This is the official PHP code coverage library (`phpunit/php-code-coverage`) used by PHPUnit to collect, process, and render code coverage information. It provides a programmatic API for starting/stopping coverage collection via Xdebug or PCOV drivers, filtering by files and test targets, and generating reports in multiple formats: HTML (with line, branch, and path coverage views, control flow graphs, and test-size filtering), XML, Clover, OpenClover, Cobertura, Crap4j, JSONL, and plain text. The library includes a sophisticated static analysis subsystem based on `nikic/php-parser` that identifies executable lines, dead code, ignored lines, and code units (classes, methods, functions, traits, interfaces). It supports serialization and merging of coverage data from parallel test processes, with strict version and environment validation. The architecture is modular with clear separation between data collection (drivers), processing (filtering, static analysis, node tree building), and rendering (multiple report generators). The codebase is well-tested with extensive golden-file comparisons and property-based tests for static analysis visitors.