PhraseCache is a simple language for matching user input.
  (see also https://PhraseCache.best)

A PhraseCache expression can consist of:

  -just a word or phrase, e.g.:
  
     school
     lunch time
    
   This will match when the phrase appears anywhere in the input, e.g.:
   
     Is it lunch time now?

  -a quoted string, e.g.:
  
     "q&a"
     "\o/"
     
   These strings can contain any special character. They are
   matched exactly character-by-character, but are
   case-insensitive. The pattern does not match when it's part
   of a bigger word (e.g. the first example would not match
   the input "faq&answers").
   
   You can even match quotes, like this:
   
     "\"hello\""
     
   This will only match a "hello" put in quotes by the user.
   
  -"or" combination
  
     fun, enjoying
    
   matches "this is fun" as well as "I am enjoying this".
    
  -"and" combination
  
     this + that
    
   matches "this and that" and "that or this", but not
   "this one" or "that one".
   
   "and" takes precedence over "or", so:
   
     the + solution, a + resolution
     
   is the same as:
   
     (the + solution), (a + resolution)
     
   (See "bracketing" below.)
  
  -negation
  
     great + !not
  
   matches "this is great", but not "this is not that great".
    
  -match start of line only (with ^)
  
     ^hello bot
    
   will match "hello bot friend", but not "oh hello bot".
  
  -match end of line only (with $)
  
     please do this$
     
   will match "now please do this", but not "please do this now".
   
   Start of line and end of line can be combined like this:
   
     ^ok!$
     
   matches just "ok" and nothing else. (See "typo" section
   below.)
   
  -bracketing (grouping)
  
     (quick, fast) + (solution, resolution)
    
   will match "we need a fast solution" as well as "the
   resolution should be quick".
   
  -disallow typos with exclamation mark, e.g.:
  
     hi!
     
   By default, PhraseCache has a crude typo detection system
   that allows one typo (1 character added, removed or inserted
   per input row). It's a cool feature, but arguably could see
   some improvement. For naive patterns, it sometimes fails
   badly, e.g. input "I" will also match the pattern "hi".
   
   To circumvent this, add an exclamation mark AFTER the phrase
   in question. (Not before the phrase as that would mean
   negation.)
  

Advanced features (not really used currently):

  -add a weight to a sub-pattern:
  
    (foo, bar)*0.5