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improve names and comments around the new macros

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Folkert 2022-07-08 23:43:36 +02:00
parent 02fa2eb086
commit a4e1de2f2d
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2 changed files with 120 additions and 119 deletions
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41
crates/compiler/module/src/low_level.rs
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@ -160,8 +160,6 @@ impl LowLevel {
pub enum LowLevelWrapperType {
/// This wrapper function contains no logic and we can remove it in code gen
CanBeReplacedBy(LowLevel),
/// This wrapper function contains important logic and we cannot remove it in code gen
WrapperIsRequired,
NotALowLevelWrapper,
}
@ -171,39 +169,39 @@ impl LowLevelWrapperType {
}
}
macro_rules! more_macro_magic {
($($lowlevel:ident <= $symbol:ident)+) => { more_macro_magic!{$($lowlevel <= $symbol),+} };
($($lowlevel:ident <= $symbol:ident),*) => {
/// We use a rust macro to ensure that every LowLevel gets handled
macro_rules! map_symbol_to_lowlevel {
($($lowlevel:ident <= $symbol:ident),* $(,)?) => {
fn for_symbol_help(symbol: Symbol) -> LowLevelWrapperType {
use $crate::low_level::LowLevelWrapperType::*;
// expands to a big (but non-exhaustive) match on symbols and maps them to a lowlevel
match symbol {
$(
Symbol::$symbol => CanBeReplacedBy(LowLevel::$lowlevel),
)*
Symbol::LIST_MAP => WrapperIsRequired,
Symbol::LIST_MAP2 => WrapperIsRequired,
Symbol::LIST_MAP3 => WrapperIsRequired,
Symbol::LIST_MAP4 => WrapperIsRequired,
Symbol::DICT_WALK => WrapperIsRequired,
Symbol::LIST_SORT_WITH => WrapperIsRequired,
Symbol::DICT_GET => WrapperIsRequired,
_ => NotALowLevelWrapper,
}
}
fn _enforce_exhaustiveness(lowlevel: LowLevel) -> Symbol {
// when adding a new lowlevel, this match will stop being exhaustive, and give a
// compiler error. Most likely, you are adding a new lowlevel that maps directly to a
// symbol. For instance, you want to have `List.foo` to stand for the `ListFoo`
// lowlevel. In that case, see below in the invocation of `map_symbol_to_lowlevel!`
//
// Below, we explicitly handle some exceptions to the pattern where a lowlevel maps
// directly to a symbol. If you are unsure if your lowlevel is an exception, assume
// that it isn't and just see if that works.
match lowlevel {
$(
LowLevel::$lowlevel => Symbol::$symbol,
)*
// these are higher-order lowlevels, hence need the surrounding function to provide
// enough type information for code generation
// these are higher-order lowlevels. these need the surrounding
// function to provide enough type information for code generation
LowLevel::ListMap => unreachable!(),
LowLevel::ListMap2 => unreachable!(),
LowLevel::ListMap3 => unreachable!(),
@ -211,11 +209,11 @@ macro_rules! more_macro_magic {
LowLevel::ListSortWith => unreachable!(),
LowLevel::DictWalk => unreachable!(),
// The BoxExpr operation is turned into mono Expr
// (un)boxing is handled in a custom way
LowLevel::BoxExpr => unreachable!(),
LowLevel::UnboxExpr => unreachable!(),
// these are implemented explicitly in for_symbol because they are polymorphic
// these functions return polymorphic values
LowLevel::NumIntCast => unreachable!(),
LowLevel::NumToFloatCast => unreachable!(),
LowLevel::NumToIntChecked => unreachable!(),
@ -239,7 +237,10 @@ macro_rules! more_macro_magic {
};
}
more_macro_magic! {
// here is where we actually specify the mapping for the fast majority of cases that follow the
// pattern of a symbol mapping directly to a lowlevel. In other words, most lowlevels (left) are generated
// by only one specific symbol (right)
map_symbol_to_lowlevel! {
StrConcat <= STR_CONCAT,
StrJoinWith <= STR_JOIN_WITH,
StrIsEmpty <= STR_IS_EMPTY,
@ -335,5 +336,5 @@ more_macro_magic! {
And <= BOOL_AND,
Or <= BOOL_OR,
Not <= BOOL_NOT,
Unreachable <= LIST_UNREACHABLE
Unreachable <= LIST_UNREACHABLE,
}