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* Speed up whitespace skipping in the lexer lexer::skip_whitespace() called get() for every whitespace byte, and get() checks the (almost always false, once past the first character) next_unget flag on every call. skip_whitespace() now reads its first character with get() (needed to honor a pending unget() left over from finishing the previous token, e.g. scan_number() always ungets the character that terminated the number) and every further whitespace character with a new get_ignoring_pending_unget() variant that skips that branch, since nothing in the loop calls unget(). This is a narrower fix than the full contiguous-buffer bulk-skip suggested in the issue (scan a run of whitespace directly in the adapter's buffer and update position counters once per run). That approach depends on bulk-scan adapter infrastructure (supports_bulk_scan/bulk_data()/bulk_skip()) introduced by the open, unmerged parser-performance PR #5283, which this change intentionally does not depend on or replicate. Building new bulk-scan adapter infrastructure from scratch was judged out of scope/riskier than warranted here, so this change is limited to the safe, always-correct improvement of removing redundant per-character bookkeeping from the existing byte-at-a-time loop; full bulk-skipping is left as future work once #5283 (or equivalent adapter support) lands. Line/column/byte-offset bookkeeping is untouched and verified bit-for-bit identical before and after this change, including for pretty-printed (dump(4)) input with embedded newlines. Fixes #5412 Stacked on top of the PR for #5411 (branch issue-5411-lexer-skip-conversion). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix codegen regression in skip_whitespace() from #5490 Benchmarking found the get()/get_ignoring_pending_unget() split in skip_whitespace() made long whitespace runs (e.g. indentation in pretty-printed JSON) 1.75x-3.2x SLOWER instead of faster, reproducible with both Apple Clang and GCC. Root cause: rewriting the loop from a plain do-while into an initial get() followed by a while-loop defeated the compiler's ability to keep the input adapter's read/end pointers in registers across iterations; both compilers instead reloaded them from memory on every character. The function split itself was not the problem (it still fully inlines); the loop's control-flow shape was. The fix keeps the same two-function structure but restores a do-while shape (guarded by an if for the "first char not whitespace" case), which lets both compilers hoist the pointers back into registers, matching or beating pre-#5490 performance. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Share the position-counter bump between get() and get_ignoring_pending_unget() Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Extract current_is_whitespace() to deduplicate skip_whitespace()'s two whitespace checks Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use a raw string literal for the multi-line error-position test input Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy raw-string-literal finding and guard a new test against JSON_NOEXCEPTION The issue #5412 whitespace-skipping test added a check_error() helper that relies on catching json::parse_error to verify the exception message; under JSON_NOEXCEPTION, JSON_THROW aborts instead of throwing, which crashed ci_test_noexceptions (and cascaded into the other ci_cmake_options jobs). Guard the whole section with #if !defined(JSON_NOEXCEPTION), matching the existing pattern used by sibling tests in this file. Also switch one escaped string literal to a raw string literal to satisfy clang-tidy's modernize-raw-string-literal check. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>