1 files changed, 209 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs b/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs
new file mode 100644
index 000000000..6636c8a23
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs
@@ -0,0 +1,209 @@
+//! Display and pretty printing routines.
+
+use std::fmt::{self, Write};
+
+use hir_expand::mod_path::PathKind;
+use itertools::Itertools;
+
+use crate::{
+    intern::Interned,
+    path::{GenericArg, GenericArgs, Path},
+    type_ref::{Mutability, TraitBoundModifier, TypeBound, TypeRef},
+};
+
+pub(crate) fn print_path(path: &Path, buf: &mut dyn Write) -> fmt::Result {
+    match path.type_anchor() {
+        Some(anchor) => {
+            write!(buf, "<")?;
+            print_type_ref(anchor, buf)?;
+            write!(buf, ">::")?;
+        }
+        None => match path.kind() {
+            PathKind::Plain => {}
+            PathKind::Super(0) => write!(buf, "self")?,
+            PathKind::Super(n) => {
+                for i in 0..*n {
+                    if i == 0 {
+                        buf.write_str("super")?;
+                    } else {
+                        buf.write_str("::super")?;
+                    }
+                }
+            }
+            PathKind::Crate => write!(buf, "crate")?,
+            PathKind::Abs => {}
+            PathKind::DollarCrate(_) => write!(buf, "$crate")?,
+        },
+    }
+
+    for (i, segment) in path.segments().iter().enumerate() {
+        if i != 0 || !matches!(path.kind(), PathKind::Plain) {
+            write!(buf, "::")?;
+        }
+
+        write!(buf, "{}", segment.name)?;
+        if let Some(generics) = segment.args_and_bindings {
+            write!(buf, "::<")?;
+            print_generic_args(generics, buf)?;
+
+            write!(buf, ">")?;
+        }
+    }
+
+    Ok(())
+}
+
+pub(crate) fn print_generic_args(generics: &GenericArgs, buf: &mut dyn Write) -> fmt::Result {
+    let mut first = true;
+    let args = if generics.has_self_type {
+        let (self_ty, args) = generics.args.split_first().unwrap();
+        write!(buf, "Self=")?;
+        print_generic_arg(self_ty, buf)?;
+        first = false;
+        args
+    } else {
+        &generics.args
+    };
+    for arg in args {
+        if !first {
+            write!(buf, ", ")?;
+        }
+        first = false;
+        print_generic_arg(arg, buf)?;
+    }
+    for binding in &generics.bindings {
+        if !first {
+            write!(buf, ", ")?;
+        }
+        first = false;
+        write!(buf, "{}", binding.name)?;
+        if !binding.bounds.is_empty() {
+            write!(buf, ": ")?;
+            print_type_bounds(&binding.bounds, buf)?;
+        }
+        if let Some(ty) = &binding.type_ref {
+            write!(buf, " = ")?;
+            print_type_ref(ty, buf)?;
+        }
+    }
+    Ok(())
+}
+
+pub(crate) fn print_generic_arg(arg: &GenericArg, buf: &mut dyn Write) -> fmt::Result {
+    match arg {
+        GenericArg::Type(ty) => print_type_ref(ty, buf),
+        GenericArg::Const(c) => write!(buf, "{}", c),
+        GenericArg::Lifetime(lt) => write!(buf, "{}", lt.name),
+    }
+}
+
+pub(crate) fn print_type_ref(type_ref: &TypeRef, buf: &mut dyn Write) -> fmt::Result {
+    // FIXME: deduplicate with `HirDisplay` impl
+    match type_ref {
+        TypeRef::Never => write!(buf, "!")?,
+        TypeRef::Placeholder => write!(buf, "_")?,
+        TypeRef::Tuple(fields) => {
+            write!(buf, "(")?;
+            for (i, field) in fields.iter().enumerate() {
+                if i != 0 {
+                    write!(buf, ", ")?;
+                }
+                print_type_ref(field, buf)?;
+            }
+            write!(buf, ")")?;
+        }
+        TypeRef::Path(path) => print_path(path, buf)?,
+        TypeRef::RawPtr(pointee, mtbl) => {
+            let mtbl = match mtbl {
+                Mutability::Shared => "*const",
+                Mutability::Mut => "*mut",
+            };
+            write!(buf, "{} ", mtbl)?;
+            print_type_ref(pointee, buf)?;
+        }
+        TypeRef::Reference(pointee, lt, mtbl) => {
+            let mtbl = match mtbl {
+                Mutability::Shared => "",
+                Mutability::Mut => "mut ",
+            };
+            write!(buf, "&")?;
+            if let Some(lt) = lt {
+                write!(buf, "{} ", lt.name)?;
+            }
+            write!(buf, "{}", mtbl)?;
+            print_type_ref(pointee, buf)?;
+        }
+        TypeRef::Array(elem, len) => {
+            write!(buf, "[")?;
+            print_type_ref(elem, buf)?;
+            write!(buf, "; {}]", len)?;
+        }
+        TypeRef::Slice(elem) => {
+            write!(buf, "[")?;
+            print_type_ref(elem, buf)?;
+            write!(buf, "]")?;
+        }
+        TypeRef::Fn(args_and_ret, varargs) => {
+            let ((_, return_type), args) =
+                args_and_ret.split_last().expect("TypeRef::Fn is missing return type");
+            write!(buf, "fn(")?;
+            for (i, (_, typeref)) in args.iter().enumerate() {
+                if i != 0 {
+                    write!(buf, ", ")?;
+                }
+                print_type_ref(typeref, buf)?;
+            }
+            if *varargs {
+                if !args.is_empty() {
+                    write!(buf, ", ")?;
+                }
+                write!(buf, "...")?;
+            }
+            write!(buf, ") -> ")?;
+            print_type_ref(return_type, buf)?;
+        }
+        TypeRef::Macro(_ast_id) => {
+            write!(buf, "<macro>")?;
+        }
+        TypeRef::Error => write!(buf, "{{unknown}}")?,
+        TypeRef::ImplTrait(bounds) => {
+            write!(buf, "impl ")?;
+            print_type_bounds(bounds, buf)?;
+        }
+        TypeRef::DynTrait(bounds) => {
+            write!(buf, "dyn ")?;
+            print_type_bounds(bounds, buf)?;
+        }
+    }
+
+    Ok(())
+}
+
+pub(crate) fn print_type_bounds(
+    bounds: &[Interned<TypeBound>],
+    buf: &mut dyn Write,
+) -> fmt::Result {
+    for (i, bound) in bounds.iter().enumerate() {
+        if i != 0 {
+            write!(buf, " + ")?;
+        }
+
+        match bound.as_ref() {
+            TypeBound::Path(path, modifier) => {
+                match modifier {
+                    TraitBoundModifier::None => (),
+                    TraitBoundModifier::Maybe => write!(buf, "?")?,
+                }
+                print_path(path, buf)?;
+            }
+            TypeBound::ForLifetime(lifetimes, path) => {
+                write!(buf, "for<{}> ", lifetimes.iter().format(", "))?;
+                print_path(path, buf)?;
+            }
+            TypeBound::Lifetime(lt) => write!(buf, "{}", lt.name)?,
+            TypeBound::Error => write!(buf, "{{unknown}}")?,
+        }
+    }
+
+    Ok(())
+}