I thought this was a much more interesting topic, but the thread was closed almost 13 years ago. This shows how niche and narrow the regex space is, let alone on Mac.

唉，沒人關心的宇宙小眾的話題：Mac平台上的Regex (RegExp) 。

js 'good_luck_buddy'.split(/_(.*)/s) ['good', 'luck_buddy', ''] // ignore the third element

```python def split_user(userid): """ Return the user and domain parts from the given user id as a dict.

For example if userid is u'acct:seanh@hypothes.is' then return
{'username': u'seanh', 'domain': u'hypothes.is'}'

:raises InvalidUserId: if the given userid isn't a valid userid

"""
match = re.match(r"^acct:([^@]+)@(.*)$", userid)
if match:
    return {"username": match.groups()[0], "domain": match.groups()[1]}
raise InvalidUserId(userid)

```

jsdoc /* * @pattern /https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#()?&//=]*)/ */

🥳

```python doi_regexp = re.compile( r"(doi:\s|(?:https?://)?(?:dx.)?doi.org/)?(10.\d+(.\d+)/.+)$", flags=re.I ) """See http://en.wikipedia.org/wiki/Digital_object_identifier."""

handle_regexp = re.compile( r"(hdl:\s|(?:https?://)?hdl.handle.net/)?" r"([^/.]+(.[^/.]+)/.)$", flags=re.I ) """See http://handle.net/rfc/rfc3651.html. <Handle> = <NamingAuthority> "/" <LocalName> <NamingAuthority> = (<NamingAuthority> ".") <NAsegment> <NAsegment> = Any UTF8 char except "/" and "." <LocalName> = Any UTF8 char """

arxiv_post_2007_regexp = re.compile(r"(arxiv:)?(\d{4}).(\d{4,5})(v\d+)?$", flags=re.I) """See http://arxiv.org/help/arxiv_identifier and http://arxiv.org/help/arxiv_identifier_for_services."""

arxiv_pre_2007_regexp = re.compile( r"(arxiv:)?([a-z-]+)(.[a-z]{2})?(/\d{4})(\d+)(v\d+)?$", flags=re.I ) """See http://arxiv.org/help/arxiv_identifier and http://arxiv.org/help/arxiv_identifier_for_services."""

arxiv_post_2007_with_class_regexp = re.compile( r"(arxiv:)?(?:[a-z-]+)(?:.[a-z]{2})?/(\d{4}).(\d{4,5})(v\d+)?$", flags=re.I ) """Matches new style arXiv ID, with an old-style class specification; technically malformed, however appears in real data."""

hal_regexp = re.compile(r"(hal:|HAL:)?([a-z]{3}[a-z]*-|(sic|mem|ijn)_)\d{8}(v\d+)?$") """Matches HAL identifiers (sic mem and ijn are old identifiers form)."""

ads_regexp = re.compile(r"(ads:|ADS:)?(\d{4}[A-Za-z]\S{13}[A-Za-z.:])$") """See http://adsabs.harvard.edu/abs_doc/help_pages/data.html"""

pmcid_regexp = re.compile(r"PMC\d+$", flags=re.I) """PubMed Central ID regular expression."""

pmid_regexp = re.compile( r"(pmid:|https?://pubmed.ncbi.nlm.nih.gov/)?(\d+)/?$", flags=re.I ) """PubMed ID regular expression."""

ark_suffix_regexp = re.compile(r"ark:/[0-9bcdfghjkmnpqrstvwxz]+/.+$") """See http://en.wikipedia.org/wiki/Archival_Resource_Key and https://confluence.ucop.edu/display/Curation/ARK."""

lsid_regexp = re.compile(r"urn:lsid:[^:]+(:[^:]+){2,3}$", flags=re.I) """See http://en.wikipedia.org/wiki/LSID."""

orcid_urls = ["http://orcid.org/", "https://orcid.org/"]

gnd_regexp = re.compile( r"(gnd:|GND:)?(" r"(1|10)\d{7}[0-9X]|" r"[47]\d{6}-\d|" r"[1-9]\d{0,7}-[0-9X]|" r"3\d{7}[0-9X]" r")" ) """See https://www.wikidata.org/wiki/Property:P227."""

gnd_resolver_url = "http://d-nb.info/gnd/"

sra_regexp = re.compile(r"[SED]R[APRSXZ]\d+$") """Sequence Read Archive regular expression. See https://www.ncbi.nlm.nih.gov/books/NBK56913/#search.what_do_the_different_sra_accessi """

bioproject_regexp = re.compile(r"PRJ(NA|EA|EB|DB)\d+$") """BioProject regular expression. See https://www.ddbj.nig.ac.jp/bioproject/faq-e.html#project-accession https://www.ebi.ac.uk/ena/submit/project-format https://www.ncbi.nlm.nih.gov/bioproject/docs/faq/#under-what-circumstances-is-it-n """

biosample_regexp = re.compile(r"SAM(N|EA|D)\d+$") """BioSample regular expression. See https://www.ddbj.nig.ac.jp/biosample/faq-e.html https://ena-docs.readthedocs.io/en/latest/submit/samples/programmatic.html#accession-numbers-in-the-receipt-xml https://www.ncbi.nlm.nih.gov/biosample/docs/submission/faq/ """

ensembl_regexp = re.compile( r"({prefixes})(E|FM|G|GT|P|R|T)\d{{11}}$".format( prefixes="|".join(ENSEMBL_PREFIXES) ) ) """Ensembl regular expression. See https://asia.ensembl.org/info/genome/stable_ids/prefixes.html """

uniprot_regexp = re.compile( r"([A-NR-Z]0-9{1,2})|" r"([OPQ][0-9][A-Z0-9]{3}[0-9])(.\d+)?$" ) """UniProt regular expression. See https://www.uniprot.org/help/accession_numbers """

refseq_regexp = re.compile( r"((AC|NC|NG|NT|NW|NM|NR|XM|XR|AP|NP|YP|XP|WP)|" r"NZ[A-Z]{4})\d+(.\d+)?$" ) """RefSeq regular expression. See https://academic.oup.com/nar/article/44/D1/D733/2502674 (Table 1) """

genome_regexp = re.compile(r"GC[AF]_\d+.\d+$") """GenBank or RefSeq genome assembly accession. See https://www.ebi.ac.uk/ena/browse/genome-assembly-database """

geo_regexp = re.compile(r"G(PL|SM|SE|DS)\d+$") """Gene Expression Omnibus (GEO) accession. See https://www.ncbi.nlm.nih.gov/geo/info/overview.html#org """

arrayexpress_array_regexp = re.compile( r"A-({codes})-\d+$".format(codes="|".join(ARRAYEXPRESS_CODES)) ) """ArrayExpress array accession. See https://www.ebi.ac.uk/arrayexpress/help/accession_codes.html """

arrayexpress_experiment_regexp = re.compile( r"E-({codes})-\d+$".format(codes="|".join(ARRAYEXPRESS_CODES)) ) """ArrayExpress array accession. See https://www.ebi.ac.uk/arrayexpress/help/accession_codes.html """

ascl_regexp = re.compile(r"^ascl:[0-9]{4}.[0-9]{3,4}$", flags=re.I) """ASCL regular expression."""

swh_regexp = re.compile( r"swh:1:(cnt|dir|rel|rev|snp):[0-9a-f]{40}" r"(;(origin|visit|anchor|path|lines)=\S+)*$" ) """Matches Software Heritage identifiers."""

ror_regexp = re.compile(r"(?:https?://)?(?:ror.org/)?(0\w{6}\d{2})$", flags=re.I) """See https://ror.org/facts/#core-components.""" ```

js var camelCased = myString.replace(/-([a-z])/g, function (g) { return g[1].toUpperCase(); });

• REFERENCIAR GRUPOS DE CAPTURA

https://regex101.com/

String.split() can also accept a regular expression:

input.split(/[ ,]+/);

• REGEX
• crear regex a partir de pattern
• CIUDADO: \b -> \b; \s -> \s en la cadena pattern

b) rgb(), rgba(), hsl() and hsla():

^(rgb|hsl)(a?)[(]\s*([\d.]+\s*%?)\s*,\s*([\d.]+\s*%?)\s*,\s*([\d.]+\s*%?)\s*(?:,\s*([\d.]+)\s*)?[)]$

• VALID ONLY for "new" format!!!
• not valid for hep-th/9108008v1

• REGEX ARXIV

• see

• REGEX ARXIV

RegEx document see https://docs.python.org/3/library/re.html

Also python re playground https://pythex.org/

playground https://regex101.com/

Sometimes the following functions are more than enough for your string matching problems

Really useful page for generating regexes of ip ranges. Note they are missing some parenthesis in places though.

Actually, it'd be better to express this as /^10.\d{4,9}/[-._;()/:a-zA-Z0-9]+$i (adding lowercase letters a-z, instead of using the case insensitivity flag "i") to avoid compatibility issues with certain regex parsers

cool, it will show how many steps are needed to performce the regex! Greatful for tuning regex for performance

Regex kontrolü https://regex101.com/

so greedy is evil? since it'll backtrack form the end!

but in log analysis field, almost every line are machted, we'just want to use regex to extract fields inside the line. Is the "the longer the better" still matter?

Interesting dive into how string slicing with String#substring is implemented in the Dart and V8 VMs and the performance consequences of that. This investigation was prompted by poor performance of a port of less.js lexer to Dart vs. the original JS implementation.

The article ends with benchmarks showing the cost of trying to match sequences of characters in a lexer using a regex vs. manually.

Neat trick for matching regular expressions within a string starting at a fixed position using pre-ES6 features:

1. Create a regex with the global flag set which matches pattern|() where () is an irrefutable pattern which is guaranteed to match
2. Set regex.lastIndex to the position you want to match at
3. Use regex.exec(str)

Notes on how to match a regex starting at a given position in a string, making use of the sticky flag introduced in ES6.