//! Eager expansion related utils //! //! Here is a dump of a discussion from Vadim Petrochenkov about Eager Expansion and //! Its name resolution : //! //! > Eagerly expanded macros (and also macros eagerly expanded by eagerly expanded macros, //! > which actually happens in practice too!) are resolved at the location of the "root" macro //! > that performs the eager expansion on its arguments. //! > If some name cannot be resolved at the eager expansion time it's considered unresolved, //! > even if becomes available later (e.g. from a glob import or other macro). //! //! > Eagerly expanded macros don't add anything to the module structure of the crate and //! > don't build any speculative module structures, i.e. they are expanded in a "flat" //! > way even if tokens in them look like modules. //! //! > In other words, it kinda works for simple cases for which it was originally intended, //! > and we need to live with it because it's available on stable and widely relied upon. //! //! //! See the full discussion : https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Eager.20expansion.20of.20built-in.20macros use crate::{ ast::{self, AstNode}, db::AstDatabase, EagerCallLoc, EagerMacroId, InFile, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind, }; use ra_parser::FragmentKind; use ra_syntax::{algo::SyntaxRewriter, SyntaxNode}; use std::sync::Arc; pub fn expand_eager_macro( db: &dyn AstDatabase, macro_call: InFile<ast::MacroCall>, def: MacroDefId, resolver: &dyn Fn(ast::Path) -> Option<MacroDefId>, ) -> Option<EagerMacroId> { let args = macro_call.value.token_tree()?; let parsed_args = mbe::ast_to_token_tree(&args)?.0; // Note: // When `lazy_expand` is called, its *parent* file must be already exists. // Here we store an eager macro id for the argument expanded subtree here // for that purpose. let arg_id = db.intern_eager_expansion({ EagerCallLoc { def, fragment: FragmentKind::Expr, subtree: Arc::new(parsed_args.clone()), file_id: macro_call.file_id, } }); let arg_file_id: MacroCallId = arg_id.into(); let parsed_args = mbe::token_tree_to_syntax_node(&parsed_args, FragmentKind::Expr).ok()?.0; let result = eager_macro_recur( db, InFile::new(arg_file_id.as_file(), parsed_args.syntax_node()), resolver, )?; let subtree = to_subtree(&result)?; if let MacroDefKind::BuiltInEager(eager) = def.kind { let (subtree, fragment) = eager.expand(db, arg_id, &subtree).ok()?; let eager = EagerCallLoc { def, fragment, subtree: Arc::new(subtree), file_id: macro_call.file_id }; Some(db.intern_eager_expansion(eager)) } else { None } } fn to_subtree(node: &SyntaxNode) -> Option<tt::Subtree> { let mut subtree = mbe::syntax_node_to_token_tree(node)?.0; subtree.delimiter = None; Some(subtree) } fn lazy_expand( db: &dyn AstDatabase, def: &MacroDefId, macro_call: InFile<ast::MacroCall>, ) -> Option<InFile<SyntaxNode>> { let ast_id = db.ast_id_map(macro_call.file_id).ast_id(¯o_call.value); let id: MacroCallId = def.as_lazy_macro(db, MacroCallKind::FnLike(macro_call.with_value(ast_id))).into(); db.parse_or_expand(id.as_file()).map(|node| InFile::new(id.as_file(), node)) } fn eager_macro_recur( db: &dyn AstDatabase, curr: InFile<SyntaxNode>, macro_resolver: &dyn Fn(ast::Path) -> Option<MacroDefId>, ) -> Option<SyntaxNode> { let original = curr.value.clone(); let children = curr.value.descendants().filter_map(ast::MacroCall::cast); let mut rewriter = SyntaxRewriter::default(); // Collect replacement for child in children { let def: MacroDefId = macro_resolver(child.path()?)?; let insert = match def.kind { MacroDefKind::BuiltInEager(_) => { let id: MacroCallId = expand_eager_macro(db, curr.with_value(child.clone()), def, macro_resolver)? .into(); db.parse_or_expand(id.as_file())? } MacroDefKind::Declarative | MacroDefKind::BuiltIn(_) | MacroDefKind::BuiltInDerive(_) | MacroDefKind::CustomDerive(_) => { let expanded = lazy_expand(db, &def, curr.with_value(child.clone()))?; // replace macro inside eager_macro_recur(db, expanded, macro_resolver)? } }; rewriter.replace(child.syntax(), &insert); } let res = rewriter.rewrite(&original); Some(res) }