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mudder-dart

pub package style: effective dart

Dart version of mudderjs.

Generate lexicographically-spaced strings between two strings from pre-defined alphabets.

Usage

  • Create a new symbol table with the list of characters you want to use. In this example, we consider lowercase hexadecimal strings:
    final hex = SymbolTable(symbolsString: '0123456789abcdef');
    final hexStrings = hex.mudder(start: 'ffff', end: 'fe0f', numStrings: 3);
    print(hexStrings); // [ 'ff8', 'ff', 'fe8' ]
  • As a convenience, the following pre-generated symbol table are provided:
    • base10: 0-9,
    • base62: 0-9A-Za-z,
    • base36: 0-9a-z (lower- and upper-case accepted),
    • alphabet: a-z (lower- and upper-case accepted).

API

Constructor

final m = SymbolTable(symbolsString: ...) creates a new symbol table using the individual characters of string.

Generate strings

m.mudder(start: '', end: '' [, numStrings[, base[, numDivisions]]]) for strings, or array-of-strings, start and end, returns a numStrings-length (default one) array of strings.

base is an integer defaulting to the size of the symbol table m, but can be less than it if you, for some reason, wish to use only a subset of the symbol table.

start can be lexicographically less than or greater than end, but in either case, the returned array will be lexicographically sorted between them.

If start or end are non-truthy, the first is replaced by the first symbol, and the second is replaced by repeating the final symbol several times—e.g., for a numeric symbol table, start would default to 0 and end to 999999 or similar. This is done so that the strings returned cover 99.99...% of the available string space.

numDivisions defaults to numStrings + 1 and must be greater than numStrings. It represents the number of pieces to subdivide the lexical space between start and end into—then the returned array will contain the first numStrings steps along that grid from start to end. You can customize numDivisions to be (much) larger than numStrings in cases where you know you are going to insert many strings between two endpoints, but only one (or a few) at a time.

For example, if you call startVal = m.mudder(start: startVal, end: endVal, numStrings: 1)[0] over and over (overwriting startVal each iteration), you halve the space between the endpoints each call, eventually making the new string very long. If you knew you were going to do this, you can call startVal = m.mudder(start: startVal, end: endVal, numStrings: 1, numDivisions: 100)[0], i.e., set numDivisons: 100, to subdivide the space between the endpoints a hundred times (instead of just two times), and return just the first 1/100th step from start to end. This makes your string length grow much more sedately, and you can always reverse start and end to get the same behavior going in the other direction. See #7 for numerous examples, and a caveat if you’re using non-truthy start.

If the symbol table was not prefix-free, the function will refuse to operate on strings start/end because, without the prefix-free criterion, a string can’t be parsed unambiguously: you have to split the string into an array of stringy symbols yourself. Invalid or unrecognized symbols are silently ignored.

m.mudder(numStrings: 1) is equivalent to m.mudder(start: '', end: '', numStrings: 1). See above.