emacs的regex替换

  好多编辑器都是正则表达式的替换的，比如emacs,其他没有尝试过，不过基本原理都应该是一样的。

   起因：在工作中碰到database的schema移植问题，比如将mysql

drop table if exists ems;

转换成oracle的：

drop table ems cascade constraints;

其中 ems 是变化的，其他都是固定不变。

emacs的解决办法是
M-x replace-regexp
回车输入：
drop table if exists \([a-z]*\);
再输入要替换的表达式：
drop table \1 cascade constraints;

DONE
简洁吧!

以下是官方文档的相关描述：

In replace-regexp, the newstring need not be constant: it can refer to all or part of what is matched by the regexp. `\&' in newstring stands for the entire match being replaced. `\d' in newstring, where d is a digit, stands for whatever matched the dth parenthesized grouping in regexp. To include a `\' in the text to replace with, you must enter `\\'. For example,



M-x replace-regexp RET c[ad]+r RET \&-safe RET

replaces (for example) `cadr' with `cadr-safe' and `cddr' with `cddr-safe'.



M-x replace-regexp RET \(c[ad]+r\)-safe RET \1 RET

可以看出，'\d'是对分组进行相应的替换