[gcc r14-8845] gccrs: TyTy: Region (lifetime) representation

[gcc r14-8845] gccrs: TyTy: Region (lifetime) representation

[Arthur Cohen]

https://gcc.gnu.org/g:a2efcc8042a9bdec25dc44f28b5e8027c643f235

commit r14-8845-ga2efcc8042a9bdec25dc44f28b5e8027c643f235
Author: Jakub Dupak <dev@jakubdupak.com>
Date:   Tue Jan 23 12:29:25 2024 +0100

    gccrs: TyTy: Region (lifetime) representation
    
    gcc/rust/ChangeLog:
    
            * typecheck/rust-tyty-region.h: New file.
    
    Signed-off-by: Jakub Dupak <dev@jakubdupak.com>

Diff:
---
 gcc/rust/typecheck/rust-tyty-region.h | 110 ++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/gcc/rust/typecheck/rust-tyty-region.h b/gcc/rust/typecheck/rust-tyty-region.h
new file mode 100644
index 000000000000..b34a2115e7a1
--- /dev/null
+++ b/gcc/rust/typecheck/rust-tyty-region.h
@@ -0,0 +1,110 @@
+#ifndef RUST_TYTY_REGION_H
+#define RUST_TYTY_REGION_H
+
+namespace Rust {
+namespace TyTy {
+
+class Region
+{
+  enum Variant : uint8_t
+  {
+    UNRESOLVED,
+    STATIC,
+    EARLY_BOUND,
+    LATE_BOUND,
+    NAMED,
+    ANONYMOUS,
+    ERASED,
+  };
+
+  uint32_t index;
+  uint16_t debruijn_index;
+  Variant variant;
+
+public:
+  Region () : Region (UNRESOLVED) {}
+  Region (const Region &other)
+    : index (other.index), debruijn_index (other.debruijn_index),
+      variant (other.variant)
+  {}
+  Region (Region &&other) noexcept
+    : index (other.index), debruijn_index (other.debruijn_index),
+      variant (other.variant)
+  {}
+  Region &operator= (const Region &other)
+  {
+    if (this == &other)
+      return *this;
+    index = other.index;
+    debruijn_index = other.debruijn_index;
+    variant = other.variant;
+    return *this;
+  }
+  Region &operator= (Region &&other) noexcept
+  {
+    if (this == &other)
+      return *this;
+    index = other.index;
+    debruijn_index = other.debruijn_index;
+    variant = other.variant;
+    return *this;
+  }
+
+  static Region make_static () { return Region (STATIC); }
+  static Region make_early_bound (uint32_t index)
+  {
+    return Region (EARLY_BOUND, index);
+  }
+  static Region make_late_bound (uint32_t index, uint16_t debruijn_index)
+  {
+    return Region (LATE_BOUND, index, debruijn_index);
+  }
+  static Region make_named (uint32_t index) { return Region (NAMED, index); }
+  static Region make_anonymous () { return Region (ANONYMOUS); }
+  static Region make_erased () { return Region (ERASED); }
+
+  size_t get_index () const { return index; }
+
+  bool is_static () const { return variant == STATIC; }
+  bool is_early_bound () const { return variant == EARLY_BOUND; }
+  bool is_late_bound () const { return variant == LATE_BOUND; }
+  bool is_named () const { return variant == NAMED; }
+  bool is_anonymous () const { return variant == ANONYMOUS; }
+
+  void shift_down () { debruijn_index++; }
+
+  WARN_UNUSED_RESULT std::string as_string () const
+  {
+    switch (variant)
+      {
+      case UNRESOLVED:
+	return "'unresolved";
+      case STATIC:
+	return "'static";
+      case EARLY_BOUND:
+	return "'early(" + std::to_string (index) + ")";
+      case LATE_BOUND:
+	return "'late(" + std::to_string (debruijn_index) + ", "
+	       + std::to_string (index) + ")";
+      case NAMED:
+	return "'named(" + std::to_string (index) + "";
+      case ANONYMOUS:
+	return "'_";
+      case ERASED:
+	return "'erased";
+      }
+
+    rust_unreachable ();
+  }
+
+private:
+  explicit Region (Variant variant, uint32_t index = 0,
+		   uint16_t debruijn_index = 0)
+    : index (index), debruijn_index (debruijn_index), variant (variant)
+  {}
+};
+
+} // namespace TyTy
+} // namespace Rust
+
+#endif // RUST_TYTY_REGION_H