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Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Niels Lohmann
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4155e2938f |
Write json_view's dump() without a call or conversion per token (#5633)
* Write json_view's dump() without a call or conversion per token The default dump() (no indentation, no ensure_ascii) gets its own writer that makes the same walk and produces the same output: - the write position stays in a local variable instead of a member, so the compiler keeps it in a register across stores through aliasing char pointers; - strings and number tokens are copied with fixed-size 32-byte moves wherever enough source bytes remain, instead of one memcpy call per token; - the innermost open container lives in local variables; a stack that starts as a local array of 32 entries holds the rest; - unedited documents are walked through the node array in order, and integer tokens are read from the source directly. On top of that, float tokens of at most 15 significant digits are written straight from their digits via zmij::to_shortest() and write_shortest(), without converting to a double and back: such decimals are farther apart than a double's rounding interval, so the token's digits are the double's shortest digits. Tokens of 16+ digits, or edited values, still go through decimal_to_float(). The view's own NEON write_decimal() is removed in favor of the shared writer, and the dump output now grows in 64 KiB steps instead of being resized to its estimate at once. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix MSVC C4127 and Infer finding in the view serializer Test the template options through enabled() so that conditions combined with them are not constant, and mark the nav::value() null dereference as a false positive like materialize.hpp does. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix out-of-bounds read when dumping a float token of an unchecked image A float node of an image loaded with image_check::bounds can hold a token whose bytes are not digits, so its value need not have the digit count recorded in the node. write_double_at() passed that count to write_short_decimal(), which indexes its table of powers of ten by it: an assertion failure in debug builds, an out-of-bounds read in release builds. Use the counted overload only if the value has exactly that many digits, otherwise count them. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tidy the view serializer: doxygen block placement, enabled() for a constant Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use a named document in the dump test: root() of a temporary does not compile Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Test write_short_decimal and powers_of_ten_16 against to_chars Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy 22 findings in unit-to_chars.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Write doubles from their bits only where double is IEEE 754 binary64 Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Split the value and pointer edit tests off unit-json_view_edit.cpp The MinGW linker of the Windows clang jobs cannot link object files with more than 32767 sections ("relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'"). unit-json_view_edit.cpp has 35409 sections since the fast dump instantiates more code for editable documents, so its test cases "views and values", "deeply nested values", "pointers below a null value", and "strings of other documents are checked" move into unit-json_view_edit_values.cpp. The helper exception_of_call() that both files use moves into json_view_test_helpers.hpp. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Move the dump tests of this branch to unit-json_view_dump.cpp The dump and comparison tests moved to their own file in the dump pull request; the tests of the fast dump() join them there. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address review: one powers-of-ten table, literal sizes from the type - dtoa_impl::powers_of_ten() (10^0 to 10^19, one entry per line) replaces powers_of_ten_16() and the table of int_pow10() - put_literal() takes the length of a string literal from its type - small_stack holds the heap vector by reference - the growth step of the output buffer is written in hex Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Explain why the growth of the dump's stack is static Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me> |
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Niels Lohmann
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823eee3b59 |
Add editable json_documents: set, push_back, insert, and erase (#5630)
* Add editable json_documents: set, push_back, insert, and erase basic_json_document gets a second template parameter, Editable (false by default), plus the aliases json_editable_document, json_editable_view, ordered_json_editable_document and ordered_json_editable_view. Editable documents can change values and structure without rewriting the source text: set()/push_back() on values, keys, array indices and JSON pointers; insert() before an array element; erase() of an object key, array index or JSON pointer. New values and element sequences go into edit storage that the document owns and never moves, so views keep referring to their value across edits and a parsed node never moves. Read-only documents walk the plain node array and are unaffected. Strings are checked for UTF-8 on entry, so dump() of an editable document never throws type_error.316. Binary values cannot be stored (type_error.319). A seeded differential test applies random edits to an editable document and to the equivalent ordered_json and compares both after every step. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix old clang and MSVC C4127 in editable json documents Value-initialize the const std::less in find_parent (clang 3.4/3.6 do not implement DR 253), and test the Editable template argument through a function to avoid MSVC C4127. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Copy nested values into a document without recursion Counting and copying the nodes of a view or a basic_json value into an editable document recursed once per nesting level, so that a deeply nested value overflowed the stack. The four functions now walk the value with an explicit stack, as materialize() does. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not leave a half-assigned container when set_moved() throws assign() rewrote the kind, length and extent of a slot before set_moved() registered its new element sequence. set_moved() can throw (std::bad_alloc from reserving the bookkeeping vectors) for a slot that is not moved yet, which left a container without the moved flag that showed its old children. The bookkeeping is now reserved first (reserve_moved()), so that nothing after the first write to the slot can throw. block_of() reserves before it marks anything for the same reason. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Check strings copied from another document for valid UTF-8 An editable document only holds valid UTF-8, but copy_scalar() copied the strings and keys of a view of another document unchecked. A document of a weaker check (or a borrowed text that changed after parsing) could therefore bring ill-formed UTF-8 into it. The copy is checked now, with the error that dump() reports for the string; copies within the same document stay unchecked. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Allow the edit arena to grow up to 4 GiB - 1 bytes append_text() doubled the capacity of the arena and rejected the result if it exceeded 4 GiB, so that an arena of more than 2 GiB could not grow even though the 32-bit offsets of nodes address 4 GiB - 1 bytes. The capacity is now clamped to that limit (text_capacity()), and an append is rejected only if the bytes themselves do not fit. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Set a null value below a pointer as basic_json does set(json_pointer, value) turned a null parent into an object for every last reference token, so "/a/0" and "/a/-" below {"a":null} made {"a":{"0":1}}, where basic_json's operator[](json_pointer) makes an array. A null parent now becomes an array for "-" and for digit tokens (filled with nulls up to the index) and an object otherwise. An invalid index is reported before the parent changes. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Replace a container by a scalar in constant time once it is linked Replacing an array or object that spans several nodes by a scalar looks up its parent from the root (find_parent), which is linear in the size of the document: setting every element of a 20,000 element array took more than half a second. The parent only has to switch to links once; afterward the extent of the replaced value no longer matters. Nodes that an entry of a moved sequence links to are now marked (node_flags::linked), and assign() skips the lookup for them. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Update the json_view banner and type_error.319 for editable documents The banner still described a read-only view, and the documentation of type_error.319 listed set and push_back only, although insert rejects binary values as well. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Assign the member that lookups find when set() meets duplicate keys An editable document reads the last member of a repeated key (as the read-only document does), but set(object, key, value) assigned the first one: a view taken from object[key] before the call did not show the new value. It now assigns the last member's value, keeps the key at the position of its first occurrence (where materialize() puts it), and drops the other members. The seeded differential test now also edits documents whose objects repeat keys and compares every lookup (operator[], at, find, value, contains, count, and JSON pointers) with the parsed basic_json value. A targeted test covers duplicates before and after edits that move the object, in large objects with an index, in moved arrays, and in values copied from other documents. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Assign the first member when set() meets duplicate keys again Lookups find the first member of a repeated key again, so set(object, key, value) assigns that member (keeping the key where it is) and drops the others, as documented before, and a view taken from object[key] shows the new value. This undoes the code and documentation changes of |