Positive and negative look-ahead assertions #95
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milseman force-pushed the progressive_avowals branch from 1ffa8cb to 4ed9b39 Compare 
milseman force-pushed the progressive_avowals branch from 332da1e to 50ecd39 Compare 
| | ||
| let positive = kind == .lookahead | ||
| assert(positive || kind == .negativeLookahead) | ||
| _ = """ |
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Can we use a comment instead? What's the benefit of using a string literal?
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Looks prettier in the editor (and sometimes better indentation than a multi-line comment), but I can use comments
| case .lookahead, .negativeLookahead, | ||
| .lookbehind, .negativeLookbehind: | ||
| try compileLookaround(g.kind.value, g.child) |
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We could use a Lookaround enum in the AST to group these four cases. Then compileLookaround(_:_:) would not need to handle unreachable cases.
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Added a var lookaroundKind: (forwards: Bool, positive: Bool)? to Group. This is probably a little more useful than an enum, which we'd want to immediately destructure or add these APIs to anyways. If we have more uses for more semantic info here, we can make the enum.
milseman force-pushed the progressive_avowals branch from 50ecd39 to 4ae4d4e Compare | @swift-ci please test linux platform |
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Compiler support by using save points.