My implementation and file format for parsing nested adventure sets. Inspired by the xkcd comic: Calendar Facts.
It's written in C, and has no dependencies! I have no idea what this structure is called, so I'm calling them nested adventure sets.
$ gcc -o nas adventure_sets.c
$ ./nas xkcd-1930
Did you know that Shark Week happens at the wrong time every year because of a decree by The Pope in the 1500s? Apparently scientists are really worried.
The file format consists of sets, choices, and strings, which the program parses into symbols, then 'flattens' into an output string. Here's a sample input
{
"The quick "
{ "brown" | "pink" }
" fox jumped over the lazy "
{ "dog" | "cat"}
}
which is internally parsed into
SET[
STRING, CHOICE[STRING, STRING], STRING, CHOICE[STRING, STRING]
]
then can be recursively flattened into any of 4 possible outputs, such as
The quick pink fox jumped over the lazy dog.
The entire list of nested sets of sets can be represented by a single recursive data structure.
struct symbol_t {
int type;
int elements;
void *data;
};
The symbol can represent either a SET or a STRING. If it represents a string, then data is a regular char* C-string, otherwise it is an array of symbol_t structs (elements is the length of this array). type declares if the struct contains a SET, CHOICE, or a STRING.
A CHOICE is a special case of SET. During the "reduction" stage, a SET is reduced to a STRING of all of its elements concatenated, i.e
{ "Drink" " your " "ovaltine" } => "Drink your ovaltine"
SET[STRING, STRING, STRING] => STRING
whereas the CHOICE discards all by one of its elements, i.e
{ {"He loves me" | "He loves me not"} | "That'll do, Donkey. That'll do." }
=> "He loves me not"
CHOICE[CHOICE[STRING, STRING], STRING] => CHOICE[STRING, STRING] => STRING