Calyx
Calyx provides a simple API for generating text with declarative recursive grammars.
Install
Command Line
gem install calyx
Gemfile
gem 'calyx'
Usage
Require the library and inherit from Calyx::Grammar to construct a set of rules to generate a text. All grammars require a start rule, which specifies the starting point for generating the text structure.
require 'calyx'
class HelloWorld < Calyx::Grammar
start 'Hello world.'
endTo generate the text itself, initialize the object and call the generate method.
hello = HelloWorld.new
hello.generate
# > "Hello world."Obviously, this hardcoded sentence isn’t very interesting by itself. Possible variations can be added to the text using the rule constructor to provide a named set of text strings and the rule delimiter syntax ({}) within the text strings to substitute the generated content of the rule.
class HelloWorld < Calyx::Grammar
start '{greeting} world.'
rule :greeting, 'Hello', 'Hi', 'Hey', 'Yo'
end
hello = HelloWorld.new
hello.generate
# > "Hi world."
hello.generate
# > "Hello world."
hello.generate
# > "Yo world."Rules are recursive. They can be arbitrarily nested and connected to generate larger and more complex texts.
class HelloWorld < Calyx::Grammar
start '{greeting} {world_phrase}.'
rule :greeting, 'Hello', 'Hi', 'Hey', 'Yo'
rule :world_phrase, '{happy_adj} world', '{sad_adj} world', 'world'
rule :happy_adj, 'wonderful', 'amazing', 'bright', 'beautiful'
rule :sad_adj, 'cruel', 'miserable'
endNesting and hierarchy can be manipulated to balance consistency with variation. The exact same word atoms can be combined in different ways to produce strikingly different resulting texts.
module HelloWorld
Sentiment < Calyx::Grammar
start '{happy_phrase}', '{sad_phrase}'
rule :happy_phrase, '{happy_greeting} {happy_adj} world.'
rule :happy_greeting, 'Hello', 'Hi', 'Hey', 'Yo'
rule :happy_adj, 'wonderful', 'amazing', 'bright', 'beautiful'
rule :sad_phrase, '{sad_greeting} {sad_adj} world.'
rule :sad_greeting, 'Goodbye', 'So long', 'Farewell'
rule :sad_adj, 'cruel', 'miserable'
end
Mixed < Calyx::Grammar
start '{greeting} {adj} world.'
rule :greeting, 'Hello', 'Hi', 'Hey', 'Yo', 'Goodbye', 'So long', 'Farewell'
rule :adj, 'wonderful', 'amazing', 'bright', 'beautiful', 'cruel', 'miserable'
end
endBy default, the outcomes of generated rules are selected with Ruby’s built-in random number generator (as seen in methods like Kernel.rand and Array.sample). If you want to supply a weighted probability list, you can pass in arrays to the rule constructor, with the first argument being the template text string and the second argument being a float representing the probability between 0 and 1 of this choice being selected.
For example, you can model the triangular distribution produced by rolling 2d6:
class Roll2D6 < Calyx::Grammar
start(
['2', 0.0278],
['3', 0.556],
['4', 0.833],
['5', 0.1111],
['6', 0.1389],
['7', 0.1667],
['8', 0.1389],
['9', 0.1111],
['10', 0.833],
['11', 0.556],
['12', 0.278]
)
endOr reproduce Gary Gygax’s famous generation table from the original Dungeon Master’s Guide (page 171):
class ChamberOrRoomContents < Calyx::Grammar
start(
[:empty, 0.6],
[:monster, 0.1],
[:monster_treasure, 0.15],
[:special, 0.05],
[:trick_trap, 0.05],
[:treasure, 0.05]
)
rule :empty, 'Empty'
rule :monster, 'Monster Only'
rule :monster_treasure, 'Monster and Treasure'
rule :special, 'Special'
rule :trick_trap, 'Trick/Trap.'
rule :treasure, 'Treasure'
endDot-notation is supported in template expressions, allowing you to call any available method on the String object returned from a rule. Formatting methods can be chained arbitrarily and will execute in the same way as they would in native Ruby code.
class Greeting < Calyx::Grammar
start '{hello.capitalize} there.', 'Why, {hello} there.'
rule :hello, 'hello'
end
# => "Hello there."
# => "Why, hello there."In order to use more intricate natural language processing capabilities, you can embed additional methods onto the String class yourself, as well as use methods from existing Gems that monkeypatch String.
require 'indefinite_article'
module FullStop
def full_stop
self << '.'
end
end
class String
include FullStop
end
class NounsWithArticles < Calyx::Grammar
start '{fruit.with_indefinite_article.capitalize.full_stop}'
rule :fruit, 'apple', 'orange', 'banana', 'pear'
end
# => "An apple."
# => "An orange."
# => "A banana."
# => "A pear."License
Calyx is open source and provided under the terms of the MIT license. Copyright (c) 2015 Mark Rickerby
See the LICENSE file included with the project distribution for more information.
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