gricha2380
commented
6 years ago Regex Syllabus
Introduction to Regex
AKA: learning the concept & reasons
- What is it for?
- Finding desired patterns within strings of text
- Treats everything as sequence of characters
- Basic syntax
- Delimiter
/ ... / - flags
/ ... /igm- g: iterative search
- i: ignore case (case insensitive)
- m: multiline support
- Delimiter
Regex Lessons
AKA: learning the commands
- Literal identifier
/literal/matches"literal"- Matching everything
./.*/
- Searching with Or
|/everything|something/
- Anchors
- Match start of string:
/^pattern/ - Match end of string:
/pattern$/
- Match start of string:
- Carrot functions & importance of placement
/^literal/will match"literal lesson"/^literal/will not match"Something literal"/^[literal]/will match anything except"literal"/literal$/will match"Something literal"
- Escaping characters
- Preceed character wth
\e.g.:\.
- Preceed character wth
-
- Matching everything
/./matches all characters including whitespaces- escape
.to match lteral period
- Quantifiers: repeating with +
+matches one or more of preceeding patternl{1,3}matches one to three repeated instances of letter l?is used to make a pattern optional/pie?/matchespi
- Shortcut classes vs long the way
\dvs[0-9]\wvs[a-zA-Z]\Dvs^[a-zA-Z]- Capture Groups
- Use parentheses around multiple tokesn to group them together, similar to math
/Greg(ory)?/imatchesgregandgregory- Probably not included in the game
- Backreferences
\1Used to repeat the previous pattern - Named groups
(?<mygroup>[abc])=\k<mygroup>same as([abc])=\1
- Backreferences
Pratice Tasks & Challenges
AKA: Applying the knowledge
- Match every version of
helloexcept the last- q:
hello helllllllo helllo helo - a:
/hel{2,6}o/
- q:
- Match only the digits
- q:
abc123xyz - a:
/\d/or/[1-3]/
- q:
- Match everything except last string
- q:
bird. mouse. house - a:
/.*\./
- q:
- Match every other word (requires array of strings with three or more words)
- Remove repeating characters
- Match valid .com web addresses
^(http|https):\/\/+[\www\d]+\.[\w]+(\/[\w\d]+)?
- Remove comma from number
- Match all zeros
- Match these email addresses (stacked enemies?)
- Match these phone numbers (stacked?)
- English & British spelling
- Matching the hard way (with easy characters locked)
Real World Use Cases
AKA: What regex can do for you
- Optional Characters (match alternate spellings)
neighbo?urapologize || apologiseJan(uary)?{3}(.)?
- Match email addresses
/[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}//^.+@.+$/
- Format phone numbers
/((\<1[\-\. ])?(\(|\<)\d\d\d[\)\.\-/ ] ?)?\<\d\d\d[\.\- ]\d\d\d\d\>/
- SSN
/\<\d\d\d[\- ]\d\d[\- ]\d\d\d\d\>/
- Remove comma from number
- TBD
- Find HTML tag
<([A-Z][A-Z0-9]*)\b[^>]*>(.*?)</\1><title>(.*)</title>
- Trimming whitespace
^[ \t]+|[ \t]+$[ \t\r\n]
- Matching valid date
^(19|20)\d\d([- /.])(0[1-9]|1[012])\2(0[1-9]|[12][0-9]|3[01])$
- Credit card numbers
/\<((\d\d\d\d)[\- ]){3}\d\d\d\d\>/
- Find or format currency [$ and 2 decimals]
^[+-]?[0-9]{1,3}(?:,?[0-9]{3})*\.[0-9]{2}$
Now that the engine is solid, there needs to be an actual game. The core purpose of this is to teach regex. A thoughtful plan needs to be produced to outline the knowledge journey that can be addressed using the tools I've created.
General approach
To kickstart the process, here is a list of game engine features to utilize. These can be kept in mind as the syllabus is being created, because each element of the syllabus will be showcased using the mechanisms below:
How to use tools: