In addition to a tiny performance improvement outlined below,
the CPU profile of traverseDoc is now more readable.
Also anonymous arrow functions changed to named regular functions
so that they are properly displayed in the CPU profile,
and moved to outer scope where there's no closure
so that they aren't re-created (this change's performance is dependent
on JS engine implementation and optimization details).
Before (profile):
```
7129.9 ms 5.43 % 13349.9 ms 10.18 % traverseDocRec
7067.4 ms 5.39 % 11285.5 ms 8.60 % traverseDocRec
31.5 ms 0.02 % 1031.9 ms 0.79 % traverseDoc
23.6 ms 0.02 % 12313.4 ms 9.39 % traverseDoc
2.6 ms 0.00 % 0.3 ms 0.00 % (anonymous)
1.7 ms 0.00 % 1.7 ms 0.00 % call
1.6 ms 0.00 % 1.6 ms 0.00 % call
0.5 ms 0.00 % 0.5 ms 0.00 % conditionalGroup
0.4 ms 0.00 % 0.4 ms 0.00 % printDocToString$1
0.1 ms 0.00 % 0.1 ms 0.00 % printGenerically
0.1 ms 0.00 % 0.1 ms 0.00 % t
0.1 ms 0.00 % 0.1 ms 0.00 % ifBreak
0.1 ms 0.00 % 0.1 ms 0.00 % (anonymous)
0 ms 0 % 0.1 ms 0.00 % forEach
```
After (profile):
```
6937.9 ms 5.37 % 12872.5 ms 9.97 % traverseDoc
5944.0 ms 4.60 % 11047.3 ms 8.55 % propagateBreaks
735.7 ms 0.57 % 1358.3 ms 1.05 % findInDoc
257.9 ms 0.20 % 466.7 ms 0.36 % findInDoc
0.1 ms 0.00 % 0.1 ms 0.00 % has
0.1 ms 0.00 % 0.1 ms 0.00 % printArgumentsList
```
Before (performance):
```
cat ../LspLanguageService.js | NODE_ENV=production node --inspect-brk ./dist/bin-prettier.js --stdin-filepath LspLanguageService.js --loglevel debug --debug-repeat 1000 > /dev/null
Debugger listening on ws://127.0.0.1:9229/4b52c027-ef62-49d6-8770-179e805a0f43
For help see https://nodejs.org/en/docs/inspector
Debugger attached.
[debug] normalized argv: {"color":true,"editorconfig":true,"stdin-filepath":"LspLanguageService.js","loglevel":"debug","debug-repeat":1000,"plugin-search-dir":[],"plugin":[],"ignore-path":".prettierignore","config-precedence":"cli-override","_":[]}
[debug] resolve config from '/Users/ivanbabak/_sompylasar/_github/prettier-2/LspLanguageService.js'
[debug] loaded options `null`
[debug] applied config-precedence (cli-override): {"filepath":"LspLanguageService.js"}
[debug] '--debug-repeat' option found, running formatWithCursor 1000 times.
[debug] '--debug-repeat' measurements for formatWithCursor: {
[debug] "repeat": 1000,
[debug] "hz": 7.774598830700336,
[debug] "ms": 128.624
[debug] }
```
After (performance):
```
cat ../LspLanguageService.js | NODE_ENV=production node --inspect-brk ./dist/bin-prettier.js --stdin-filepath LspLanguageService.js --loglevel debug --debug-repeat 1000 > /dev/null
Debugger listening on ws://127.0.0.1:9229/aa76e134-a68c-44ed-89a8-efb68bc46baa
For help see https://nodejs.org/en/docs/inspector
Debugger attached.
[debug] normalized argv: {"color":true,"editorconfig":true,"stdin-filepath":"LspLanguageService.js","loglevel":"debug","debug-repeat":1000,"plugin-search-dir":[],"plugin":[],"ignore-path":".prettierignore","config-precedence":"cli-override","_":[]}
[debug] resolve config from '/Users/ivanbabak/_sompylasar/_github/prettier/LspLanguageService.js'
[debug] loaded options `null`
[debug] applied config-precedence (cli-override): {"filepath":"LspLanguageService.js"}
[debug] '--debug-repeat' option found, running formatWithCursor 1000 times.
[debug] '--debug-repeat' measurements for formatWithCursor: {
[debug] "repeat": 1000,
[debug] "hz": 7.888114977163907,
[debug] "ms": 126.773
[debug] }
```
- `--debug-benchmark` uses `benchmark` module to produce statistically significant time measurements.
- `--debug-repeat` uses a naive loop and measures just the average run time, but useful for profiling to highlight hot functions.
Ivan Babak