Define the PdfSource trait abstraction over PDF byte sources. This trait
provides a uniform API for reading PDF data from different sources:
local files (MmapSource, FileSource), and eventually remote HTTPS PDFs.
Trait features:
- Read + Seek + Send + Sync supertrait bounds for rayon page-parallelism
- len() returns total source length
- read_range() returns Bytes for zero-copy slicing
- prefetch() with no-op default (MmapSource overrides for MADV_SEQUENTIAL)
MmapSource:
- Memory-mapped file access via memmap2
- Applies MADV_SEQUENTIAL advice via prefetch()
- Zero-copy read_range() using Bytes::copy_from_slice()
- Fallback for platforms/filesystems where mmap fails
FileSource:
- Standard I/O implementation using std::fs::File
- Read+Seek delegation to underlying File
- read_range() uses try_clone() for thread-safe concurrent access
Re-exports from pdftract-core::source::PdfSource.
Verification note: notes/pdftract-1mmq9.md documents completion status.
Parser module migration to use new PdfSource is deferred to follow-up.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
