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
// Copyright (c) 2018, 2022 The predicates-rs Project Developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/license/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Definition of `Predicate`s for comparisons over `Ord` and `Eq` types.

use std::fmt;

use crate::reflection;
use crate::utils;
use crate::Predicate;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum EqOps {
    Equal,
    NotEqual,
}

impl fmt::Display for EqOps {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let op = match *self {
            EqOps::Equal => "==",
            EqOps::NotEqual => "!=",
        };
        write!(f, "{}", op)
    }
}

/// Predicate that returns `true` if `variable` matches the pre-defined `Eq`
/// value, otherwise returns `false`.
///
/// This is created by the `predicate::{eq, ne}` functions.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct EqPredicate<T> {
    constant: T,
    op: EqOps,
}

impl<P, T> Predicate<P> for EqPredicate<T>
where
    T: std::borrow::Borrow<P> + fmt::Debug,
    P: fmt::Debug + PartialEq + ?Sized,
{
    fn eval(&self, variable: &P) -> bool {
        match self.op {
            EqOps::Equal => variable.eq(self.constant.borrow()),
            EqOps::NotEqual => variable.ne(self.constant.borrow()),
        }
    }

    fn find_case<'a>(&'a self, expected: bool, variable: &P) -> Option<reflection::Case<'a>> {
        utils::default_find_case(self, expected, variable).map(|case| {
            case.add_product(reflection::Product::new(
                "var",
                utils::DebugAdapter::new(variable).to_string(),
            ))
        })
    }
}

impl<T> reflection::PredicateReflection for EqPredicate<T> where T: fmt::Debug {}

impl<T> fmt::Display for EqPredicate<T>
where
    T: fmt::Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let palette = crate::Palette::new(f.alternate());
        write!(
            f,
            "{} {} {}",
            palette.var("var"),
            palette.description(self.op),
            palette.expected(utils::DebugAdapter::new(&self.constant)),
        )
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// equal to a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate_fn = predicate::eq(5);
/// assert_eq!(true, predicate_fn.eval(&5));
/// assert_eq!(false, predicate_fn.eval(&10));
///
/// let predicate_fn = predicate::eq("Hello");
/// assert_eq!(true, predicate_fn.eval("Hello"));
/// assert_eq!(false, predicate_fn.eval("Goodbye"));
///
/// let predicate_fn = predicate::eq(String::from("Hello"));
/// assert_eq!(true, predicate_fn.eval("Hello"));
/// assert_eq!(false, predicate_fn.eval("Goodbye"));
/// ```
pub fn eq<T>(constant: T) -> EqPredicate<T>
where
    T: fmt::Debug + PartialEq,
{
    EqPredicate {
        constant,
        op: EqOps::Equal,
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// _not_ equal to a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate_fn = predicate::ne(5);
/// assert_eq!(false, predicate_fn.eval(&5));
/// assert_eq!(true, predicate_fn.eval(&10));
/// ```
pub fn ne<T>(constant: T) -> EqPredicate<T>
where
    T: PartialEq + fmt::Debug,
{
    EqPredicate {
        constant,
        op: EqOps::NotEqual,
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum OrdOps {
    LessThan,
    LessThanOrEqual,
    GreaterThanOrEqual,
    GreaterThan,
}

impl fmt::Display for OrdOps {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let op = match *self {
            OrdOps::LessThan => "<",
            OrdOps::LessThanOrEqual => "<=",
            OrdOps::GreaterThanOrEqual => ">=",
            OrdOps::GreaterThan => ">",
        };
        write!(f, "{}", op)
    }
}

/// Predicate that returns `true` if `variable` matches the pre-defined `Ord`
/// value, otherwise returns `false`.
///
/// This is created by the `predicate::{gt, ge, lt, le}` functions.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct OrdPredicate<T> {
    constant: T,
    op: OrdOps,
}

impl<P, T> Predicate<P> for OrdPredicate<T>
where
    T: std::borrow::Borrow<P> + fmt::Debug,
    P: fmt::Debug + PartialOrd + ?Sized,
{
    fn eval(&self, variable: &P) -> bool {
        match self.op {
            OrdOps::LessThan => variable.lt(self.constant.borrow()),
            OrdOps::LessThanOrEqual => variable.le(self.constant.borrow()),
            OrdOps::GreaterThanOrEqual => variable.ge(self.constant.borrow()),
            OrdOps::GreaterThan => variable.gt(self.constant.borrow()),
        }
    }

    fn find_case<'a>(&'a self, expected: bool, variable: &P) -> Option<reflection::Case<'a>> {
        utils::default_find_case(self, expected, variable).map(|case| {
            case.add_product(reflection::Product::new(
                "var",
                utils::DebugAdapter::new(variable).to_string(),
            ))
        })
    }
}

impl<T> reflection::PredicateReflection for OrdPredicate<T> where T: fmt::Debug {}

impl<T> fmt::Display for OrdPredicate<T>
where
    T: fmt::Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let palette = crate::Palette::new(f.alternate());
        write!(
            f,
            "{} {} {}",
            palette.var("var"),
            palette.description(self.op),
            palette.expected(utils::DebugAdapter::new(&self.constant)),
        )
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// less than a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate_fn = predicate::lt(5);
/// assert_eq!(true, predicate_fn.eval(&4));
/// assert_eq!(false, predicate_fn.eval(&6));
///
/// let predicate_fn = predicate::lt("b");
/// assert_eq!(true, predicate_fn.eval("a"));
/// assert_eq!(false, predicate_fn.eval("c"));
///
/// let predicate_fn = predicate::lt(String::from("b"));
/// assert_eq!(true, predicate_fn.eval("a"));
/// assert_eq!(false, predicate_fn.eval("c"));
/// ```
pub fn lt<T>(constant: T) -> OrdPredicate<T>
where
    T: fmt::Debug + PartialOrd,
{
    OrdPredicate {
        constant,
        op: OrdOps::LessThan,
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// less than or equal to a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate_fn = predicate::le(5);
/// assert_eq!(true, predicate_fn.eval(&4));
/// assert_eq!(true, predicate_fn.eval(&5));
/// assert_eq!(false, predicate_fn.eval(&6));
/// ```
pub fn le<T>(constant: T) -> OrdPredicate<T>
where
    T: PartialOrd + fmt::Debug,
{
    OrdPredicate {
        constant,
        op: OrdOps::LessThanOrEqual,
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// greater than or equal to a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate = predicate::ge(5);
/// assert_eq!(false, predicate.eval(&4));
/// assert_eq!(true, predicate.eval(&5));
/// assert_eq!(true, predicate.eval(&6));
/// ```
pub fn ge<T>(constant: T) -> OrdPredicate<T>
where
    T: PartialOrd + fmt::Debug,
{
    OrdPredicate {
        constant,
        op: OrdOps::GreaterThanOrEqual,
    }
}

/// Creates a new predicate that will return `true` when the given `variable` is
/// greater than a pre-defined value.
///
/// # Examples
///
/// ```
/// use predicates::prelude::*;
///
/// let predicate_fn = predicate::gt(5);
/// assert_eq!(false, predicate_fn.eval(&4));
/// assert_eq!(false, predicate_fn.eval(&5));
/// assert_eq!(true, predicate_fn.eval(&6));
/// ```
pub fn gt<T>(constant: T) -> OrdPredicate<T>
where
    T: PartialOrd + fmt::Debug,
{
    OrdPredicate {
        constant,
        op: OrdOps::GreaterThan,
    }
}