RegEx how to properly use OR pipelines - ios

I need to know how to properly use "OR" when it comes to individual characters and whole phrases... For example I have code that is checking for any number of characters OR words that are found in an array...
I want to check for some unicode characters and also some html lines of code.
I'm currently just checking for the characters using this:
([\u200b\u200c\u200d\0\1\2\3\4\5\6\7]*)
(the backslashes are representing the unicode characters u+200b - u+200d and the special characters in my software \0-\7 (They are all individual characters), these are valid escape sequences in Objective-C.)
Now what if I wanted to check for these characters AND check for phrases like <b> or <font color="#FF0000">
I found stuff while doing research that said to use pipelines | but I'm not sure if I put them only in-between the words or also in-between the individual characters and I'm not sure if I put quotes around the words or what not... I need help before I screw this up badly haha!
(p.s., not sure if it will be any different but I'm also doing it for this:
([^\u200b\u200c\u200d\0\1\2\3\4\5\6\7])

it's be someting like
/([^....]|\<b\/\>|\<font color .... \>)/
though, the usual caveats about regexes and html apply here.
As for the confusion about where to put the |, consider this this hackneyed example: You want to find the word color, but also want to accommodate the british spelling, colour:
/(color|colour)/
/(colou?r)/
/(colo(r|ur))/
are all basically equivalent.

Related

Regex that finds a line with exactly 3 words in it

I have a problem that requires me to write a regex that finds a line that containing exactly 3 groups of characters (it could be words or numbers) and that ends with another specific word. The way I had in mind was to find a pattern that ended in a space, and look for it 3 times. assuming this is the correct way to go about it, I do no know how to find a space, but I thought it would look like .*"find a space"{3} endword$. Is this the way it would be done? Even if it is not the way to do it how do you find a space? Any suggestions?
Assuming by three groups of words you would accept any non-space character, you could write:
/^\s*(?:\S+\s+){3}endword$/
The initial caret is to make sure you have exactly 3 non-space groups on the line.
Of course you need to consider whether things like control characters could appear, and adjust accordingly.
Depending on your flavor, something like the below would do it:
\b+.+?\b+.+?\b+.+?\bendword$
This makes use of the word boundary mark (\b) and non-greedy repetitions (+?), so it may be slightly different in your specific implementation, especially if you're using something old like grep.

is it ever appropriate to localize a single ascii character

When would it be appropriate to localize a single ascii character?
for instance /, or | ?
is it ever necessary to add these "strings" to the localization effort?
just want to give some people the benefit of the doubt and make sure there's not something I didn't think of.
Generally it wouldn't be appropriate to use something like that except as a graphic element (which of course wouldn't be I18N'd in the first place, much less L10N'd). If you are trying to use it to e.g. indicate a ratio then you should have something like "%d / %d" instead, and localize the whole thing.
Yes, there are cases where these individual characters change in localization. This is not a comprehensive list, just examples I happen to know.
Not every locale uses , to separate thousands and . for the decimal. (However, these will usually be handled by your number formatter. If you do so yourself, you're probably doing it wrong. See this MSDN blog post by Michael Kaplan, Number format and currency format are not always the same.)
Not every language uses the same quotation marks (“, ”, ‘ and ’). See Wikipedia on Non-English Uses of Quotation Marks. (Many of these are only easy to replace if you use full quote marks. If you use the " and ' on your keyboard to mark both the start and end of sentences, you won't know which of two symbols to substitute.)
In Spanish, a question or exclamation is preceded by an inverted ? or !. ¿Question? ¡Exclamation! (Obviously, you can't fix this with a locale substitution for a single character. Any questions or exclamations in your application should be entire strings anyway, unless you're writing some stunningly intelligent natural language generator.)
If you do find a circumstance where you need to localize these symbols, be extra cautious not to accidentally localize a symbol like / used as a file separator, " to denote a string literal or ? for a search wildcard.
However, this has already happened with CSV files. These may be separated by ,, or may be separated by the local list separator. See What would happen if you defined your system's CSV delimiter as being a quotation mark?
In Greek, questions end with a semicolon rather than ?, so essentially the ? is replaced with ; ... however, you should aim to always translate the question as a complete string including question mark anyway.

Grails UrlEncoding non latin characters like åäö

I have some link resources with none latin characters like åäö
These are usually user uploaded files
The problem is that i am not successfull in encoding them
using filename.encodeAsURL seems to not encode it the right way
For example the character ö is turned into o%CC%88
Testing to type the same thing in firefox and copy the contents gives %C3%B6
What are the difference between these encodings and what should i use to get the correct encoding??
Both encodings are correct. You are actually seeing the encoding of two different strings.
The key here is noticing the o at the beginning of the string:
o%CC%88 is the letter o followed by Unicode Character Combining Diaeresis, which combines with the previous character when rendered.
%C3%B6 is Unicode Character Latin Small O With Diaeresis.
What you are seeing is that in the first case, the string entered is something like these two characters: o ¨, which are actually rendered as ö.
In the second case, it's the actual character ö.
My guess is you are seeing the difference between two different inputs.
Update based on below discussion: If you are dynamically processing Unicode characters, and you do not have control over the input methods, you can try to normalize the Unicode, using java.text.Normalizer (Java 1.6 or newer).
Normalizing attempts to ensure that all characters are consistently represented, so that accented characters are always represented by a combined character or always by the character+combining mark.
Rough example:
String.metaClass.normalizeUnicode = {
return java.text.Normalizer.normalize(delegate, java.text.Normalizer.Form.NFC)
}
input = input.normalizeUnicode()
There are four forms of normalization. I picked the one that seems to be best for your case based on the description of how they work, but you may prefer to try the other ones and see what works most consistently.
All that being said, if you are try to representing Unicode characters in a URL, and they are not being loaded and processed by the code directly, it's probably best to avoid using non-latin characters altogether. Not only does this have the benefit of consistently, but also significantly shorter and more legible URLs. boo.pdf is a lot easier to read than bo%CC%88o.pdf.

Yaml gotcha's, are there any issues with storing certain types of characters in Yaml?

I'm very new to yaml, and I just want to know what I can and can't store character wise in yaml?
What are the escape characters for double quotes etc?
Can I span multiple lines?
Basically, you can store everything. Quotes aren't an issue, you can type text out without quotes (and for non-printable characters that you can't incorporate casually, there are the usual escape sequences). That means purely numerical text is considered a number, though - but then again, you can add quotes or an explicit type annotation (and I assume most libraries do that when necessary), e.g. !!str 100. Also, if you want to include the comment sign (#), you have to add quotes.
Another issue is that some strings may look like more complex YAML (e.g. certain uses of exclamation signs look like casts and certain uses of colons look like singleton associative tables). You can avoid these by using "multi-line" strings that just consist of a single line. Multi-line strings exist and come in two flavors, preserving linebreaks (--- |) and ignoring newlines except for blank lines (--- >, much like markdown).

Why do you need to encode URLs?

Why do you need to encode urls? Is there a good reason why you have to change every space in the GET data to %20?
Because some characters have special meanings.
For instance, in a query string, the ampersand (&) is used as a separator between key-value pairs. If you were to put an ampersand into one of those values, it would look like the separator between the end of a value and the beginning of the next key. So for special characters like this, we use percent encoding so that we can be sure that the data is unambiguously encoded.
From RFC 2936, section 2.4.3:
The space character is excluded
because significant spaces may
disappear and insignificant spaces may
be introduced when URI are transcribed
or typeset or subjected to the
treatment of word- processing
programs. Whitespace is also used to
delimit URI in many contexts.
originally older browsers could get confused by the spaces (not really an issue anymore).
now, if someone copies the url to send as a link - the space can break the hyperlink - ie
Hey! Check out this derping cat playing a piano!
http://www.mysite.com/?video=funny cat plays piano.
See how the link breaks?
Now look at this:
http://www.mysite.com/?video=funny%20cat%20plays%20piano.
Let's break down your question.
Why do you need to encode URL?
A URL is composed of only a limited number of characters and those are digits(0-9), letters(A-Z, a-z), and a few special characters("-", ".", "_", "~").
So does it mean that we cannot use any other character?
The answer to this question is "YES". But wait a minute, there is a hack and the hack is URL Encoding or Perchantage Encoding. So if you want to transmit any character which is not a member of the above mentioned (digits, letters, and special chars), then we need to encode them. And that is why we need to encode "space" as "%20".
OK? Is this enough for URL encoding? No this is not enough, there's a lot about URL encoding but here, I'm not gonna make it a pretty big, boring technical answer. But If you want to know more, then you can read it from here: https://www.urlencoder.io/learn/ (Credit goes to this writer)
Well, you do so because every different browsers knows how the string that makes up the URL is encoded. converting the space to %20, etc makes that URL/URI portable. It could be latin-1 it could be unicode. It needs normalized to something that is understood universally. Take a look at rfc3986 https://www.rfc-editor.org/rfc/rfc3986#section-2.1

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