Skip to content

Instantly share code, notes, and snippets.

@netvl netvl/test.rs
Last active Jan 9, 2016

Embed
What would you like to do?
// 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)
};
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.