Bye bye, fast compilation times

[Nathan S.]

On Tuesday, 6 February 2018 at 22:29:07 UTC, Walter Bright wrote:
> nobody uses regex for lexer in a compiler.

Some years ago I was surprised when I saw this in Clojure's 
source code. It appears to still be there today:

https://github.com/clojure/clojure/blob/1215ba346ffea3fe48def6ec70542e3300b6f9ed/src/jvm/clojure/lang/LispReader.java#L66-L73

---
static Pattern symbolPat = 
Pattern.compile("[:]?([\\D&&[^/]].*/)?(/|[\\D&&[^/]][^/]*)");
//static Pattern varPat = 
Pattern.compile("([\\D&&[^:\\.]][^:\\.]*):([\\D&&[^:\\.]][^:\\.]*)");
//static Pattern intPat = Pattern.compile("[-+]?[0-9]+\\.?");
static Pattern intPat =
		Pattern.compile(
				"([-+]?)(?:(0)|([1-9][0-9]*)|0[xX]([0-9A-Fa-f]+)|0([0-7]+)|([1-9][0-9]?)[rR]([0-9A-Za-z]+)|0[0-9]+)(N)?");
static Pattern ratioPat = 
Pattern.compile("([-+]?[0-9]+)/([0-9]+)");
static Pattern floatPat = 
Pattern.compile("([-+]?[0-9]+(\\.[0-9]*)?([eE][-+]?[0-9]+)?)(M)?");
---