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extract tt cursor

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This commit is contained in:
Aleksey Kladov 2019-01-31 15:26:01 +03:00
parent 8d5a8f085c
commit be03aa5ee7
4 changed files with 101 additions and 96 deletions
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1
crates/ra_macros/src/lib.rs
View File

@ -12,5 +12,6 @@ macro_rules! impl_froms {
pub mod tt;
pub mod mbe;
mod tt_cursor;
mod mbe_parser;
mod mbe_expander;

2
crates/ra_macros/src/mbe.rs
View File

@ -1,6 +1,6 @@
use smol_str::SmolStr;
use crate::tt::{self, Delimiter};
use crate::tt::Delimiter;
pub use crate::{
mbe_parser::parse,

102
crates/ra_macros/src/mbe_parser.rs
View File

@ -1,99 +1,12 @@
use crate::{tt, mbe};
use crate::tt_cursor::TtCursor;
/// This module parses a raw `tt::TokenStream` into macro-by-example token
/// stream. This is a *mostly* identify function, expect for handling of
/// `$var:tt_kind` and `$(repeat),*` constructs.
struct RulesParser<'a> {
subtree: &'a tt::Subtree,
pos: usize,
}
impl<'a> RulesParser<'a> {
fn new(subtree: &'a tt::Subtree) -> RulesParser<'a> {
RulesParser { subtree, pos: 0 }
}
fn is_eof(&self) -> bool {
self.pos == self.subtree.token_trees.len()
}
fn current(&self) -> Option<&'a tt::TokenTree> {
self.subtree.token_trees.get(self.pos)
}
fn at_punct(&self) -> Option<&'a tt::Punct> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Punct(it))) => Some(it),
_ => None,
}
}
fn at_char(&self, char: char) -> bool {
match self.at_punct() {
Some(tt::Punct { char: c }) if *c == char => true,
_ => false,
}
}
fn at_ident(&mut self) -> Option<&'a tt::Ident> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Ident(i))) => Some(i),
_ => None,
}
}
fn bump(&mut self) {
self.pos += 1;
}
fn eat(&mut self) -> Option<&'a tt::TokenTree> {
match self.current() {
Some(it) => {
self.bump();
Some(it)
}
None => None,
}
}
fn eat_subtree(&mut self) -> Option<&'a tt::Subtree> {
match self.current()? {
tt::TokenTree::Subtree(sub) => {
self.bump();
Some(sub)
}
_ => return None,
}
}
fn eat_punct(&mut self) -> Option<&'a tt::Punct> {
if let Some(it) = self.at_punct() {
self.bump();
return Some(it);
}
None
}
fn eat_ident(&mut self) -> Option<&'a tt::Ident> {
if let Some(i) = self.at_ident() {
self.bump();
return Some(i);
}
None
}
fn expect_char(&mut self, char: char) -> Option<()> {
if self.at_char(char) {
self.bump();
return Some(());
}
None
}
}
pub fn parse(tt: &tt::Subtree) -> Option<mbe::MacroRules> {
let mut parser = RulesParser::new(tt);
let mut parser = TtCursor::new(tt);
let mut rules = Vec::new();
while !parser.is_eof() {
rules.push(parse_rule(&mut parser)?)
@ -101,7 +14,7 @@ pub fn parse(tt: &tt::Subtree) -> Option<mbe::MacroRules> {
Some(mbe::MacroRules { rules })
}
fn parse_rule(p: &mut RulesParser) -> Option<mbe::Rule> {
fn parse_rule(p: &mut TtCursor) -> Option<mbe::Rule> {
let lhs = parse_subtree(p.eat_subtree()?)?;
p.expect_char('=')?;
p.expect_char('>')?;
@ -111,7 +24,7 @@ fn parse_rule(p: &mut RulesParser) -> Option<mbe::Rule> {
fn parse_subtree(tt: &tt::Subtree) -> Option<mbe::Subtree> {
let mut token_trees = Vec::new();
let mut p = RulesParser::new(tt);
let mut p = TtCursor::new(tt);
while let Some(tt) = p.eat() {
let child: mbe::TokenTree = match tt {
tt::TokenTree::Leaf(leaf) => match leaf {
@ -142,7 +55,7 @@ fn parse_subtree(tt: &tt::Subtree) -> Option<mbe::Subtree> {
})
}
fn parse_var(p: &mut RulesParser) -> Option<mbe::Var> {
fn parse_var(p: &mut TtCursor) -> Option<mbe::Var> {
let ident = p.eat_ident().unwrap();
let text = ident.text.clone();
let kind = if p.at_char(':') {
@ -150,8 +63,7 @@ fn parse_var(p: &mut RulesParser) -> Option<mbe::Var> {
if let Some(ident) = p.eat_ident() {
Some(ident.text.clone())
} else {
// ugly as hell :(
p.pos -= 1;
p.rev_bump();
None
}
} else {
@ -160,7 +72,7 @@ fn parse_var(p: &mut RulesParser) -> Option<mbe::Var> {
Some(mbe::Var { text, kind })
}
fn parse_repeat(p: &mut RulesParser) -> Option<mbe::Repeat> {
fn parse_repeat(p: &mut TtCursor) -> Option<mbe::Repeat> {
let subtree = p.eat_subtree().unwrap();
let subtree = parse_subtree(subtree)?;
let sep = p.eat_punct()?;

92
crates/ra_macros/src/tt_cursor.rs Normal file
View File

@ -0,0 +1,92 @@
use crate::tt;
pub(crate) struct TtCursor<'a> {
subtree: &'a tt::Subtree,
pos: usize,
}
impl<'a> TtCursor<'a> {
pub(crate) fn new(subtree: &'a tt::Subtree) -> TtCursor<'a> {
TtCursor { subtree, pos: 0 }
}
pub(crate) fn is_eof(&self) -> bool {
self.pos == self.subtree.token_trees.len()
}
pub(crate) fn current(&self) -> Option<&'a tt::TokenTree> {
self.subtree.token_trees.get(self.pos)
}
pub(crate) fn at_punct(&self) -> Option<&'a tt::Punct> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Punct(it))) => Some(it),
_ => None,
}
}
pub(crate) fn at_char(&self, char: char) -> bool {
match self.at_punct() {
Some(tt::Punct { char: c }) if *c == char => true,
_ => false,
}
}
pub(crate) fn at_ident(&mut self) -> Option<&'a tt::Ident> {
match self.current() {
Some(tt::TokenTree::Leaf(tt::Leaf::Ident(i))) => Some(i),
_ => None,
}
}
pub(crate) fn bump(&mut self) {
self.pos += 1;
}
pub(crate) fn rev_bump(&mut self) {
self.pos -= 1;
}
pub(crate) fn eat(&mut self) -> Option<&'a tt::TokenTree> {
match self.current() {
Some(it) => {
self.bump();
Some(it)
}
None => None,
}
}
pub(crate) fn eat_subtree(&mut self) -> Option<&'a tt::Subtree> {
match self.current()? {
tt::TokenTree::Subtree(sub) => {
self.bump();
Some(sub)
}
_ => return None,
}
}
pub(crate) fn eat_punct(&mut self) -> Option<&'a tt::Punct> {
if let Some(it) = self.at_punct() {
self.bump();
return Some(it);
}
None
}
pub(crate) fn eat_ident(&mut self) -> Option<&'a tt::Ident> {
if let Some(i) = self.at_ident() {
self.bump();
return Some(i);
}
None
}
pub(crate) fn expect_char(&mut self, char: char) -> Option<()> {
if self.at_char(char) {
self.bump();
return Some(());
}
None
}
}