A mechanism to markup mud output

It looks a bit like HTML

You are in a [fairy]huge[/fairy] cavern. [day]Shafts of light descend from an opening high in the cavern ceiling.[/day]...

This implementation does support ==, && (and), || (or) logic, though it's subtle.

[fairy][mage]Show to fairy mage[/mage][/fairy] --> (race == fairy && class == mage)

[fairy]Show to fairy[/fairy][elf]Show to elf[/elf] --> (race == fairy || race == elf)

...but not integral value tests or intergral comparison tests.

(age > 25)

(level == 1)

It can be easily extended to do things like that:

[dwarf][age 25+]Something for old dwarves[/age][/dwarf] --> (race == dwarf && age >= 25)

[level 1]Welcome newbie.[/level] --> (level == 1)

[detect hidden 50]something really secret[/detect hidden] --> (skill_check("detect hidden", 50) == true)

[evil]a view from the dark side[/evil] --> (alignment <= -350)

I think it's a good example of creating an interface that tries its damndest to not turn builders into coders. I suspect trying to convert them often makes them unhappy and disgruntled. I don't know if that's really true or not.

Ahh the power of regular expressions.

Ruby Version

# a simple dynamic description markup processor - Ruby version
require 'ostruct';
Termwidth=[40,60,80];Sex=%w(male female);Race=%w(human elf fairy)
TOD = %w(day night);Keywords = Sex+Race+TOD
Desc=<<-EOD
You are in a [fairy]huge[/fairy] cavern. [day]Shafts of light descend from
an opening high in the cavern ceiling.[/day] Writhing on the cavern floor
is a decaying corpse writhing with maggots. Feasting on the corpse is a
[elf]foul-smelling[/elf][fairy]disgusting[/fairy][human]hideous[/human]
hobbit. [female]You shriek hysterically.[/female]
EOD

def show(s, p)
  pf=[];pf<<p.sex<<p.race<<p.tod;str=s.dup
  pf.each {|k| str.gsub!(/\[#{k}\](.*?)\[\/#{k}\]/mi,'\1')}
  Keywords.each {|k| str.gsub!(/\[#{k}\].*?\[\/#{k}\]/mi,'')}
  str.gsub!(/\n/,' ');str.squeeze!(' ')
  str.gsub!(/(\S{#{p.tw}})(?=\S)/,'\1 ')
  str.scan(/(.{1,#{p.tw}})(?:\s+|$)/).flatten.join("\n")
end

def mockplayer
  p = OpenStruct.new
  p.sex=Sex[rand(Sex.size)]
  p.race=Race[rand(Race.size)]
  p.tod=TOD[rand(TOD.size)]
  p.tw=Termwidth[rand(Termwidth.size)]
  p
end

5.times do
  p=mockplayer
  puts "Sex:#{p.sex} Race:#{p.race} TOD:#{p.tod} TW:#{p.tw}"
  puts show(Desc,p)
  puts
end

Output

$ ruby dyndesc.rb

Sex:female Race:fairy TOD:day TW:80
You are in a huge cavern. Shafts of light descend from an opening high in the
cavern ceiling. Writhing on the cavern floor is a decaying corpse writhing with
maggots. Feasting on the corpse is a disgusting hobbit. You shriek hysterically.

Sex:male Race:fairy TOD:night TW:40
You are in a huge cavern. Writhing on
the cavern floor is a decaying corpse
writhing with maggots. Feasting on the
corpse is a disgusting hobbit. 

Sex:female Race:fairy TOD:night TW:40
You are in a huge cavern. Writhing on
the cavern floor is a decaying corpse
writhing with maggots. Feasting on the
corpse is a disgusting hobbit. You
shriek hysterically. 

Sex:female Race:human TOD:day TW:60
You are in a cavern. Shafts of light descend from an opening
high in the cavern ceiling. Writhing on the cavern floor is
a decaying corpse writhing with maggots. Feasting on the
corpse is a hideous hobbit. You shriek hysterically. 

Sex:male Race:fairy TOD:night TW:40
You are in a huge cavern. Writhing on
the cavern floor is a decaying corpse
writhing with maggots. Feasting on the
corpse is a disgusting hobbit. 

C++ Version

// a simple dynamic description markup processor - C++ version
#include <vector>
#include <string>
#include <iostream>
#include <pcrecpp.h>
using namespace std;
using namespace pcrecpp;

int Termwidth[] = {40,60,80};
string Sex[] = {"male", "female"};
string Race[] = {"human", "elf", "fairy"};
string TOD[] = {"day", "night"};
string Desc =
"You are in a [fairy]huge[/fairy] cavern. [day]Shafts of light descend from "
"an opening high in the cavern ceiling.[/day] Writhing on the cavern floor "
"is a decaying corpse writhing with maggots. Feasting on the corpse is a "
"[elf]foul-smelling[/elf][fairy]disgusting[/fairy][human]hideous[/human] "
"hobbit. [female]You shriek hysterically.[/female] ";
vector<string> Keywords;

class Player {
public:
  int tw;
  string sex;
  string race;
  string tod;
  vector<string> pf;
  Player(string _sex,string _race,string _tod, int _tw)
    : sex(_sex), race(_race), tod(_tod), tw(_tw) {
    pf.insert(pf.end(),sex);
    pf.insert(pf.end(),race);
    pf.insert(pf.end(),tod);
  }
};

string show(string s, Player& p) {
  char tws[10];
  string str(s);

  for(vector<string>::iterator i = p.pf.begin(); i != p.pf.end(); i++) {
    RE("\\[" + *i + "\\](.*?)\\[\\/" + *i + "\\]",
      RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).GlobalReplace("\\1",&str);
  }
  for(vector<string>::iterator i = Keywords.begin(); i != Keywords.end(); i++) {
    RE("\\[" + *i + "\\].*?\\[\\/" + *i + "\\]",
      RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).GlobalReplace("",&str);
  }
  RE("\\n").GlobalReplace(" ", &str);
  RE("  ").GlobalReplace(" ", &str);
  sprintf(tws,"%d",p.tw);
  RE("\\S{" + string(tws) + "})(?=\\S)").GlobalReplace("\\1", &str);
  RE("(.{1," + string(tws) + "})(?:\\s+|$)").GlobalReplace("\\1\n", &str);
  return str;
}

int main(int argc, char** argv) {
  Keywords.insert(Keywords.end(), Sex, Sex+2);
  Keywords.insert(Keywords.end(), Race, Race+3);
  Keywords.insert(Keywords.end(), TOD, TOD+2);
  for(int i=0; i<10; i++) {
    Player p(
      Sex[rand() % 2],
      Race[rand() % 3],
      TOD[rand() % 2],
      Termwidth[rand() % 3]
      );
    cout << "Sex:" << p.sex << " Race:" << p.race <<
       " TOD:" << p.tod << " TW:" << p.tw << endl;
    cout << show(Desc,p) << endl;
    cout << endl;
  }
  return 0;
}

Output

$ g++ dyndesc.cpp -lpcrecpp

$ ./a
Sex:male Race:human TOD:night TW:40
You are in a cavern. Writhing on the
cavern floor is a decaying corpse
writhing with maggots. Feasting on the
corpse is a hideous hobbit. 


Sex:male Race:human TOD:day TW:80
You are in a cavern. Shafts of light descend from an opening high in the cavern
ceiling. Writhing on the cavern floor is a decaying corpse writhing with
maggots. Feasting on the corpse is a hideous hobbit. 


Sex:female Race:elf TOD:day TW:40
You are in a cavern. Shafts of light
descend from an opening high in the
cavern ceiling. Writhing on the cavern
floor is a decaying corpse writhing with
maggots. Feasting on the corpse is a
foul-smelling hobbit. You shriek
hysterically. 


Sex:male Race:fairy TOD:night TW:80
You are in a huge cavern. Writhing on the cavern floor is a decaying corpse
writhing with maggots. Feasting on the corpse is a disgusting hobbit. 


Sex:female Race:human TOD:day TW:80
You are in a cavern. Shafts of light descend from an opening high in the cavern
ceiling. Writhing on the cavern floor is a decaying corpse writhing with
maggots. Feasting on the corpse is a hideous hobbit. You shriek hysterically.