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Clarify the positions of the lexer and parser #36969

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merged 6 commits into from
Oct 18, 2016
Merged

Clarify the positions of the lexer and parser #36969

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2747923
Rename Parser::last_span as prev_span.
nnethercote Sep 21, 2016
3c4c859
Rename Parser::last_token_kind as prev_token_kind.
nnethercote Sep 21, 2016
94565a4
Rename StringReader::pos as next_pos.
nnethercote Oct 4, 2016
cb92f5c
Rename StringReader::last_pos as pos.
nnethercote Oct 4, 2016
e263120
Rename StringReader::curr as ch.
nnethercote Oct 4, 2016
94b3659
Clarify StringReader::bump.
nnethercote Oct 4, 2016
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Rename Parser::last_token_kind as prev_token_kind. 
Likewise, rename LastTokenKind as PrevTokenKind.

This is a [breaking-change] for libsyntax.
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@nnethercote
nnethercote committed Oct 4, 2016
commit 3c4c85947cddac2d36854e5bf8c7a8edb32e1245
34 changes: 17 additions & 17 deletions src/libsyntax/parse/parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,7 +238,7 @@ fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
}

#[derive(PartialEq)]
enum LastTokenKind {
enum PrevTokenKind {
DocComment,
Comma,
Interpolated,
Expand All @@ -258,7 +258,7 @@ pub struct Parser<'a> {
pub prev_span: Span,
pub cfg: CrateConfig,
/// the previous token kind
last_token_kind: LastTokenKind,
prev_token_kind: PrevTokenKind,
pub buffer: [TokenAndSpan; 4],
pub buffer_start: isize,
pub buffer_end: isize,
Expand Down Expand Up @@ -369,7 +369,7 @@ impl<'a> Parser<'a> {
token: tok0.tok,
span: span,
prev_span: span,
last_token_kind: LastTokenKind::Other,
prev_token_kind: PrevTokenKind::Other,
buffer: [
placeholder.clone(),
placeholder.clone(),
Expand Down Expand Up @@ -504,7 +504,7 @@ impl<'a> Parser<'a> {
expr: PResult<'a, P<Expr>>)
-> PResult<'a, (Span, P<Expr>)> {
expr.map(|e| {
if self.last_token_kind == LastTokenKind::Interpolated {
if self.prev_token_kind == PrevTokenKind::Interpolated {
(self.prev_span, e)
} else {
(e.span, e)
Expand All @@ -524,7 +524,7 @@ impl<'a> Parser<'a> {
self.bug("ident interpolation not converted to real token");
}
_ => {
Err(if self.last_token_kind == LastTokenKind::DocComment {
Err(if self.prev_token_kind == PrevTokenKind::DocComment {
self.span_fatal_help(self.prev_span,
"found a documentation comment that doesn't document anything",
"doc comments must come before what they document, maybe a comment was \
Expand Down Expand Up @@ -922,20 +922,20 @@ impl<'a> Parser<'a> {

/// Advance the parser by one token
pub fn bump(&mut self) {
if self.last_token_kind == LastTokenKind::Eof {
if self.prev_token_kind == PrevTokenKind::Eof {
// Bumping after EOF is a bad sign, usually an infinite loop.
self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
}

self.prev_span = self.span;

// Record last token kind for possible error recovery.
self.last_token_kind = match self.token {
token::DocComment(..) => LastTokenKind::DocComment,
token::Comma => LastTokenKind::Comma,
token::Interpolated(..) => LastTokenKind::Interpolated,
token::Eof => LastTokenKind::Eof,
_ => LastTokenKind::Other,
self.prev_token_kind = match self.token {
token::DocComment(..) => PrevTokenKind::DocComment,
token::Comma => PrevTokenKind::Comma,
token::Interpolated(..) => PrevTokenKind::Interpolated,
token::Eof => PrevTokenKind::Eof,
_ => PrevTokenKind::Other,
};

let next = if self.buffer_start == self.buffer_end {
Expand Down Expand Up @@ -976,8 +976,8 @@ impl<'a> Parser<'a> {
self.prev_span = mk_sp(self.span.lo, lo);
// It would be incorrect to record the kind of the current token, but
// fortunately for tokens currently using `bump_with`, the
// last_token_kind will be of no use anyway.
self.last_token_kind = LastTokenKind::Other;
// prev_token_kind will be of no use anyway.
self.prev_token_kind = PrevTokenKind::Other;
self.span = mk_sp(lo, hi);
self.token = next;
self.expected_tokens.clear();
Expand Down Expand Up @@ -2950,7 +2950,7 @@ impl<'a> Parser<'a> {
self.expected_tokens.push(TokenType::Operator);
while let Some(op) = AssocOp::from_token(&self.token) {

let lhs_span = if self.last_token_kind == LastTokenKind::Interpolated {
let lhs_span = if self.prev_token_kind == PrevTokenKind::Interpolated {
self.prev_span
} else {
lhs.span
Expand Down Expand Up @@ -4019,7 +4019,7 @@ impl<'a> Parser<'a> {
None => {
let unused_attrs = |attrs: &[_], s: &mut Self| {
if attrs.len() > 0 {
if s.last_token_kind == LastTokenKind::DocComment {
if s.prev_token_kind == PrevTokenKind::DocComment {
s.span_err_help(s.prev_span,
"found a documentation comment that doesn't document anything",
"doc comments must come before what they document, maybe a \
Expand Down Expand Up @@ -4338,7 +4338,7 @@ impl<'a> Parser<'a> {

let missing_comma = !lifetimes.is_empty() &&
!self.token.is_like_gt() &&
self.last_token_kind != LastTokenKind::Comma;
self.prev_token_kind != PrevTokenKind::Comma;

if missing_comma {

Expand Down