deploy: 54f6b3ef06

api/basic_json/operator%5B%5D.md

@@ -92,12 +92,20 @@ Strong exception safety: if an exception occurs, the original value stays intact
     For the **const** version, an object key or array index in `ptr` that does not exist is not reported by an
     exception, but is undefined behavior (see the notes below). Use [`at`](at.md) for checked access.
 
+    If the **non-const** version throws, the value is left unchanged: values it created for earlier reference tokens
+    of `ptr` are removed again. This also holds for exceptions such as `#!cpp std::bad_alloc` or
+    `#!cpp std::length_error` thrown while padding an array up to a very large index. With custom
+    [template parameters](../../features/types/template_parameters.md), this requires that `erase()` of the object and
+    array types and the move operations of the custom base class do not throw.
+
 ## Complexity
 
 1. Constant if `idx` is in the range of the array. Otherwise, linear in `idx - size()`.
 2. Logarithmic in the size of the container.
 3. Logarithmic in the size of the container.
-4. Logarithmic in the size of the container.
+4. Linear in the number of reference tokens of `ptr`; for each of them, logarithmic in the size of the object, or
+   constant for an array. When the non-const version pads an array with `#!json null` values, it is additionally
+   linear in `idx - size()` for that array.
 
 ## Notes
 
@@ -145,6 +153,14 @@ Strong exception safety: if an exception occurs, the original value stays intact
         specified by the JSON Pointer RFC; it is this library's own, intentional disambiguation rule. See also
         [JSON Pointer](../../features/json_pointer.md).
 
+    !!! warning "Large array indices"
+
+        As the array is filled up with `#!json null` values to the given index, the memory used grows with the index
+        and not with the size of the pointer: on a 64-bit platform, the index `10000000` allocates about 160 MB.
+        The library does not limit the index, so check the array indices of a JSON pointer from untrusted input
+        before using it with the non-const version. See
+        [Parsing untrusted input](../../features/parsing/untrusted_input.md#json-pointers-and-flattened-keys).
+
 !!! warning "Deprecation"
 
     Overload (4) also accepts a [`json_pointer`](../json_pointer/index.md) whose template argument is a `basic_json`
@@ -564,4 +580,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
 4. Added in version 2.0.0. A missing array index in the const version is guarded by a runtime assertion since
    version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
 [`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
-a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones.
+a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones. Fixed in version 3.13.0 to leave the value
+unchanged if the non-const version throws (strong exception safety, as documented); before, values created for earlier
+reference tokens of `ptr` were kept.