mv compiler to compiler/

1 files changed, 152 insertions, 0 deletions

diff --git a/compiler/rustc_expand/src/mbe.rs b/compiler/rustc_expand/src/mbe.rs
new file mode 100644
index 00000000000..9aed307ec93
--- /dev/null
+++ b/compiler/rustc_expand/src/mbe.rs
@@ -0,0 +1,152 @@
+//! This module implements declarative macros: old `macro_rules` and the newer
+//! `macro`. Declarative macros are also known as "macro by example", and that's
+//! why we call this module `mbe`. For external documentation, prefer the
+//! official terminology: "declarative macros".
+
+crate mod macro_check;
+crate mod macro_parser;
+crate mod macro_rules;
+crate mod quoted;
+crate mod transcribe;
+
+use rustc_ast::token::{self, NonterminalKind, Token, TokenKind};
+use rustc_ast::tokenstream::DelimSpan;
+
+use rustc_span::symbol::Ident;
+use rustc_span::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, Encodable, Decodable, Debug)]
+struct Delimited {
+    delim: token::DelimToken,
+    tts: Vec<TokenTree>,
+}
+
+impl Delimited {
+    /// Returns a `self::TokenTree` with a `Span` corresponding to the opening delimiter.
+    fn open_tt(&self, span: DelimSpan) -> TokenTree {
+        TokenTree::token(token::OpenDelim(self.delim), span.open)
+    }
+
+    /// Returns a `self::TokenTree` with a `Span` corresponding to the closing delimiter.
+    fn close_tt(&self, span: DelimSpan) -> TokenTree {
+        TokenTree::token(token::CloseDelim(self.delim), span.close)
+    }
+}
+
+#[derive(Clone, PartialEq, Encodable, Decodable, Debug)]
+struct SequenceRepetition {
+    /// The sequence of token trees
+    tts: Vec<TokenTree>,
+    /// The optional separator
+    separator: Option<Token>,
+    /// Whether the sequence can be repeated zero (*), or one or more times (+)
+    kleene: KleeneToken,
+    /// The number of `Match`s that appear in the sequence (and subsequences)
+    num_captures: usize,
+}
+
+#[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
+struct KleeneToken {
+    span: Span,
+    op: KleeneOp,
+}
+
+impl KleeneToken {
+    fn new(op: KleeneOp, span: Span) -> KleeneToken {
+        KleeneToken { span, op }
+    }
+}
+
+/// A Kleene-style [repetition operator](https://en.wikipedia.org/wiki/Kleene_star)
+/// for token sequences.
+#[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
+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 `$(...)`
+/// are "first-class" token trees. Useful for parsing macros.
+#[derive(Debug, Clone, PartialEq, Encodable, Decodable)]
+enum TokenTree {
+    Token(Token),
+    Delimited(DelimSpan, Lrc<Delimited>),
+    /// A kleene-style repetition sequence
+    Sequence(DelimSpan, Lrc<SequenceRepetition>),
+    /// e.g., `$var`
+    MetaVar(Span, Ident),
+    /// e.g., `$var:expr`. This is only used in the left hand side of MBE macros.
+    MetaVarDecl(Span, Ident /* name to bind */, NonterminalKind),
+}
+
+impl TokenTree {
+    /// Return the number of tokens in the tree.
+    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.
+    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.
+    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.
+    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);
+                }
+                if index == delimed.tts.len() + 1 {
+                    return delimed.close_tt(span);
+                }
+                delimed.tts[index - 1].clone()
+            }
+            (&TokenTree::Sequence(_, ref seq), _) => seq.tts[index].clone(),
+            _ => panic!("Cannot expand a token tree"),
+        }
+    }
+
+    /// Retrieves the `TokenTree`'s span.
+    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(),
+        }
+    }
+
+    fn token(kind: TokenKind, span: Span) -> TokenTree {
+        TokenTree::Token(Token::new(kind, span))
+    }
+}