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

use crate::types::Primitive;
use crate::types::{Bind, Field};
use crate::{CheckedSql, Table};
use std::{fmt::Write, marker::PhantomData};

pub trait Predicate {
    fn write_predicate(&self, sql: &mut String);
}

pub struct And<H, T> {
    pub(crate) head: H,
    pub(crate) tail: T,
}

impl<H, T> Predicate for And<H, T>
where
    H: Predicate,
    T: Predicate,
{
    fn write_predicate(&self, sql: &mut String) {
        self.head.write_predicate(sql);
        sql.push_str(" AND ");
        self.tail.write_predicate(sql);
    }
}

impl<H: CheckedSql, T: CheckedSql> CheckedSql for And<H, T> {}

pub struct Or<H, T> {
    pub(crate) head: H,
    pub(crate) tail: T,
}

impl<H, T> Predicate for Or<H, T>
where
    H: Predicate,
    T: Predicate,
{
    fn write_predicate(&self, sql: &mut String) {
        self.head.write_predicate(sql);
        sql.push_str(" OR ");
        self.tail.write_predicate(sql);
    }
}

impl<H: CheckedSql, T: CheckedSql> CheckedSql for Or<H, T> {}

pub trait Operator {
    fn write_operator(sql: &mut String);
}

pub struct Eq;

impl Operator for Eq {
    fn write_operator(sql: &mut String) {
        sql.push('=');
    }
}

pub struct Neq;

impl Operator for Neq {
    fn write_operator(sql: &mut String) {
        sql.push_str("!=");
    }
}

pub struct Gt;

impl Operator for Gt {
    fn write_operator(sql: &mut String) {
        sql.push('>');
    }
}

pub struct Lt;

impl Operator for Lt {
    fn write_operator(sql: &mut String) {
        sql.push('<');
    }
}

pub struct Op<T, A, U, O> {
    lhs: Field<T, A>,
    rhs: U,
    _operator: PhantomData<O>,
}

impl<T, A, U, O> Op<T, A, U, O> {
    pub(crate) fn new(lhs: Field<T, A>, rhs: U) -> Self {
        Self {
            lhs,
            rhs,
            _operator: PhantomData,
        }
    }
}

impl<T, A, U, O> Predicate for Op<T, A, U, O>
where
    T: Table,
    U: Primitive,
    O: Operator,
{
    fn write_predicate(&self, sql: &mut String) {
        self.lhs.write_field(sql);
        sql.push(' ');
        O::write_operator(sql);
        sql.push(' ');
        self.rhs.write_primative(sql);
    }
}

impl<T, T2, A, O> Predicate for Op<T, A, Field<T2, A>, O>
where
    T: Table,
    T2: Table,
    O: Operator,
{
    fn write_predicate(&self, sql: &mut String) {
        self.lhs.write_field(sql);
        sql.push(' ');
        O::write_operator(sql);
        sql.push(' ');
        self.rhs.write_field(sql);
    }
}

impl<T, A, O> Predicate for Op<T, A, Bind, O>
where
    T: Table,
    O: Operator,
{
    fn write_predicate(&self, sql: &mut String) {
        self.lhs.write_field(sql);
        sql.push(' ');
        O::write_operator(sql);
        sql.write_fmt(format_args!(" ${}", self.rhs.n)).unwrap();
    }
}

impl<T, A, U: CheckedSql, O> CheckedSql for Op<T, A, U, O> {}