tmplgen

README

tmplgen

A tiny Go CLI that generates lines of strings from a template file. Each line in the input may contain one or more regex patterns wrapped in {{ … }}; tmplgen expands each pattern into a randomly generated string that matches it, cycling round-robin through the input until the requested number of lines has been produced.

Install

go install github.com/JordanSinko/tmplgen@latest

Usage

tmplgen [flags] <input-file>

Flags

Flag	Default	Description
-n, --count	required	total number of lines to generate (must be > 0)
-o, --out	stdout	output file path
--delim-open	{{	opening delimiter
--delim-close	}}	closing delimiter
--seed	time-based	RNG seed for reproducible output
--max-repeat	10	maximum expansion length for unbounded quantifiers (+, *)

Example

Given templates.txt:

user_{{[a-z]{6}}}@example.com
order-{{[0-9]{8}}}
{{[A-Z]{3}}}-{{[0-9]{4}}}

Run:

tmplgen -n 6 --seed 42 templates.txt

Produces 6 lines, round-robining through the three templates:

user_abcdef@example.com
order-12345678
XYZ-1234
user_ghijkl@example.com
order-87654321
ABC-5678

Pattern syntax

Patterns use Go's regexp/syntax (Perl mode), resolved by lucasjones/reggen. Common patterns:

{{[a-z]{10}}}          10 lowercase letters
{{[A-Z0-9]{5}}}        5 uppercase letters or digits
{{\d{3}-\d{4}}}        phone-number-ish
{{(cat|dog|fish)}}     alternation
{{[a-z]+}}             one or more lowercase (bounded by --max-repeat)

Input file rules

• Blank / whitespace-only lines are ignored and don't participate in the round-robin rotation.
• Leading and trailing whitespace on each line is trimmed.
• # has no special meaning; commented-looking lines are treated as data.
• CRLF line endings are accepted.

Determinism

Same --seed, same input, same --count produces identical output. Decreasing --count yields a strict prefix of the larger-count output. No guarantees are made across versions of tmplgen or its dependencies.

License

MIT — see LICENSE.