Engine: Compute relative file paths lazily - #2262
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marcoroth merged 2 commits intoAug 17, 2026
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Avoid normalizing each template filename during context construction when compilation does not consume the relative path. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: ccc00bcf-145f-4f65-8675-5d004f02dd98
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August 17, 2026 20:20
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Cache the lazily derived path through a private mutable holder so VisitorContext can remain frozen. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 30890d9a-a37a-4e59-b7bc-f23153d5768a
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Aug 17, 2026
| @file_path = self.class.coerce_file_path(file_path) | ||
| @project_path = self.class.coerce_project_path(project_path) | ||
| @relative_file_path = self.class.derive_relative_file_path(@file_path, @project_path) | ||
| @relative_file_path_cache = [] #: Array[String] |
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@marcoroth this approach keeps VisitorContext frozen, FYI.
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Thank you @joelhawksley! 馃檹馃徏
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This was referenced Aug 17, 2026
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This pull request stops `VisitorContext` from asking the operating system where it is for every template it builds a context for. `coerce_project_path` falls back to `Pathname.new(Dir.pwd)` when no project path is given, and it ran during construction. The project path is only read when a visitor, a diagnostic, an overlay or the relative file path asks for it, so a template compiled without any of those still paid for a `getcwd` and two allocations. Deriving it on demand takes about 7% off compile time over the `examples/` corpus, measured A/B interleaved against `main`. The value is unchanged. `coerce_project_path` keeps its behavior for a caller that passes a path, and the derived one is cached through the same mutable holder #2262 introduced for the relative file path, so the context can stay frozen. Follow-up to #2262, which left this the last eagerly computed field on the context.
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This pull request stops `VisitorContext` from asking the operating system where it is for every template it builds a context for. `coerce_project_path` falls back to `Pathname.new(Dir.pwd)` when no project path is given, and it ran during construction. The project path is only read when a visitor, a diagnostic, an overlay or the relative file path asks for it, so a template compiled without any of those still paid for a `getcwd` and two allocations. Deriving it on demand takes about 7% off compile time over the `examples/` corpus. The value is unchanged. `coerce_project_path` keeps its behavior for a caller that passes a path, and the derived one is cached through the same mutable holder #2262 introduced for the relative file path, so the context can stay frozen. Follow-up to #2262.
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What
Compute
VisitorContext#relative_file_pathon demand instead of eagerly duringcontext construction.
Herb::Enginecreates a context for every template, but the relative path isprimarily consumed by diagnostics, overlays, debug output, and visitors that
explicitly request it. Valid templates compiled without those features
previously still paid for
Pathname#absolute?, path joining,Pathname#relative_path_from, and#to_s.The public behavior is unchanged:
relative_file_path, context hash access,merging, inspection, and serialization still return the same value. A
regression test verifies that derivation does not happen during initialization.
Split out of #1872.
Benchmark
Measured
Herb::Enginecompilation overmarcoroth/herb-corpusat5560d823, using Ruby 4.0.2.The benchmark compiled the 36,046 corpus templates accepted by both variants
with a filename and project path,
escape: true, no visitors, non-strictparsing, and Ruby validation disabled. Results are medians of three full-corpus
runs:
main(cc3eb8bc)Generated Ruby was byte-identical in every run
(
aee36910bcd428792272440a7d39cabcd14c641544c6e35e2b610a14fbd9892b).