背景

最近在 Emacs 中使用 helm-projectile-find-file 命令搜索源码文件时，发现卡顿很严重。后寻找资料发现原来是 helm 的搜索框内默认使用了 Fuzzy 搜索方式，导致搜索时间复杂度上升。

解决方案

只需要在待搜索字符串前输入一个空格即可取消 Fuzzy 搜索模式。比如想搜索 ArrayList.java ，则需输入 [space]ArrayList.java （注意：[space] 表示空格）

查阅以下 Helm 的帮助文档可知当输入空格时，将不启用 Fuzzy 模式。

All that you write in minibuffer is interpreted as a regexp or
multiple regexps if separated by a space.  This is true for most
sources unless the developer of the source has disabled it or
have choosen to use fuzzy matching.  Even if a source has fuzzy
matching enabled, Helm will switch to multi match as soon as it
detects a space in the pattern.  It may also switch to multi match
as well if pattern starts with a "^" beginning of line sign.  In
those cases each pattern separated with space should be a regexp
and not a fuzzy pattern.  When using multi match patterns, each
pattern starting with "!" is interpreted as a negation i.e.
match everything but this.