Skip to content

Parser builder map transform throws #119

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 4 commits into from
Closed

Parser builder map transform throws #119

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
733b3c2
Added reversion to original if any parsers in `Zip` variations throw …
randomeizer Feb 8, 2022
133beab
Updated ParserBuilderTests to check correct consumption of the input
randomeizer Feb 8, 2022
5487594
Merge remote-tracking branch 'upstream/parser-builder-throws-2' into …
randomeizer Feb 11, 2022
d0bd54a
Added `throws` to map transform function
randomeizer Feb 11, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 5 additions & 5 deletions Sources/Parsing/Parsers/Map.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ extension Parser {
@_disfavoredOverload
@inlinable
public func map<NewOutput>(
_ transform: @escaping (Output) -> NewOutput
_ transform: @escaping (Output) throws -> NewOutput
) -> Parsers.Map<Self, NewOutput> {
.init(upstream: self, transform: transform)
}
Expand All @@ -25,18 +25,18 @@ extension Parsers {
public let upstream: Upstream

/// The closure that transforms output from the upstream parser.
public let transform: (Upstream.Output) -> NewOutput
public let transform: (Upstream.Output) throws -> NewOutput

@inlinable
public init(upstream: Upstream, transform: @escaping (Upstream.Output) -> NewOutput) {
public init(upstream: Upstream, transform: @escaping (Upstream.Output) throws -> NewOutput) {
self.upstream = upstream
self.transform = transform
}

@inlinable
@inline(__always)
public func parse(_ input: inout Upstream.Input) rethrows -> NewOutput {
self.transform(try self.upstream.parse(&input))
public func parse(_ input: inout Upstream.Input) throws -> NewOutput {
try self.transform(self.upstream.parse(&input))
Comment on lines +38 to +39
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Losing rethrows is probably the main reason why we'd want a dedicated operator for a throwing map. Combine does the same thing with tryMap. We're definitely open to adding tryMap! Want to start a discussion about tryMap and other potential throwing operators?

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I've started one at #121.

}
}
}
12 changes: 12 additions & 0 deletions Tests/ParsingTests/MapTests.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,18 @@ final class MapTests: XCTestCase {
XCTAssertEqual("42", try Int.parser().map(String.init).parse(&input))
XCTAssertEqual(" Hello, world!", Substring(input))
}

func testFail() {
enum MyError: String, Error, Equatable {
case fails
}

var input = "42 Hello, world!"[...].utf8
XCTAssertThrowsError(try Int.parser().map { _ in throw MyError.fails }.parse(&input)) { error in
XCTAssertEqual(error as? MyError, MyError.fails)
}
XCTAssertEqual(Substring(input), " Hello, world!"[...])
}

func testOverloadArray() {
let array = [1].map { "\($0)" }
Expand Down