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
use std::fmt;
#[derive(Clone, Debug)]
pub enum Value<T> {
Const(T),
Column(usize),
}
impl<T> Value<T> {
pub fn value<'a>(&'a self, row: &'a [T]) -> &'a T {
match *self {
Value::Column(i) => &row[i],
Value::Const(ref val) => val,
}
}
}
#[derive(Clone, Debug)]
pub enum Comparison<T: PartialOrd> {
Equal(Value<T>),
}
impl<T: PartialOrd> Comparison<T> {
pub fn matches(&self, value: &T, row: &[T]) -> bool {
match *self {
Comparison::Equal(ref v) => value == v.value(row),
}
}
}
#[derive(Clone, Debug)]
pub struct Condition<T: PartialOrd> {
pub column: usize,
pub cmp: Comparison<T>,
}
impl<T: PartialOrd> Condition<T> {
pub fn matches(&self, row: &[T]) -> bool {
self.cmp.matches(&row[self.column], row)
}
}
impl<T: fmt::Display> fmt::Display for Value<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Value::Column(i) => write!(f, "[{}]", i),
Value::Const(ref val) => write!(f, "{}", val),
}
}
}
impl<T: PartialOrd + fmt::Display> fmt::Display for Comparison<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Comparison::Equal(ref v) => write!(f, "= {}", v),
}
}
}
impl<T: PartialOrd + fmt::Display> fmt::Display for Condition<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "[{}] {}", self.column, self.cmp)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn value() {
assert_eq!(Value::Column(0).value(&["a"]), &"a");
assert_eq!(Value::Const("a").value(&["b"]), &"a");
}
#[test]
fn cmp_eq() {
assert!(Comparison::Equal(Value::Column(0)).matches(&"a", &["a"]));
assert!(!Comparison::Equal(Value::Column(0)).matches(&"a", &["b"]));
assert!(Comparison::Equal(Value::Const("a")).matches(&"a", &["b"]));
assert!(!Comparison::Equal(Value::Const("b")).matches(&"a", &["a"]));
}
#[test]
fn cond_eq() {
let cmpf0 = Comparison::Equal(Value::Column(0));
let cmpca = Comparison::Equal(Value::Const("a"));
let cmpcb = Comparison::Equal(Value::Const("b"));
let cf10 = Condition {
column: 1,
cmp: cmpf0,
};
let cca = Condition {
column: 0,
cmp: cmpca,
};
let ccb = Condition {
column: 0,
cmp: cmpcb,
};
assert!(cf10.matches(&["a", "a"]));
assert!(!cf10.matches(&["a", "b"]));
assert!(cca.matches(&["a"]));
assert!(!cca.matches(&["b"]));
assert!(ccb.matches(&["b"]));
assert!(!ccb.matches(&["a"]));
}
#[test]
fn display() {
let cf01: Condition<String> = Condition {
column: 0,
cmp: Comparison::Equal(Value::Column(1)),
};
let cca = Condition {
column: 0,
cmp: Comparison::Equal(Value::Const("a")),
};
assert_eq!(format!("{}", cf01), "[0] = [1]");
assert_eq!(format!("{}", cca), "[0] = a")
}
}