Rename mbe_expander for consistency

1 files changed, 0 insertions, 182 deletions

diff --git a/crates/mbe/src/mbe_expander.rs b/crates/mbe/src/mbe_expander.rs
deleted file mode 100644
index 802c8fb0f..000000000
--- a/crates/mbe/src/mbe_expander.rs
+++ /dev/null
@@ -1,182 +0,0 @@
-//! This module takes a (parsed) definition of `macro_rules` invocation, a
-//! `tt::TokenTree` representing an argument of macro invocation, and produces a
-//! `tt::TokenTree` for the result of the expansion.
-
-mod matcher;
-mod transcriber;
-
-use rustc_hash::FxHashMap;
-use syntax::SmolStr;
-
-use crate::{ExpandError, ExpandResult};
-
-pub(crate) fn expand_rules(
-    rules: &[crate::Rule],
-    input: &tt::Subtree,
-) -> ExpandResult<tt::Subtree> {
-    let mut match_: Option<(matcher::Match, &crate::Rule)> = None;
-    for rule in rules {
-        let new_match = match matcher::match_(&rule.lhs, input) {
-            Ok(m) => m,
-            Err(_e) => {
-                // error in pattern parsing
-                continue;
-            }
-        };
-        if new_match.err.is_none() {
-            // If we find a rule that applies without errors, we're done.
-            // Unconditionally returning the transcription here makes the
-            // `test_repeat_bad_var` test fail.
-            let ExpandResult { value, err: transcribe_err } =
-                transcriber::transcribe(&rule.rhs, &new_match.bindings);
-            if transcribe_err.is_none() {
-                return ExpandResult::ok(value);
-            }
-        }
-        // Use the rule if we matched more tokens, or had fewer errors
-        if let Some((prev_match, _)) = &match_ {
-            if (new_match.unmatched_tts, new_match.err_count)
-                < (prev_match.unmatched_tts, prev_match.err_count)
-            {
-                match_ = Some((new_match, rule));
-            }
-        } else {
-            match_ = Some((new_match, rule));
-        }
-    }
-    if let Some((match_, rule)) = match_ {
-        // if we got here, there was no match without errors
-        let ExpandResult { value, err: transcribe_err } =
-            transcriber::transcribe(&rule.rhs, &match_.bindings);
-        ExpandResult { value, err: match_.err.or(transcribe_err) }
-    } else {
-        ExpandResult::only_err(ExpandError::NoMatchingRule)
-    }
-}
-
-/// The actual algorithm for expansion is not too hard, but is pretty tricky.
-/// `Bindings` structure is the key to understanding what we are doing here.
-///
-/// On the high level, it stores mapping from meta variables to the bits of
-/// syntax it should be substituted with. For example, if `$e:expr` is matched
-/// with `1 + 1` by macro_rules, the `Binding` will store `$e -> 1 + 1`.
-///
-/// The tricky bit is dealing with repetitions (`$()*`). Consider this example:
-///
-/// ```not_rust
-/// macro_rules! foo {
-///     ($($ i:ident $($ e:expr),*);*) => {
-///         $(fn $ i() { $($ e);*; })*
-///     }
-/// }
-/// foo! { foo 1,2,3; bar 4,5,6 }
-/// ```
-///
-/// Here, the `$i` meta variable is matched first with `foo` and then with
-/// `bar`, and `$e` is matched in turn with `1`, `2`, `3`, `4`, `5`, `6`.
-///
-/// To represent such "multi-mappings", we use a recursive structures: we map
-/// variables not to values, but to *lists* of values or other lists (that is,
-/// to the trees).
-///
-/// For the above example, the bindings would store
-///
-/// ```not_rust
-/// i -> [foo, bar]
-/// e -> [[1, 2, 3], [4, 5, 6]]
-/// ```
-///
-/// We construct `Bindings` in the `match_lhs`. The interesting case is
-/// `TokenTree::Repeat`, where we use `push_nested` to create the desired
-/// nesting structure.
-///
-/// The other side of the puzzle is `expand_subtree`, where we use the bindings
-/// to substitute meta variables in the output template. When expanding, we
-/// maintain a `nesting` stack of indices which tells us which occurrence from
-/// the `Bindings` we should take. We push to the stack when we enter a
-/// repetition.
-///
-/// In other words, `Bindings` is a *multi* mapping from `SmolStr` to
-/// `tt::TokenTree`, where the index to select a particular `TokenTree` among
-/// many is not a plain `usize`, but an `&[usize]`.
-#[derive(Debug, Default)]
-struct Bindings {
-    inner: FxHashMap<SmolStr, Binding>,
-}
-
-#[derive(Debug)]
-enum Binding {
-    Fragment(Fragment),
-    Nested(Vec<Binding>),
-    Empty,
-}
-
-#[derive(Debug, Clone)]
-enum Fragment {
-    /// token fragments are just copy-pasted into the output
-    Tokens(tt::TokenTree),
-    /// Ast fragments are inserted with fake delimiters, so as to make things
-    /// like `$i * 2` where `$i = 1 + 1` work as expectd.
-    Ast(tt::TokenTree),
-}
-
-#[cfg(test)]
-mod tests {
-    use syntax::{ast, AstNode};
-
-    use super::*;
-    use crate::ast_to_token_tree;
-
-    #[test]
-    fn test_expand_rule() {
-        assert_err(
-            "($($i:ident);*) => ($i)",
-            "foo!{a}",
-            ExpandError::BindingError(String::from(
-                "expected simple binding, found nested binding `i`",
-            )),
-        );
-
-        // FIXME:
-        // Add an err test case for ($($i:ident)) => ($())
-    }
-
-    fn assert_err(macro_body: &str, invocation: &str, err: ExpandError) {
-        assert_eq!(
-            expand_first(&create_rules(&format_macro(macro_body)), invocation).err,
-            Some(err)
-        );
-    }
-
-    fn format_macro(macro_body: &str) -> String {
-        format!(
-            "
-        macro_rules! foo {{
-            {}
-        }}
-",
-            macro_body
-        )
-    }
-
-    fn create_rules(macro_definition: &str) -> crate::MacroRules {
-        let source_file = ast::SourceFile::parse(macro_definition).ok().unwrap();
-        let macro_definition =
-            source_file.syntax().descendants().find_map(ast::MacroRules::cast).unwrap();
-
-        let (definition_tt, _) =
-            ast_to_token_tree(&macro_definition.token_tree().unwrap()).unwrap();
-        crate::MacroRules::parse(&definition_tt).unwrap()
-    }
-
-    fn expand_first(rules: &crate::MacroRules, invocation: &str) -> ExpandResult<tt::Subtree> {
-        let source_file = ast::SourceFile::parse(invocation).ok().unwrap();
-        let macro_invocation =
-            source_file.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
-
-        let (invocation_tt, _) =
-            ast_to_token_tree(&macro_invocation.token_tree().unwrap()).unwrap();
-
-        expand_rules(&rules.rules, &invocation_tt)
-    }
-}