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@@ -133,10 +133,10 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
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ahead, so the stream is left exactly where it would be after reading one character at a time. With glibc
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and the Apple C library, the characters the `#!cpp FILE` holds in its buffer are scanned in bulk like a stream's;
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elsewhere a `#!cpp FILE*` is read one character at a time. Where the C library has unlocked stdio functions, the
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file is locked only once, so other threads that use the same `FILE` object wait until parsing is done. See
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[input sources and performance](../../features/parsing/index.md#input-sources-and-performance),
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[`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md), and
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[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md).
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file is locked only once, so other threads that use the same `FILE` object wait until parsing is done, unless
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[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) is defined to `1`. See
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[input sources and performance](../../features/parsing/index.md#input-sources-and-performance) and
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[`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md).
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## Examples
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@@ -313,10 +313,6 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
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it as end of input; planned to become the default in version 4.0.0.
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- Extended empty-input detection to also cover an `std::istream` without a stream buffer, and fixed a crash
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(`std::terminate`) when parsing from an `std::istream` with `eofbit` in its exception mask, in version 3.13.0.
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- Fixed the position that a [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101) reports for an
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unexpected number that is followed by a line feed in version 3.13.0: for the input `1`, line feed, `2`, line feed,
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version 3.12.0 reported "line 2, column 0" and version 3.13.0 reports "line 2, column 1"; for `1 2` and a line feed,
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the report was "line 1, column 0" and is now "line 1, column 3".
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- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
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([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) restores reading one character at a
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time).
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@@ -124,8 +124,8 @@ consumer `sax` has a super-linear complexity.
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A UTF-8 byte order mark is silently ignored.
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When reading from a `#!c FILE*`, where the C library has unlocked stdio functions (see
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[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)), the file is locked while it is parsed.
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When reading from a `#!c FILE*` where the C library has unlocked stdio functions, the file is locked while it is parsed,
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unless [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) is defined to `1`.
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The lock is recursive, so the SAX handler may use the same file with stdio functions, but it must not wait for another
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thread that uses the same `FILE` object.
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@@ -67,7 +67,3 @@ Constant.
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## Version history
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- Added in version 3.12.0.
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- Fixed in version 3.13.0: in version 3.12.0, the start position of a string that contains escape sequences (for
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example `#!cpp "\n"` or `#!cpp "\u00e4"`) was too large, by the number of bytes the escape sequences add to the
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source text. The position is now always that of the opening `"`. The "(bytes a-b)" range in the messages of
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[`JSON_DIAGNOSTICS`](../macros/json_diagnostics.md) was wrong in the same way.
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@@ -125,5 +125,3 @@ When the macro is not defined, the library will define it to its default value.
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## Version history
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- Added in version 3.12.0.
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- Fixed in version 3.13.0: in version 3.12.0, [`start_pos()`](../basic_json/start_pos.md) of a string that contains
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escape sequences was too large; it is now the position of the opening `"`.
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@@ -80,6 +80,12 @@ them faster than others:
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| `#!cpp FILE*` | with glibc and the Apple C library, the characters the `FILE` holds in its buffer are scanned in bulk like a stream's; elsewhere one character at a time; where the C library has unlocked stdio functions, the file is locked once for the whole parse |
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| other iterator ranges (e.g., `#!cpp std::list<char>`, `#!cpp std::istreambuf_iterator<char>`), wide strings | one character at a time |
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Defining [`JSON_DISABLE_STREAM_BULK_SCAN`](../../api/macros/json_disable_stream_bulk_scan.md) to `1` turns off the bulk
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scan of a stream buffer, so a `#!cpp std::istream` is read one character at a time. Defining
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[`JSON_DISABLE_UNLOCKED_FILE_IO`](../../api/macros/json_disable_unlocked_file_io.md) to `1` makes a `#!cpp FILE*` read
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every character with `std::fgetc`, without locking the file for the whole parse and without the bulk scan of its buffer
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(which `JSON_DISABLE_STREAM_BULK_SCAN` does not affect). Neither changes any result.
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Input in one block of memory is read even faster with the default options (no
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[parser callback](../../api/basic_json/parser_callback_t.md), no comments, no trailing commas, and for `sax_parse()`
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`strict = true`): `parse()`, `accept()`, and `sax_parse()` then read the grammar and the tokens in one loop over the
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@@ -29,8 +29,11 @@ up. Nothing is read ahead, so the stream is left exactly where it would be after
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[`operator>>`](../api/operator_gtgt.md) can still read several values from one stream. A stream buffer without a get
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area is read one character at a time. Where the C library has unlocked stdio functions, a `#!cpp FILE*` is locked once
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per parse instead of once per character, and with glibc and the Apple C library, the characters in its buffer are
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scanned in bulk as a stream's get area is. See
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[input sources and performance](parsing/index.md#input-sources-and-performance) for the full table. Parsing from a
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scanned in bulk as a stream's get area is.
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[`JSON_DISABLE_STREAM_BULK_SCAN`](../api/macros/json_disable_stream_bulk_scan.md) turns off the bulk scan of streams, and
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[`JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md) both the single lock and the bulk scan
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of a `#!cpp FILE*`. See [input sources and performance](parsing/index.md#input-sources-and-performance) for the full
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table. Parsing from a
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stream takes about 1.15 to 1.45 times as long as parsing an equivalent `#!cpp std::string`, which `parse()` reads with
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a parser of its own (see there).
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