This reverts commit 7148184d65.
There are four types of literals where escapes were normalized:
1. Strings ('\xAb' and "\xAb")
2. Regexes (/\xAb/)
3. Untagged template literals (`\xAb`)
4. Tagged template literals (tag`\xAb`)
However, changing the case of the escapes alters the runtime behavior of
in two of the above cases.
```js
/\xAb/.source === '\\xAb' // true
String.raw`\xAb` === '\\xAb' // true
```
So for regexes and tagged template literals the escapes must not be
changed. Instead of enforcing lowercase escapes in only 50% of the
different cases, it was decided not to bother with escapes at all.
Closes#562.
* Print \x and \u escapes in strings and regexes lowercase
Theoretically, we would want to do this for escapes int identifiers as
well. However, neither flow nor babylon preserves escapes in
identifiers. For example, `\u0061.\u{0061}` cannot be distinguished from
`a.a`. Nobody uses such escapes in real code anyway. It could also be
considered a feature that such escapes are converted to real unicode
characters.
* Update snapshots
* Normalize escapes in template literals
* Update snapshots
According to @mroch, "Flow is using CESU-8, not UTF-8. http://www.unicode.org/reports/tr26/ ". While this is being fixed in flow, we can easily work around it inside of prettier. The downside of this approach is that we can't convert those strings to single or double quotes anymore.
Babylon has a bug where it doesn't escape DirectiveLiteral properly. Except for `'use strict';`, this never happens in real world code, so let's put strings in a array in order to workaround this bug and have the same output on both parsers.
https://github.com/babel/babylon/issues/289
- This brings in the flow test suite that contains a ton of JavaScript parsing edge cases
- This creates snapshot tests using the pretty printer for all of them
- If uncomment `RUN_AST_TESTS` line in `tests/run_specs.js`, it checks ast(pretty_print(x)) == ast(x). Right now, "178 failed, 197 passed, 375 of 377 total". So half of the tests are not passing, most of them are crashes and many of the rest are subtle issues.
James Long