50 lines
1.4 KiB
Rust
50 lines
1.4 KiB
Rust
const IMAGE_TYPES: [(&str, &str); 4] = [
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("image/png", "png"),
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("image/jpeg", "jpg"),
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("image/gif", "gif"),
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("image/webp", "webp"),
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];
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/// The extension to store `media_type` under, or `None` if it isn't an
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/// image type this server handles.
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pub fn extension_for(media_type: &str) -> Option<&'static str> {
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IMAGE_TYPES
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.iter()
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.find(|(known, _)| *known == media_type)
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.map(|(_, extension)| *extension)
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}
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/// The media type of a stored file, from its extension. Names are
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/// server-generated (`<hex>.<extension>`, always lowercase), so no case
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/// folding is needed; `None` for anything else.
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pub fn media_type_for(name: &str) -> Option<&'static str> {
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let (_, extension) = name.rsplit_once('.')?;
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IMAGE_TYPES
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.iter()
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.find(|(_, known)| *known == extension)
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.map(|(media_type, _)| *media_type)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn the_two_directions_agree() {
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for (media_type, extension) in IMAGE_TYPES {
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assert_eq!(extension_for(media_type), Some(extension));
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assert_eq!(
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media_type_for(&format!("abc123.{extension}")),
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Some(media_type)
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);
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}
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}
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#[test]
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fn unknown_types_are_the_callers_problem() {
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assert_eq!(extension_for("application/pdf"), None);
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assert_eq!(media_type_for("abc123.pdf"), None);
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assert_eq!(media_type_for("abc123"), None);
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}
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}
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