artichoke_backend/convert/
maybe_to_int.rs

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1use artichoke_core::debug::Debug as _;
2use artichoke_core::value::Value as _;
3use spinoso_exception::TypeError;
4
5use crate::Artichoke;
6use crate::error::Error;
7use crate::value::Value;
8
9#[derive(Debug)]
10pub enum MaybeToInt {
11    Int(i64),
12    NotApplicable,
13    Err(TypeError),
14    UncriticalReturn(Value),
15}
16
17/// Attempt a fallible conversion of the given value to `i64`.
18///
19/// Conversion steps:
20///
21/// - If the given value is an `Integer`, return its underlying [`i64`].
22/// - If the value does not have a `to_int` method, the conversion is not
23///   applicable so return [`None`].
24/// - If `value.to_int` raises, return the exception in `Err(_)`.
25/// - If the value returned by the conversion is an `Integer`, return its
26///   underlying [`i64`].
27/// - Else, the conversion is not applicable so return [`None`].
28pub fn maybe_to_int(interp: &mut Artichoke, value: Value) -> Result<MaybeToInt, Error> {
29    if let Ok(int) = value.try_convert_into::<i64>(interp) {
30        return Ok(MaybeToInt::Int(int));
31    }
32    if value.respond_to(interp, "to_int")? {
33        let to_int = value.funcall(interp, "to_int", &[], None)?;
34        if let Ok(int) = to_int.try_convert_into::<i64>(interp) {
35            return Ok(MaybeToInt::Int(int));
36        }
37    }
38    if !value.respond_to(interp, "to_i")? {
39        return Ok(MaybeToInt::NotApplicable);
40    }
41    let to_i = value.funcall(interp, "to_i", &[], None)?;
42    if to_i.is_nil() {
43        let message = format!(
44            "can't convert {class} to Integer ({class}#to_i gives NilClass)",
45            class = interp.class_name_for_value(value)
46        );
47        return Ok(MaybeToInt::Err(TypeError::from(message)));
48    }
49    // Uncritically return the result of `#to_i`.
50    Ok(MaybeToInt::UncriticalReturn(to_i))
51}
52
53#[cfg(test)]
54mod tests {
55    use super::{MaybeToInt, maybe_to_int};
56    use crate::test::prelude::*;
57
58    #[test]
59    fn integer_is_returned() {
60        let mut interp = interpreter();
61        let int = interp.eval(b"5").unwrap();
62        assert!(matches!(maybe_to_int(&mut interp, int).unwrap(), MaybeToInt::Int(5)));
63        let int = interp.eval(b"-5").unwrap();
64        assert!(matches!(maybe_to_int(&mut interp, int).unwrap(), MaybeToInt::Int(-5)));
65    }
66
67    #[test]
68    fn object_is_is_not_applicable() {
69        let mut interp = interpreter();
70        let int = interp.eval(b"BasicObject.new").unwrap();
71        assert!(matches!(
72            maybe_to_int(&mut interp, int).unwrap(),
73            MaybeToInt::NotApplicable
74        ));
75        let int = interp.eval(b"Object.new").unwrap();
76        assert!(matches!(
77            maybe_to_int(&mut interp, int).unwrap(),
78            MaybeToInt::NotApplicable
79        ));
80        let int = interp.eval(b"[1, 2, 3]").unwrap();
81        assert!(matches!(
82            maybe_to_int(&mut interp, int).unwrap(),
83            MaybeToInt::NotApplicable
84        ));
85    }
86
87    #[test]
88    fn conversion_with_to_int_not_applicable_to_i_nil_is_err() {
89        let mut interp = interpreter();
90        let int = interp
91            .eval(b"class A; def to_int; Object.new; end; def to_i; nil; end; end; A.new")
92            .unwrap();
93        assert!(matches!(
94            maybe_to_int(&mut interp, int).unwrap(),
95            MaybeToInt::Err(err) if err.message() == b"can't convert A to Integer (A#to_i gives NilClass)"
96        ));
97    }
98
99    #[test]
100    fn conversion_without_to_to_i_is_nil_is_err() {
101        let mut interp = interpreter();
102        let int = interp.eval(b"class A; def to_i; nil; end; end; A.new").unwrap();
103        assert!(matches!(
104            maybe_to_int(&mut interp, int).unwrap(),
105            MaybeToInt::Err(err) if err.message() == b"can't convert A to Integer (A#to_i gives NilClass)"
106        ));
107    }
108
109    #[test]
110    fn conversion_without_to_to_i_non_nil_is_uncritically_returned() {
111        let mut interp = interpreter();
112        let int = interp.eval(b"class A; def to_i; Object.new; end; end; A.new").unwrap();
113        assert!(matches!(
114            maybe_to_int(&mut interp, int).unwrap(),
115            MaybeToInt::UncriticalReturn(..)
116        ));
117    }
118
119    #[test]
120    fn conversion_with_to_int_is_returned() {
121        let mut interp = interpreter();
122        let int = interp.eval(b"class A; def to_int; 99; end; end; A.new").unwrap();
123        assert!(matches!(maybe_to_int(&mut interp, int).unwrap(), MaybeToInt::Int(99)));
124    }
125
126    #[test]
127    fn conversion_with_raising_to_int_is_error() {
128        let mut interp = interpreter();
129        let int = interp
130            .eval(b"class A; def to_int; raise 'bonk'; end; end; A.new")
131            .unwrap();
132        maybe_to_int(&mut interp, int).unwrap_err();
133    }
134
135    #[test]
136    fn conversion_with_unapplicable_to_int_is_not_applicable() {
137        let mut interp = interpreter();
138        let int = interp.eval(b"class A; def to_int; [1, 2, 3]; end; end; A.new").unwrap();
139        assert!(matches!(
140            maybe_to_int(&mut interp, int).unwrap(),
141            MaybeToInt::NotApplicable
142        ));
143        let int = interp.eval(b"class B; def to_int; 'rip'; end; end; B.new").unwrap();
144        assert!(matches!(
145            maybe_to_int(&mut interp, int).unwrap(),
146            MaybeToInt::NotApplicable
147        ));
148    }
149}
artichoke_backend/convert/maybe_to_int.rs

artichoke_backend/convert/
maybe_to_int.rs
