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// cargo-deps: ejdb="0.1" | |
extern crate ejbd; | |
use ejdb::bson::{Bson, Document}; | |
use ejdb::bson::oid::ObjectId; | |
#[derive(Debug, Clone)] | |
pub enum BsonDestructureError { | |
InvalidType { | |
field_name: &'static str, | |
expected: &'static str, | |
actual: Bson | |
}, | |
InvalidArrayItemType { | |
index: usize, | |
expected: &'static str, | |
actual: Bson | |
}, | |
MissingField { | |
field_name: &'static str, | |
expected: &'static str | |
} | |
} | |
macro_rules! bson_destructure { | |
// required field | |
( | |
@collect req, | |
[$target:ident, $source:expr, $field:expr, Bson, $f:expr], | |
[]; | |
$($rest:tt)* | |
) => {{ | |
let $target = try!(match $source.remove($field) { | |
Some(v) => $f(v), | |
None => Err(BsonDestructureError::MissingField { | |
field_name: $field, | |
expected: "Bson" | |
}), | |
}); | |
bson_destructure!($($rest)*) | |
}}; | |
( | |
@collect req, | |
[$target:ident, $source:expr, $field:expr, $variant:ident, $f:expr], | |
[]; | |
$($rest:tt)* | |
) => {{ | |
let $target = try!(match $source.remove($field) { | |
Some(v) => match v { | |
::ejdb::bson::Bson::$variant(v) => $f(v), | |
v => Err(BsonDestructureError::InvalidType { | |
field_name: $field, | |
expected: stringify!($variant), | |
actual: v | |
}) | |
}, | |
None => Err(BsonDestructureError::MissingField { | |
field_name: $field, | |
expected: stringify!($variant) | |
}), | |
}); | |
bson_destructure!($($rest)*) | |
}}; | |
// optional field | |
( | |
@collect opt, | |
[$target:ident, $source:expr, $field:expr, Bson, $f:expr], | |
[]; | |
$($rest:tt)* | |
) => {{ | |
let $target = try!(match $source.remove($field) { | |
Some(v) => $f(v).map(Some), | |
None => Ok(None), | |
}); | |
bson_destructure!($($rest)*) | |
}}; | |
( | |
@collect opt, | |
[$target:ident, $source:expr, $field:expr, $variant:ident, $f:expr], | |
[]; | |
$($rest:tt)* | |
) => {{ | |
let $target = try!(match $source.remove($field) { | |
Some(v) => match v { | |
::ejdb::bson::Bson::$variant(v) => $f(v).map(Some), | |
v => Err(BsonDestructureError::InvalidType { | |
field_name: $field, | |
expected: stringify!($variant), | |
actual: v | |
}) | |
}, | |
None => Ok(None), | |
}); | |
bson_destructure!($($rest)*) | |
}}; | |
// change variant name | |
( | |
@collect $k:tt, | |
[$target:ident, $source:expr, $field:expr, $variant:ident, $f:expr], | |
[as $nv:ident, $($word:ident $arg:tt),*]; | |
$($rest:tt)* | |
) => { | |
bson_destructure!( | |
@collect $k, | |
[$target, $source, $field, $nv, $f], | |
[$($word $arg),*]; | |
$($rest)* | |
) | |
}; | |
// change final mapping function | |
( | |
@collect $k:tt, | |
[$target:ident, $source:expr, $field:expr, $variant:ident, $f:expr], | |
[through ($nf:expr), $($word:ident $arg:tt),*]; | |
$($rest:tt)* | |
) => { | |
bson_destructure!( | |
@collect $k, | |
[$target, $source, $field, $variant, $nf], | |
[$($word $arg),*]; | |
$($rest)* | |
) | |
}; | |
// change field name | |
( | |
@collect $k:tt, | |
[$target:ident, $source:expr, $field:expr, $variant:ident, $f:expr], | |
[name ($nn:expr), $($word:ident $arg:tt),*]; | |
$($rest:tt)* | |
) => { | |
bson_destructure!( | |
@collect $k, | |
[$target, $source, $nn, $variant, $f], | |
[$($word $arg),*]; | |
$($rest)* | |
) | |
}; | |
// main forms | |
(get $target:ident = from ($source:expr), $($word:ident $arg:tt),*; $($rest:tt)*) => { | |
bson_destructure!( | |
@collect req, | |
[$target, $source, stringify!($target), Bson, Ok], | |
[$($word $arg),*]; | |
$($rest)* | |
) | |
}; | |
(get $target:ident = from ($source:expr), optional, $($word:ident $arg:tt),*; $($rest:tt)*) => { | |
bson_destructure!( | |
@collect opt, | |
[$target, $source, stringify!($target), Bson, Ok], | |
[$($word $arg),*]; | |
$($rest)* | |
) | |
}; | |
// final form | |
(ret $e:expr) => { $e } | |
} | |
fn main() { | |
let (id, hash, name, path, modification_time, size, metadata, commit_data) = bson_destructure! { | |
get id = from (bson), optional, name ("_id"), as ObjectId; | |
get hash = from (bson), as String; | |
get name = from (bson), as String; | |
get path = from (bson), as Bson; | |
get modification_time = from (bson), as UtcDatetime; | |
get size = from (bson), as I64, through (|n| n as u64); | |
get metadata = from (bson), as Document; | |
get commit_data = from (bson), optional, as Document; | |
ret (id, hash, name, path, modification_time, size, metadata, commit_data) | |
}; | |
} |
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