bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir_expand/src/lib.rs')
-rw-r--r--crates/hir_expand/src/lib.rs96
1 files changed, 59 insertions, 37 deletions
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index f982679b64..a814a2886d 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -19,7 +19,6 @@ use base_db::ProcMacroKind;
use either::Either;
pub use mbe::{ExpandError, ExpandResult};
-pub use parser::FragmentKind;
use std::{hash::Hash, iter, sync::Arc};
@@ -268,7 +267,7 @@ pub struct MacroCallLoc {
pub enum MacroCallKind {
FnLike {
ast_id: AstId<ast::MacroCall>,
- fragment: FragmentKind,
+ expand_to: ExpandTo,
},
Derive {
ast_id: AstId<ast::Item>,
@@ -327,11 +326,11 @@ impl MacroCallKind {
}
}
- fn fragment_kind(&self) -> FragmentKind {
+ fn expand_to(&self) -> ExpandTo {
match self {
- MacroCallKind::FnLike { fragment, .. } => *fragment,
- MacroCallKind::Derive { .. } => FragmentKind::Items,
- MacroCallKind::Attr { .. } => FragmentKind::Items, // is this always correct?
+ MacroCallKind::FnLike { expand_to, .. } => *expand_to,
+ MacroCallKind::Derive { .. } => ExpandTo::Items,
+ MacroCallKind::Attr { .. } => ExpandTo::Items, // is this always correct?
}
}
}
@@ -653,38 +652,61 @@ impl<N: AstNode> InFile<N> {
}
}
-/// Given a `MacroCallId`, return what `FragmentKind` it belongs to.
-/// FIXME: Not completed
-pub fn to_fragment_kind(call: &ast::MacroCall) -> FragmentKind {
- use syntax::SyntaxKind::*;
-
- let syn = call.syntax();
-
- let parent = match syn.parent() {
- Some(it) => it,
- None => return FragmentKind::Statements,
- };
-
- match parent.kind() {
- MACRO_ITEMS | SOURCE_FILE | ITEM_LIST => FragmentKind::Items,
- MACRO_STMTS | EXPR_STMT | BLOCK_EXPR => FragmentKind::Statements,
- MACRO_PAT => FragmentKind::Pattern,
- MACRO_TYPE => FragmentKind::Type,
-
- ARG_LIST | TRY_EXPR | TUPLE_EXPR | PAREN_EXPR | ARRAY_EXPR | FOR_EXPR | PATH_EXPR
- | CLOSURE_EXPR | CONDITION | BREAK_EXPR | RETURN_EXPR | MATCH_EXPR | MATCH_ARM
- | MATCH_GUARD | RECORD_EXPR_FIELD | CALL_EXPR | INDEX_EXPR | METHOD_CALL_EXPR
- | FIELD_EXPR | AWAIT_EXPR | CAST_EXPR | REF_EXPR | PREFIX_EXPR | RANGE_EXPR | BIN_EXPR => {
- FragmentKind::Expr
- }
- LET_STMT => {
- // FIXME: Handle LHS Pattern
- FragmentKind::Expr
- }
+/// In Rust, macros expand token trees to token trees. When we want to turn a
+/// token tree into an AST node, we need to figure out what kind of AST node we
+/// want: something like `foo` can be a type, an expression, or a pattern.
+///
+/// Naively, one would think that "what this expands to" is a property of a
+/// particular macro: macro `m1` returns an item, while macro `m2` returns an
+/// expression, etc. That's not the case -- macros are polymorphic in the
+/// result, and can expand to any type of the AST node.
+///
+/// What defines the actual AST node is the syntactic context of the macro
+/// invocation. As a contrived example, in `let T![*] = T![*];` the first `T`
+/// expands to a pattern, while the second one expands to an expression.
+///
+/// `ExpandTo` captures this bit of information about a particular macro call
+/// site.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ExpandTo {
+ Statements,
+ Items,
+ Pattern,
+ Type,
+ Expr,
+}
- _ => {
- // Unknown , Just guess it is `Items`
- FragmentKind::Items
+impl ExpandTo {
+ pub fn from_call_site(call: &ast::MacroCall) -> ExpandTo {
+ use syntax::SyntaxKind::*;
+
+ let syn = call.syntax();
+
+ let parent = match syn.parent() {
+ Some(it) => it,
+ None => return ExpandTo::Statements,
+ };
+
+ match parent.kind() {
+ MACRO_ITEMS | SOURCE_FILE | ITEM_LIST => ExpandTo::Items,
+ MACRO_STMTS | EXPR_STMT | BLOCK_EXPR => ExpandTo::Statements,
+ MACRO_PAT => ExpandTo::Pattern,
+ MACRO_TYPE => ExpandTo::Type,
+
+ ARG_LIST | TRY_EXPR | TUPLE_EXPR | PAREN_EXPR | ARRAY_EXPR | FOR_EXPR | PATH_EXPR
+ | CLOSURE_EXPR | CONDITION | BREAK_EXPR | RETURN_EXPR | MATCH_EXPR | MATCH_ARM
+ | MATCH_GUARD | RECORD_EXPR_FIELD | CALL_EXPR | INDEX_EXPR | METHOD_CALL_EXPR
+ | FIELD_EXPR | AWAIT_EXPR | CAST_EXPR | REF_EXPR | PREFIX_EXPR | RANGE_EXPR
+ | BIN_EXPR => ExpandTo::Expr,
+ LET_STMT => {
+ // FIXME: Handle LHS Pattern
+ ExpandTo::Expr
+ }
+
+ _ => {
+ // Unknown , Just guess it is `Items`
+ ExpandTo::Items
+ }
}
}
}