cel 0.14.0

A parser and interpreter for the Common Expression Language (CEL)
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

use std::{borrow::Cow, collections::BTreeMap, ops::Deref, sync::Arc};

use crate::{
    common::{
        traits::{Indexer, Zeroer},
        types::{CelString, Type},
        value::Val,
    },
    ExecutionError,
};

/// A CEL struct value.
///
/// A struct has a type and a set of field values.
#[derive(Debug, Eq, PartialEq)]
pub struct Struct {
    r#type: Type,
    entries: BTreeMap<String, Arc<dyn Val>>,
}

impl Struct {
    /// Creates a new struct with the given name and no fields.
    pub fn new(name: String) -> Self {
        Self {
            r#type: Type::new_struct(name),
            entries: BTreeMap::default(),
        }
    }

    /// Returns the name of the struct type.
    pub fn name(&self) -> &str {
        self.r#type.name()
    }

    /// Returns the value of the field with the given name, if it exists.
    pub fn field_value(&self, name: &str) -> Option<&dyn Val> {
        self.entries.get(name).map(Deref::deref)
    }

    /// Adds a field value to the struct.
    pub fn add_field_value(&mut self, name: String, value: Cow<dyn Val>) {
        self.entries.insert(name, Arc::from(value.into_owned()));
    }

    /// Returns a map of all field values in the struct.
    pub fn field_values(&self) -> BTreeMap<String, Arc<dyn Val>> {
        self.entries.clone()
    }
}

impl Val for Struct {
    fn get_type(&self) -> &Type {
        &self.r#type
    }

    fn clone_as_boxed(&self) -> Box<dyn Val> {
        Box::new(Self {
            r#type: Type::new_struct(self.name().to_owned()),
            entries: self
                .entries
                .iter()
                .map(|(k, v)| (k.clone(), Arc::from(v.clone_as_boxed())))
                .collect(),
        })
    }

    fn as_indexer(&self) -> Option<&dyn crate::common::traits::Indexer> {
        Some(self)
    }

    fn into_indexer(self: Box<Self>) -> Option<Box<dyn crate::common::traits::Indexer>> {
        Some(self)
    }

    fn as_zeroer(&self) -> Option<&dyn Zeroer> {
        Some(self)
    }

    fn equals(&self, other: &dyn Val) -> bool {
        other
            .downcast_ref::<Struct>()
            .is_some_and(|other| self == other)
    }
}

impl Indexer for Struct {
    fn get<'a>(&'a self, idx: &dyn Val) -> Result<Cow<'a, dyn Val>, crate::ExecutionError> {
        if let Some(field) = idx.downcast_ref::<CelString>() {
            self.field_value(field.inner())
                .map(Cow::Borrowed)
                .ok_or(ExecutionError::NoSuchKey(Arc::new(String::from(
                    field.inner(),
                ))))
        } else {
            Err(ExecutionError::UnsupportedIndex(
                idx.try_into()?,
                (self as &dyn Val).try_into()?,
            ))
        }
    }

    fn steal(self: Box<Self>, idx: &dyn Val) -> Result<Box<dyn Val>, crate::ExecutionError> {
        self.get(idx).map(Cow::into_owned)
    }
}

impl Zeroer for Struct {
    fn is_zero_value(&self) -> bool {
        self.entries.is_empty()
    }
}

#[cfg(test)]
mod tests {
    use std::borrow::Cow;

    use crate::common::{
        types::{CelBool, CelStruct},
        value::Val,
    };

    #[test]
    fn equality() {
        let mut s1 = CelStruct::new("foo".to_owned());
        s1.add_field_value(
            "bar".to_owned(),
            Cow::<dyn Val>::Owned(Box::new(CelBool::from(true))),
        );
        let mut s2 = CelStruct::new("foo".to_owned());
        assert_ne!(s1, s2);
        s2.add_field_value(
            "bar".to_owned(),
            Cow::<dyn Val>::Owned(Box::new(CelBool::from(true))),
        );
        assert_eq!(s1, s2);
        s2.add_field_value(
            "bar".to_owned(),
            Cow::<dyn Val>::Owned(Box::new(CelBool::from(false))),
        );
        assert_ne!(s1, s2);
    }
}