk_sp(lo, p.last_span.hi);
let local_span = mk_sp(lo, p.prev_span.hi);

// Mark the attrs as used
for attr in &def.attrs {
Expand Down
10 changes: 5 additions & 5 deletions src/librustc_save_analysis/span_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -139,9 +139,9 @@ impl<'a> SpanUtils<'a> {
let mut prev = toks.real_token();
let mut result = None;
let mut bracket_count = 0;
let mut last_span = None;
let mut prev_span = None;
while prev.tok != token::Eof {
last_span = None;
prev_span = None;
let mut next = toks.real_token();

if (next.tok == token::OpenDelim(token::Paren) || next.tok == token::Lt) &&
Expand All @@ -166,12 +166,12 @@ impl<'a> SpanUtils<'a> {
};

if prev.tok.is_ident() && bracket_count == 0 {
last_span = Some(prev.sp);
prev_span = Some(prev.sp);
}
prev = next;
}
if result.is_none() && last_span.is_some() {
return self.make_sub_span(span, last_span);
if result.is_none() && prev_span.is_some() {
return self.make_sub_span(span, prev_span);
}
return self.make_sub_span(span, result);
}
Expand Down
6 changes: 3 additions & 3 deletions src/libsyntax/codemap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -804,7 +804,7 @@ impl CodeMap {
}

pub fn macro_backtrace(&self, span: Span) -> Vec<MacroBacktrace> {
let mut last_span = DUMMY_SP;
let mut prev_span = DUMMY_SP;
let mut span = span;
let mut result = vec![];
loop {
Expand All @@ -827,14 +827,14 @@ impl CodeMap {
None => break,
Some((call_site, macro_decl_name, def_site_span)) => {
// Don't print recursive invocations
if !call_site.source_equal(&last_span) {
if !call_site.source_equal(&prev_span) {
result.push(MacroBacktrace {
call_site: call_site,
macro_decl_name: macro_decl_name,
def_site_span: def_site_span,
});
}
last_span = span;
prev_span = span;
span = call_site;
}
}
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12 changes: 6 additions & 6 deletions src/libsyntax/parse/attr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -126,7 +126,7 @@ impl<'a> Parser<'a> {
self.expect(&token::OpenDelim(token::Bracket))?;
let meta_item = self.parse_meta_item()?;
self.expect(&token::CloseDelim(token::Bracket))?;
let hi = self.last_span.hi;
let hi = self.prev_span.hi;

(mk_sp(lo, hi), meta_item, style)
}
Expand Down Expand Up @@ -231,16 +231,16 @@ impl<'a> Parser<'a> {
token::Eq => {
self.bump();
let lit = self.parse_unsuffixed_lit()?;
let hi = self.last_span.hi;
let hi = self.prev_span.hi;
Ok(P(spanned(lo, hi, ast::MetaItemKind::NameValue(name, lit))))
}
token::OpenDelim(token::Paren) => {
let inner_items = self.parse_meta_seq()?;
let hi = self.last_span.hi;
let hi = self.prev_span.hi;
Ok(P(spanned(lo, hi, ast::MetaItemKind::List(name, inner_items))))
}
_ => {
let hi = self.last_span.hi;
let hi = self.prev_span.hi;
Ok(P(spanned(lo, hi, ast::MetaItemKind::Word(name))))
}
}
Expand All @@ -253,14 +253,14 @@ impl<'a> Parser<'a> {

match self.parse_unsuffixed_lit() {
Ok(lit) => {
return Ok(spanned(lo, self.last_span.hi, ast::NestedMetaItemKind::Literal(lit)))
return Ok(spanned(lo, self.prev_span.hi, ast::NestedMetaItemKind::Literal(lit)))
}
Err(ref mut err) => self.diagnostic().cancel(err)
}

match self.parse_meta_item() {
Ok(mi) => {
return Ok(spanned(lo, self.last_span.hi, ast::NestedMetaItemKind::MetaItem(mi)))
return Ok(spanned(lo, self.prev_span.hi, ast::NestedMetaItemKind::MetaItem(mi)))
}
Err(ref mut err) => self.diagnostic().cancel(err)
}
Expand Down
40 changes: 20 additions & 20 deletions src/libsyntax/parse/lexer/comments.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -149,13 +149,13 @@ fn push_blank_line_comment(rdr: &StringReader, comments: &mut Vec<Comment>) {
comments.push(Comment {
style: BlankLine,
lines: Vec::new(),
pos: rdr.last_pos,
pos: rdr.pos,
});
}

fn consume_whitespace_counting_blank_lines(rdr: &mut StringReader, comments: &mut Vec<Comment>) {
while is_pattern_whitespace(rdr.curr) && !rdr.is_eof() {
if rdr.col == CharPos(0) && rdr.curr_is('\n') {
while is_pattern_whitespace(rdr.ch) && !rdr.is_eof() {
if rdr.col == CharPos(0) && rdr.ch_is('\n') {
push_blank_line_comment(rdr, &mut *comments);
}
rdr.bump();
Expand All @@ -167,7 +167,7 @@ fn read_shebang_comment(rdr: &mut StringReader,
code_to_the_left: bool,
comments: &mut Vec<Comment>) {
debug!(">>> shebang comment");
let p = rdr.last_pos;
let p = rdr.pos;
debug!("<<< shebang comment");
comments.push(Comment {
style: if code_to_the_left { Trailing } else { Isolated },
Expand All @@ -180,9 +180,9 @@ fn read_line_comments(rdr: &mut StringReader,
code_to_the_left: bool,
comments: &mut Vec<Comment>) {
debug!(">>> line comments");
let p = rdr.last_pos;
let p = rdr.pos;
let mut lines: Vec<String> = Vec::new();
while rdr.curr_is('/') && rdr.nextch_is('/') {
while rdr.ch_is('/') && rdr.nextch_is('/') {
let line = rdr.read_one_line_comment();
debug!("{}", line);
// Doc comments are not put in comments.
Expand Down Expand Up @@ -240,7 +240,7 @@ fn read_block_comment(rdr: &mut StringReader,
code_to_the_left: bool,
comments: &mut Vec<Comment>) {
debug!(">>> block comment");
let p = rdr.last_pos;
let p = rdr.pos;
let mut lines: Vec<String> = Vec::new();
let col = rdr.col;
rdr.bump();
Expand All @@ -249,9 +249,9 @@ fn read_block_comment(rdr: &mut StringReader,
let mut curr_line = String::from("/*");

// doc-comments are not really comments, they are attributes
if (rdr.curr_is('*') && !rdr.nextch_is('*')) || rdr.curr_is('!') {
while !(rdr.curr_is('*') && rdr.nextch_is('/')) && !rdr.is_eof() {
curr_line.push(rdr.curr.unwrap());
if (rdr.ch_is('*') && !rdr.nextch_is('*')) || rdr.ch_is('!') {
while !(rdr.ch_is('*') && rdr.nextch_is('/')) && !rdr.is_eof() {
curr_line.push(rdr.ch.unwrap());
rdr.bump();
}
if !rdr.is_eof() {
Expand All @@ -271,19 +271,19 @@ fn read_block_comment(rdr: &mut StringReader,
if rdr.is_eof() {
panic!(rdr.fatal("unterminated block comment"));
}
if rdr.curr_is('\n') {
if rdr.ch_is('\n') {
trim_whitespace_prefix_and_push_line(&mut lines, curr_line, col);
curr_line = String::new();
rdr.bump();
} else {
curr_line.push(rdr.curr.unwrap());
if rdr.curr_is('/') && rdr.nextch_is('*') {
curr_line.push(rdr.ch.unwrap());
if rdr.ch_is('/') && rdr.nextch_is('*') {
rdr.bump();
rdr.bump();
curr_line.push('*');
level += 1;
} else {
if rdr.curr_is('*') && rdr.nextch_is('/') {
if rdr.ch_is('*') && rdr.nextch_is('/') {
rdr.bump();
rdr.bump();
curr_line.push('/');
Expand All @@ -305,7 +305,7 @@ fn read_block_comment(rdr: &mut StringReader,
Isolated
};
rdr.consume_non_eol_whitespace();
if !rdr.is_eof() && !rdr.curr_is('\n') && lines.len() == 1 {
if !rdr.is_eof() && !rdr.ch_is('\n') && lines.len() == 1 {
style = Mixed;
}
debug!("<<< block comment");
Expand All @@ -319,11 +319,11 @@ fn read_block_comment(rdr: &mut StringReader,

fn consume_comment(rdr: &mut StringReader, code_to_the_left: bool, comments: &mut Vec<Comment>) {
debug!(">>> consume comment");
if rdr.curr_is('/') && rdr.nextch_is('/') {
if rdr.ch_is('/') && rdr.nextch_is('/') {
read_line_comments(rdr, code_to_the_left, comments);
} else if rdr.curr_is('/') && rdr.nextch_is('*') {
} else if rdr.ch_is('/') && rdr.nextch_is('*') {
read_block_comment(rdr, code_to_the_left, comments);
} else if rdr.curr_is('#') && rdr.nextch_is('!') {
} else if rdr.ch_is('#') && rdr.nextch_is('!') {
read_shebang_comment(rdr, code_to_the_left, comments);
} else {
panic!();
Expand Down Expand Up @@ -357,7 +357,7 @@ pub fn gather_comments_and_literals(span_diagnostic: &errors::Handler,
loop {
let mut code_to_the_left = !first_read;
rdr.consume_non_eol_whitespace();
if rdr.curr_is('\n') {
if rdr.ch_is('\n') {
code_to_the_left = false;
consume_whitespace_counting_blank_lines(&mut rdr, &mut comments);
}
Expand All @@ -369,7 +369,7 @@ pub fn gather_comments_and_literals(span_diagnostic: &errors::Handler,
}


let bstart = rdr.last_pos;
let bstart = rdr.pos;
rdr.next_token();
// discard, and look ahead; we're working with internal state
let TokenAndSpan { tok, sp } = rdr.peek();
Expand Down
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