diff options
Diffstat (limited to 'dhall_core/src/parser.rs')
| -rw-r--r-- | dhall_core/src/parser.rs | 176 |
1 files changed, 45 insertions, 131 deletions
diff --git a/dhall_core/src/parser.rs b/dhall_core/src/parser.rs index 6f84abe..45930d4 100644 --- a/dhall_core/src/parser.rs +++ b/dhall_core/src/parser.rs @@ -71,102 +71,11 @@ fn debug_pair(pair: Pair<Rule>) -> String { s } -/* Macro to pattern-match iterators. - * Returns `Result<_, IterMatchError<_>>`. - * - * Example: - * ``` - * let vec = vec![1, 2, 3]; - * - * match_iter!(vec.into_iter(); (x, y?, z) => { - * // x: T - * // y: Option<T> - * // z: T - * }) - * - * // or - * match_iter!(vec.into_iter(); (x, y, z*) => { - * // x, y: T - * // z: impl Iterator<T> - * }) - * ``` - * -*/ #[derive(Debug)] enum IterMatchError<T> { - NotEnoughItems, - TooManyItems, NoMatchFound, Other(T), // Allow other macros to inject their own errors } -macro_rules! match_iter { - // Everything else pattern - (@match 0, $iter:expr, $x:ident* $($rest:tt)*) => { - match_iter!(@match 2, $iter $($rest)*); - #[allow(unused_mut)] - let mut $x = $iter; - }; - // Alias to use in macros - (@match 0, $iter:expr, $x:ident?? $($rest:tt)*) => { - match_iter!(@match 2, $iter $($rest)*); - #[allow(unused_mut)] - let mut $x = $iter; - }; - // Optional pattern - (@match 0, $iter:expr, $x:ident? $($rest:tt)*) => { - match_iter!(@match 1, $iter $($rest)*); - #[allow(unused_mut)] - let mut $x = $iter.next(); - if $iter.next().is_some() { - break Err(IterMatchError::TooManyItems); - } - }; - // Normal pattern - (@match 0, $iter:expr, $x:ident $($rest:tt)*) => { - #[allow(unused_mut)] - let mut $x = match $iter.next() { - Some(x) => x, - None => break Err(IterMatchError::NotEnoughItems), - }; - match_iter!(@match 0, $iter $($rest)*); - }; - // Normal pattern after a variable length one: declare reversed and take from the end - (@match $w:expr, $iter:expr, $x:ident $($rest:tt)*) => { - match_iter!(@match $w, $iter $($rest)*); - #[allow(unused_mut)] - let mut $x = match $iter.next_back() { - Some(x) => x, - None => break Err(IterMatchError::NotEnoughItems), - }; - }; - - // Check no elements remain - (@match 0, $iter:expr $(,)*) => { - if $iter.next().is_some() { - break Err(IterMatchError::TooManyItems); - } - }; - (@match $_:expr, $iter:expr) => {}; - - (@panic; $($args:tt)*) => { - { - let ret: Result<_, IterMatchError<()>> = match_iter!($($args)*); - ret.unwrap() - } - }; - ($iter:expr; ($($args:tt)*) => $body:expr) => { - { - #[allow(unused_mut)] - let mut iter = $iter; - // Not a real loop; used for error handling - let ret: Result<_, IterMatchError<_>> = loop { - match_iter!(@match 0, iter, $($args)*); - break Ok($body); - }; - ret - } - }; -} /* Extends match_iter with typed matches. Takes a callback that determines * when a capture matches. @@ -200,21 +109,21 @@ macro_rules! match_iter_typed { (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident : $ty:ident, $($rest:tt)*)) => { match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x), ($($rest)*)) }; - (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident? : $ty:ident, $($rest:tt)*)) => { - match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x?), ($($rest)*)) - }; - (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident* : $ty:ident, $($rest:tt)*)) => { - match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x??), ($($rest)*)) + (@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident.. : $ty:ident, $($rest:tt)*)) => { + match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x..), ($($rest)*)) }; // Catch extra comma if exists (@collect, ($($vars:tt)*), ($($args:tt)*), (,$($acc:tt)*), ($(,)*)) => { match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*), ()) }; (@collect, ($iter:expr, $body:expr, $callback:ident, $error:ident), ($($args:tt)*), ($($acc:tt)*), ($(,)*)) => { - match_iter!($iter; ($($acc)*) => { - match_iter_typed!(@callback, $callback, $iter, $($args)*); - $body - }) + { + let res = iter_patterns::destructure_iter!($iter; [$($acc)*] => { + match_iter_typed!(@callback, $callback, $iter, $($args)*); + $body + }); + res.ok_or(IterMatchError::NoMatchFound) + } }; // Pass the matches through the callback @@ -227,17 +136,7 @@ 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!(@type_callback, $ty, x)); - #[allow(unused_mut)] - let mut $x = match $x { - Some(Ok(x)) => Some(x), - Some(Err(e)) => break Err(IterMatchError::Other(e)), - None => None, - }; - match_iter_typed!(@callback, $callback, $iter $($rest)*); - }; - (@callback, $callback: ident, $iter:expr, $x:ident* : $ty:ident $($rest:tt)*) => { + (@callback, $callback: ident, $iter:expr, $x:ident.. : $ty:ident $($rest:tt)*) => { let $x = $x.map(|x| $callback!(@type_callback, $ty, x)).collect(); let $x: Vec<_> = match $x { Ok(x) => x, @@ -253,10 +152,13 @@ macro_rules! match_iter_typed { { #[allow(unused_mut)] let mut iter = $iter; - match_iter_typed!(@collect, - (iter, $body, $callback, last_error), - ($($args)*), (), ($($args)*,) - ) + let res: Result<_, IterMatchError<_>> = loop { + break match_iter_typed!(@collect, + (iter, $body, $callback, last_error), + ($($args)*), (), ($($args)*,) + ) + }; + res } }; } @@ -430,7 +332,7 @@ named!(raw_str<&'a str>; captured_str!(s) => s); named!(label<Label>; captured_str!(s) => Label::from(s.trim().to_owned())); rule!(double_quote_literal<ParsedText>; - children!(chunks*: double_quote_chunk) => { + children!(chunks..: double_quote_chunk) => { chunks.collect() } ); @@ -639,13 +541,14 @@ rule!(ifthenelse_expression<RcExpr>; ); rule!(let_expression<RcExpr>; - children!(bindings*: let_binding, final_expr: expression) => { + children!(bindings..: let_binding, final_expr: expression) => { bindings.fold(final_expr, |acc, x| bx(Expr::Let(x.0, x.1, x.2, acc))) } ); rule!(let_binding<(Label, Option<RcExpr>, RcExpr)>; - children!(name: label, annot?: expression, expr: expression) => (name, annot, expr) + children!(name: label, annot: expression, expr: expression) => (name, Some(annot), expr), + children!(name: label, expr: expression) => (name, None, expr), ); rule!(forall_expression<RcExpr>; @@ -661,9 +564,8 @@ rule!(arrow_expression<RcExpr>; ); rule!(merge_expression<RcExpr>; - children!(x: expression, y: expression, z?: expression) => { - bx(Expr::Merge(x, y, z)) - } + children!(x: expression, y: expression, z: expression) => bx(Expr::Merge(x, y, Some(z))), + children!(x: expression, y: expression) => bx(Expr::Merge(x, y, None)), ); rule!(empty_collection<RcExpr>; @@ -738,7 +640,7 @@ macro_rules! binop { expression(pair)? } } - // children!(first: expression, rest*: expression) => { + // children!(first: expression, rest..: expression) => { // rest.fold(first, |acc, e| bx(Expr::BinOp(BinOp::$op, acc, e))) // } ); @@ -766,7 +668,7 @@ rule!(annotated_expression<RcExpr>; ); rule!(application_expression<RcExpr>; - children!(first: expression, rest*: expression) => { + children!(first: expression, rest..: expression) => { let rest: Vec<_> = rest.collect(); if rest.is_empty() { first @@ -777,7 +679,7 @@ rule!(application_expression<RcExpr>; ); rule!(selector_expression_raw<RcExpr>; - children!(first: expression, rest*: label) => { + children!(first: expression, rest..: label) => { rest.fold(first, |acc, e| bx(Expr::Field(acc, e))) } ); @@ -795,7 +697,7 @@ rule!(literal_expression_raw<RcExpr>; ); rule!(identifier_raw<RcExpr>; - children!(name: str, idx?: natural_literal_raw) => { + children!(name: str, idx: natural_literal_raw) => { match Builtin::parse(name) { Some(b) => bx(Expr::Builtin(b)), None => match name { @@ -803,10 +705,22 @@ rule!(identifier_raw<RcExpr>; "False" => bx(Expr::BoolLit(false)), "Type" => bx(Expr::Const(Const::Type)), "Kind" => bx(Expr::Const(Const::Kind)), - name => bx(Expr::Var(V(Label::from(name.to_owned()), idx.unwrap_or(0)))), + name => bx(Expr::Var(V(Label::from(name.to_owned()), idx))), } } - } + }, + children!(name: str) => { + match Builtin::parse(name) { + Some(b) => bx(Expr::Builtin(b)), + None => match name { + "True" => bx(Expr::BoolLit(true)), + "False" => bx(Expr::BoolLit(false)), + "Type" => bx(Expr::Const(Const::Type)), + "Kind" => bx(Expr::Const(Const::Kind)), + name => bx(Expr::Var(V(Label::from(name.to_owned()), 0))), + } + } + }, ); rule!(empty_record_literal<RcExpr>; @@ -835,7 +749,7 @@ rule!(non_empty_record_type<(RcExpr, BTreeMap<Label, RcExpr>)>; ); named!(partial_record_entries<(RcExpr, BTreeMap<Label, RcExpr>)>; - children!(expr: expression, entries*: record_entry) => { + children!(expr: expression, entries..: record_entry) => { (expr, entries.collect()) } ); @@ -880,7 +794,7 @@ rule!(non_empty_union_type_or_literal ); rule!(union_type_entries<BTreeMap<Label, RcExpr>>; - children!(entries*: union_type_entry) => { + children!(entries..: union_type_entry) => { entries.collect() } ); @@ -890,7 +804,7 @@ rule!(union_type_entry<(Label, RcExpr)>; ); rule!(non_empty_list_literal_raw<RcExpr>; - children!(items*: expression) => { + children!(items..: expression) => { bx(Expr::NEListLit(items.collect())) } ); @@ -903,7 +817,7 @@ pub fn parse_expr(s: &str) -> ParseResult<RcExpr> { let pairs = DhallParser::parse(Rule::final_expression, s)?; // Match the only item in the pairs iterator // println!("{}", debug_pair(pairs.clone().next().unwrap())); - match_iter!(@panic; pairs; (p) => expression(p)) + iter_patterns::destructure_iter!(pairs; [p] => expression(p)).unwrap() // Ok(bx(Expr::BoolLit(false))) } |