Generative Grammar

Parser and generator for a simple generative grammar

Disclaimer: Work-in-progress.

Grammar

Definitions:

<symbol> := Capitalized word

<terminal> := Lowercase word

<construct> := <symbol> | <terminal>

<result> := <construct> + <result> | <construct>

<probability> := Positive number

Syntax:

<symbol> => <result>

Including a probability (optional, defaults to 1):

<symbol> [<probability>]=> <result>

Comments can be inserted starting with # and stopping at the end of the line.

Syntax Examples:

Symbol => Symbol + terminal
Symbol => terminal1
Symbol => terminal_blah1 + terminal2 + terminal3
# blah
Symbol => Symbol1 + Symbol2\nSymbol1 => terminal
# this is a comment\n\rSymbol => Symbol1 + Symbol2\nSymbol1 => terminal
Symbol [20]=> terminal1
Symbol [12.3]=> terminal1
Symbol [3.4567989]=> terminal1

Example Grammars

Quest

Grammar:

# generates a simple quest
Quest => SubQuest + return + Reward
SubQuest => TalkTo + Kill
SubQuest => GoTo + Retrieve
SubQuest [0.5]=> SubQuest + SubQuest
TalkTo => Person
GoTo => Location
Kill => Monster
Kill => Person
Reward => treasure
Reward [0.1]=> you_win
Retrieve => treasure

Example results:

Quest
· SubQuest
· · TalkTo
· · · Person
· · · · [ john ]
· · Kill
· · · Person
· · · · [ carl ]
· [ return ]
· Reward
· · [ you_win ]

Quest
· SubQuest
· · SubQuest
· · · TalkTo
· · · · Person
· · · · · [ john ]
· · · Kill
· · · · Monster
· · · · · [ imp ]
· · SubQuest
· · · TalkTo
· · · · Person
· · · · · [ carl ]
· · · Kill
· · · · Monster
· · · · · [ orc ]
· [ return ]
· Reward
· · [ treasure ]

Map

Grammar:

Map => Region + Region
Region => RegionType + RegionAffilication
RegionType => island_small + Town
RegionType => island_big + City + Town
RegionAffilication => hostile
RegionAffilication => neutral
RegionAffilication => friendly
Town => House + House
City => city_center + House + House
House => House + House
House => shop
House => blacksmith
House => herbalist
House => casino

Encounter

Grammar:

Encounter => Animals
Encounter => druid + Animals
Encounter => Monsters
Encounter => Chief + Monster + Monster
Encounter => leader + Bandits + Bandits
Encounter => Bandits
Animals => bear
Animals => wolf + wolf
Animals => rat + rat + rat
Animals => bee + bee + bee
Monsters => Monster + Monster
Monsters => Monsters + Monster
Monster => imp
Monster => ogre
Monster => slime
Chief => mage
Chief => berserker
Bandits [0.5]=> Bandits + bandit
Bandits => bandit