Strings

Generation of strings. More...

Classes
struct	tgen::str
	String generator. More...
struct	tgen::str::value
	String value. More...

Detailed Description

Generation of strings.

Regex

Regex syntax compatible with testlib's regex. Regexes may generate an empty string (for example, a{0}). Empty groups and alternatives are supported: a()b yields ab, and a| yields either a or the empty string.

Operations:

• A single character yields itself (a, 3).
• A list of characters inside square braces yields any a random element from the list ([abc123]).
  • A range of characters inside [] is equivalent to listing them ([a-z1-9A-Z]).
• A pattern followed by {n} yields the pattern repeated n times (a{3}).
• A pattern followed by {l,r} yields the pattern repeated between l and r times (a{3,5}).
• A list of patterns separated by | yields a random pattern from the list (abc|def|ghi).
• Parentheses can be used for grouping (a((a|b){3})).

Operations defined by {n} and {l,r} are applied to what comes before it: a character, a group defined by [] or (), or {n}/{l,r} expressions.

Regex generation is uniform (each string has the same probability of being generated), as long as each generated string can be generated uniquely from the regex. Otherwise, the probability of each string being generated is proportional to the number of ways it can be generated from the regex.

Examples:

1. str("0 | [1-9][0-9]{0,2} | 1000") generates random numbers in [0, 1000].
2. str("a[b-d]{2}|e") generates e or a random string of length 3, with the first character being a and the second and third characters being b, c, or d.
3. str("[1-9][0-9]{%d}", n-1) generates n-digit numbers.

Examples

Prints a random string of 20 lower and uppercase letters.

std::cout << tgen::str("[a-zA-Z]{20}").gen() << std::endl;

OewztXVHjOvOTZwYWRrf

Prints 2 uniformly random numbers in [0, 10^n].

const int n = 3; // Numbers in [0, 10^n].
auto leq1eN = tgen::str("0 | [1-9][0-9]{0,%d} | 10{%d}", n - 1, n);
std::cout << leq1eN.gen() << " " << leq1eN.gen() << std::endl;

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