simple-placeholder-slot-numberizer-pmb

Assign number-counting string placeholders for values, remembering the ones already seen.

API

This module exports one function:

makeNumberizer(opt)

Return a function numb(x) that will assign distinct numbers for each distinct x and return a string based on that number.

opt is an optional options object that supports these optional keys:

• pattern: An array of string parts that will be glued together with the counter number. Default: ['$', '']
• values: An Array used for determining the internal next number, and collecting the encountered x values in order of discovery. Default: a new empty Array.
• offset: Number added to the values array index in order to obtain the pattern-printed slot number. Default: 1
• dict: A Map that maps discovered x values to an object with these keys i (index in the values array) and s (the string resulting from applying pattern). Default: new empty Map.

The numb function will carry all the keys that are supported in opt, and modifying them will modify behavior for future encounters.

In addition, the numb function will carry these other properties:

• tag: A renderer function that will numb() all slot values in a tagged string.

Bonus knowledge

• For arbitrarily fancy render functions, make pattern an object that has a join method. It will be invoked with one single argument, a number primitive.

• The default pattern with default offset is useful for…

  • up to 9 JS RegExp capture groups.
  • up to 9 bash function arguments. (bash -c 'f() { echo "a$42z"; }; f b{1..100}y' → ab4y2z)
    • If you want more, use pattern: ['${', '}'] (bash -c 'f() { echo "a${42}z"; }; f b{1..100}y' → ab42yz)
  • PostgreSQL positional parameters up to more than 32k (haven't tested though).
    • However, function arguments are limited to 100. You can use arrays though.

Usage

See test/usage.mjs.

Known issues

• Needs more/better tests and docs.

License

ISC