Refactor `Name` ready for hygienic macro

4 files changed, 94 insertions, 84 deletions

diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index fbb4ff4d8..99d286215 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -133,7 +133,7 @@ impl VariantData {
                     .fields()
                     .enumerate()
                     .map(|(i, fd)| StructFieldData {
-                        name: Name::tuple_field_name(i),
+                        name: Name::new_tuple_field(i),
                         type_ref: TypeRef::from_ast_opt(fd.type_ref()),
                     })
                     .collect();
diff --git a/crates/ra_hir/src/name.rs b/crates/ra_hir/src/name.rs
index 1bf993ffb..d50867f5d 100644
--- a/crates/ra_hir/src/name.rs
+++ b/crates/ra_hir/src/name.rs
@@ -5,20 +5,21 @@ use ra_syntax::{ast, SmolStr};
 /// `Name` is a wrapper around string, which is used in hir for both references
 /// and declarations. In theory, names should also carry hygiene info, but we are
 /// not there yet!
-#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
-pub struct Name {
-    text: SmolStr,
-}
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Name(Repr);
 
-impl fmt::Display for Name {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.text, f)
-    }
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+enum Repr {
+    Text(SmolStr),
+    TupleField(usize),
 }
 
-impl fmt::Debug for Name {
+impl fmt::Display for Name {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&self.text, f)
+        match &self.0 {
+            Repr::Text(text) => fmt::Display::fmt(&text, f),
+            Repr::TupleField(idx) => fmt::Display::fmt(&idx, f),
+        }
     }
 }
 
@@ -26,29 +27,38 @@ impl Name {
     /// Note: this is private to make creating name from random string hard.
     /// Hopefully, this should allow us to integrate hygiene cleaner in the
     /// future, and to switch to interned representation of names.
-    const fn new(text: SmolStr) -> Name {
-        Name { text }
+    const fn new_text(text: SmolStr) -> Name {
+        Name(Repr::Text(text))
     }
 
-    pub(crate) fn missing() -> Name {
-        Name::new("[missing name]".into())
+    pub(crate) fn new_tuple_field(idx: usize) -> Name {
+        Name(Repr::TupleField(idx))
     }
 
-    pub(crate) fn tuple_field_name(idx: usize) -> Name {
-        Name::new(idx.to_string().into())
+    /// Shortcut to create inline plain text name
+    const fn new_inline_ascii(len: usize, text: &[u8]) -> Name {
+        Name::new_text(SmolStr::new_inline_from_ascii(len, text))
     }
 
-    // There's should be no way to extract a string out of `Name`: `Name` in the
-    // future, `Name` will include hygiene information, and you can't encode
-    // hygiene into a String.
-    //
-    // If you need to compare something with `Name`, compare `Name`s directly.
-    //
-    // If you need to render `Name` for the user, use the `Display` impl, but be
-    // aware that it strips hygiene info.
-    #[deprecated(note = "use to_string instead")]
-    pub fn as_smolstr(&self) -> &SmolStr {
-        &self.text
+    /// Resolve a name from the text of token.
+    fn resolve(raw_text: &SmolStr) -> Name {
+        let raw_start = "r#";
+        if raw_text.as_str().starts_with(raw_start) {
+            Name::new_text(SmolStr::new(&raw_text[raw_start.len()..]))
+        } else {
+            Name::new_text(raw_text.clone())
+        }
+    }
+
+    pub(crate) fn missing() -> Name {
+        Name::new_text("[missing name]".into())
+    }
+
+    pub(crate) fn as_tuple_index(&self) -> Option<usize> {
+        match self.0 {
+            Repr::TupleField(idx) => Some(idx),
+            _ => None,
+        }
     }
 }
 
@@ -58,15 +68,16 @@ pub(crate) trait AsName {
 
 impl AsName for ast::NameRef {
     fn as_name(&self) -> Name {
-        let name = resolve_name(self.text());
-        Name::new(name)
+        match self.as_tuple_field() {
+            Some(idx) => Name::new_tuple_field(idx),
+            None => Name::resolve(self.text()),
+        }
     }
 }
 
 impl AsName for ast::Name {
     fn as_name(&self) -> Name {
-        let name = resolve_name(self.text());
-        Name::new(name)
+        Name::resolve(self.text())
     }
 }
 
@@ -74,66 +85,56 @@ impl AsName for ast::FieldKind {
     fn as_name(&self) -> Name {
         match self {
             ast::FieldKind::Name(nr) => nr.as_name(),
-            ast::FieldKind::Index(idx) => Name::new(idx.text().clone()),
+            ast::FieldKind::Index(idx) => Name::new_tuple_field(idx.text().parse().unwrap()),
         }
     }
 }
 
 impl AsName for ra_db::Dependency {
     fn as_name(&self) -> Name {
-        Name::new(self.name.clone())
+        Name::new_text(self.name.clone())
     }
 }
 
 // Primitives
-pub(crate) const ISIZE: Name = Name::new(SmolStr::new_inline_from_ascii(5, b"isize"));
-pub(crate) const I8: Name = Name::new(SmolStr::new_inline_from_ascii(2, b"i8"));
-pub(crate) const I16: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"i16"));
-pub(crate) const I32: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"i32"));
-pub(crate) const I64: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"i64"));
-pub(crate) const I128: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"i128"));
-pub(crate) const USIZE: Name = Name::new(SmolStr::new_inline_from_ascii(5, b"usize"));
-pub(crate) const U8: Name = Name::new(SmolStr::new_inline_from_ascii(2, b"u8"));
-pub(crate) const U16: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"u16"));
-pub(crate) const U32: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"u32"));
-pub(crate) const U64: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"u64"));
-pub(crate) const U128: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"u128"));
-pub(crate) const F32: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"f32"));
-pub(crate) const F64: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"f64"));
-pub(crate) const BOOL: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"bool"));
-pub(crate) const CHAR: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"char"));
-pub(crate) const STR: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"str"));
+pub(crate) const ISIZE: Name = Name::new_inline_ascii(5, b"isize");
+pub(crate) const I8: Name = Name::new_inline_ascii(2, b"i8");
+pub(crate) const I16: Name = Name::new_inline_ascii(3, b"i16");
+pub(crate) const I32: Name = Name::new_inline_ascii(3, b"i32");
+pub(crate) const I64: Name = Name::new_inline_ascii(3, b"i64");
+pub(crate) const I128: Name = Name::new_inline_ascii(4, b"i128");
+pub(crate) const USIZE: Name = Name::new_inline_ascii(5, b"usize");
+pub(crate) const U8: Name = Name::new_inline_ascii(2, b"u8");
+pub(crate) const U16: Name = Name::new_inline_ascii(3, b"u16");
+pub(crate) const U32: Name = Name::new_inline_ascii(3, b"u32");
+pub(crate) const U64: Name = Name::new_inline_ascii(3, b"u64");
+pub(crate) const U128: Name = Name::new_inline_ascii(4, b"u128");
+pub(crate) const F32: Name = Name::new_inline_ascii(3, b"f32");
+pub(crate) const F64: Name = Name::new_inline_ascii(3, b"f64");
+pub(crate) const BOOL: Name = Name::new_inline_ascii(4, b"bool");
+pub(crate) const CHAR: Name = Name::new_inline_ascii(4, b"char");
+pub(crate) const STR: Name = Name::new_inline_ascii(3, b"str");
 
 // Special names
-pub(crate) const SELF_PARAM: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"self"));
-pub(crate) const SELF_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"Self"));
-pub(crate) const MACRO_RULES: Name = Name::new(SmolStr::new_inline_from_ascii(11, b"macro_rules"));
+pub(crate) const SELF_PARAM: Name = Name::new_inline_ascii(4, b"self");
+pub(crate) const SELF_TYPE: Name = Name::new_inline_ascii(4, b"Self");
+pub(crate) const MACRO_RULES: Name = Name::new_inline_ascii(11, b"macro_rules");
 
 // Components of known path (value or mod name)
-pub(crate) const STD: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"std"));
-pub(crate) const ITER: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"iter"));
-pub(crate) const OPS: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"ops"));
-pub(crate) const FUTURE: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"future"));
-pub(crate) const RESULT: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"result"));
-pub(crate) const BOXED: Name = Name::new(SmolStr::new_inline_from_ascii(5, b"boxed"));
+pub(crate) const STD: Name = Name::new_inline_ascii(3, b"std");
+pub(crate) const ITER: Name = Name::new_inline_ascii(4, b"iter");
+pub(crate) const OPS: Name = Name::new_inline_ascii(3, b"ops");
+pub(crate) const FUTURE: Name = Name::new_inline_ascii(6, b"future");
+pub(crate) const RESULT: Name = Name::new_inline_ascii(6, b"result");
+pub(crate) const BOXED: Name = Name::new_inline_ascii(5, b"boxed");
 
 // Components of known path (type name)
-pub(crate) const INTO_ITERATOR_TYPE: Name =
-    Name::new(SmolStr::new_inline_from_ascii(12, b"IntoIterator"));
-pub(crate) const ITEM_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(4, b"Item"));
-pub(crate) const TRY_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"Try"));
-pub(crate) const OK_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(2, b"Ok"));
-pub(crate) const FUTURE_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"Future"));
-pub(crate) const RESULT_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"Result"));
-pub(crate) const OUTPUT_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"Output"));
-pub(crate) const TARGET_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(6, b"Target"));
-pub(crate) const BOX_TYPE: Name = Name::new(SmolStr::new_inline_from_ascii(3, b"Box"));
-
-fn resolve_name(text: &SmolStr) -> SmolStr {
-    let raw_start = "r#";
-    if text.as_str().starts_with(raw_start) {
-        SmolStr::new(&text[raw_start.len()..])
-    } else {
-        text.clone()
-    }
-}
+pub(crate) const INTO_ITERATOR_TYPE: Name = Name::new_inline_ascii(12, b"IntoIterator");
+pub(crate) const ITEM_TYPE: Name = Name::new_inline_ascii(4, b"Item");
+pub(crate) const TRY_TYPE: Name = Name::new_inline_ascii(3, b"Try");
+pub(crate) const OK_TYPE: Name = Name::new_inline_ascii(2, b"Ok");
+pub(crate) const FUTURE_TYPE: Name = Name::new_inline_ascii(6, b"Future");
+pub(crate) const RESULT_TYPE: Name = Name::new_inline_ascii(6, b"Result");
+pub(crate) const OUTPUT_TYPE: Name = Name::new_inline_ascii(6, b"Output");
+pub(crate) const TARGET_TYPE: Name = Name::new_inline_ascii(6, b"Target");
+pub(crate) const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index db3377357..8f92468e6 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -609,7 +609,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         for (i, &subpat) in subpats.iter().enumerate() {
             let expected_ty = def
-                .and_then(|d| d.field(self.db, &Name::tuple_field_name(i)))
+                .and_then(|d| d.field(self.db, &Name::new_tuple_field(i)))
                 .map_or(Ty::Unknown, |field| field.ty(self.db))
                 .subst(&substs);
             let expected_ty = self.normalize_associated_types_in(expected_ty);
@@ -1375,10 +1375,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 )
                 .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
                     Ty::Apply(a_ty) => match a_ty.ctor {
-                        TypeCtor::Tuple { .. } => {
-                            let i = name.to_string().parse::<usize>().ok();
-                            i.and_then(|i| a_ty.parameters.0.get(i).cloned())
-                        }
+                        TypeCtor::Tuple { .. } => name
+                            .as_tuple_index()
+                            .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
                         TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| {
                             self.write_field_resolution(tgt_expr, field);
                             field.ty(self.db).subst(&a_ty.parameters)
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index 5f7e9f5b1..0433edb84 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -21,6 +21,16 @@ impl ast::NameRef {
     pub fn text(&self) -> &SmolStr {
         text_of_first_token(self.syntax())
     }
+
+    pub fn as_tuple_field(&self) -> Option<usize> {
+        self.syntax().children_with_tokens().find_map(|c| {
+            if c.kind() == SyntaxKind::INT_NUMBER {
+                c.as_token().and_then(|tok| tok.text().as_str().parse().ok())
+            } else {
+                None
+            }
+        })
+    }
 }
 
 fn text_of_first_token(node: &SyntaxNode) -> &SmolStr {