use ast;
use ext::tt::macro_parser;
-use parse::{ParseSess, token};
+use parse::{token, ParseSess};
use print::pprust;
use symbol::keywords;
-use syntax_pos::{DUMMY_SP, Span, BytePos};
+use syntax_pos::{BytePos, Span, DUMMY_SP};
use tokenstream;
use std::rc::Rc;
/// for token sequences.
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
pub enum KleeneOp {
+ /// Kleene star (`*`) for zero or more repetitions
ZeroOrMore,
+ /// Kleene star (`+`) for one or more repetitions
OneOrMore,
}
/// E.g. `$var`
MetaVar(Span, ast::Ident),
/// E.g. `$var:expr`. This is only used in the left hand side of MBE macros.
- MetaVarDecl(Span, ast::Ident /* name to bind */, ast::Ident /* kind of nonterminal */),
+ MetaVarDecl(
+ Span,
+ ast::Ident, /* name to bind */
+ ast::Ident, /* kind of nonterminal */
+ ),
}
impl TokenTree {
/// Retrieve the `TokenTree`'s span.
pub fn span(&self) -> Span {
match *self {
- TokenTree::Token(sp, _) |
- TokenTree::MetaVar(sp, _) |
- TokenTree::MetaVarDecl(sp, _, _) |
- TokenTree::Delimited(sp, _) |
- TokenTree::Sequence(sp, _) => sp,
+ TokenTree::Token(sp, _)
+ | TokenTree::MetaVar(sp, _)
+ | TokenTree::MetaVarDecl(sp, _, _)
+ | TokenTree::Delimited(sp, _)
+ | TokenTree::Sequence(sp, _) => sp,
}
}
}
-pub fn parse(input: tokenstream::TokenStream, expect_matchers: bool, sess: &ParseSess)
- -> Vec<TokenTree> {
+pub fn parse(
+ input: tokenstream::TokenStream,
+ expect_matchers: bool,
+ sess: &ParseSess,
+) -> Vec<TokenTree> {
let mut result = Vec::new();
let mut trees = input.trees();
while let Some(tree) = trees.next() {
Some(kind) => {
let span = end_sp.with_lo(start_sp.lo());
result.push(TokenTree::MetaVarDecl(span, ident, kind));
- continue
+ continue;
}
_ => end_sp,
},
- tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(span),
+ tree => tree.as_ref()
+ .map(tokenstream::TokenTree::span)
+ .unwrap_or(span),
},
- tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(start_sp),
+ tree => tree.as_ref()
+ .map(tokenstream::TokenTree::span)
+ .unwrap_or(start_sp),
};
sess.missing_fragment_specifiers.borrow_mut().insert(span);
- result.push(TokenTree::MetaVarDecl(span, ident, keywords::Invalid.ident()));
+ result.push(TokenTree::MetaVarDecl(
+ span,
+ ident,
+ keywords::Invalid.ident(),
+ ));
}
_ => result.push(tree),
}
result
}
-fn parse_tree<I>(tree: tokenstream::TokenTree,
- trees: &mut I,
- expect_matchers: bool,
- sess: &ParseSess)
- -> TokenTree
- where I: Iterator<Item = tokenstream::TokenTree>,
+fn parse_tree<I>(
+ tree: tokenstream::TokenTree,
+ trees: &mut I,
+ expect_matchers: bool,
+ sess: &ParseSess,
+) -> TokenTree
+where
+ I: Iterator<Item = tokenstream::TokenTree>,
{
match tree {
tokenstream::TokenTree::Token(span, token::Dollar) => match trees.next() {
let sequence = parse(delimited.tts.into(), expect_matchers, sess);
let (separator, op) = parse_sep_and_kleene_op(trees, span, sess);
let name_captures = macro_parser::count_names(&sequence);
- TokenTree::Sequence(span, Rc::new(SequenceRepetition {
- tts: sequence,
- separator,
- op,
- num_captures: name_captures,
- }))
+ TokenTree::Sequence(
+ span,
+ Rc::new(SequenceRepetition {
+ tts: sequence,
+ separator,
+ op,
+ num_captures: name_captures,
+ }),
+ )
}
Some(tokenstream::TokenTree::Token(ident_span, ref token)) if token.is_ident() => {
let ident = token.ident().unwrap();
let span = ident_span.with_lo(span.lo());
if ident.name == keywords::Crate.name() {
- let ident = ast::Ident { name: keywords::DollarCrate.name(), ..ident };
+ let ident = ast::Ident {
+ name: keywords::DollarCrate.name(),
+ ..ident
+ };
TokenTree::Token(span, token::Ident(ident))
} else {
TokenTree::MetaVar(span, ident)
}
}
Some(tokenstream::TokenTree::Token(span, tok)) => {
- let msg = format!("expected identifier, found `{}`", pprust::token_to_string(&tok));
+ let msg = format!(
+ "expected identifier, found `{}`",
+ pprust::token_to_string(&tok)
+ );
sess.span_diagnostic.span_err(span, &msg);
TokenTree::MetaVar(span, keywords::Invalid.ident())
}
None => TokenTree::Token(span, token::Dollar),
},
tokenstream::TokenTree::Token(span, tok) => TokenTree::Token(span, tok),
- tokenstream::TokenTree::Delimited(span, delimited) => {
- TokenTree::Delimited(span, Rc::new(Delimited {
+ tokenstream::TokenTree::Delimited(span, delimited) => TokenTree::Delimited(
+ span,
+ Rc::new(Delimited {
delim: delimited.delim,
tts: parse(delimited.tts.into(), expect_matchers, sess),
- }))
- }
+ }),
+ ),
}
}
-fn parse_sep_and_kleene_op<I>(input: &mut I, span: Span, sess: &ParseSess)
- -> (Option<token::Token>, KleeneOp)
- where I: Iterator<Item = tokenstream::TokenTree>,
+/// Attempt to parse a single Kleene star, possibly with a separator.
+///
+/// For example, in a pattern such as `$(a),*`, `a` is the pattern to be repeated, `,` is the
+/// separator, and `*` is the Kleene operator. This function is specifically concerned with parsing
+/// the last two tokens of such a pattern: namely, the optional separator and the Kleene operator
+/// itself. Note that here we are parsing the _pattern_ itself, rather than trying to match some
+/// stream of tokens against the pattern.
+///
+/// This function will take some input iterator `input` corresponding to `span` and a parsing
+/// session `sess`. If the next one (or possibly two) tokens in `input` correspond to a Kleene
+/// operator and separator, then a tuple with `(separator, KleeneOp)` is returned. Otherwise, an
+/// error with the appropriate span is emitted to `sess` and a dummy value is returned.
+fn parse_sep_and_kleene_op<I>(
+ input: &mut I,
+ span: Span,
+ sess: &ParseSess,
+) -> (Option<token::Token>, KleeneOp)
+where
+ I: Iterator<Item = tokenstream::TokenTree>,
{
fn kleene_op(token: &token::Token) -> Option<KleeneOp> {
match *token {
}
}
+ // We attempt to look at the next two token trees in `input`. I will call the first #1 and the
+ // second #2. If #1 and #2 don't match a valid KleeneOp with/without separator, that is an
+ // error, and we should emit an error on the most specific span possible.
let span = match input.next() {
+ // #1 is a token
Some(tokenstream::TokenTree::Token(span, tok)) => match kleene_op(&tok) {
+ // #1 is a KleeneOp with no separator
Some(op) => return (None, op),
+
+ // #1 is not a KleeneOp, but may be a separator... need to look at #2
None => match input.next() {
+ // #2 is a token
Some(tokenstream::TokenTree::Token(span, tok2)) => match kleene_op(&tok2) {
+ // #2 is a KleeneOp, so #1 must be a separator
Some(op) => return (Some(tok), op),
+
+ // #2 is not a KleeneOp... error
None => span,
},
- tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(span),
- }
+
+ // #2 is not a token at all... error
+ tree => tree.as_ref()
+ .map(tokenstream::TokenTree::span)
+ .unwrap_or(span),
+ },
},
- tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(span),
+
+ // #1 is not a token at all... error
+ tree => tree.as_ref()
+ .map(tokenstream::TokenTree::span)
+ .unwrap_or(span),
};
+ // Error...
sess.span_diagnostic.span_err(span, "expected `*` or `+`");
(None, KleeneOp::ZeroOrMore)
}
projects / rust.git / commitdiff