Shuffle hir-expand things around

crates/hir-expand/src/declarative.rs

@@ -0,0 +1,176 @@
+use std::sync::OnceLock;
+
+use base_db::{CrateId, Edition, VersionReq};
+use span::{MacroCallId, Span};
+use syntax::{ast, AstNode};
+use triomphe::Arc;
+
+use crate::{
+    attrs::RawAttrs,
+    db::ExpandDatabase,
+    hygiene::{apply_mark, Transparency},
+    tt, AstId, ExpandError, ExpandResult,
+};
+
+/// Old-style `macro_rules` or the new macros 2.0
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct DeclarativeMacroExpander {
+    pub mac: mbe::DeclarativeMacro<span::Span>,
+    pub transparency: Transparency,
+}
+
+// FIXME: Remove this once we drop support for 1.76
+static REQUIREMENT: OnceLock<VersionReq> = OnceLock::new();
+
+impl DeclarativeMacroExpander {
+    pub fn expand(
+        &self,
+        db: &dyn ExpandDatabase,
+        tt: tt::Subtree,
+        call_id: MacroCallId,
+    ) -> ExpandResult<tt::Subtree> {
+        let loc = db.lookup_intern_macro_call(call_id);
+        let toolchain = &db.crate_graph()[loc.def.krate].toolchain;
+        let new_meta_vars = toolchain.as_ref().map_or(false, |version| {
+            REQUIREMENT.get_or_init(|| VersionReq::parse(">=1.76").unwrap()).matches(
+                &base_db::Version {
+                    pre: base_db::Prerelease::EMPTY,
+                    build: base_db::BuildMetadata::EMPTY,
+                    major: version.major,
+                    minor: version.minor,
+                    patch: version.patch,
+                },
+            )
+        });
+        match self.mac.err() {
+            Some(e) => ExpandResult::new(
+                tt::Subtree::empty(tt::DelimSpan { open: loc.call_site, close: loc.call_site }),
+                ExpandError::other(format!("invalid macro definition: {e}")),
+            ),
+            None => self
+                .mac
+                .expand(
+                    &tt,
+                    |s| s.ctx = apply_mark(db, s.ctx, call_id, self.transparency),
+                    new_meta_vars,
+                    loc.call_site,
+                )
+                .map_err(Into::into),
+        }
+    }
+
+    pub fn expand_unhygienic(
+        &self,
+        db: &dyn ExpandDatabase,
+        tt: tt::Subtree,
+        krate: CrateId,
+        call_site: Span,
+    ) -> ExpandResult<tt::Subtree> {
+        let toolchain = &db.crate_graph()[krate].toolchain;
+        let new_meta_vars = toolchain.as_ref().map_or(false, |version| {
+            REQUIREMENT.get_or_init(|| VersionReq::parse(">=1.76").unwrap()).matches(
+                &base_db::Version {
+                    pre: base_db::Prerelease::EMPTY,
+                    build: base_db::BuildMetadata::EMPTY,
+                    major: version.major,
+                    minor: version.minor,
+                    patch: version.patch,
+                },
+            )
+        });
+        match self.mac.err() {
+            Some(e) => ExpandResult::new(
+                tt::Subtree::empty(tt::DelimSpan { open: call_site, close: call_site }),
+                ExpandError::other(format!("invalid macro definition: {e}")),
+            ),
+            None => self.mac.expand(&tt, |_| (), new_meta_vars, call_site).map_err(Into::into),
+        }
+    }
+
+    pub(crate) fn expander(
+        db: &dyn ExpandDatabase,
+        def_crate: CrateId,
+        id: AstId<ast::Macro>,
+    ) -> Arc<DeclarativeMacroExpander> {
+        let crate_data = &db.crate_graph()[def_crate];
+        let is_2021 = crate_data.edition >= Edition::Edition2021;
+        let (root, map) = crate::db::parse_with_map(db, id.file_id);
+        let root = root.syntax_node();
+
+        let transparency = |node| {
+            // ... would be nice to have the item tree here
+            let attrs = RawAttrs::new(db, node, map.as_ref()).filter(db, def_crate);
+            match &*attrs
+                .iter()
+                .find(|it| {
+                    it.path.as_ident().and_then(|it| it.as_str())
+                        == Some("rustc_macro_transparency")
+                })?
+                .token_tree_value()?
+                .token_trees
+            {
+                [tt::TokenTree::Leaf(tt::Leaf::Ident(i)), ..] => match &*i.text {
+                    "transparent" => Some(Transparency::Transparent),
+                    "semitransparent" => Some(Transparency::SemiTransparent),
+                    "opaque" => Some(Transparency::Opaque),
+                    _ => None,
+                },
+                _ => None,
+            }
+        };
+        let toolchain = crate_data.toolchain.as_ref();
+        let new_meta_vars = toolchain.as_ref().map_or(false, |version| {
+            REQUIREMENT.get_or_init(|| VersionReq::parse(">=1.76").unwrap()).matches(
+                &base_db::Version {
+                    pre: base_db::Prerelease::EMPTY,
+                    build: base_db::BuildMetadata::EMPTY,
+                    major: version.major,
+                    minor: version.minor,
+                    patch: version.patch,
+                },
+            )
+        });
+
+        let (mac, transparency) = match id.to_ptr(db).to_node(&root) {
+            ast::Macro::MacroRules(macro_rules) => (
+                match macro_rules.token_tree() {
+                    Some(arg) => {
+                        let tt = mbe::syntax_node_to_token_tree(
+                            arg.syntax(),
+                            map.as_ref(),
+                            map.span_for_range(
+                                macro_rules.macro_rules_token().unwrap().text_range(),
+                            ),
+                        );
+
+                        mbe::DeclarativeMacro::parse_macro_rules(&tt, is_2021, new_meta_vars)
+                    }
+                    None => mbe::DeclarativeMacro::from_err(
+                        mbe::ParseError::Expected("expected a token tree".into()),
+                        is_2021,
+                    ),
+                },
+                transparency(&macro_rules).unwrap_or(Transparency::SemiTransparent),
+            ),
+            ast::Macro::MacroDef(macro_def) => (
+                match macro_def.body() {
+                    Some(arg) => {
+                        let tt = mbe::syntax_node_to_token_tree(
+                            arg.syntax(),
+                            map.as_ref(),
+                            map.span_for_range(macro_def.macro_token().unwrap().text_range()),
+                        );
+
+                        mbe::DeclarativeMacro::parse_macro2(&tt, is_2021, new_meta_vars)
+                    }
+                    None => mbe::DeclarativeMacro::from_err(
+                        mbe::ParseError::Expected("expected a token tree".into()),
+                        is_2021,
+                    ),
+                },
+                transparency(&macro_def).unwrap_or(Transparency::Opaque),
+            ),
+        };
+        Arc::new(DeclarativeMacroExpander { mac, transparency })
+    }
+}