(restLen() < patternsize()) return context.nil;` checks in
`!headonly`.
(https://github.com/ruby/strscan/pull/110)
- before: #109
## Why?
d31274f41b/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java (L371-L373)
This means the following :
`if (str.size() - curr < pattern.size()) return context.nil;`
A similar check is made within `StringSupport#index()` within
`!headonly`.
be7815ec02/core/src/main/java/org/jruby/util/StringSupport.java (L1706-L1720)
```Java
public static int index(ByteList source, ByteList other, int offset, Encoding enc) {
int sourceLen = source.realSize();
int sourceBegin = source.begin();
int otherLen = other.realSize();
if (otherLen == 0) return offset;
if (sourceLen - offset < otherLen) return -1;
```
- source = `strBL`
- other = `patternBL`
- offset = `strBeg + curr`
This means the following :
`if (strBL.realSize() - (strBeg + curr) < patternBL.realSize()) return
-1;`
Both checks are the same.
## Benchmark
It shows String as a pattern is 2.40x faster than Regexp as a pattern.
```
$ benchmark-driver benchmark/check_until.yaml
Warming up --------------------------------------
regexp 7.613M i/s - 7.593M times in 0.997350s (131.35ns/i)
regexp_var 7.793M i/s - 7.772M times in 0.997364s (128.32ns/i)
string 13.222M i/s - 13.199M times in 0.998297s (75.63ns/i)
string_var 15.283M i/s - 15.216M times in 0.995667s (65.43ns/i)
Calculating -------------------------------------
regexp 10.003M i/s - 22.840M times in 2.283361s (99.97ns/i)
regexp_var 9.991M i/s - 23.378M times in 2.340019s (100.09ns/i)
string 23.454M i/s - 39.666M times in 1.691221s (42.64ns/i)
string_var 23.998M i/s - 45.848M times in 1.910447s (41.67ns/i)
Comparison:
string_var: 23998466.3 i/s
string: 23453777.5 i/s - 1.02x slower
regexp: 10002809.4 i/s - 2.40x slower
regexp_var: 9990580.1 i/s - 2.40x slower
```
https://github.com/ruby/strscan/commit/843e931d13
e61bb75a86