1 files changed, 85 insertions, 0 deletions
diff --git a/snapshot/src/format.rs b/snapshot/src/format.rs
new file mode 100644
index 0000000..1a22938
--- /dev/null
+++ b/snapshot/src/format.rs
@@ -0,0 +1,85 @@
+use buffer::CapacityError;
+use packer::Packer;
+use packer::Unpacker;
+use packer;
+use snap::Error;
+use warn::Warn;
+use warn::wrap;
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum Warning {
+    Packer(packer::Warning),
+    NonZeroPadding,
+    DuplicateDelete,
+    DuplicateUpdate,
+    UnknownDelete,
+    DeleteUpdate,
+    NumUpdatedItems,
+}
+
+impl From<packer::Warning> for Warning {
+    fn from(w: packer::Warning) -> Warning {
+        Warning::Packer(w)
+    }
+}
+
+pub fn key_to_type_id(key: i32) -> u16 {
+    ((key as u32 >> 16) & 0xffff) as u16
+}
+
+pub fn key_to_id(key: i32) -> u16 {
+    ((key as u32) & 0xffff) as u16
+}
+
+pub fn key(type_id: u16, id: u16) -> i32 {
+    (((type_id as u32) << 16) | (id as u32)) as i32
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct Item<'a> {
+    pub type_id: u16,
+    pub id: u16,
+    pub data: &'a [i32],
+}
+
+impl<'a> Item<'a> {
+    pub fn from_key(key: i32, data: &[i32]) -> Item {
+        Item {
+            type_id: key_to_type_id(key),
+            id: key_to_id(key),
+            data: data,
+        }
+    }
+    pub fn key(&self) -> i32 {
+        key(self.type_id, self.id)
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct DeltaHeader {
+    pub num_deleted_items: i32,
+    pub num_updated_items: i32,
+}
+
+impl DeltaHeader {
+    pub fn decode<W: Warn<Warning>>(warn: &mut W, p: &mut Unpacker)
+        -> Result<DeltaHeader, Error>
+    {
+        let result = DeltaHeader {
+            num_deleted_items: packer::positive(p.read_int(wrap(warn))?)?,
+            num_updated_items: packer::positive(p.read_int(wrap(warn))?)?,
+        };
+        if p.read_int(wrap(warn))? != 0 {
+            warn.warn(Warning::NonZeroPadding);
+        }
+        Ok(result)
+    }
+    pub fn encode<'d, 's>(&self, mut p: Packer<'d, 's>)
+        -> Result<&'d [u8], CapacityError>
+    {
+        p.write_int(self.num_deleted_items)?;
+        p.write_int(self.num_updated_items)?;
+        p.write_int(0)?;
+        Ok(p.written())
+    }
+}