Stop traversing whole subtrees to decide if syntax is one line or many#841
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Stop traversing whole subtrees to decide if syntax is one line or many#841jackfirth wants to merge 1 commit into
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`oneline-syntax?` and `multiline-syntax?` were implemented by counting every distinct source line among all the atoms in a syntax object, using a `syntax-search` stream fed through a rebellion transducer pipeline. Neither caller needs an exact count, and both build a lazy stream over the entire subtree even when the second line is found immediately. Counting directly with a recursive traversal that stops at two distinct lines cuts analysis time for `xrepl-lib/xrepl/xrepl.rkt` (1877 lines) from ~78 seconds to ~65 seconds. The traversal deliberately mirrors `syntax-search`'s shape, including its handling of improper lists and its treatment of non-list, non-atom syntax (such as vectors) as having no lines at all. Both implementations were run against every subform of several large source files, plus hand-built edge cases, with identical results on all 28,585 syntax objects. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Coverage is 96.59% — perf/syntax-line-count into master. No base build found for |
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oneline-syntax?andmultiline-syntax?counted every distinct source line among all the atoms in a syntax object, streaming the whole subtree through a transducer pipeline. Neither caller needs an exact count, and both build the full stream even when the second line turns up immediately.Counting with a direct traversal that stops at two distinct lines takes analysis of
xrepl-lib/xrepl/xrepl.rkt(1877 lines) from ~71s to ~63s.The new traversal deliberately mirrors
syntax-search's shape, including how it handles improper lists and how it treats non-list, non-atom syntax (vectors, say) as having no lines at all. I ran both implementations over every subform of several large source files plus some hand-built edge cases and got identical answers on all 28,585 syntax objects.raco test -p resyntaxpasses.Found by profiling, in the same vein as #800.
Measurement note: figures are the minimum of 3 runs after a warmup. An earlier version of this description said ~78s → ~65s; that baseline was taken on a thermally throttled machine and overstated the ratio. Repeated runs on identical code vary by up to ~6% here, so treat differences smaller than that as unresolved.