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Pull Request Overview
This PR optimizes the ConcatSource implementation by replacing rope-based string concatenation with direct string building using pre-allocated capacity. The changes improve performance by reducing intermediate allocations and avoiding the overhead of rope operations when building the final source string.
Key changes:
- Refactored
source()method to build strings directly with pre-allocated capacity instead of using rope - Added capacity pre-allocation to
buffer()method usingself.size()
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CodSpeed Performance ReportMerging #199 will improve performances by 81.88%Comparing Summary
Benchmarks breakdown
Footnotes
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ahabhgk
approved these changes
Nov 5, 2025
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Since the performance of the RspackSource
sizemethod has been optimized previously, it is a very good optimization to pre-allocate the capacity for String using the size method here.