diff options
Diffstat (limited to 'dhall/src')
| -rw-r--r-- | dhall/src/parser.rs | 77 |
1 files changed, 58 insertions, 19 deletions
diff --git a/dhall/src/parser.rs b/dhall/src/parser.rs index d9b405a..fb32ff0 100644 --- a/dhall/src/parser.rs +++ b/dhall/src/parser.rs @@ -277,10 +277,39 @@ macro_rules! match_iter_typed { * using IterMatchError::Other. * Allows multiple branches. The passed iterator must be Clone. * Will check the branches in order, testing each branch using the callback macro provided. + * + * Example: + * ``` + * macro_rules! callback { + * (@type_callback, positive, $x:expr) => { + * if $x >= 0 { Ok($x) } else { Err(()) } + * }; + * (@type_callback, negative, $x:expr) => { + * if $x <= 0 { Ok($x) } else { Err(()) } + * }; + * (@type_callback, any, $x:expr) => { + * Ok($x) + * }; + * (@branch_callback, typed, $($args:tt)*) => { + * match_iter_typed!(@get_err, callback; $($args)*) + * }; + * (@branch_callback, untyped, $($args:tt)*) => { + * match_iter!(@get_err, $($args)*) + * }; + * } + * + * let vec = vec![-1, 2, 3]; + * + * match_iter_branching!(branch_callback; vec.into_iter(); + * typed!(x: positive, y?: negative, z: any) => { ... }, + * untyped!(x, y, z) => { ... }, + * ) + * ``` + * */ macro_rules! match_iter_branching { // Entrypoints - (@get_err, $callback:ident; $iter:expr; $( ($($args:tt)*) => $body:expr ),* $(,)*) => { + (@get_err, $callback:ident; $iter:expr; $( $submac:ident!($($args:tt)*) => $body:expr ),* $(,)*) => { { #[allow(unused_mut)] let mut iter = $iter; @@ -291,8 +320,7 @@ macro_rules! match_iter_branching { #[allow(unreachable_code)] loop { $( - let matched: Result<_, IterMatchError<_>> = - match_iter_typed!(@get_err, $callback; iter.clone(); ($($args)*) => $body); + let matched: Result<_, IterMatchError<_>> = $callback!(@branch_callback, $submac, iter.clone(); ($($args)*) => $body); #[allow(unused_assignments)] match matched { Ok(v) => break v, @@ -328,17 +356,20 @@ macro_rules! named_rule { ); } -macro_rules! match_children { +macro_rules! match_pest { (@type_callback, $ty:ident, $x:expr) => { $ty($x) }; + (@branch_callback, children, $($args:tt)*) => { + match_iter_typed!(@get_err, match_pest; $($args)*) + }; ($pair:expr; $($args:tt)*) => { { let pair = $pair; #[allow(unused_mut)] let mut pairs = pair.clone().into_inner(); - let result = match_iter_branching!(@get_err, match_children; pairs; $($args)*); + let result = match_iter_branching!(@get_err, match_pest; pairs; $($args)*); result.map_err(|e| match e { IterMatchError::Other(e) => e, _ => custom_parse_error(&pair, "No match found".to_owned()), @@ -347,6 +378,12 @@ macro_rules! match_children { }; } +macro_rules! match_children { + ($pairs:expr; ($($args:tt)*) => $body:expr) => { + match_pest!($pairs; children!($($args)*) => $body) + }; +} + macro_rules! with_captured_str { ($pair:expr; $x:ident; $body:expr) => {{ #[allow(unused_mut)] @@ -420,22 +457,22 @@ named!(raw_str<&'a str>; with_captured_str!(s; s)); named_rule!(escaped_quote_pair<&'a str>; plain_value!("''")); named_rule!(escaped_interpolation<&'a str>; plain_value!("${")); -named_rule!(single_quote_continue<Vec<&'a str>>; match_children!( +named_rule!(single_quote_continue<Vec<&'a str>>; match_pest!( // TODO: handle interpolation - // (c: expression, rest: single_quote_continue) => { + // children!(c: expression, rest: single_quote_continue) => { // rest.push(c); rest // }, - (c: escaped_quote_pair, rest: single_quote_continue) => { + children!(c: escaped_quote_pair, rest: single_quote_continue) => { rest.push(c); rest }, - (c: escaped_interpolation, rest: single_quote_continue) => { + children!(c: escaped_interpolation, rest: single_quote_continue) => { rest.push(c); rest }, // capture interpolation as string - (c: raw_str, rest: single_quote_continue) => { + children!(c: raw_str, rest: single_quote_continue) => { rest.push(c); rest }, - () => { + children!() => { vec![] }, )); @@ -488,16 +525,16 @@ named_rule!(union_type_entries<BTreeMap<&'a str, ParsedExpr<'a>>>; named_rule!(non_empty_union_type_or_literal <(Option<(&'a str, BoxExpr<'a>)>, BTreeMap<&'a str, ParsedExpr<'a>>)>; - match_children!( - (label: str, e: expression, entries: union_type_entries) => { + match_pest!( + children!(label: str, e: expression, entries: union_type_entries) => { (Some((label, e)), entries) }, - (l: str, e: expression, rest: non_empty_union_type_or_literal) => { + children!(l: str, e: expression, rest: non_empty_union_type_or_literal) => { let (x, mut entries) = rest; entries.insert(l, *e); (x, entries) }, - (l: str, e: expression) => { + children!(l: str, e: expression) => { let mut entries = BTreeMap::new(); entries.insert(l, *e); (None, entries) @@ -505,7 +542,9 @@ named_rule!(non_empty_union_type_or_literal ) ); -named_rule!(empty_union_type<()>; plain_value!(())); +named_rule!(empty_union_type<()>; match_children!(() => { + () +})); named!(expression<BoxExpr<'a>>; match_rule!( // TODO: parse escapes and interpolation @@ -614,11 +653,11 @@ named!(expression<BoxExpr<'a>>; match_rule!( }), Rule::union_type_or_literal => - match_children!( - (_e: empty_union_type) => { + match_pest!( + children!(_e: empty_union_type) => { bx(Expr::Union(BTreeMap::new())) }, - (x: non_empty_union_type_or_literal) => { + children!(x: non_empty_union_type_or_literal) => { match x { (Some((l, e)), entries) => bx(Expr::UnionLit(l, e, entries)), (None, entries) => bx(Expr::Union(entries)), |