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use super::*;
use crate::Tuple;
use std::marker::PhantomData;
/// Is a builder for building [`Expression`] values.
///
/// [`Expression`]: ./trait.Expression.html
pub struct Builder<L, Left>
where
L: Tuple,
Left: Expression<L>,
{
/// Is the expression constructed by this builder.
expression: Left,
_marker: PhantomData<L>,
}
impl<L, Left> Builder<L, Left>
where
L: Tuple,
Left: Expression<L>,
{
/// Builds a [`Project`] expression over the receiver's expression.
///
/// [`Project`]: ./struct.Project.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let fruit = db.add_relation::<String>("R").unwrap();
///
/// db.insert(&fruit, vec!["Apple".to_string(), "BANANA".into(), "cherry".into()].into());
///
/// let lower = fruit.builder().project(|t| t.to_lowercase()).build();
///
/// assert_eq!(vec!["apple", "banana", "cherry"], db.evaluate(&lower).unwrap().into_tuples());
/// ```
pub fn project<T>(self, f: impl FnMut(&L) -> T + 'static) -> Builder<T, Project<L, T, Left>>
where
T: Tuple,
{
Builder {
expression: Project::new(self.expression, f),
_marker: PhantomData,
}
}
/// Builds a [`Select`] expression over the receiver's expression.
///
/// [`Select`]: ./struct.Select.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let fruit = db.add_relation::<String>("Fruit").unwrap();
///
/// db.insert(&fruit, vec!["Apple".to_string(), "BANANA".into(), "cherry".into()].into());
///
/// let select = fruit.builder().select(|t| t.contains('A')).build();
///
/// assert_eq!(vec!["Apple", "BANANA"], db.evaluate(&select).unwrap().into_tuples());
/// ```
pub fn select(self, f: impl FnMut(&L) -> bool + 'static) -> Builder<L, Select<L, Left>> {
Builder {
expression: Select::new(self.expression, f),
_marker: PhantomData,
}
}
/// Builds an [`Intersect`] expression with the receiver's expression on left and `other` on right.
///
/// [`Intersect`]: ./struct.Intersect.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let r = db.add_relation::<i32>("R").unwrap();
/// let s = db.add_relation::<i32>("S").unwrap();
///
/// db.insert(&r, vec![0, 1, 2].into());
/// db.insert(&s, vec![2, 4].into());
///
/// let intersect = r.builder().intersect(s).build();
///
/// assert_eq!(vec![2], db.evaluate(&intersect).unwrap().into_tuples());
/// ```
pub fn intersect<Right, I>(self, other: I) -> Builder<L, Intersect<L, Left, Right>>
where
Right: Expression<L>,
I: IntoExpression<L, Right>,
{
Builder {
expression: Intersect::new(self.expression, other.into_expression()),
_marker: PhantomData,
}
}
/// Builds a [`Difference`] expression with the receiver's expression on left and `other` on right.
///
/// [`Difference`]: ./struct.Difference.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let r = db.add_relation::<i32>("R").unwrap();
/// let s = db.add_relation::<i32>("S").unwrap();
///
/// db.insert(&r, vec![0, 1, 2].into());
/// db.insert(&s, vec![2, 4].into());
///
/// let r_s = r.builder().difference(&s).build();
/// let s_r = s.builder().difference(r).build();
///
/// assert_eq!(vec![0, 1], db.evaluate(&r_s).unwrap().into_tuples());
/// assert_eq!(vec![4], db.evaluate(&s_r).unwrap().into_tuples());
/// ```
pub fn difference<Right, I>(self, other: I) -> Builder<L, Difference<L, Left, Right>>
where
Right: Expression<L>,
I: IntoExpression<L, Right>,
{
Builder {
expression: Difference::new(self.expression, other.into_expression()),
_marker: PhantomData,
}
}
/// Builds a [`Union`] expression with the receiver's expression on left and `other` on right.
///
/// [`Union`]: ./struct.Union.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let r = db.add_relation::<i32>("R").unwrap();
/// let s = db.add_relation::<i32>("S").unwrap();
///
/// db.insert(&r, vec![0, 1, 2].into());
/// db.insert(&s, vec![2, 4].into());
///
/// let union = r.builder().union(s).build();
///
/// assert_eq!(vec![0, 1, 2, 4], db.evaluate(&union).unwrap().into_tuples());
/// ```
pub fn union<Right, I>(self, other: I) -> Builder<L, Union<L, Left, Right>>
where
Right: Expression<L>,
I: IntoExpression<L, Right>,
{
Builder {
expression: Union::new(self.expression, other.into_expression()),
_marker: PhantomData,
}
}
/// Combines the receiver's expression with `other` in a temporary builder, which then can be turned into
/// a [`Product`] expression using a combining closure provided by method `on`.
///
/// [`Product`]: ./struct.Product.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let r = db.add_relation::<i32>("R").unwrap();
/// let s = db.add_relation::<i32>("S").unwrap();
///
/// db.insert(&r, vec![0, 1, 2].into());
/// db.insert(&s, vec![2, 4].into());
///
/// let prod = r.builder().product(s).on(|l, r| l*r).build();
///
/// assert_eq!(vec![0, 2, 4, 8], db.evaluate(&prod).unwrap().into_tuples());
/// ```
pub fn product<R, Right, I>(self, other: I) -> ProductBuilder<L, R, Left, Right>
where
R: Tuple,
Right: Expression<R>,
I: IntoExpression<R, Right>,
{
ProductBuilder {
left: self.expression,
right: other.into_expression(),
_marker: PhantomData,
}
}
/// Combines the receiver's expression with closure `f` as the join key. This value can then be joined with
/// another expression and it's key to create a temporary join builder. Finally, the temporary builder
/// can be turned into a [`Join`] expression using a combining closure provided by method `on`.
///
/// [`Join`]: ./struct.Join.html
///
/// **Example**:
/// ```rust
/// use codd::{Database, Expression};
///
/// let mut db = Database::new();
/// let fruit = db.add_relation::<(i32, String)>("R").unwrap();
/// let numbers = db.add_relation::<i32>("S").unwrap();
///
/// db.insert(&fruit, vec![
/// (0, "Apple".to_string()),
/// (1, "Banana".into()),
/// (2, "Cherry".into())
/// ].into());
/// db.insert(&numbers, vec![0, 2].into());
///
/// let join = fruit
/// .builder()
/// .with_key(|t| t.0) // first element of tuples in `r` is the key for join
/// .join(numbers.builder().with_key(|&t| t))
/// .on(|k, l, r| format!("{}{}", l.1, k + r))
/// // combine the key `k`, left tuple `l` and right tuple `r`:
/// .build();
///
/// assert_eq!(vec!["Apple0", "Cherry4"], db.evaluate(&join).unwrap().into_tuples());
/// ```
pub fn with_key<K>(self, f: impl FnMut(&L) -> K + 'static) -> WithKeyBuilder<K, L, Left>
where
K: Tuple,
{
WithKeyBuilder {
expression: self.expression,
key: Box::new(f),
}
}
/// Builds an expression from the receiver.
pub fn build(self) -> Left {
self.into_expression()
}
}
impl<T, E> IntoExpression<T, E> for Builder<T, E>
where
T: Tuple,
E: Expression<T>,
{
fn into_expression(self) -> E {
self.expression
}
}
impl<T, E> From<E> for Builder<T, E>
where
T: Tuple,
E: Expression<T>,
{
fn from(expression: E) -> Self {
Builder {
expression,
_marker: PhantomData,
}
}
}
pub struct ProductBuilder<L, R, Left, Right>
where
L: Tuple,
R: Tuple,
Left: Expression<L>,
Right: Expression<R>,
{
left: Left,
right: Right,
_marker: PhantomData<(L, R)>,
}
impl<L, R, Left, Right> ProductBuilder<L, R, Left, Right>
where
L: Tuple,
R: Tuple,
Left: Expression<L>,
Right: Expression<R>,
{
pub fn on<T: Tuple>(
self,
f: impl FnMut(&L, &R) -> T + 'static,
) -> Builder<T, Product<L, R, Left, Right, T>> {
Builder {
expression: Product::new(self.left, self.right, f),
_marker: PhantomData,
}
}
}
pub struct WithKeyBuilder<K, L, Left>
where
K: Tuple + 'static,
L: Tuple + 'static,
Left: Expression<L>,
{
expression: Left,
key: Box<dyn FnMut(&L) -> K>,
}
impl<K, L, Left> WithKeyBuilder<K, L, Left>
where
K: Tuple,
L: Tuple,
Left: Expression<L>,
{
pub fn join<R, Right>(
self,
other: WithKeyBuilder<K, R, Right>,
) -> JoinBuilder<K, L, R, Left, Right>
where
R: Tuple,
Right: Expression<R>,
{
JoinBuilder {
left: self,
right: other,
}
}
}
pub struct JoinBuilder<K, L, R, Left, Right>
where
K: Tuple + 'static,
L: Tuple + 'static,
R: Tuple + 'static,
Left: Expression<L>,
Right: Expression<R>,
{
left: WithKeyBuilder<K, L, Left>,
right: WithKeyBuilder<K, R, Right>,
}
impl<K, L, R, Left, Right> JoinBuilder<K, L, R, Left, Right>
where
K: Tuple + 'static,
L: Tuple + 'static,
R: Tuple + 'static,
Left: Expression<L>,
Right: Expression<R>,
{
pub fn on<T: Tuple>(
self,
f: impl FnMut(&K, &L, &R) -> T + 'static,
) -> Builder<T, Join<K, L, R, Left, Right, T>> {
Builder {
expression: Join::new(
self.left.expression,
self.right.expression,
self.left.key,
self.right.key,
f,
),
_marker: PhantomData,
}
}
}