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|
use super::*;
#[derive(Debug, Clone)]
pub struct Record {
pub values: Vec<Value>,
pub tombstone: bool,
}
impl Record {
pub fn serialize(&self) -> Vec<u8> {
let mut bytes = Vec::new();
if self.tombstone {
bytes.extend(&[B_TOMBSTONE]);
} else {
bytes.extend(&[B_LIVE]);
}
for value in &self.values {
bytes.extend(value.serialize());
}
bytes
}
pub fn deserialize(bytes: &[u8]) -> Record {
assert!(bytes.len() > 0);
let mut values = Vec::new();
let tombstone = bytes[0] == B_TOMBSTONE;
let mut start = 1;
while start < bytes.len() {
let (rv, consumed) = Value::deserialize(&bytes[start..]);
values.push(rv);
start += consumed;
}
Record { values, tombstone }
}
pub fn from(values: &[Value]) -> Record {
Record {
values: values.to_vec(),
tombstone: false,
}
}
pub fn at(&self, index: usize) -> &Value {
&self.values[index]
}
pub fn validate<Field: Eq>(&self, schema: &Vec<(Field, ValueType)>) -> DBResult<()> {
// Validate the record length
if self.values.len() != schema.len() {
return Err(DBError::ValidationError(format!(
"Record has an incorrect number of fields: {}, expected {}",
self.values.len(),
schema.len()
)));
}
// Validate that record fields match schema types
for (i, (_, field)) in schema.iter().enumerate() {
match (&self.values[i], field) {
(
Value::Null,
ValueType {
nullable: true,
prim_value_type: _,
},
) => {}
(
Value::Int(_),
ValueType {
prim_value_type: PrimValueType::Int,
..
},
) => {}
(
Value::String(_),
ValueType {
prim_value_type: PrimValueType::String,
..
},
) => {}
(
Value::Bytes(_),
ValueType {
prim_value_type: PrimValueType::Bytes,
..
},
) => {}
_ => {
return Err(DBError::ValidationError(format!(
"Record field {} has incorrect type: {:?}, expected {:?}",
&i, &self.values[i], &field.prim_value_type
)));
}
}
}
Ok(())
}
}
/// A trait that describes how to convert a data structure into a database record and vice versa.
pub trait Recordable {
/// The field type of the data structure implementing the `Recordable` trait.
type Field: Eq + Clone + Debug;
/// Define the schema of the instance implementing the `Recordable` trait.
fn schema() -> Vec<(Self::Field, ValueType)>;
/// Define the primary key of the instance implementing the `Recordable` trait.
fn primary_key() -> Self::Field;
/// Define the secondary keys of the instance implementing the `Recordable` trait.
fn secondary_keys() -> Vec<Self::Field> {
Vec::new()
}
/// Convert the data structure implementing the `Recordable` trait into a vector of database values.
fn into_record(self) -> Vec<Value>;
/// Convert a vector of database values into the data structure implementing the `Recordable` trait.
fn from_record(record: Vec<Value>) -> Self;
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_record_serialize_deserialize() {
let record = Record {
values: vec![
Value::Int(1),
Value::String("hello".to_string()),
Value::Bytes(vec![0, 1, 2, 3]),
],
tombstone: true,
};
let serialized = record.serialize();
let deserialized = Record::deserialize(&serialized);
let reserialized = deserialized.serialize();
assert_eq!(serialized.len(), reserialized.len());
assert_eq!(record.values, deserialized.values);
}
}
|
