Related to this question, based on a comment of user Eric Lippert.
Is there any scenario where the Rope data structure is more efficient than a string builder? It is some people's opinion that rope data structures are almost never better in terms of speed than the native string or string builder operations in typical cases, so I am curious to see realistic scenarios where indeed ropes are better.
In computer programming, a rope, or cord, is a data structure composed of smaller strings that is used to efficiently store and manipulate a very long string.
A rope is a data structure used to represent strings. Ropes are typically implemented with B-trees [L1 ] of (possibly immutable) strings. The potential immutability of source strings makes rope a good candidate for a mutable string structure on systems where the native string representation is immutable, such as Java.
StringBuilder class can be used when you want to modify a string without creating a new object. For example, using the StringBuilder class can boost performance when concatenating many strings together in a loop.
The documentation for the SGI C++ implementation goes into some detail on the big O behaviours verses the constant factors which is instructive.
Their documentation assumes very long strings being involved, the examples posited for reference talk about 10 MB strings. Very few programs will be written which deal with such things and, for many classes of problems with such requirements reworking them to be stream based rather than requiring the full string to be available where possible will lead to significantly superior results. As such ropes are for non streaming manipulation of multi megabyte character sequences when you are able to appropriately treat the rope as sections (themselves ropes) rather than just a sequence of characters.
Significant Pros:
Significant Cons:
This leads to a few 'obvious' uses (the first mentioned explicitly by SGI).
There are cases where domain specific behaviour in the string can be coupled with relatively simple augmentations to the Rope implementation to allow:
As you can see from the examples listed, all fall well into the 'niche' category. Further, several may well have superior alternatives if you are willing/able to rewrite the algorithm as a stream processing operation instead.
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