StringBuilder 与 Ropes
早上好，
我正在编写一个语言解析器，并且正在寻找用于回滚缓存的最佳结构，该结构当前执行以下操作：
- 当从流中请求新字符时，该字符被添加到缓存中，以防回滚被要求。
- 当请求回滚时，返回到缓存中的某个点，以便当请求另一个字符时，它会从那里获取它。
- 找到令牌后，删除回滚缓存中直到当前位置的所有内容。
简而言之，我很想知道您认为哪种数据结构是最佳数据结构：
- 优先级 1：附加字符（codePoints 将是一个受欢迎的添加）
- 优先级 2：执行子字符串（例如 StringBuilder.delete(...) ）关于数据结构（或完全清除）
- 优先级 3：能够创建缓存字符串（例如 StringBuilder.toString()）
我希望很快能收到您的来信！
Good morning,
I am writing a language parser, and am looking for the best structure to use for a rollback cache which currently does the following:
- When requesting a new character from the stream, the character is added to the cache, in case a rollback is requested.
- When a rollback is requested, go back to a certain point in the cache so that when another character is requested, it gets it from there instead.
- When a token is found, remove everything in the rollback cache up to the current position.
So in short, I would love to know which you feel to be the best data structure for:
- Priority 1: appending characters (codePoints would be a welcome addition)
- Priority 2: Doing a substring (such as StringBuilder.delete(...)) on the data structure (or clearing completely)
- Priority 3: Being able to create a string of the cache (e.g. StringBuilder.toString())
I hope to hear from you soon!
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如果我是您，对于这样的专门用途以及可能的性能和资源限制，我会从基元实现我自己的缓冲区。我认为适应现有的结构会更麻烦。当然，如果不影响的话，我会尽量遵循众所周知的相关接口，例如
CharSequence、Appendable、List> 等If I were you, for such a specialised use and with possible performance and resource constraints, I'd implement my own buffer from primitives. I think it's more trouble adapting existing structures. Of course, if it didn't hurt, I'd try to conform to the well known relevant interfaces, such as
CharSequence,Appendable,List, etc.我怀疑 StringBuilder 和
PushbackReader 的组合会给你你所需要的。使用StringBuilder积累字符并创建token String，使用PushbackReader的mark和reset方法实现回滚。或者，将整个输入文件作为字符串预读取，然后通过索引字符串并获取子字符串来实现分词器。
I suspect that a combination of a StringBuilder and
PushbackReaderwill give you what you need. Use the StringBuilder to accumulate characters and create token Strings, and the PushbackReader'smarkandresetmethods to implement rollback.Alternatively, pre-read the entire input file as a String and then implement the tokenizer by indexing the String and taking substrings.