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
#[cfg(test)]
mod tests;
use std::collections::HashMap;
#[cfg(feature = "serialization")]
use std::fmt;
use rand::seq::SliceRandom;
#[cfg(feature = "serialization")]
use serde::{de::Visitor, Deserialize, Deserializer, Serialize, Serializer};
#[cfg(feature = "serialization")]
const KEY_NO_WORD: &str = "\n";
#[cfg(feature = "serialization")]
const KEY_SEPARATOR: &str = " ";
#[derive(Debug, Hash, Clone, PartialEq, Eq)]
pub struct ChainKey(Vec<Option<String>>);
impl ChainKey {
pub fn blank(order: usize) -> Self {
ChainKey(vec![None; order])
}
pub fn from_vec(vec: Vec<Option<String>>) -> Self {
ChainKey(vec)
}
pub fn to_vec(self) -> Vec<Option<String>> {
self.0
}
pub fn advance(&mut self, next_word: &Option<String>) {
self.0 = self.0[1..self.0.len()].to_vec();
self.0.push(next_word.clone());
}
#[cfg(feature = "serialization")]
fn to_string(&self) -> String {
let mut result = String::new();
let mut first = true;
for word in &self.0 {
if first {
first = false;
} else {
result.push_str(KEY_SEPARATOR);
}
if let Some(word) = word {
result.push_str(&word);
} else {
result.push_str(KEY_NO_WORD);
}
}
result
}
#[cfg(feature = "serialization")]
fn from_str(string: &str) -> Self {
let mut result = Vec::new();
for word in string.split(KEY_SEPARATOR) {
if word == KEY_NO_WORD {
result.push(None);
} else {
result.push(Some(word.to_string()));
}
}
ChainKey(result)
}
}
#[cfg(feature = "serialization")]
impl Serialize for ChainKey {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
serializer.serialize_str(&self.to_string())
}
}
#[cfg(feature = "serialization")]
struct ChainKeyVisitor;
#[cfg(feature = "serialization")]
impl<'de> Visitor<'de> for ChainKeyVisitor {
type Value = ChainKey;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a string")
}
fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
where
E: serde::de::Error,
{
Ok(ChainKey::from_str(value))
}
}
#[cfg(feature = "serialization")]
impl<'de> Deserialize<'de> for ChainKey {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
deserializer.deserialize_str(ChainKeyVisitor)
}
}
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serialization", derive(Serialize, Deserialize))]
pub struct Chain {
map: HashMap<ChainKey, Vec<Option<String>>>,
order: usize,
}
impl Chain {
pub fn new(order: usize) -> Self {
Chain {
map: HashMap::new(),
order,
}
}
pub fn train(&mut self, string: &str) {
let mut words = vec![None; self.order];
for word in string.split_whitespace() {
words.push(Some(word.to_string()));
}
words.push(None);
for window in words.windows(self.order + 1) {
let key = &window[..self.order];
let word = &window[self.order];
let map_entry = self
.map
.entry(ChainKey::from_vec(key.to_vec()))
.or_insert(Vec::new());
map_entry.push(word.clone());
}
}
pub fn generate(&self) -> Option<String> {
let seed = ChainKey::blank(self.order);
self.generate_from_seed(&seed)
}
pub fn generate_from_seed(&self, seed: &ChainKey) -> Option<String> {
if !self.map.contains_key(seed) {
return None;
}
let mut rng = rand::thread_rng();
let mut result: Vec<String> = Vec::new();
let mut cursor = seed.clone();
loop {
let possible_words = &self.map[&cursor];
let next_word = possible_words.choose(&mut rng).unwrap();
if let Some(next_word) = next_word {
result.push(next_word.clone());
} else {
break;
}
cursor.advance(next_word);
}
Some(result.join(" "))
}
#[cfg(feature = "serialization")]
pub fn to_json(&self) -> serde_json::Result<String> {
serde_json::to_string(self)
}
#[cfg(feature = "serialization")]
pub fn from_json(json: &str) -> serde_json::Result<Self> {
serde_json::from_str(json)
}
}