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Niels LohmannandClaude Opus 4.8
84939c11be
scan_number() reads a number one character at a time through the input adapter (get()) and appends each byte to token_buffer (add()) before converting. For contiguous input, the per-character get()/add() overhead dominates: it is roughly two thirds of the time spent on number-heavy parsing, far more than the value conversion itself. Add scan_number_bulk_contiguous(), which parses the whole number token straight from the input buffer: it validates and classifies the extent with the same grammar as scan_number()'s state machine, materializes token_buffer in one copy (substituting the locale decimal point exactly as scan_number() does), advances the adapter, and reuses the shared convert_number() tail. On anything it does not recognize as a well-formed number it makes no state change and returns token_type::uninitialized, so the caller falls back to scan_number(), which then produces the exact diagnostic. Errors and their positions are therefore unchanged. The conversion tail is factored out of scan_number() into convert_number() so both scanners share it; the fast path is selected by tag dispatch on the existing bulk_scan capability, so streaming/wide/user adapters are unaffected. Measured on pointer input, g++ 13 -O3: - integers: parse +65%, accept +98% - floats: parse +39%, accept +70% Verified: 2,000,000 randomized number documents (including overflow-range integers, long digit strings and %.17g doubles) parse identically via the contiguous path and the streaming byte path, matching value, type and round-trip text; the locale suite and existing parser/lexer/conversions/ deserialization tests pass; a new "lexer number fast path" test checks contiguous-vs-streaming parity, token classification, and that malformed numbers are rejected identically. Pure C++11, no intrinsics. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AXcDtEma2PjxgmPS9cQGzA Signed-off-by: Niels Lohmann <mail@nlohmann.me>