rust/src/lib/either.rs
Brian Anderson 7ae757583a Begin documenting std and add doc generation using naturaldocs
Naturaldocs isn't really that great but it seems easier to get
something working than with doxygen, for which we would need to
convert rust code to something C++ish. We probably want to just
write a rustdoc utility at some point.
2011-10-25 18:01:52 -07:00

91 lines
1.9 KiB
Rust

/*
Module: either
A type that represents one of two alternatives
*/
import option;
import option::{some, none};
/*
Tag: t
The either type
*/
tag t<T, U> {
/* Variant: left */
left(T);
/* Variant: right */
right(U);
}
/* Section: Operations */
/*
Function: either
Applies a function based on the given either value
If `value` is left(T) then `f_left` is applied to its contents, if
`value` is right(U) then `f_right` is applied to its contents, and
the result is returned.
*/
fn either<T, U,
V>(f_left: block(T) -> V, f_right: block(U) -> V, value: t<T, U>) ->
V {
alt value { left(l) { f_left(l) } right(r) { f_right(r) } }
}
/*
Function: lefts
Extracts from a vector of either all the left values.
*/
fn lefts<T, U>(eithers: [t<T, U>]) -> [T] {
let result: [T] = [];
for elt: t<T, U> in eithers {
alt elt { left(l) { result += [l]; } _ {/* fallthrough */ } }
}
ret result;
}
/*
Function: rights
Extracts from a vector of either all the right values
*/
fn rights<T, U>(eithers: [t<T, U>]) -> [U] {
let result: [U] = [];
for elt: t<T, U> in eithers {
alt elt { right(r) { result += [r]; } _ {/* fallthrough */ } }
}
ret result;
}
/*
Function: partition
Extracts from a vector of either all the left values and right values
Returns a structure containing a vector of left values and a vector of
right values.
*/
fn partition<T, U>(eithers: [t<T, U>]) -> {lefts: [T], rights: [U]} {
let lefts: [T] = [];
let rights: [U] = [];
for elt: t<T, U> in eithers {
alt elt { left(l) { lefts += [l]; } right(r) { rights += [r]; } }
}
ret {lefts: lefts, rights: rights};
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//