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-rw-r--r--dhall/src/parser.rs189
1 files changed, 126 insertions, 63 deletions
diff --git a/dhall/src/parser.rs b/dhall/src/parser.rs
index 93d5329..5075a24 100644
--- a/dhall/src/parser.rs
+++ b/dhall/src/parser.rs
@@ -23,6 +23,8 @@ pub type ParseError = pest::error::Error<Rule>;
pub type ParseResult<T> = Result<T, ParseError>;
pub fn custom_parse_error(pair: &Pair<Rule>, msg: String) -> ParseError {
+ let msg =
+ format!("{} while matching on:\n{}", msg, debug_pair(pair.clone()));
let e = pest::error::ErrorVariant::CustomError { message: msg };
pest::error::Error::new_from_span(e, pair.as_span())
}
@@ -69,7 +71,7 @@ fn debug_pair(pair: Pair<Rule>) -> String {
}
/* Macro to pattern-match iterators.
- * Panics if the sequence doesn't match;
+ * Panics if the sequence doesn't match, unless you use the @get_err entrypoint.
*
* Example:
* ```
@@ -93,7 +95,8 @@ fn debug_pair(pair: Pair<Rule>) -> String {
enum IterMatchError<T> {
NotEnoughItems,
TooManyItems,
- Other(T), // Allow other macros to inkect their own errors
+ NoMatchFound,
+ Other(T), // Allow other macros to inject their own errors
}
macro_rules! match_iter {
// Everything else pattern
@@ -111,7 +114,8 @@ macro_rules! match_iter {
// Optional pattern
(@match 0, $iter:expr, $x:ident? $($rest:tt)*) => {
match_iter!(@match 1, $iter $($rest)*);
- let $x = $iter.next();
+ #[allow(unused_mut)]
+ let mut $x = $iter.next();
match $iter.next() {
Some(_) => break Err(IterMatchError::TooManyItems),
None => {},
@@ -119,7 +123,8 @@ macro_rules! match_iter {
};
// Normal pattern
(@match 0, $iter:expr, $x:ident $($rest:tt)*) => {
- let $x = match $iter.next() {
+ #[allow(unused_mut)]
+ let mut $x = match $iter.next() {
Some(x) => x,
None => break Err(IterMatchError::NotEnoughItems),
};
@@ -128,7 +133,8 @@ macro_rules! match_iter {
// 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)*);
- let $x = match $iter.next_back() {
+ #[allow(unused_mut)]
+ let mut $x = match $iter.next_back() {
Some(x) => x,
None => break Err(IterMatchError::NotEnoughItems),
};
@@ -148,6 +154,7 @@ macro_rules! match_iter {
{
#[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($body);
@@ -163,107 +170,163 @@ macro_rules! match_iter {
};
}
-macro_rules! named {
- ($name:ident<$o:ty>; $submac:ident!( $($args:tt)* )) => (
- #[allow(unused_variables)]
- fn $name<'a>(pair: Pair<'a, Rule>) -> ParseResult<$o> {
- $submac!(pair; $($args)*)
- }
- );
-}
-
-macro_rules! named_rule {
- ($name:ident<$o:ty>; $submac:ident!( $($args:tt)* )) => (
- named!($name<$o>; match_rule!(
- Rule::$name => $submac!( $($args)* ),
- ));
- );
-}
-
-macro_rules! match_children {
+/* Extends match_iter with typed matches. Takes a callback that determines
+ * when a capture matches.
+ * 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) => {
+ * if $x >= 0 { Ok($x) } else { Err(()) }
+ * };
+ * (negative, $x:expr) => {
+ * if $x <= 0 { Ok($x) } else { Err(()) }
+ * };
+ * (any, $x:expr) => {
+ * Ok($x)
+ * };
+ * }
+ *
+ * let vec = vec![-1, 2, 3];
+ *
+ * match_iter_typed!(callback; vec.into_iter();
+ * (x: positive, y?: negative, z: any) => { ... },
+ * (x: negative, y?: any, z: any) => { ... },
+ * )
+ * ```
+ *
+*/
+macro_rules! match_iter_typed {
+ // Collect untyped arguments to pass to match_iter!
(@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident : $ty:ident, $($rest:tt)*)) => {
- match_children!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x), ($($rest)*))
+ match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x), ($($rest)*))
};
(@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident? : $ty:ident, $($rest:tt)*)) => {
- match_children!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x?), ($($rest)*))
+ match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x?), ($($rest)*))
};
(@collect, ($($vars:tt)*), ($($args:tt)*), ($($acc:tt)*), ($x:ident* : $ty:ident, $($rest:tt)*)) => {
- match_children!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x??), ($($rest)*))
+ match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*, $x??), ($($rest)*))
};
// Catch extra comma if exists
(@collect, ($($vars:tt)*), ($($args:tt)*), (,$($acc:tt)*), ($(,)*)) => {
- match_children!(@collect, ($($vars)*), ($($args)*), ($($acc)*), ())
+ match_iter_typed!(@collect, ($($vars)*), ($($args)*), ($($acc)*), ())
};
- (@collect, ($pairs:expr, $body:expr, $error:ident), ($($args:tt)*), ($($acc:tt)*), ($(,)*)) => {
+ (@collect, ($iter:expr, $body:expr, $callback:ident, $error:ident), ($($args:tt)*), ($($acc:tt)*), ($(,)*)) => {
let matched: Result<_, IterMatchError<ParseError>> =
- match_iter!(@get_err, $pairs; ($($acc)*) => {
- match_children!(@parse, $pairs, $($args)*);
+ 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 = Some(e),
+ Err(e) => $error = e,
};
};
- (@parse, $pairs:expr, $x:ident : $ty:ident $($rest:tt)*) => {
- let $x = $ty($x);
- let $x = match $x {
+ // Pass the matches through the callback
+ (@callback, $callback:ident, $iter:expr, $x:ident : $ty:ident $($rest:tt)*) => {
+ let $x = $callback!($ty, $x);
+ #[allow(unused_mut)]
+ let mut $x = match $x {
Ok(x) => x,
Err(e) => break Err(IterMatchError::Other(e)),
};
- match_children!(@parse, $pairs $($rest)*);
+ match_iter_typed!(@callback, $callback, $iter $($rest)*);
};
- (@parse, $pairs:expr, $x:ident? : $ty:ident $($rest:tt)*) => {
- let $x = $x.map($ty);
- let $x = match $x {
+ (@callback, $callback: ident, $iter:expr, $x:ident? : $ty:ident $($rest:tt)*) => {
+ let $x = $x.map(|x| $callback!($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_children!(@parse, $pairs $($rest)*);
+ match_iter_typed!(@callback, $callback, $iter $($rest)*);
};
- (@parse, $pairs:expr, $x:ident* : $ty:ident $($rest:tt)*) => {
- let $x = $x.map($ty).collect::<ParseResult<Vec<_>>>();
- #[allow(unused_mut)]
- let mut $x = match $x {
- Ok(x) => x.into_iter(),
+ (@callback, $callback: ident, $iter:expr, $x:ident* : $ty:ident $($rest:tt)*) => {
+ let $x = $x.map(|x| $callback!($ty, x)).collect();
+ let $x: Vec<_> = match $x {
+ Ok(x) => x,
Err(e) => break Err(IterMatchError::Other(e)),
};
- match_children!(@parse, $pairs $($rest)*);
+ #[allow(unused_mut)]
+ let mut $x = $x.into_iter();
+ match_iter_typed!(@callback, $callback, $iter $($rest)*);
};
- (@parse, $pairs:expr $(,)*) => {};
+ (@callback, $callback:ident, $iter:expr $(,)*) => {};
// Entrypoint
- ($pair:expr; $( ($($args:tt)*) => $body:expr ),* $(,)*) => {
+ (@get_err, $callback:ident; $iter:expr; $( ($($args:tt)*) => $body:expr ),* $(,)*) => {
{
- let pair = $pair;
#[allow(unused_mut)]
+ let mut iter = $iter;
#[allow(unused_assignments)]
- let mut last_error = None;
- #[allow(unused_mut)]
- let mut pairs = pair.clone().into_inner();
- #[allow(unreachable_code)]
+ let mut last_error = IterMatchError::NoMatchFound;
+ // Not a real loop; used for error handling
// Would use loop labels but they create warnings
+ #[allow(unreachable_code)]
loop {
$(
- match_children!(@collect, (pairs.clone(), $body, last_error), ($($args)*), (), ($($args)*,));
+ match_iter_typed!(@collect,
+ (iter.clone(), $body, $callback, last_error),
+ ($($args)*), (), ($($args)*,)
+ );
)*
- break Err(match last_error {
- Some(IterMatchError::Other(e)) => e,
- _ => custom_parse_error(
- &pair.clone(),
- format!(
- "No match found while matching on:\n{}",
- debug_pair(pair)
- )
- ),
- });
+ break Err(last_error);
}
}
};
+ ($($args:tt)*) => {
+ {
+ let ret: Result<_, IterMatchError<()>> = match_iter!(@get_err, $($args)*);
+ ret.unwrap()
+ }
+ };
+}
+
+macro_rules! named {
+ ($name:ident<$o:ty>; $submac:ident!( $($args:tt)* )) => (
+ #[allow(unused_variables)]
+ fn $name<'a>(pair: Pair<'a, Rule>) -> ParseResult<$o> {
+ $submac!(pair; $($args)*)
+ }
+ );
+}
+
+macro_rules! named_rule {
+ ($name:ident<$o:ty>; $submac:ident!( $($args:tt)* )) => (
+ named!($name<$o>; match_rule!(
+ Rule::$name => $submac!( $($args)* ),
+ ));
+ );
+}
+
+macro_rules! match_children_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)*);
+ result.map_err(|e| match e {
+ IterMatchError::Other(e) => e,
+ _ => custom_parse_error(&pair, "No match found".to_owned()),
+ })
+ }
+ };
}
macro_rules! with_captured_str {
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-25 15:08:20 +0000