pull mbe token tree definition up

rust-lang · Centril · Aug 7, 2019 · Aug 8, 2019 · Aug 15, 2019 · Aug 26, 2019
commit 9fd75f52877a3e23a7b9a6a9675f37a42340a428
diff --git a/src/libsyntax/ext/mbe.rs b/src/libsyntax/ext/mbe.rs
@@ -8,3 +8,159 @@ crate mod macro_check;
 crate mod macro_parser;
 crate mod macro_rules;
 crate mod quoted;
+
+use crate::ast;
+use crate::parse::token::{self, Token, TokenKind};
+use crate::tokenstream::{DelimSpan};
+
+use syntax_pos::{BytePos, Span};
+
+use rustc_data_structures::sync::Lrc;
+
+/// Contains the sub-token-trees of a "delimited" token tree, such as the contents of `(`. Note
+/// that the delimiter itself might be `NoDelim`.
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+crate struct Delimited {
+    crate delim: token::DelimToken,
+    crate tts: Vec<TokenTree>,
+}
+
+impl Delimited {
+    /// Returns a `self::TokenTree` with a `Span` corresponding to the opening delimiter.
+    crate fn open_tt(&self, span: Span) -> TokenTree {
+        let open_span = if span.is_dummy() {
+            span
+        } else {
+            span.with_hi(span.lo() + BytePos(self.delim.len() as u32))
+        };
+        TokenTree::token(token::OpenDelim(self.delim), open_span)
+    }
+
+    /// Returns a `self::TokenTree` with a `Span` corresponding to the closing delimiter.
+    crate fn close_tt(&self, span: Span) -> TokenTree {
+        let close_span = if span.is_dummy() {
+            span
+        } else {
+            span.with_lo(span.hi() - BytePos(self.delim.len() as u32))
+        };
+        TokenTree::token(token::CloseDelim(self.delim), close_span)
+    }
+}
+
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug)]
+crate struct SequenceRepetition {
+    /// The sequence of token trees
+    crate tts: Vec<TokenTree>,
+    /// The optional separator
+    crate separator: Option<Token>,
+    /// Whether the sequence can be repeated zero (*), or one or more times (+)
+    crate kleene: KleeneToken,
+    /// The number of `Match`s that appear in the sequence (and subsequences)
+    crate num_captures: usize,
+}
+
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, Copy)]
+crate struct KleeneToken {
+    crate span: Span,
+    crate op: KleeneOp,
+}
+
+impl KleeneToken {
+    crate fn new(op: KleeneOp, span: Span) -> KleeneToken {
+        KleeneToken { span, op }
+    }
+}
+
+/// A Kleene-style [repetition operator](http://en.wikipedia.org/wiki/Kleene_star)
+/// for token sequences.
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+crate enum KleeneOp {
+    /// Kleene star (`*`) for zero or more repetitions
+    ZeroOrMore,
+    /// Kleene plus (`+`) for one or more repetitions
+    OneOrMore,
+    /// Kleene optional (`?`) for zero or one reptitions
+    ZeroOrOne,
+}
+
+/// Similar to `tokenstream::TokenTree`, except that `$i`, `$i:ident`, and `$(...)`
+/// are "first-class" token trees. Useful for parsing macros.
+#[derive(Debug, Clone, PartialEq, RustcEncodable, RustcDecodable)]
+crate enum TokenTree {
+    Token(Token),
+    Delimited(DelimSpan, Lrc<Delimited>),
+    /// A kleene-style repetition sequence
+    Sequence(DelimSpan, Lrc<SequenceRepetition>),
+    /// e.g., `$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 */
+    ),
+}
+
+impl TokenTree {
+    /// Return the number of tokens in the tree.
+    crate fn len(&self) -> usize {
+        match *self {
+            TokenTree::Delimited(_, ref delimed) => match delimed.delim {
+                token::NoDelim => delimed.tts.len(),
+                _ => delimed.tts.len() + 2,
+            },
+            TokenTree::Sequence(_, ref seq) => seq.tts.len(),
+            _ => 0,
+        }
+    }
+
+    /// Returns `true` if the given token tree is delimited.
+    crate fn is_delimited(&self) -> bool {
+        match *self {
+            TokenTree::Delimited(..) => true,
+            _ => false,
+        }
+    }
+
+    /// Returns `true` if the given token tree is a token of the given kind.
+    crate fn is_token(&self, expected_kind: &TokenKind) -> bool {
+        match self {
+            TokenTree::Token(Token { kind: actual_kind, .. }) => actual_kind == expected_kind,
+            _ => false,
+        }
+    }
+
+    /// Gets the `index`-th sub-token-tree. This only makes sense for delimited trees and sequences.
+    crate fn get_tt(&self, index: usize) -> TokenTree {
+        match (self, index) {
+            (&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.open);
+                }
+                if index == delimed.tts.len() + 1 {
+                    return delimed.close_tt(span.close);
+                }
+                delimed.tts[index - 1].clone()
+            }
+            (&TokenTree::Seq
8000
uence(_, ref seq), _) => seq.tts[index].clone(),
+            _ => panic!("Cannot expand a token tree"),
+        }
+    }
+
+    /// Retrieves the `TokenTree`'s span.
+    crate fn span(&self) -> Span {
+        match *self {
+            TokenTree::Token(Token { span, .. })
+            | TokenTree::MetaVar(span, _)
+            | TokenTree::MetaVarDecl(span, _, _) => span,
+            TokenTree::Delimited(span, _) | TokenTree::Sequence(span, _) => span.entire(),
+        }
+    }
+
+    crate fn token(kind: TokenKind, span: Span) -> TokenTree {
+        TokenTree::Token(Token::new(kind, span))
+    }
+}
diff --git a/src/libsyntax/ext/mbe/macro_check.rs b/src/libsyntax/ext/mbe/macro_check.rs
@@ -106,7 +106,7 @@
 //! bound.
 use crate::ast::NodeId;
 use crate::early_buffered_lints::BufferedEarlyLintId;
-use crate::ext::mbe::quoted::{KleeneToken, TokenTree};
+use crate::ext::mbe::{KleeneToken, TokenTree};
 use crate::parse::token::TokenKind;
 use crate::parse::token::{DelimToken, Token};
 use crate::parse::ParseSess;

diff --git a/src/libsyntax/ext/mbe/macro_parser.rs b/src/libsyntax/ext/mbe/macro_parser.rs
@@ -75,7 +75,7 @@ crate use ParseResult::*;
 use TokenTreeOrTokenTreeSlice::*;
 
 use crate::ast::{Ident, Name};
-use crate::ext::mbe::quoted::{self, TokenTree};
+use crate::ext::mbe::{self, TokenTree};
 use crate::parse::{Directory, ParseSess};
 use crate::parse::parser::{Parser, PathStyle};
 use crate::parse::token::{self, DocComment, Nonterminal, Token};
@@ -195,7 +195,7 @@ struct MatcherPos<'root, 'tt> {
     // `None`.
 
     /// The KleeneOp of this sequence if we are in a repetition.
-    seq_op: Option<quoted::KleeneOp>,
+    seq_op: Option<mbe::KleeneOp>,
 
     /// The separator if we are in a repetition.
     sep: Option<Token>,
@@ -532,7 +532,7 @@ fn inner_parse_loop<'root, 'tt>(
                 }
                 // We don't need a separator. Move the "dot" back to the beginning of the matcher
                 // and try to match again UNLESS we are only allowed to have _one_ repetition.
-                else if item.seq_op != Some(quoted::KleeneOp::ZeroOrOne) {
+                else if item.seq_op != Some(mbe::KleeneOp::ZeroOrOne) {
                     item.match_cur = item.match_lo;
                     item.idx = 0;
                     cur_items.push(item);
@@ -555,8 +555,8 @@ fn inner_parse_loop<'root, 'tt>(
                     // implicitly disallowing OneOrMore from having 0 matches here. Thus, that will
                     // result in a "no rules expected token" error by virtue of this matcher not
                     // working.
-                    if seq.kleene.op == quoted::KleeneOp::ZeroOrMore
-                        || seq.kleene.op == quoted::KleeneOp::ZeroOrOne
+                    if seq.kleene.op == mbe::KleeneOp::ZeroOrMore
+                        || seq.kleene.op == mbe::KleeneOp::ZeroOrOne
                     {
                         let mut new_item = item.clone();
                         new_item.match_cur += seq.num_captures;