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
|
use crate::ast::*;
pub fn parse(arg: &str) -> Value {
if let Some(token) = tokenize(arg).first() {
return parse_number(token)
.or(parse_bool(token))
.or(parse_symbol(token))
.unwrap();
}
panic!("No value to parse");
}
fn tokenize(arg: &str) -> Vec<String> {
arg.split(|c: char| c.is_whitespace())
.filter(|s| !s.is_empty())
.map(|s| s.to_string())
.collect()
}
fn parse_symbol(token: &str) -> Result<Value, String> {
Ok(Value::Sym(token.to_string()))
}
fn parse_bool(token: &str) -> Result<Value, String> {
token
.parse::<bool>()
.map(Value::Bool)
.map_err(|e| e.to_string())
}
fn parse_number(token: &str) -> Result<Value, String> {
token
.parse::<i32>()
.map(Value::Num)
.map_err(|e| e.to_string())
}
#[cfg(test)]
mod tests {
use super::Value::*;
use super::{parse, tokenize};
use proptest::prelude::*;
proptest! {
#[test]
fn parse_integer_as_number(i in -1000i32..1000) {
let result = parse(&i.to_string());
assert_eq!(Num(i), result);
}
}
#[test]
fn parse_truth_values_as_booleans() {
assert_eq!(Bool(true), parse("true"));
assert_eq!(Bool(false), parse("false"));
}
#[test]
fn parse_identifiers_values_as_symbols() {
assert_eq!(Sym("foo".to_string()), parse("foo"));
}
#[test]
fn ignores_whitespace() {
assert_eq!(Sym("foo".to_string()), parse(" foo \n\r"));
assert_eq!(Num(-42), parse("\n-42"));
}
#[test]
fn tokenize_several_values() {
assert_eq!(vec!["42", "foo", "true"], tokenize("42 foo \ntrue "));
}
}
|
