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Introduce `syntax::parse::parser::TokenCursor`.

This commit is contained in:
Jeffrey Seyfried 2017-02-20 05:44:06 +00:00
parent 8dca72be9b
commit 8cd0c0885f
2 changed files with 173 additions and 115 deletions
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174
src/libsyntax/parse/parser.rs
View File

@ -9,7 +9,7 @@
// except according to those terms.
use abi::{self, Abi};
use ast::BareFnTy;
use ast::{AttrStyle, BareFnTy};
use ast::{RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
use ast::Unsafety;
use ast::{Mod, Arg, Arm, Attribute, BindingMode, TraitItemKind};
@ -46,21 +46,21 @@ use errors::{self, DiagnosticBuilder};
use parse::{self, classify, token};
use parse::common::SeqSep;
use parse::lexer::TokenAndSpan;
use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
use parse::obsolete::ObsoleteSyntax;
use parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
use util::parser::{AssocOp, Fixity};
use print::pprust;
use ptr::P;
use parse::PResult;
use tokenstream::{Delimited, TokenTree};
use tokenstream::{self, Delimited, TokenTree, TokenStream};
use symbol::{Symbol, keywords};
use util::ThinVec;
use std::collections::HashSet;
use std::mem;
use std::{cmp, mem, slice};
use std::path::{Path, PathBuf};
use std::rc::Rc;
use std::slice;
bitflags! {
flags Restrictions: u8 {
@ -175,12 +175,108 @@ pub struct Parser<'a> {
/// into modules, and sub-parsers have new values for this name.
pub root_module_name: Option<String>,
pub expected_tokens: Vec<TokenType>,
pub tts: Vec<(TokenTree, usize)>,
token_cursor: TokenCursor,
pub desugar_doc_comments: bool,
/// Whether we should configure out of line modules as we parse.
pub cfg_mods: bool,
}
struct TokenCursor {
frame: TokenCursorFrame,
stack: Vec<TokenCursorFrame>,
}
struct TokenCursorFrame {
delim: token::DelimToken,
span: Span,
open_delim: bool,
tree_cursor: tokenstream::Cursor,
close_delim: bool,
}
impl TokenCursorFrame {
fn new(sp: Span, delimited: &Delimited) -> Self {
TokenCursorFrame {
delim: delimited.delim,
span: sp,
open_delim: delimited.delim == token::NoDelim,
tree_cursor: delimited.tts.iter().cloned().collect::<TokenStream>().into_trees(),
close_delim: delimited.delim == token::NoDelim,
}
}
}
impl TokenCursor {
fn next(&mut self) -> TokenAndSpan {
loop {
let tree = if !self.frame.open_delim {
self.frame.open_delim = true;
Delimited { delim: self.frame.delim, tts: Vec::new() }.open_tt(self.frame.span)
} else if let Some(tree) = self.frame.tree_cursor.next() {
tree
} else if !self.frame.close_delim {
self.frame.close_delim = true;
Delimited { delim: self.frame.delim, tts: Vec::new() }.close_tt(self.frame.span)
} else if let Some(frame) = self.stack.pop() {
self.frame = frame;
continue
} else {
return TokenAndSpan { tok: token::Eof, sp: self.frame.span }
};
match tree {
TokenTree::Token(sp, tok) => return TokenAndSpan { tok: tok, sp: sp },
TokenTree::Delimited(sp, ref delimited) => {
let frame = TokenCursorFrame::new(sp, delimited);
self.stack.push(mem::replace(&mut self.frame, frame));
}
}
}
}
fn next_desugared(&mut self) -> TokenAndSpan {
let (sp, name) = match self.next() {
TokenAndSpan { sp, tok: token::DocComment(name) } => (sp, name),
tok @ _ => return tok,
};
let stripped = strip_doc_comment_decoration(&name.as_str());
// Searches for the occurrences of `"#*` and returns the minimum number of `#`s
// required to wrap the text.
let mut num_of_hashes = 0;
let mut count = 0;
for ch in stripped.chars() {
count = match ch {
'"' => 1,
'#' if count > 0 => count + 1,
_ => 0,
};
num_of_hashes = cmp::max(num_of_hashes, count);
}
let body = TokenTree::Delimited(sp, Rc::new(Delimited {
delim: token::Bracket,
tts: vec![TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"))),
TokenTree::Token(sp, token::Eq),
TokenTree::Token(sp, token::Literal(
token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))],
}));
self.stack.push(mem::replace(&mut self.frame, TokenCursorFrame::new(sp, &Delimited {
delim: token::NoDelim,
tts: if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
[TokenTree::Token(sp, token::Pound), TokenTree::Token(sp, token::Not), body]
.iter().cloned().collect()
} else {
[TokenTree::Token(sp, token::Pound), body].iter().cloned().collect()
},
})));
self.next()
}
}
#[derive(PartialEq, Eq, Clone)]
pub enum TokenType {
Token(token::Token),
@ -313,10 +409,6 @@ impl<'a> Parser<'a> {
directory: Option<Directory>,
desugar_doc_comments: bool)
-> Self {
let tt = TokenTree::Delimited(syntax_pos::DUMMY_SP, Rc::new(Delimited {
delim: token::NoDelim,
tts: tokens,
}));
let mut parser = Parser {
sess: sess,
token: token::Underscore,
@ -328,7 +420,13 @@ impl<'a> Parser<'a> {
directory: Directory { path: PathBuf::new(), ownership: DirectoryOwnership::Owned },
root_module_name: None,
expected_tokens: Vec::new(),
tts: if tt.len() > 0 { vec![(tt, 0)] } else { Vec::new() },
token_cursor: TokenCursor {
frame: TokenCursorFrame::new(syntax_pos::DUMMY_SP, &Delimited {
delim: token::NoDelim,
tts: tokens,
}),
stack: Vec::new(),
},
desugar_doc_comments: desugar_doc_comments,
cfg_mods: true,
};
@ -346,28 +444,9 @@ impl<'a> Parser<'a> {
}
fn next_tok(&mut self) -> TokenAndSpan {
loop {
let tok = if let Some((tts, i)) = self.tts.pop() {
let tt = tts.get_tt(i);
if i + 1 < tts.len() {
self.tts.push((tts, i + 1));
}
if let TokenTree::Token(sp, tok) = tt {
TokenAndSpan { tok: tok, sp: sp }
} else {
self.tts.push((tt, 0));
continue
}
} else {
TokenAndSpan { tok: token::Eof, sp: self.span }
};
match tok.tok {
token::DocComment(name) if self.desugar_doc_comments => {
self.tts.push((TokenTree::Token(tok.sp, token::DocComment(name)), 0));
}
_ => return tok,
}
match self.desugar_doc_comments {
true => self.token_cursor.next_desugared(),
false => self.token_cursor.next(),
}
}
@ -972,19 +1051,16 @@ impl<'a> Parser<'a> {
F: FnOnce(&token::Token) -> R,
{
if dist == 0 {
return f(&self.token);
return f(&self.token)
}
let mut tok = token::Eof;
if let Some(&(ref tts, mut i)) = self.tts.last() {
i += dist - 1;
if i < tts.len() {
tok = match tts.get_tt(i) {
TokenTree::Token(_, tok) => tok,
TokenTree::Delimited(_, delimited) => token::OpenDelim(delimited.delim),
};
}
}
f(&tok)
f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) {
Some(tree) => match tree {
TokenTree::Token(_, tok) => tok,
TokenTree::Delimited(_, delimited) => token::OpenDelim(delimited.delim),
},
None => token::CloseDelim(self.token_cursor.frame.delim),
})
}
pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_fatal(self.span, m)
@ -2569,10 +2645,14 @@ impl<'a> Parser<'a> {
pub fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> {
match self.token {
token::OpenDelim(..) => {
let tt = self.tts.pop().unwrap().0;
self.span = tt.span();
let frame = mem::replace(&mut self.token_cursor.frame,
self.token_cursor.stack.pop().unwrap());
self.span = frame.span;
self.bump();
return Ok(tt);
return Ok(TokenTree::Delimited(frame.span, Rc::new(Delimited {
delim: frame.delim,
tts: frame.tree_cursor.original_stream().trees().collect(),
})));
},
token::CloseDelim(_) | token::Eof => unreachable!(),
_ => Ok(TokenTree::Token(self.span, self.bump_and_get())),

114
src/libsyntax/tokenstream.rs
View File

@ -22,12 +22,11 @@
//! and a borrowed TokenStream is sufficient to build an owned TokenStream without taking
//! ownership of the original.
use ast::{self, AttrStyle, LitKind};
use ast::{self, LitKind};
use syntax_pos::{BytePos, Span, DUMMY_SP};
use codemap::Spanned;
use ext::base;
use ext::tt::{macro_parser, quoted};
use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
use parse::{self, Directory};
use parse::token::{self, Token, Lit};
use print::pprust;
@ -103,72 +102,6 @@ pub enum TokenTree {
}
impl TokenTree {
pub fn len(&self) -> usize {
match *self {
TokenTree::Token(_, token::DocComment(name)) => {
match doc_comment_style(&name.as_str()) {
AttrStyle::Outer => 2,
AttrStyle::Inner => 3,
}
}
TokenTree::Delimited(_, ref delimed) => match delimed.delim {
token::NoDelim => delimed.tts.len(),
_ => delimed.tts.len() + 2,
},
TokenTree::Token(..) => 0,
}
}
pub fn get_tt(&self, index: usize) -> TokenTree {
match (self, index) {
(&TokenTree::Token(sp, token::DocComment(_)), 0) => TokenTree::Token(sp, token::Pound),
(&TokenTree::Token(sp, token::DocComment(name)), 1)
if doc_comment_style(&name.as_str()) == AttrStyle::Inner => {
TokenTree::Token(sp, token::Not)
}
(&TokenTree::Token(sp, token::DocComment(name)), _) => {
let stripped = strip_doc_comment_decoration(&name.as_str());
// Searches for the occurrences of `"#*` and returns the minimum number of `#`s
// required to wrap the text.
let num_of_hashes = stripped.chars()
.scan(0, |cnt, x| {
*cnt = if x == '"' {
1
} else if *cnt != 0 && x == '#' {
*cnt + 1
} else {
0
};
Some(*cnt)
})
.max()
.unwrap_or(0);
TokenTree::Delimited(sp, Rc::new(Delimited {
delim: token::Bracket,
tts: vec![TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"))),
TokenTree::Token(sp, token::Eq),
TokenTree::Token(sp, token::Literal(
token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))],
}))
}
(&TokenTree::Delimited(_, ref delimed), _) if delimed.delim == token::NoDelim => {
delimed.tts[index].clone()
}
(&TokenTree::Delimited(span, ref delimed), _) => {
if index == 0 {
return delimed.open_tt(span);
}
if index == delimed.tts.len() + 1 {
return delimed.close_tt(span);
}
delimed.tts[index - 1].clone()
}
_ => panic!("Cannot expand a token tree"),
}
}
/// Use this token tree as a matcher to parse given tts.
pub fn parse(cx: &base::ExtCtxt, mtch: &[quoted::TokenTree], tts: &[TokenTree])
-> macro_parser::NamedParseResult {
@ -416,6 +349,51 @@ impl Cursor {
}
})
}
pub fn original_stream(self) -> TokenStream {
match self.0 {
CursorKind::Empty => TokenStream::empty(),
CursorKind::Tree(tree, _) => tree.into(),
CursorKind::Stream(cursor) => TokenStream::concat_rc_slice({
cursor.stack.get(0).cloned().map(|(stream, _)| stream).unwrap_or(cursor.stream)
}),
}
}
pub fn look_ahead(&self, n: usize) -> Option<TokenTree> {
fn look_ahead(streams: &[TokenStream], mut n: usize) -> Result<TokenTree, usize> {
for stream in streams {
n = match stream.kind {
TokenStreamKind::Tree(ref tree) if n == 0 => return Ok(tree.clone()),
TokenStreamKind::Tree(..) => n - 1,
TokenStreamKind::Stream(ref stream) => match look_ahead(stream, n) {
Ok(tree) => return Ok(tree),
Err(n) => n,
},
_ => n,
};
}
Err(n)
}
match self.0 {
CursorKind::Empty | CursorKind::Tree(_, true) => Err(n),
CursorKind::Tree(ref tree, false) => look_ahead(&[tree.clone().into()], n),
CursorKind::Stream(ref cursor) => {
look_ahead(&cursor.stream[cursor.index ..], n).or_else(|mut n| {
for &(ref stream, index) in cursor.stack.iter().rev() {
n = match look_ahead(&stream[index..], n) {
Ok(tree) => return Ok(tree),
Err(n) => n,
}
}
Err(n)
})
}
}.ok()
}
}
impl fmt::Display for TokenStream {