Vendor things

third-party/vendor/smartstring/src/marker_byte.rs

@@ -0,0 +1,65 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub(crate) enum Discriminant {
+    Boxed,
+    Inline,
+}
+
+impl Discriminant {
+    #[inline(always)]
+    pub(crate) const fn from_bit(bit: bool) -> Self {
+        if bit {
+            Self::Inline
+        } else {
+            Self::Boxed
+        }
+    }
+
+    #[inline(always)]
+    const fn bit(self) -> u8 {
+        match self {
+            Self::Boxed => 0,
+            Self::Inline => 1,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub(crate) struct Marker(u8);
+
+impl Marker {
+    #[inline(always)]
+    const fn assemble(discriminant: Discriminant, data: u8) -> u8 {
+        data << 1 | discriminant.bit()
+    }
+
+    #[inline(always)]
+    pub(crate) const fn empty() -> Self {
+        Self(Self::assemble(Discriminant::Inline, 0))
+    }
+
+    #[inline(always)]
+    pub(crate) const fn new_inline(data: u8) -> Self {
+        debug_assert!(data < 0x80);
+        Self(Self::assemble(Discriminant::Inline, data))
+    }
+
+    #[inline(always)]
+    pub(crate) const fn discriminant(self) -> Discriminant {
+        Discriminant::from_bit(self.0 & 0x01 != 0)
+    }
+
+    #[inline(always)]
+    pub(crate) const fn data(self) -> u8 {
+        self.0 >> 1
+    }
+
+    #[inline(always)]
+    pub(crate) fn set_data(&mut self, byte: u8) {
+        debug_assert!(byte < 0x80);
+        self.0 = Self::assemble(self.discriminant(), byte);
+    }
+}