This crate is an implementation of .NET's LINQ query syntax in rust as a declarative macro. The declarative macro is generated by another declarative macro, specifically the branchingparser from my other crate, bigmac.
Available statements closely mirror standard LINQ operations; notably join is missing, as I was unable to find equivalent functionality from iterators.
Generally, each statement maps to an iterator method; here is a list of them, with a description and equivalent method if present: - from # in #: selects and names variables from a collection. Maps to into_iter(). - select #: ends a linq query and returns an iterator. Maps to map(). - select # into #: partially ends a linq query and puts an iterator into a range variable. Creates a continuation. - where #: selects only elements that match a particular criteria. Maps to filter(). - let # = #: creates a range element. Does not map to a method. - collect #: calls .collect(). - collect # as #: calls .collect with a generic type. Follows select syntax but the as parameter is the destination type.
REQUIRES ITERTOOLS: - orderby #: sorts iterator ascending by a criteria. Maps to unstablesortbykey(). - orderby # ascending: sorts iterator ascending by a criteria. Maps to unstablesortbykey(). - orderby # descending: sorts iterator descending by a criteria. Maps to unstablesortbykey().rev(). - group # by #: groups elements into groups based on some criteria and returns the result. Maps to groupby(). - group # by # into #: groups elements into groups based on some criteria, and then creates a continuation.. Maps to group_by().
For more explanation of how LINQ works, check Microsoft's docs here
Also useful: Keyword breakdowns
``` use chain_linq::linq;
let xs = [(3, 1), (2, 2), (1, 3)];
let x = linq!( from (x, y) in xs let z = x + y select z into zs from z in zs select z * 2 ); ```
``` use chain_linq::linq;
let xss = [vec!(27, 13, 12), vec!(69), vec!(76, 7, 420)];
let x = linq!(
from xs in xss
group xs by xs.len() into gs
from iter in gs
from x in iter
collect x + 1 as Vec
``` use chain_linq::linq;
let xss = [vec!(27, 13, 12), vec!(69), vec!(76, 7, 420)];
let x = linq!(
from xs in xss
from x in xs.into_iter().rev()
collect x as Vec