pushr 0.4.1

Pushr is a Rust based interpreter for Push programs.
Documentation 
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
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386

use std::fmt;

#[derive(Clone, Debug)]
pub struct PushStack<T> {
    elements: Vec<T>,
}

pub trait PushPrint {
    fn to_pstring(&self) -> String; 
}

impl PushPrint for f32 {
    fn to_pstring(&self) -> String {
        format!("{:.1}", self)
    }
}

impl PushPrint for i32 {
   fn to_pstring(&self) -> String {
       self.to_string()
   }
}

impl PushPrint for String {
   fn to_pstring(&self) -> String {
       self.to_string()
   }
}

impl PushPrint for bool {
   fn to_pstring(&self) -> String {
       format!("{}", self.to_string().to_uppercase())
   }
}

impl<T> PushStack<T>
where
    T: Clone + fmt::Display + PartialEq + PushPrint,
{
    pub fn new() -> Self {
        Self {
            elements: Vec::new(),
        }
    }

    /// Initializes the stack with the argument. Its last
    /// element becomes the top element of the stack.
    pub fn from_vec(elements: Vec<T>) -> Self {
        Self { elements: elements }
    }

    /// Prints the stack from top to bottom enumerating its elements.
    pub fn to_string(&self) -> String {
        let mut result = "".to_string();
        for (_i, x) in self.elements.iter().rev().enumerate() {
             result.push_str(&format!(" {}", x.to_pstring()));
        }
        result.trim().to_string()
    }

    /// Returns the stack size.
    pub fn size(&self) -> usize {
        return self.elements.len();
    }

    /// Returns true if the argument equals the
    /// top element of the stack. Uses the = operator for
    /// comparison (shallow for Items)
    pub fn last_eq(&self, item: &T) -> bool {
        return Some(item) == self.elements.last();
    }

    /// Returns true if the element at stack position i counting
    /// from the top. Uses string representation for comparison
    /// (deep)
    pub fn equal_at(&self, i: usize, el: &T) -> Option<bool> {
        if i > self.size() {
            None
        } else {
            Some(self.elements[self.size() - (i + 1)].to_string() == *el.to_string())
        }
    }

    /// Returns a mutable pointer to the element at the bottom
    /// of the stack.
    pub fn bottom_mut(&mut self) -> Option<&mut T> {
        if self.size() > 0 {
            self.elements.first_mut()
        } else {
            None
        }
    }

    /// Removes all elements from the stack.
    pub fn flush(&mut self) {
        self.elements = Vec::new();
    }

    /// Replace element at position i counting from the top. In case the index does not
    /// exist it returns the offset to the size of the stack wrapped in the Err enum.
    pub fn replace(&mut self, i: usize, new_el: T) -> Result<(), usize> {
        let size = &mut self.size();
        match i.checked_sub(*size) {
            None => {
                let _ = std::mem::replace(&mut self.elements[*size - (i + 1)], new_el);
                Ok(())
            }
            Some(diff) => Err(diff + 1),
        }
    }

    /// Removes element at position i counting from the top.
    pub fn remove(&mut self, i: usize) {
        let size = self.size();
        if i < size {
            self.elements.remove(size - (i + 1));
        }
    }

    /// Reverse elements of stack.
    pub fn reverse(&mut self) {
        self.elements.reverse();
    }

    /// Returns a mutable reference to the element at stack position i counting
    /// from the top of the stack
    pub fn get_mut(&mut self, i: usize) -> Option<&mut T> {
        let size = &mut self.size();
        if i < *size {
            Some(&mut self.elements[*size - (i + 1)])
        } else {
            None
        }
    }

    /// Returns a reference to the element at stack position i counting from the
    /// top of the stack
    pub fn get(&self, i: usize) -> Option<&T> {
        let size = self.size();
        if i < size {
            Some(&self.elements[size - (i + 1)])
        } else {
            None
        }
    }

    /// Pushes element to the top of the stack.
    pub fn push(&mut self, value: T) {
        self.elements.push(value);
    }

    /// Pushes element to the bottom of the stack.
    pub fn push_front(&mut self, value: T) {
        self.elements.insert(0, value);
    }

    /// Removes an indexed item from stack position i counting from the top and
    /// pushes it on top of the stack.
    pub fn yank(&mut self, index: usize) {
        if index > 0 && index < self.size() {
            let el = self.elements.remove(self.size() - (index + 1));
            self.elements.push(el);
        }
    }

    /// Removes the top element from the stack and inserts it at
    /// position index counting from the top.
    pub fn shove(&mut self, index: usize) {
        if index > 0 && index < self.size() {
            if let Some(el) = self.elements.pop() {
                let top_down_index = self.size() - index;
                self.elements.insert(top_down_index, el);
            }
        }
    }

    /// Swaps vector elements
    pub fn swap(&mut self, i: usize, j: usize) {
        self.elements.swap(i, j);
    }

    /// Removes the bottom element from the stack and returns it.
    pub fn pop_front(&mut self) -> Option<T> {
        if self.elements.is_empty() {
            return None;
        }
        Some(self.elements.remove(0))
    }

    /// Removes the top element from the stack and returns it.
    pub fn pop(&mut self) -> Option<T> {
        self.elements.pop()
    }

    /// Pops and returns the n top-most elements of the stack.
    /// The last element of the returned vector is the top
    /// element of the stack.
    pub fn pop_vec(&mut self, n: usize) -> Option<Vec<T>> {
        if n > self.elements.len() {
            None
        } else {
            Some(
                self.elements
                    .split_off(self.elements.len() - n)
                    .into_iter()
                    .collect(),
            )
        }
    }

    /// Returns a copy of the element at stack position i counting
    /// from top to bottom.
    pub fn copy(&self, i: usize) -> Option<T> {
        if self.size() == 0 || i > self.size() - 1 {
            None
        } else {
            Some(self.elements[self.size() - (i + 1)].clone())
        }
    }

    /// Returns a copy of the n top-most elements
    /// of the stack. The first element of the returned vector
    /// is the nth element counted from the top of the stack.
    pub fn copy_vec(&self, n: usize) -> Option<Vec<T>> {
        if n > self.size() {
            None
        } else {
            let mut cpy = Vec::with_capacity(n);
            for i in 0..n {
                cpy.push(self.elements[self.size() - n + i].clone());
            }
            Some(cpy)
        }
    }

    /// Pushes the argument to the stack where the last
    /// element of the argument will at the top of the stack.
    pub fn push_vec(&mut self, to_push: Vec<T>) {
        self.elements.extend(to_push);
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn pop_vec_in_right_order() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3],
        };

        match test_stack.pop_vec(2) {
            None => assert!(false),
            Some(pv) => assert_eq!(pv[0], 2),
        }
    }

    #[test]
    fn pop_vec_max_index() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3],
        };
        match test_stack.pop_vec(4) {
            None => assert!(true),
            Some(_pv) => assert!(false),
        }
    }

    #[test]
    fn push_vec_in_right_order() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3],
        };
        let test_vec = vec![4, 5];
        test_stack.push_vec(test_vec);
        assert_eq!(test_stack.elements, [1, 2, 3, 4, 5]);
    }

    #[test]
    fn copy_vec_preserves_stack() {
        let test_stack = PushStack {
            elements: vec![1, 2, 3],
        };

        match test_stack.copy_vec(2) {
            None => assert!(false, "Should return values"),
            Some(cv) => {
                assert_eq!(cv.len(), 2);
                assert_eq!(cv[0], 2);
                assert_eq!(cv[1], 3);
            }
        }
        assert_eq!(
            test_stack.elements.len(),
            3,
            "Test stack should remain the same"
        )
    }

    #[test]
    fn equal_at_checks_equality_at_right_index() {
        let test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        assert_eq!(test_stack.equal_at(0, &5), Some(true));
        assert_eq!(test_stack.equal_at(3, &2), Some(true));
        assert_eq!(test_stack.equal_at(3, &1), Some(false));
    }

    #[test]
    fn yank_vec_returns_right_order() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        let mut test_idx = 1;
        test_stack.yank(test_idx);
        assert_eq!(test_stack.elements, [1, 2, 3, 5, 4]);
        test_idx = 5; // No change
        test_stack.yank(test_idx);
        assert_eq!(test_stack.elements, [1, 2, 3, 5, 4]);
        test_idx = 3;
        test_stack.yank(test_idx);
        assert_eq!(test_stack.elements, [1, 3, 5, 4, 2]);
        test_idx = 0; // No change
        test_stack.yank(test_idx);
        assert_eq!(test_stack.elements, [1, 3, 5, 4, 2]);
    }

    #[test]
    fn shove_vec_returns_right_order() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        let mut test_idx = 1;
        test_stack.shove(test_idx);
        assert_eq!(test_stack.elements, [1, 2, 3, 5, 4]);
        test_idx = 4; // Push to bottom
        test_stack.shove(test_idx);
        assert_eq!(test_stack.elements, [4, 1, 2, 3, 5]);
        test_idx = 3;
        test_stack.shove(test_idx);
        assert_eq!(test_stack.elements, [4, 5, 1, 2, 3]);
        test_idx = 0; // No change
        test_stack.shove(test_idx);
        assert_eq!(test_stack.elements, [4, 5, 1, 2, 3]);
    }

    #[test]
    fn last_eq_preserves_vector() {
        let test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        let candidate = 5;
        assert_eq!(test_stack.last_eq(&candidate), true);
        let candidate = 4;
        assert_eq!(test_stack.last_eq(&candidate), false);
        assert_eq!(test_stack.size(), 5);
        let test_stack = PushStack {
            elements: Vec::new(),
        };
        assert_eq!(test_stack.last_eq(&candidate), false);
    }

    #[test]
    fn replace_returns_right_offset() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        assert_eq!(test_stack.replace(1, 19), Ok(()));
        assert_eq!(test_stack.replace(5, 19), Err(1));
        assert_eq!(test_stack.replace(6, 19), Err(2));
        assert_eq!(test_stack.replace(4, 19), Ok(()));
        assert_eq!(test_stack.replace(0, 19), Ok(()));
        assert_eq!(test_stack.to_string(), "19 19 3 2 19");
    }

    #[test]
    fn reverse_elements() {
        let mut test_stack = PushStack {
            elements: vec![1, 2, 3, 4, 5],
        };
        test_stack.reverse();
        assert_eq!(test_stack.elements, [5, 4, 3, 2, 1]);
    }
}