使用 prolog DCG 查找 &替换 - 代码审查

问题描述

我想出了以下代码来替换 Request 中所有出现的 Find w/Replace &将答案放在 Result 中.这是使用 DCG，因此它们都是字符代码列表.客户端代码将使用的谓词是 substitute.

I came up w/ the following code to replace all occurences of Find w/ Replace in Request & put the answer in Result. This is using a DCG, so they are all lists of character codes. The predicate that client code would use is substitute.

findReplace(_, _, [], []) -->
    [].  % The end.
findReplace(Find, Replace, Result, ResultRest) -->
    Find,  % Found Find.
    { append(Replace, Intermediate, Result) },  % Put in Replace in Find's place.
    !,  % Make sure we don't backtrack & interpret Find as the next case.
    findReplace(Find, Replace, Intermediate, ResultRest).
findReplace(Find, Replace, [ C | Intermediate ], ResultRest) -->
    [ C ],  % Any other character.
    findReplace(Find, Replace, Intermediate, ResultRest).

substitute(Find, Replace, Request, Result):-
    phrase(findReplace(Find, Replace, Result, []), Request).

这适用于 SWI-Prolog.有没有人对我如何改进它有任何意见?我正在学习如何使用 DCG 的 &差异列表.例如，我加入了剪辑，以便在找到 Find 后，prolog 永远不会回溯 &在 [ C ] 情况下将其解释为普通字符.这是必要的，还是有更声明性的方法?

This works in SWI-Prolog. Does anyone have any comments on how I could improve it? I'm learning how to use DCG's & difference lists. E.g., I put in the cut so that, after finding Find, prolog doesn't ever backtrack & interpret that as an ordinary character in the [ C ] case. Is this needed, or is there a more declarative way of doing so?

另一个问题 - 是否有一个谓词已经可以用来做与替代相同的事情，也许是在原子上?

Another question - is there a predicate already available to do the same thing that substitute does, maybe on atoms?

提前致谢.

推荐答案

考虑使用半上下文表示法来替换 DCG 中的子序列:

Consider using semicontext notation to replace subsequences in DCGs:

eos([], []).

replace(_, _) --> call(eos), !.
replace(Find, Replace), Replace -->
        Find,
        !,
        replace(Find, Replace).
replace(Find, Replace), [C] -->
        [C],
        replace(Find, Replace).

substitute(Find, Replace, Request, Result):-
        phrase(replace(Find, Replace), Request, Result).

示例:

?- substitute("a", "b", "atesta", R), atom_codes(A, R).
R = [98, 116, 101, 115, 116, 98],
A = btestb.

此外，underscores_are_much_more_readable thanMixedCaseNamesAsYouSee.

Also, underscores_are_much_more_readable thanMixedCaseNamesAsYouSee.

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