rama_http_headers/common/
if_match.rs

1use rama_core::telemetry::tracing;
2use rama_http_types::HeaderValue;
3use rama_utils::collections::NonEmptyVec;
4
5use super::ETag;
6use crate::util::{EntityTagRange, TryFromValues};
7
8/// `If-Match` header, defined in
9/// [RFC7232](https://tools.ietf.org/html/rfc7232#section-3.1)
10///
11/// The `If-Match` header field makes the request method conditional on
12/// the recipient origin server either having at least one current
13/// representation of the target resource, when the field-value is "*",
14/// or having a current representation of the target resource that has an
15/// entity-tag matching a member of the list of entity-tags provided in
16/// the field-value.
17///
18/// An origin server MUST use the strong comparison function when
19/// comparing entity-tags for `If-Match`, since the client
20/// intends this precondition to prevent the method from being applied if
21/// there have been any changes to the representation data.
22///
23/// # ABNF
24///
25/// ```text
26/// If-Match = "*" / 1#entity-tag
27/// ```
28///
29/// # Example values
30///
31/// * `"xyzzy"`
32/// * "xyzzy", "r2d2xxxx", "c3piozzzz"
33///
34/// # Examples
35///
36/// ```
37/// use rama_http_headers::IfMatch;
38///
39/// let if_match = IfMatch::any();
40/// ```
41#[derive(Clone, Debug, PartialEq)]
42pub struct IfMatch(EntityTagRange);
43
44impl crate::TypedHeader for IfMatch {
45    fn name() -> &'static ::rama_http_types::header::HeaderName {
46        &::rama_http_types::header::IF_MATCH
47    }
48}
49
50impl crate::HeaderDecode for IfMatch {
51    fn decode<'i, I>(values: &mut I) -> Result<Self, crate::Error>
52    where
53        I: Iterator<Item = &'i ::rama_http_types::header::HeaderValue>,
54    {
55        EntityTagRange::try_from_values(values).map(Self)
56    }
57}
58
59impl crate::HeaderEncode for IfMatch {
60    fn encode<E: Extend<::rama_http_types::HeaderValue>>(&self, values: &mut E) {
61        match HeaderValue::try_from(&self.0) {
62            Ok(value) => values.extend(::std::iter::once(value)),
63            Err(err) => {
64                tracing::debug!(
65                    "failed to encode if-match entity-tag-range as header value: {err}"
66                );
67            }
68        }
69    }
70}
71
72impl IfMatch {
73    /// Create a new `If-Match: *` header.
74    pub fn any() -> Self {
75        Self(EntityTagRange::Any)
76    }
77
78    /// Returns whether this is `If-Match: *`, matching any entity tag.
79    pub fn is_any(&self) -> bool {
80        match self.0 {
81            EntityTagRange::Any => true,
82            EntityTagRange::Tags(..) => false,
83        }
84    }
85
86    /// Checks whether the `ETag` strongly matches.
87    pub fn precondition_passes(&self, etag: &ETag) -> bool {
88        self.0.matches_strong(&etag.0)
89    }
90}
91
92impl From<ETag> for IfMatch {
93    fn from(etag: ETag) -> Self {
94        Self(EntityTagRange::Tags(NonEmptyVec::new(etag.0)))
95    }
96}
97
98#[cfg(test)]
99mod tests {
100    use super::*;
101
102    #[test]
103    fn is_any() {
104        assert!(IfMatch::any().is_any());
105        assert!(!IfMatch::from(ETag::from_static("\"yolo\"")).is_any());
106    }
107
108    #[test]
109    fn precondition_fails() {
110        let if_match = IfMatch::from(ETag::from_static("\"foo\""));
111
112        let bar = ETag::from_static("\"bar\"");
113        let weak_foo = ETag::from_static("W/\"foo\"");
114
115        assert!(!if_match.precondition_passes(&bar));
116        assert!(!if_match.precondition_passes(&weak_foo));
117    }
118
119    #[test]
120    fn precondition_passes() {
121        let foo = ETag::from_static("\"foo\"");
122
123        let if_match = IfMatch::from(foo.clone());
124
125        assert!(if_match.precondition_passes(&foo));
126    }
127
128    #[test]
129    fn precondition_any() {
130        let foo = ETag::from_static("\"foo\"");
131
132        let if_match = IfMatch::any();
133
134        assert!(if_match.precondition_passes(&foo));
135    }
136}
rama_http_headers/common/if_match.rs

rama_http_headers/common/
if_match.rs
