diff options
Diffstat (limited to 'dhall')
| -rw-r--r-- | dhall/src/parser.rs | 80 |
1 files changed, 49 insertions, 31 deletions
diff --git a/dhall/src/parser.rs b/dhall/src/parser.rs index ee93a7d..d9b405a 100644 --- a/dhall/src/parser.rs +++ b/dhall/src/parser.rs @@ -175,19 +175,17 @@ macro_rules! match_iter { * Panics if the sequence doesn't match, unless you use the @get_err entrypoint. * If using the @get_err entrypoint, errors returned by the callback will get propagated * using IterMatchError::Other. - * Allows multiple branches. The passed iterator must be Clone. - * Will check the patterns in order, testing for matches using the callback macro provided. * * Example: * ``` * macro_rules! callback { - * (positive, $x:expr) => { + * (@type_callback, positive, $x:expr) => { * if $x >= 0 { Ok($x) } else { Err(()) } * }; - * (negative, $x:expr) => { + * (@type_callback, negative, $x:expr) => { * if $x <= 0 { Ok($x) } else { Err(()) } * }; - * (any, $x:expr) => { + * (@type_callback, any, $x:expr) => { * Ok($x) * }; * } @@ -196,7 +194,6 @@ macro_rules! match_iter { * * match_iter_typed!(callback; vec.into_iter(); * (x: positive, y?: negative, z: any) => { ... }, - * (x: negative, y?: any, z: any) => { ... }, * ) * ``` * @@ -217,22 +214,15 @@ macro_rules! match_iter_typed { match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*), ()) }; (@collect, ($iter:expr, $body:expr, $callback:ident, $error:ident), ($($args:tt)*), ($($acc:tt)*), ($(,)*)) => { - let matched: Result<_, IterMatchError<ParseError>> = - match_iter!(@get_err, $iter; ($($acc)*) => { - match_iter_typed!(@callback, $callback, $iter, $($args)*); - Ok($body) - } - ); - #[allow(unused_assignments)] - match matched { - Ok(v) => break v, - Err(e) => $error = e, - }; + match_iter!(@get_err, $iter; ($($acc)*) => { + match_iter_typed!(@callback, $callback, $iter, $($args)*); + Ok($body) + }) }; // Pass the matches through the callback (@callback, $callback:ident, $iter:expr, $x:ident : $ty:ident $($rest:tt)*) => { - let $x = $callback!($ty, $x); + let $x = $callback!(@type_callback, $ty, $x); #[allow(unused_mut)] let mut $x = match $x { Ok(x) => x, @@ -241,7 +231,7 @@ macro_rules! match_iter_typed { match_iter_typed!(@callback, $callback, $iter $($rest)*); }; (@callback, $callback: ident, $iter:expr, $x:ident? : $ty:ident $($rest:tt)*) => { - let $x = $x.map(|x| $callback!($ty, x)); + let $x = $x.map(|x| $callback!(@type_callback, $ty, x)); #[allow(unused_mut)] let mut $x = match $x { Some(Ok(x)) => Some(x), @@ -251,7 +241,7 @@ macro_rules! match_iter_typed { match_iter_typed!(@callback, $callback, $iter $($rest)*); }; (@callback, $callback: ident, $iter:expr, $x:ident* : $ty:ident $($rest:tt)*) => { - let $x = $x.map(|x| $callback!($ty, x)).collect(); + let $x = $x.map(|x| $callback!(@type_callback, $ty, x)).collect(); let $x: Vec<_> = match $x { Ok(x) => x, Err(e) => break Err(IterMatchError::Other(e)), @@ -262,7 +252,34 @@ macro_rules! match_iter_typed { }; (@callback, $callback:ident, $iter:expr $(,)*) => {}; - // Entrypoint + // Entrypoints + (@get_err, $callback:ident; $iter:expr; ($($args:tt)*) => $body:expr) => { + { + #[allow(unused_mut)] + let mut iter = $iter; + match_iter_typed!(@collect, + (iter, $body, $callback, last_error), + ($($args)*), (), ($($args)*,) + ) + } + }; + ($($args:tt)*) => { + { + let ret: Result<_, IterMatchError<()>> = match_iter_typed!(@get_err, $($args)*); + ret.unwrap() + } + }; +} + +/* Extends match_iter and match_iter_typed with branching. + * Panics if the sequence doesn't match, unless you use the @get_err entrypoint. + * If using the @get_err entrypoint, errors returned by the callback will get propagated + * 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. +*/ +macro_rules! match_iter_branching { + // Entrypoints (@get_err, $callback:ident; $iter:expr; $( ($($args:tt)*) => $body:expr ),* $(,)*) => { { #[allow(unused_mut)] @@ -274,10 +291,13 @@ macro_rules! match_iter_typed { #[allow(unreachable_code)] loop { $( - match_iter_typed!(@collect, - (iter.clone(), $body, $callback, last_error), - ($($args)*), (), ($($args)*,) - ); + let matched: Result<_, IterMatchError<_>> = + match_iter_typed!(@get_err, $callback; iter.clone(); ($($args)*) => $body); + #[allow(unused_assignments)] + match matched { + Ok(v) => break v, + Err(e) => last_error = e, + }; )* break Err(last_error); } @@ -285,7 +305,7 @@ macro_rules! match_iter_typed { }; ($($args:tt)*) => { { - let ret: Result<_, IterMatchError<()>> = match_iter!(@get_err, $($args)*); + let ret: Result<_, IterMatchError<()>> = match_iter_branching!(@get_err, $($args)*); ret.unwrap() } }; @@ -308,19 +328,17 @@ macro_rules! named_rule { ); } -macro_rules! match_children_callback { - ($ty:ident, $x:expr) => { +macro_rules! match_children { + (@type_callback, $ty:ident, $x:expr) => { $ty($x) }; -} -macro_rules! match_children { ($pair:expr; $($args:tt)*) => { { let pair = $pair; #[allow(unused_mut)] let mut pairs = pair.clone().into_inner(); - let result = match_iter_typed!(@get_err, match_children_callback; pairs; $($args)*); + let result = match_iter_branching!(@get_err, match_children; pairs; $($args)*); result.map_err(|e| match e { IterMatchError::Other(e) => e, _ => custom_parse_error(&pair, "No match found".to_owned()), |