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Replace option with result in mbe

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This commit is contained in:
Wilco Kusee 2019-03-02 20:20:26 +01:00
parent 592b906604
commit d3a252b559
4 changed files with 93 additions and 74 deletions
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33
crates/ra_mbe/src/mbe_parser.rs
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@ -1,40 +1,41 @@
/// 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.
use crate::{MacroRulesError, Result};
use crate::tt_cursor::TtCursor;
pub(crate) fn parse(tt: &tt::Subtree) -> Option<crate::MacroRules> {
pub(crate) fn parse(tt: &tt::Subtree) -> Result<crate::MacroRules> {
let mut parser = TtCursor::new(tt);
let mut rules = Vec::new();
while !parser.is_eof() {
rules.push(parse_rule(&mut parser)?);
if parser.expect_char(';') == None {
if let Err(e) = parser.expect_char(';') {
if !parser.is_eof() {
return None;
return Err(e);
}
break;
}
}
Some(crate::MacroRules { rules })
Ok(crate::MacroRules { rules })
}
fn parse_rule(p: &mut TtCursor) -> Option<crate::Rule> {
fn parse_rule(p: &mut TtCursor) -> Result<crate::Rule> {
let lhs = parse_subtree(p.eat_subtree()?)?;
p.expect_char('=')?;
p.expect_char('>')?;
let mut rhs = parse_subtree(p.eat_subtree()?)?;
rhs.delimiter = crate::Delimiter::None;
Some(crate::Rule { lhs, rhs })
Ok(crate::Rule { lhs, rhs })
}
fn parse_subtree(tt: &tt::Subtree) -> Option<crate::Subtree> {
fn parse_subtree(tt: &tt::Subtree) -> Result<crate::Subtree> {
let mut token_trees = Vec::new();
let mut p = TtCursor::new(tt);
while let Some(tt) = p.eat() {
while let Ok(tt) = p.eat() {
let child: crate::TokenTree = match tt {
tt::TokenTree::Leaf(leaf) => match leaf {
tt::Leaf::Punct(tt::Punct { char: '$', .. }) => {
if p.at_ident().is_some() {
if p.at_ident().is_ok() {
crate::Leaf::from(parse_var(&mut p)?).into()
} else {
parse_repeat(&mut p)?.into()
@ -52,15 +53,15 @@ fn parse_subtree(tt: &tt::Subtree) -> Option<crate::Subtree> {
};
token_trees.push(child);
}
Some(crate::Subtree { token_trees, delimiter: tt.delimiter })
Ok(crate::Subtree { token_trees, delimiter: tt.delimiter })
}
fn parse_var(p: &mut TtCursor) -> Option<crate::Var> {
fn parse_var(p: &mut TtCursor) -> Result<crate::Var> {
let ident = p.eat_ident().unwrap();
let text = ident.text.clone();
let kind = if p.at_char(':') {
p.bump();
if let Some(ident) = p.eat_ident() {
if let Ok(ident) = p.eat_ident() {
Some(ident.text.clone())
} else {
p.rev_bump();
@ -69,10 +70,10 @@ fn parse_var(p: &mut TtCursor) -> Option<crate::Var> {
} else {
None
};
Some(crate::Var { text, kind })
Ok(crate::Var { text, kind })
}
fn parse_repeat(p: &mut TtCursor) -> Option<crate::Repeat> {
fn parse_repeat(p: &mut TtCursor) -> Result<crate::Repeat> {
let subtree = p.eat_subtree().unwrap();
let mut subtree = parse_subtree(subtree)?;
subtree.delimiter = crate::Delimiter::None;
@ -86,8 +87,8 @@ fn parse_repeat(p: &mut TtCursor) -> Option<crate::Repeat> {
'*' => crate::RepeatKind::ZeroOrMore,
'+' => crate::RepeatKind::OneOrMore,
'?' => crate::RepeatKind::ZeroOrOne,
_ => return None,
_ => return Err(MacroRulesError::ParseError),
};
p.bump();
Some(crate::Repeat { subtree, kind, separator })
Ok(crate::Repeat { subtree, kind, separator })
}