Class: StringUtilities

• Inheritance
• Description
• Class protocol
  • edit distance
  • matching
  • queries

Inheritance:

   Object
   |
   +--StringUtilities

Package:

stx:libbasic2

Category:

Collections-Text-Support

Version:

rev: 1.14 date: 2022/12/15 11:58:13

user: stefan

file: StringUtilities.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

some less often used algorithms have been moved to here to
make libbasic more compact.

copyright
COPYRIGHT (c) 1994 by Claus Gittinger
COPYRIGHT (c) 2009 by eXept Software AG
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

 editDistanceFrom: s1 to: s2 s: substWeight k: kbdTypoWeight c: caseWeight e: exchangeWeight i: insrtWeight

another, simpler editing distance between two strings.
See also: levenshtein

Usage example(s):

'comptuer' levenshteinTo:'computer' -> 8 self editDistanceFrom:'comptuer' to:'computer' s:4 k:2 c:1 e:nil i:2 -> 8 'computr' levenshteinTo:'computer' -> 2 self editDistanceFrom:'computr' to:'computer' s:4 k:2 c:1 e:nil i:2 -> 2 'computer' levenshteinTo:'computre' -> 8 self editDistanceFrom:'computer' to:'computre' s:4 k:2 c:1 e:nil i:2 -> 8 'copmuter' levenshteinTo:'computer' -> 8 self editDistanceFrom:'copmuter' to:'computer' s:4 k:2 c:1 e:nil i:2 -> 8

 isKey: k1 nextTo: k2

return true, if k1 and k2 are adjacent keys on the keyboard.
This is used to specially priorize plausible typing errors of adjacent keys.

Usage example(s):

self isKey:$a nextTo:$a self isKey:$a nextTo:$s self isKey:$a nextTo:$q self isKey:$a nextTo:$w self isKey:$a nextTo:$y self isKey:$a nextTo:$z self isKey:$a nextTo:$x self isKey:$ö nextTo:$ä onKeyboard:(StringUtilities keyboardLayoutForLanguage:#de) self isKey:$ü nextTo:$ä onKeyboard:(StringUtilities keyboardLayoutForLanguage:#de) self isKey:$t nextTo:$z onKeyboard:(StringUtilities keyboardLayoutForLanguage:#de) self isKey:$t nextTo:$z onKeyboard:(StringUtilities keyboardLayoutForLanguage:#en)

 isKey: k1 nextTo: k2 onKeyboard: keys

return true, if k1 and k2 are adjacent keys on the keyboard defined by keys

Usage example(s):

self isKey:$a nextTo:$q onKeyboard:(StringUtilities keyboardLayoutForLanguage:#de) self isKey:$a nextTo:$x onKeyboard:(StringUtilities keyboardLayoutForLanguage:#de)

 keyboardLayout

the keyboard layout (used with algorithms to find possible typing errors,
for example: edit distance in levenshtein)

Usage example(s):

self keyboardLayout

 keyboardLayoutForLanguage: lang

the keyboard layout (used with algorithms to find possible nearby-key typing errors,
for example: edit distance in levenshtein).
CAVEAT:
hard coded some common languages' keyboards here - should go into resource file.

Usage example(s):

self keyboardLayoutForLanguage:#de

 levenshteinDistanceFrom: string1 to: string2 s: substWeight k: kbdTypoWeight c: caseWeight e: exchangeWeight i: insrtWeight d: deleteWeight

parametrized levenshtein.
return the levenshtein distance of two strings;
this value corrensponds to the number of replacements that have to be
made to get string2 from string1. The smaller the returned number,
the more similar are the two strings.

This levenshtein is customizable, and (with proper parameters) better suited
to find matches while programming (typically: case differences and typo-swapping-characters).
(the default entry via levenshtein: provides the standard weights, as documented and implemented elsewhere).

The arguments are the costs for
s:substitution,
k:keyboard type (substitution), if nil, s is used
c:case-change, if nil, s is used
i:insertion
d:deletion
e:exchange if nil, s*2 is used
of a character.
The default levenshtein has k=nil, c=nil and e=nil,
whereas to get better matches when searching for eg. code, better results are generated
when c< k < s and e < 2*2.
See IEEE transactions on Computers 1976 Pg 172 ff.

Usage example(s):

'comptuer' levenshteinTo:'computer' self levenshteinDistanceFrom:'comptuer' to:'computer' s:4 k:2 c:1 e:nil i:2 d:6

 stringMatchFunctionFor: aMultiPattern glob: searchForGlobPattern regex: searchForRegexPattern caseSensitive: searchIsCaseSensitive

generates a check function which - given a string - checks for a match.
The match-pattern argument aMultiPattern
may contain multiple patterns separated by ';' (for and-search) or '|' (for or-search).
If the pattern is invalid, nil is returned and an information-notification
is signalled

Usage example(s):

|fn| fn := self stringMatchFunctionFor:'aaa|bbb' glob:false regex:false caseSensitive:false. fn value:' aaa '. fn value:' aa '. fn value:' bbb '. fn value:' aa bb '.

Usage example(s):

|fn| fn := self stringMatchFunctionFor:'aaa;bbb' glob:false regex:false caseSensitive:false. fn value:' aaa '. fn value:' aa '. fn value:' bbb '. fn value:' aa bb '. fn value:' aaa bb '. fn value:' aaa bbb '.

Usage example(s):

|fn| fn := self stringMatchFunctionFor:'aa*;bb*' glob:true regex:false caseSensitive:false. fn value:' aaa '. fn value:' aa '. fn value:' bbb '. fn value:' aa bb '. fn value:' aaa bb '. fn value:' aaa bbb '.

 isUtilityClass

(comment from inherited method)
a utility class is one which is not to be instantiated,
but only provides a number of utility functions on the class side.
It is usually also abstract