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Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Niels Lohmann
|
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 |