From f816813d41271043473f8740bbc8c257f9b54982 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Fri, 23 Sep 2022 03:14:34 +0300 Subject: feat(tvix/eval): implement 'builtins.filter' This is a little ugly because the plain Iterator::filter method can not be used (it does not support fallible primitives), so we need to resort to an `Iterator::filter_map` and deal with the wrapping in Options everywhere. This prevents use of `?` which introduces the need for some matching, but it's not *too* bad. Change-Id: Ie2c3c0c9756c4c627176f64fb4e0054e717c26d1 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6765 Tested-by: BuildkiteCI Reviewed-by: sterni --- tvix/eval/src/builtins/mod.rs | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'tvix/eval/src/builtins') diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs index 872033648aff..17094a6f9452 100644 --- a/tvix/eval/src/builtins/mod.rs +++ b/tvix/eval/src/builtins/mod.rs @@ -132,6 +132,35 @@ fn pure_builtins() -> Vec { } } }), + Builtin::new("filter", &[true, true], |args, vm| { + let list: NixList = args[1].to_list()?; + + list.into_iter() + .filter_map(|elem| { + vm.push(elem.clone()); + + let result = match vm.call_value(&args[0]) { + Err(err) => return Some(Err(err)), + Ok(result) => result, + }; + + // Must be assigned to a local to avoid a borrowcheck + // failure related to the ForceResult destructor. + let result = match result.force(vm) { + Err(err) => Some(Err(vm.error(err))), + Ok(value) => match value.as_bool() { + Ok(true) => Some(Ok(elem)), + Ok(false) => None, + Err(err) => Some(Err(vm.error(err))), + }, + }; + + result + }) + .collect::, _>>() + .map(|list| Value::List(NixList::from(list))) + .map_err(Into::into) + }), Builtin::new("getAttr", &[true, true], |args, _| { let k = args[0].to_str()?; let xs = args[1].to_attrs()?; -- cgit 1.4.1