1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376
pub mod de;
pub mod ser;
use crate::{AlgebraicType, ArrayValue, MapValue, ProductValue, SumValue};
use derive_more::From;
use enum_as_inner::EnumAsInner;
use std::ops::{Bound, RangeBounds};
/// Totally ordered [`f32`] allowing all IEEE-754 floating point values.
pub type F32 = decorum::Total<f32>;
/// Totally ordered [`f64`] allowing all IEEE-754 floating point values.
pub type F64 = decorum::Total<f64>;
/// A value in SATS typed at some [`AlgebraicType`].
///
/// Values are type erased, so they do not store their type.
/// This is important mainly for space efficiency,
/// including network latency and bandwidth.
///
/// These are only values and not expressions.
/// That is, they are canonical and cannot be simplified further by some evaluation.
/// So forms like `42 + 24` are not represented in an `AlgebraicValue`.
#[derive(EnumAsInner, Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, From)]
pub enum AlgebraicValue {
/// A structural sum value.
///
/// Given a sum type `{ N_0(T_0), N_1(T_1), ..., N_n(T_n) }`
/// where `N_i` denotes a variant name
/// and where `T_i` denotes the type the variant stores,
/// a sum value makes a specific choice as to the variant.
/// So for example, we might chose `N_1(T_1)`
/// and represent this choice with `(1, v)` where `v` is a value of type `T_1`.
Sum(SumValue),
/// A structural product value.
///
/// Given a product type `{ N_0: T_0, N_1: T_1, ..., N_n: T_n }`
/// where `N_i` denotes a field / element name
/// and where `T_i` denotes the type the field stores,
/// a product value stores a value `v_i` of type `T_i` for each field `N_i`.
Product(ProductValue),
/// A homogeneous array of `AlgebraicValue`s.
/// The array has the type [`AlgebraicType::Array(elem_ty)`].
///
/// The contained values are stored packed in a representation appropriate for their type.
/// See [`ArrayValue`] for details on the representation.
Array(ArrayValue),
/// An ordered map value of `key: AlgebraicValue`s mapped to `value: AlgebraicValue`s.
/// Each `key` must be of the same [`AlgebraicType`] as all the others
/// and the same applies to each `value`.
/// A map as a whole has the type [`AlgebraicType::Map(key_ty, val_ty)`].
///
/// Maps are implemented internally as [`BTreeMap<AlgebraicValue, AlgebraicValue>`].
/// This implies that key/values are ordered first by key and then value
/// as if they were a sorted slice `[(key, value)]`.
/// This order is observable as maps are exposed both directly
/// and indirectly via `Ord for `[`AlgebraicValue`].
/// The latter lets us observe that e.g., `{ a: 42 } < { b: 42 }`.
/// However, we cannot observe any difference between `{ a: 0, b: 0 }` and `{ b: 0, a: 0 }`,
/// as the natural order is used as opposed to insertion order.
/// Where insertion order is relevant,
/// a [`AlgebraicValue::Array`] with `(key, value)` pairs can be used instead.
///
/// We box the `MapValue` to reduce size
/// and because we assume that map values will be uncommon.
Map(MapValue),
/// A [`bool`] value of type [`AlgebraicType::Bool`].
Bool(bool),
/// An [`i8`] value of type [`AlgebraicType::I8`].
I8(i8),
/// A [`u8`] value of type [`AlgebraicType::U8`].
U8(u8),
/// An [`i16`] value of type [`AlgebraicType::I16`].
I16(i16),
/// A [`u16`] value of type [`AlgebraicType::U16`].
U16(u16),
/// An [`i32`] value of type [`AlgebraicType::I32`].
I32(i32),
/// A [`u32`] value of type [`AlgebraicType::U32`].
U32(u32),
/// An [`i64`] value of type [`AlgebraicType::I64`].
I64(i64),
/// A [`u64`] value of type [`AlgebraicType::U64`].
U64(u64),
/// An [`i128`] value of type [`AlgebraicType::I128`].
///
/// We box these up as they allow us to shrink `AlgebraicValue`.
I128(i128),
/// A [`u128`] value of type [`AlgebraicType::U128`].
///
/// We box these up as they allow us to shrink `AlgebraicValue`.
U128(u128),
/// A totally ordered [`F32`] value of type [`AlgebraicType::F32`].
///
/// All floating point values defined in IEEE-754 are supported.
/// However, unlike the primitive [`f32`], a [total order] is established.
///
/// [total order]: https://docs.rs/decorum/0.3.1/decorum/#total-ordering
F32(F32),
/// A totally ordered [`F64`] value of type [`AlgebraicType::F64`].
///
/// All floating point values defined in IEEE-754 are supported.
/// However, unlike the primitive [`f64`], a [total order] is established.
///
/// [total order]: https://docs.rs/decorum/0.3.1/decorum/#total-ordering
F64(F64),
/// A UTF-8 string value of type [`AlgebraicType::String`].
///
/// Uses Rust's standard representation of strings.
String(String),
}
#[allow(non_snake_case)]
impl AlgebraicValue {
/// Interpret the value as a byte slice or `None` if it isn't a byte slice.
#[inline]
pub fn as_bytes(&self) -> Option<&[u8]> {
match self {
Self::Array(ArrayValue::U8(a)) => Some(a),
_ => None,
}
}
/// The canonical unit value defined as the nullary product value `()`.
///
/// The type of `UNIT` is `()`.
pub fn unit() -> Self {
Self::product([].into())
}
/// Returns an [`AlgebraicValue`] representing `v: Vec<u8>`.
#[inline]
pub const fn Bytes(v: Vec<u8>) -> Self {
Self::Array(ArrayValue::U8(v))
}
/// Converts `self` into a byte string, if applicable.
pub fn into_bytes(self) -> Result<Vec<u8>, Self> {
match self {
Self::Array(ArrayValue::U8(v)) => Ok(v),
_ => Err(self),
}
}
/// Returns an [`AlgebraicValue`] for `some: v`.
///
/// The `some` variant is assigned the tag `0`.
#[inline]
pub fn OptionSome(v: Self) -> Self {
Self::sum(0, v)
}
/// Returns an [`AlgebraicValue`] for `none`.
///
/// The `none` variant is assigned the tag `1`.
#[inline]
pub fn OptionNone() -> Self {
Self::sum(1, Self::unit())
}
/// Returns an [`AlgebraicValue`] representing a sum value with `tag` and `value`.
pub fn sum(tag: u8, value: Self) -> Self {
let value = Box::new(value);
Self::Sum(SumValue { tag, value })
}
/// Returns an [`AlgebraicValue`] representing a product value with the given `elements`.
pub const fn product(elements: Vec<Self>) -> Self {
Self::Product(ProductValue { elements })
}
/// Returns an [`AlgebraicValue`] representing a map value defined by the given `map`.
pub fn map(map: MapValue) -> Self {
Self::Map(map)
}
/// Returns the [`AlgebraicType`] of the sum value `x`.
pub(crate) fn type_of_sum(x: &SumValue) -> AlgebraicType {
// TODO(centril, #104): This is unsound!
//
// The type of a sum value must be a sum type and *not* a product type.
// Suppose `x.tag` is for the variant `VarName(VarType)`.
// Then `VarType` is *not* the same type as `{ VarName(VarType) | r }`
// where `r` represents a polymorphic variants compontent.
//
// To assign this a correct type we either have to store the type with the value
// or alternatively, we must have polymorphic variants (see row polymorphism)
// *and* derive the correct variant name.
AlgebraicType::product([x.value.type_of()])
}
/// Returns the [`AlgebraicType`] of the product value `x`.
pub(crate) fn type_of_product(x: &ProductValue) -> AlgebraicType {
AlgebraicType::product(x.elements.iter().map(|x| x.type_of().into()).collect::<Vec<_>>())
}
/// Returns the [`AlgebraicType`] of the map with key type `k` and value type `v`.
pub(crate) fn type_of_map(val: &MapValue) -> AlgebraicType {
AlgebraicType::product(if let Some((k, v)) = val.first_key_value() {
[k.type_of(), v.type_of()]
} else {
// TODO(centril): What is the motivation for this?
// I think this requires a soundness argument.
// I could see that it is OK with the argument that this is an empty map
// under the requirement that we cannot insert elements into the map.
[AlgebraicType::never(), AlgebraicType::never()]
})
}
/// Infer the [`AlgebraicType`] of an [`AlgebraicValue`].
pub fn type_of(&self) -> AlgebraicType {
// TODO: What are the types of empty arrays/maps/sums?
match self {
Self::Sum(x) => Self::type_of_sum(x),
Self::Product(x) => Self::type_of_product(x),
Self::Array(x) => x.type_of().into(),
Self::Map(x) => Self::type_of_map(x),
Self::Bool(_) => AlgebraicType::Bool,
Self::I8(_) => AlgebraicType::I8,
Self::U8(_) => AlgebraicType::U8,
Self::I16(_) => AlgebraicType::I16,
Self::U16(_) => AlgebraicType::U16,
Self::I32(_) => AlgebraicType::I32,
Self::U32(_) => AlgebraicType::U32,
Self::I64(_) => AlgebraicType::I64,
Self::U64(_) => AlgebraicType::U64,
Self::I128(_) => AlgebraicType::I128,
Self::U128(_) => AlgebraicType::U128,
Self::F32(_) => AlgebraicType::F32,
Self::F64(_) => AlgebraicType::F64,
Self::String(_) => AlgebraicType::String,
}
}
/// Returns whether this value represents a numeric zero.
///
/// Can only be true where the type is numeric.
pub fn is_numeric_zero(&self) -> bool {
match *self {
Self::I8(x) => x == 0,
Self::U8(x) => x == 0,
Self::I16(x) => x == 0,
Self::U16(x) => x == 0,
Self::I32(x) => x == 0,
Self::U32(x) => x == 0,
Self::I64(x) => x == 0,
Self::U64(x) => x == 0,
Self::I128(x) => x == 0,
Self::U128(x) => x == 0,
Self::F32(x) => x == 0.0,
Self::F64(x) => x == 0.0,
_ => false,
}
}
/// Converts `sequence_value` to an appropriate `AlgebraicValue` based on `ty`.
/// Truncates the `sequence_value` to fit `ty`.
///
/// Panics if `ty` is not an integer type.
pub fn from_sequence_value(ty: &AlgebraicType, sequence_value: i128) -> Self {
match *ty {
AlgebraicType::I8 => (sequence_value as i8).into(),
AlgebraicType::U8 => (sequence_value as u8).into(),
AlgebraicType::I16 => (sequence_value as i16).into(),
AlgebraicType::U16 => (sequence_value as u16).into(),
AlgebraicType::I32 => (sequence_value as i32).into(),
AlgebraicType::U32 => (sequence_value as u32).into(),
AlgebraicType::I64 => (sequence_value as i64).into(),
AlgebraicType::U64 => (sequence_value as u64).into(),
AlgebraicType::I128 => sequence_value.into(),
AlgebraicType::U128 => (sequence_value as u128).into(),
_ => panic!("`{ty:?}` is not an integer type"),
}
}
}
impl<T: Into<AlgebraicValue>> From<Option<T>> for AlgebraicValue {
fn from(value: Option<T>) -> Self {
match value {
None => AlgebraicValue::OptionNone(),
Some(x) => AlgebraicValue::OptionSome(x.into()),
}
}
}
// An AlgebraicValue can be interpreted as a range containing a only the value itself.
// This is useful for BTrees where single key scans are still viewed range scans.
impl RangeBounds<AlgebraicValue> for AlgebraicValue {
fn start_bound(&self) -> Bound<&AlgebraicValue> {
Bound::Included(self)
}
fn end_bound(&self) -> Bound<&AlgebraicValue> {
Bound::Included(self)
}
}
#[cfg(test)]
mod tests {
use std::collections::BTreeMap;
use crate::satn::Satn;
use crate::{AlgebraicType, AlgebraicValue, ArrayValue, Typespace, ValueWithType, WithTypespace};
fn in_space<'a, T: crate::Value>(ts: &'a Typespace, ty: &'a T::Type, val: &'a T) -> ValueWithType<'a, T> {
WithTypespace::new(ts, ty).with_value(val)
}
#[test]
fn unit() {
let val = AlgebraicValue::unit();
let unit = AlgebraicType::unit();
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &unit, &val).to_satn(), "()");
}
#[test]
fn product_value() {
let product_type = AlgebraicType::product([("foo", AlgebraicType::I32)]);
let typespace = Typespace::new(vec![]);
let product_value = AlgebraicValue::product([AlgebraicValue::I32(42)].into());
assert_eq!(
"(foo = 42)",
in_space(&typespace, &product_type, &product_value).to_satn(),
);
}
#[test]
fn option_some() {
let option = AlgebraicType::option(AlgebraicType::never());
let sum_value = AlgebraicValue::OptionNone();
let typespace = Typespace::new(vec![]);
assert_eq!("(none = ())", in_space(&typespace, &option, &sum_value).to_satn(),);
}
#[test]
fn primitive() {
let u8 = AlgebraicType::U8;
let value = AlgebraicValue::U8(255);
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &u8, &value).to_satn(), "255");
}
#[test]
fn array() {
let array = AlgebraicType::array(AlgebraicType::U8);
let value = AlgebraicValue::Array(ArrayValue::Sum(Vec::new()));
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &array, &value).to_satn(), "[]");
}
#[test]
fn array_of_values() {
let array = AlgebraicType::array(AlgebraicType::U8);
let value = AlgebraicValue::Array([3u8].into());
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &array, &value).to_satn(), "0x03");
}
#[test]
fn map() {
let map = AlgebraicType::map(AlgebraicType::U8, AlgebraicType::U8);
let value = AlgebraicValue::map(BTreeMap::new());
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &map, &value).to_satn(), "[:]");
}
#[test]
fn map_of_values() {
let map = AlgebraicType::map(AlgebraicType::U8, AlgebraicType::U8);
let mut val = BTreeMap::<AlgebraicValue, AlgebraicValue>::new();
val.insert(AlgebraicValue::U8(2), AlgebraicValue::U8(3));
let value = AlgebraicValue::map(val);
let typespace = Typespace::new(vec![]);
assert_eq!(in_space(&typespace, &map, &value).to_satn(), "[2: 3]");
}
}