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use std::borrow::Cow;
use crate::types::ToSql;
#[derive(Debug, Copy, Clone)]
pub enum ExprValueType {
Value,
Array,
}
#[derive(Debug, Clone)]
pub struct Expr<'a> {
pub ty: ExprValueType,
pub column: Cow<'a, str>,
pub condition: &'a str,
pub value: &'a (dyn ToSql + Sync),
}
#[derive(Debug, Clone)]
pub enum Predicate<'a> {
Value(Expr<'a>),
And(&'a [Predicate<'a>]),
Or(&'a [Predicate<'a>]),
Empty
}
impl<'a> Default for Predicate<'a> {
fn default() -> Self {
Predicate::Empty
}
}
impl<'a> Predicate<'a> {
pub fn to_sql(
&self,
params_index: &mut usize,
) -> (Option<String>, Vec<&'a (dyn ToSql + Sync)>) {
match self {
Predicate::Value(expr) => {
let query = match expr.ty {
ExprValueType::Value => {
format!("{} {} ${}", expr.column, expr.condition, params_index)
}
ExprValueType::Array => {
format!("{} {} ANY(${})", expr.column, expr.condition, params_index)
}
};
let params = vec![expr.value];
*params_index += 1;
(Some(query), params)
}
Predicate::And(predicates) => {
if predicates.is_empty() {
return (None, vec![]);
}
let mut results = vec![];
let mut params = vec![];
for predicate in *predicates {
let (q, p) = predicate.to_sql(params_index);
if let Some(q) = q {
results.push(q);
params.extend_from_slice(&p);
}
}
let query = format!("({})", results.join(" AND "));
(Some(query), params)
}
Predicate::Or(predicates) => {
if predicates.is_empty() {
return (None, vec![]);
}
let mut results = vec![];
let mut params = vec![];
for predicate in *predicates {
let (q, p) = predicate.to_sql(params_index);
if let Some(q) = q {
results.push(q);
params.extend_from_slice(&p);
}
}
let query = format!("({})", results.join(" OR "));
(Some(query), params)
}
Predicate::Empty => (None, vec![]),
}
}
}
pub fn and<'a>(predicates: &'a [Predicate<'a>]) -> Predicate<'a> {
Predicate::And(predicates)
}
pub fn or<'a>(predicates: &'a [Predicate<'a>]) -> Predicate<'a> {
Predicate::Or(predicates)
}
pub fn equals<'a, T: ToSql + Sync>(column: &'a str, value: &'a T) -> Predicate<'a> {
Predicate::Value(Expr {
ty: ExprValueType::Value,
column: column.into(),
condition: "=",
value,
})
}
pub fn in_list<'a, T: ToSql + Sync>(column: &'a str, values: &'a T) -> Predicate<'a> {
Predicate::Value(Expr {
ty: ExprValueType::Array,
column: column.into(),
condition: "=",
value: values,
})
}
#[cfg(test)]
mod tests {
#[test]
fn test_and() {
// use super::{and, eq, in_list, Op};
// use crate::types::ToSql;
//
// let op = and(&[eq("foo", &1), eq("bar", &2), in_list("baz", &vec![3, 4, 5])]);
//
// match op {
// Op::And(predicates) => {
// assert_eq!(predicates.len(), 3);
// match &predicates[0] {
// Op::Value(op_value) => {
// assert_eq!(op_value.column, "foo");
// assert_eq!(op_value.op, "=");
// assert_eq!(
// op_value
// .value
// .to_sql(&crate::types::Type::INT4, &mut vec![])
// .unwrap(),
// 1
// );
// }
// _ => panic!("Expected Op::Value"),
// }
// match &predicates[1] {
// Op::Value(op_value) => {
// assert_eq!(op_value.column, "bar");
// assert_eq!(op_value.op, "=");
// assert_eq!(
// op_value
// .value
// .to_sql(&crate::types::Type::INT4, &mut vec![])
// .unwrap(),
// 2
// );
// }
// _ => panic!("Expected Op::Value"),
// }
// match &predicates[2] {
// Op::Value(op_value) => {
// assert_eq!(op_value.column, "baz");
// assert_eq!(op_value.op, "IN");
// assert_eq!(
// op_value
// .value
// .to_sql(&crate::types::Type::INT4, &mut vec![])
// .unwrap(),
// vec![3, 4, 5]
// );
// }
// _ => panic!("Expected Op::Value"),
// }
// }
// _ => panic!("Expected Op::And"),
// }
}
}