1 files changed, 230 insertions, 0 deletions

diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
new file mode 100644
index 000000000..49841c7a1
--- /dev/null
+++ b/crates/hir_expand/src/name.rs
@@ -0,0 +1,230 @@
+//! FIXME: write short doc here
+
+use std::fmt;
+
+use 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(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Name(Repr);
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+enum Repr {
+    Text(SmolStr),
+    TupleField(usize),
+}
+
+impl fmt::Display for Name {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match &self.0 {
+            Repr::Text(text) => fmt::Display::fmt(&text, f),
+            Repr::TupleField(idx) => fmt::Display::fmt(&idx, f),
+        }
+    }
+}
+
+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(text: SmolStr) -> Name {
+        Name(Repr::Text(text))
+    }
+
+    pub fn new_tuple_field(idx: usize) -> Name {
+        Name(Repr::TupleField(idx))
+    }
+
+    pub fn new_lifetime(lt: &syntax::SyntaxToken) -> Name {
+        assert!(lt.kind() == syntax::SyntaxKind::LIFETIME);
+        Name(Repr::Text(lt.text().clone()))
+    }
+
+    /// Shortcut to create inline plain text name
+    const fn new_inline_ascii(text: &[u8]) -> Name {
+        Name::new_text(SmolStr::new_inline_from_ascii(text.len(), 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 fn missing() -> Name {
+        Name::new_text("[missing name]".into())
+    }
+
+    pub fn as_tuple_index(&self) -> Option<usize> {
+        match self.0 {
+            Repr::TupleField(idx) => Some(idx),
+            _ => None,
+        }
+    }
+}
+
+pub trait AsName {
+    fn as_name(&self) -> Name;
+}
+
+impl AsName for ast::NameRef {
+    fn as_name(&self) -> 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 {
+        Name::resolve(self.text())
+    }
+}
+
+impl AsName for ast::NameOrNameRef {
+    fn as_name(&self) -> Name {
+        match self {
+            ast::NameOrNameRef::Name(it) => it.as_name(),
+            ast::NameOrNameRef::NameRef(it) => it.as_name(),
+        }
+    }
+}
+
+impl AsName for tt::Ident {
+    fn as_name(&self) -> Name {
+        Name::resolve(&self.text)
+    }
+}
+
+impl AsName for ast::FieldKind {
+    fn as_name(&self) -> Name {
+        match self {
+            ast::FieldKind::Name(nr) => nr.as_name(),
+            ast::FieldKind::Index(idx) => {
+                let idx = idx.text().parse::<usize>().unwrap_or(0);
+                Name::new_tuple_field(idx)
+            }
+        }
+    }
+}
+
+impl AsName for base_db::Dependency {
+    fn as_name(&self) -> Name {
+        Name::new_text(SmolStr::new(&*self.name))
+    }
+}
+
+pub mod known {
+    macro_rules! known_names {
+        ($($ident:ident),* $(,)?) => {
+            $(
+                #[allow(bad_style)]
+                pub const $ident: super::Name =
+                    super::Name::new_inline_ascii(stringify!($ident).as_bytes());
+            )*
+        };
+    }
+
+    known_names!(
+        // Primitives
+        isize,
+        i8,
+        i16,
+        i32,
+        i64,
+        i128,
+        usize,
+        u8,
+        u16,
+        u32,
+        u64,
+        u128,
+        f32,
+        f64,
+        bool,
+        char,
+        str,
+        // Special names
+        macro_rules,
+        doc,
+        // Components of known path (value or mod name)
+        std,
+        core,
+        alloc,
+        iter,
+        ops,
+        future,
+        result,
+        boxed,
+        // Components of known path (type name)
+        IntoIterator,
+        Item,
+        Try,
+        Ok,
+        Future,
+        Result,
+        Output,
+        Target,
+        Box,
+        RangeFrom,
+        RangeFull,
+        RangeInclusive,
+        RangeToInclusive,
+        RangeTo,
+        Range,
+        Neg,
+        Not,
+        Index,
+        // Builtin macros
+        file,
+        column,
+        compile_error,
+        line,
+        assert,
+        stringify,
+        concat,
+        include,
+        include_bytes,
+        include_str,
+        format_args,
+        format_args_nl,
+        env,
+        option_env,
+        // Builtin derives
+        Copy,
+        Clone,
+        Default,
+        Debug,
+        Hash,
+        Ord,
+        PartialOrd,
+        Eq,
+        PartialEq,
+    );
+
+    // self/Self cannot be used as an identifier
+    pub const SELF_PARAM: super::Name = super::Name::new_inline_ascii(b"self");
+    pub const SELF_TYPE: super::Name = super::Name::new_inline_ascii(b"Self");
+
+    #[macro_export]
+    macro_rules! name {
+        (self) => {
+            $crate::name::known::SELF_PARAM
+        };
+        (Self) => {
+            $crate::name::known::SELF_TYPE
+        };
+        ($ident:ident) => {
+            $crate::name::known::$ident
+        };
+    }
+}
+
+pub use crate::name;