Royce  Reinger

Royce Reinger

1658977500

A Ruby Library for Generating Text with Recursive Template Grammars

Calyx

Calyx provides a simple API for generating text with declarative recursive grammars.

Install

Command Line

gem install calyx

Gemfile

gem 'calyx'

Examples

The best way to get started quickly is to install the gem and run the examples locally.

Any Gradient

Requires Roda and Rack to be available.

gem install roda

Demonstrates how to use Calyx to construct SVG graphics. Any Gradient generates a rectangle with a linear gradient of random colours.

Run as a web server and preview the output in a browser (http://localhost:9292):

ruby examples/any_gradient.rb

Or generate SVG files via a command line pipe:

ruby examples/any_gradient > gradient1.xml

Tiny Woodland Bot

Requires the Twitter client gem and API access configured for a specific Twitter handle.

gem install twitter

Demonstrates how to use Calyx to make a minimal Twitter bot that periodically posts unique tweets. See @tiny_woodland on Twitter and the writeup here.

TWITTER_CONSUMER_KEY=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
TWITTER_ACCESS_TOKEN=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
ruby examples/tiny_woodland_bot.rb

Faker

Faker is a popular library for generating fake names and associated sample data like internet addresses, company names and locations.

This example demonstrates how to use Calyx to reproduce the same functionality using custom lists defined in a YAML configuration file.

ruby examples/faker.rb

Usage

Require the library and inherit from Calyx::Grammar to construct a set of rules to generate a text.

require 'calyx'

class HelloWorld < Calyx::Grammar
  start 'Hello world.'
end

To 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 by adding additional rules which provide a named set of text strings. The rule delimiter syntax ({}) can be used to substitute the generated content of other rules.

class HelloWorld < Calyx::Grammar
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

Each time #generate runs, it evaluates the tree and randomly selects variations of rules to construct a resulting string.

hello = HelloWorld.new

hello.generate
# > "Hi world."

hello.generate
# > "Hello world."

hello.generate
# > "Yo world."

By convention, the start rule specifies the default starting point for generating the final text. You can start from any other named rule by passing it explicitly to the generate method.

class HelloWorld < Calyx::Grammar
  hello 'Hello world.'
end

hello = HelloWorld.new
hello.generate(:hello)

Block Constructors

As an alternative to subclassing, you can also construct rules unique to an instance by passing a block when initializing the class:

hello = Calyx::Grammar.new do
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

hello.generate

Template Expressions

Basic rule substitution uses single curly brackets as delimiters for template expressions:

fruit = Calyx::Grammar.new do
  start '{colour} {fruit}'
  colour 'red', 'green', 'yellow'
  fruit 'apple', 'pear', 'tomato'
end

6.times { fruit.generate }
# => "yellow pear"
# => "red apple"
# => "green tomato"
# => "red pear"
# => "yellow tomato"
# => "green apple"

Nesting and Substitution

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}.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
  world_phrase '{happy_adj} world', '{sad_adj} world', 'world'
  happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
  sad_adj 'cruel', 'miserable'
end

Nesting and hierarchy can be manipulated to balance consistency with novelty. The exact same word atoms can be combined in a variety of ways to produce strikingly different resulting texts.

module HelloWorld
  class Sentiment < Calyx::Grammar
    start '{happy_phrase}', '{sad_phrase}'
    happy_phrase '{happy_greeting} {happy_adj} world.'
    happy_greeting 'Hello', 'Hi', 'Hey', 'Yo'
    happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
    sad_phrase '{sad_greeting} {sad_adj} world.'
    sad_greeting 'Goodbye', 'So long', 'Farewell'
    sad_adj 'cruel', 'miserable'
  end

  class Mixed < Calyx::Grammar
    start '{greeting} {adj} world.'
    greeting 'Hello', 'Hi', 'Hey', 'Yo', 'Goodbye', 'So long', 'Farewell'
    adj 'wonderful', 'amazing', 'bright', 'beautiful', 'cruel', 'miserable'
  end
end

Random Sampling

By default, the outcomes of generated rules are selected with Ruby’s built-in pseudorandom number generator (as seen in methods like Kernel.rand and Array.sample). To seed the random number generator, pass in an integer seed value as the first argument to the constructor:

grammar = Calyx::Grammar.new(seed: 12345) do
  # rules...
end

Alternatively, you can pass a preconfigured instance of Ruby’s stdlib Random class:

random = Random.new(12345)

grammar = Calyx::Grammar.new(rng: random) do
  # rules...
end

When a random seed isn’t supplied, Time.new.to_i is used as the default seed, which makes each run of the generator relatively unique.

Weighted Choices

Choices can be weighted so that some rules have a greater probability of expanding than others.

Weights are defined by passing a hash instead of a list of rules where the keys are strings or symbols representing the grammar rules and the values are weights.

Weights can be represented as floats, integers or ranges.

  • Floats must be in the interval 0..1 and the given weights for a production must sum to 1.
  • Ranges must be contiguous and cover the entire interval from 1 to the maximum value of the largest range.
  • Integers (Fixnums) will produce a distribution based on the sum of all given numbers, with each number being a fraction of that sum.

The following definitions produce an equivalent weighting of choices:

Calyx::Grammar.new do
  start 'heads' => 1, 'tails' => 1
end

Calyx::Grammar.new do
  start 'heads' => 0.5, 'tails' => 0.5
end

Calyx::Grammar.new do
  start 'heads' => 1..5, 'tails' => 6..10
end

Calyx::Grammar.new do
  start 'heads' => 50, 'tails' => 50
end

There’s a lot of interesting things you can do with this. For example, you can model the triangular distribution produced by rolling 2d6:

Calyx::Grammar.new do
  start(
    '2' => 1,
    '3' => 2,
    '4' => 3,
    '5' => 4,
    '6' => 5,
    '7' => 6,
    '8' => 5,
    '9' => 4,
    '10' => 3,
    '11' => 2,
    '12' => 1
  )
end

Or reproduce Gary Gygax’s famous generation table from the original Dungeon Master’s Guide (page 171):

Calyx::Grammar.new do
  start(
    :empty => 0.6,
    :monster => 0.1,
    :monster_treasure => 0.15,
    :special => 0.05,
    :trick_trap => 0.05,
    :treasure => 0.05
  )
  empty 'Empty'
  monster 'Monster Only'
  monster_treasure 'Monster and Treasure'
  special 'Special'
  trick_trap 'Trick/Trap.'
  treasure 'Treasure'
end

String Modifiers

Dot-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.

greeting = Calyx::Grammar.new do
  start '{hello.capitalize} there.', 'Why, {hello} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "Hello there."
# => "Hi there."
# => "Why, hello there."
# => "Why, hi there."

You can also extend the grammar with custom modifiers that provide useful formatting functions.

Filters

Filters accept an input string and return the transformed output:

greeting = Calyx::Grammar.new do
  filter :shoutycaps do |input|
    input.upcase
  end

  start '{hello.shoutycaps} there.', 'Why, {hello.shoutycaps} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "HELLO there."
# => "HI there."
# => "Why, HELLO there."
# => "Why, HI there."

Mappings

The mapping shortcut allows you to specify a map of regex patterns pointing to their resulting substitution strings:

green_bottle = Calyx::Grammar.new do
  mapping :pluralize, /(.+)/ => '\\1s'
  start 'One green {bottle}.', 'Two green {bottle.pluralize}.'
  bottle 'bottle'
end

2.times { green_bottle.generate }
# => "One green bottle."
# => "Two green bottles."

Modifier Mixins

In order to use more intricate rewriting and formatting methods in a modifier chain, you can add methods to a module and embed it in a grammar using the modifier classmethod.

Modifier methods accept a single argument representing the input string from the previous step in the expression chain and must return a string, representing the modified output.

module FullStop
  def full_stop(input)
    input << '.'
  end
end

hello = Calyx::Grammar.new do
  modifier FullStop
  start '{hello.capitalize.full_stop}'
  hello 'hello'
end

hello.generate
# => "Hello."

To share custom modifiers across multiple grammars, you can include the module in Calyx::Modifiers. This will make the methods available to all subsequent instances:

module FullStop
  def full_stop(input)
    input << '.'
  end
end

class Calyx::Modifiers
  include FullStop
end

Monkeypatching String

Alternatively, you can combine methods from existing Gems that monkeypatch String:

require 'indefinite_article'

module FullStop
  def full_stop
    self << '.'
  end
end

class String
  include FullStop
end

noun_articles = Calyx::Grammar.new do
  start '{fruit.with_indefinite_article.capitalize.full_stop}'
  fruit 'apple', 'orange', 'banana', 'pear'
end

4.times { noun_articles.generate }
# => "An apple."
# => "An orange."
# => "A banana."
# => "A pear."

Memoized Rules

Rule expansions can be ‘memoized’ so that multiple references to the same rule return the same value. This is useful for picking a noun from a list and reusing it in multiple places within a text.

The @ sigil is used to mark memoized rules. This evaluates the rule and stores it in memory the first time it’s referenced. All subsequent references to the memoized rule use the same stored value.

# Without memoization
grammar = Calyx::Grammar.new do
  start '{name} <{name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Daenerys <jon>
# => Tyrion <daenerys>
# => Jon <tyrion>

# With memoization
grammar = Calyx::Grammar.new do
  start '{@name} <{@name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Tyrion <tyrion>
# => Daenerys <daenerys>
# => Jon <jon>

Note that the memoization symbol can only be used on the right hand side of a production rule.

Unique Rules

Rule expansions can be marked as ‘unique’, meaning that multiple references to the same rule always return a different value. This is useful for situations where the same result appearing twice would appear awkward and messy.

Unique rules are marked by the $ sigil.

grammar = Calyx::Grammar.new do
  start "{$medal}, {$medal}, {$medal}"
  medal 'Gold', 'Silver', 'Bronze'
end

grammar.generate
# => Silver, Bronze, Gold

Dynamically Constructing Rules

Template expansions can be dynamically constructed at runtime by passing a context map of rules to the #generate method:

class AppGreeting < Calyx::Grammar
  start 'Hi {username}!', 'Welcome back {username}...', 'Hola {username}'
end

context = {
  username: UserModel.username
}

greeting = AppGreeting.new
greeting.generate(context)

External File Formats

In addition to defining grammars in pure Ruby, you can load them from external JSON and YAML files:

hello = Calyx::Grammar.load('hello.yml')
hello.generate

The format requires a flat map with keys representing the left-hand side named symbols and the values representing the right hand side substitution rules.

In JSON:

{
  "start": "{greeting} world.",
  "greeting": ["Hello", "Hi", "Hey", "Yo"]
}

In YAML:

---
start: "{greeting} world."
greeting:
  - Hello
  - Hi
  - Hey
  - Yo

Accessing the Raw Generated Tree

Calling #evaluate on the grammar instance will give you access to the raw generated tree structure before it gets flattened into a string.

The tree is encoded as an array of nested arrays, with the leading symbols labeling the choices and rules selected, and the trailing terminal leaves encoding string values.

This may not make a lot of sense unless you’re familiar with the concept of s-expressions. It’s a fairly speculative feature at this stage, but it leads to some interesting possibilities.

grammar = Calyx::Grammar.new do
  start 'Riddle me ree.'
end

grammar.evaluate
# => [:start, [:choice, [:concat, [[:atom, "Riddle me ree."]]]]]

Roadmap

Rough plan for stabilising the API and features for a 1.0 release.

VersionFeatures planned
0.6block constructor
0.7support for template context map passed to generate
0.8method missing metaclass API
0.9return grammar tree from #evaluate, with flattened string from #generate being separate
0.10inject custom string functions for parameterised rules, transforms and mappings
0.11support YAML format (and JSON?)
0.12API documentation
0.13Support for unique rules
0.14Support for Ruby 2.4
0.15Options config and ‘strict mode’ error handling
0.16Improve representation of weighted probability selection
0.17Return result object from #generate calls

Credits

Author & Maintainer

Contributors

Author: Maetl
Source Code: https://github.com/maetl/calyx 
License: MIT license

#ruby #text 

What is GEEK

Buddha Community

A Ruby Library for Generating Text with Recursive Template Grammars
Royce  Reinger

Royce Reinger

1658977500

A Ruby Library for Generating Text with Recursive Template Grammars

Calyx

Calyx provides a simple API for generating text with declarative recursive grammars.

Install

Command Line

gem install calyx

Gemfile

gem 'calyx'

Examples

The best way to get started quickly is to install the gem and run the examples locally.

Any Gradient

Requires Roda and Rack to be available.

gem install roda

Demonstrates how to use Calyx to construct SVG graphics. Any Gradient generates a rectangle with a linear gradient of random colours.

Run as a web server and preview the output in a browser (http://localhost:9292):

ruby examples/any_gradient.rb

Or generate SVG files via a command line pipe:

ruby examples/any_gradient > gradient1.xml

Tiny Woodland Bot

Requires the Twitter client gem and API access configured for a specific Twitter handle.

gem install twitter

Demonstrates how to use Calyx to make a minimal Twitter bot that periodically posts unique tweets. See @tiny_woodland on Twitter and the writeup here.

TWITTER_CONSUMER_KEY=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
TWITTER_ACCESS_TOKEN=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
ruby examples/tiny_woodland_bot.rb

Faker

Faker is a popular library for generating fake names and associated sample data like internet addresses, company names and locations.

This example demonstrates how to use Calyx to reproduce the same functionality using custom lists defined in a YAML configuration file.

ruby examples/faker.rb

Usage

Require the library and inherit from Calyx::Grammar to construct a set of rules to generate a text.

require 'calyx'

class HelloWorld < Calyx::Grammar
  start 'Hello world.'
end

To 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 by adding additional rules which provide a named set of text strings. The rule delimiter syntax ({}) can be used to substitute the generated content of other rules.

class HelloWorld < Calyx::Grammar
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

Each time #generate runs, it evaluates the tree and randomly selects variations of rules to construct a resulting string.

hello = HelloWorld.new

hello.generate
# > "Hi world."

hello.generate
# > "Hello world."

hello.generate
# > "Yo world."

By convention, the start rule specifies the default starting point for generating the final text. You can start from any other named rule by passing it explicitly to the generate method.

class HelloWorld < Calyx::Grammar
  hello 'Hello world.'
end

hello = HelloWorld.new
hello.generate(:hello)

Block Constructors

As an alternative to subclassing, you can also construct rules unique to an instance by passing a block when initializing the class:

hello = Calyx::Grammar.new do
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

hello.generate

Template Expressions

Basic rule substitution uses single curly brackets as delimiters for template expressions:

fruit = Calyx::Grammar.new do
  start '{colour} {fruit}'
  colour 'red', 'green', 'yellow'
  fruit 'apple', 'pear', 'tomato'
end

6.times { fruit.generate }
# => "yellow pear"
# => "red apple"
# => "green tomato"
# => "red pear"
# => "yellow tomato"
# => "green apple"

Nesting and Substitution

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}.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
  world_phrase '{happy_adj} world', '{sad_adj} world', 'world'
  happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
  sad_adj 'cruel', 'miserable'
end

Nesting and hierarchy can be manipulated to balance consistency with novelty. The exact same word atoms can be combined in a variety of ways to produce strikingly different resulting texts.

module HelloWorld
  class Sentiment < Calyx::Grammar
    start '{happy_phrase}', '{sad_phrase}'
    happy_phrase '{happy_greeting} {happy_adj} world.'
    happy_greeting 'Hello', 'Hi', 'Hey', 'Yo'
    happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
    sad_phrase '{sad_greeting} {sad_adj} world.'
    sad_greeting 'Goodbye', 'So long', 'Farewell'
    sad_adj 'cruel', 'miserable'
  end

  class Mixed < Calyx::Grammar
    start '{greeting} {adj} world.'
    greeting 'Hello', 'Hi', 'Hey', 'Yo', 'Goodbye', 'So long', 'Farewell'
    adj 'wonderful', 'amazing', 'bright', 'beautiful', 'cruel', 'miserable'
  end
end

Random Sampling

By default, the outcomes of generated rules are selected with Ruby’s built-in pseudorandom number generator (as seen in methods like Kernel.rand and Array.sample). To seed the random number generator, pass in an integer seed value as the first argument to the constructor:

grammar = Calyx::Grammar.new(seed: 12345) do
  # rules...
end

Alternatively, you can pass a preconfigured instance of Ruby’s stdlib Random class:

random = Random.new(12345)

grammar = Calyx::Grammar.new(rng: random) do
  # rules...
end

When a random seed isn’t supplied, Time.new.to_i is used as the default seed, which makes each run of the generator relatively unique.

Weighted Choices

Choices can be weighted so that some rules have a greater probability of expanding than others.

Weights are defined by passing a hash instead of a list of rules where the keys are strings or symbols representing the grammar rules and the values are weights.

Weights can be represented as floats, integers or ranges.

  • Floats must be in the interval 0..1 and the given weights for a production must sum to 1.
  • Ranges must be contiguous and cover the entire interval from 1 to the maximum value of the largest range.
  • Integers (Fixnums) will produce a distribution based on the sum of all given numbers, with each number being a fraction of that sum.

The following definitions produce an equivalent weighting of choices:

Calyx::Grammar.new do
  start 'heads' => 1, 'tails' => 1
end

Calyx::Grammar.new do
  start 'heads' => 0.5, 'tails' => 0.5
end

Calyx::Grammar.new do
  start 'heads' => 1..5, 'tails' => 6..10
end

Calyx::Grammar.new do
  start 'heads' => 50, 'tails' => 50
end

There’s a lot of interesting things you can do with this. For example, you can model the triangular distribution produced by rolling 2d6:

Calyx::Grammar.new do
  start(
    '2' => 1,
    '3' => 2,
    '4' => 3,
    '5' => 4,
    '6' => 5,
    '7' => 6,
    '8' => 5,
    '9' => 4,
    '10' => 3,
    '11' => 2,
    '12' => 1
  )
end

Or reproduce Gary Gygax’s famous generation table from the original Dungeon Master’s Guide (page 171):

Calyx::Grammar.new do
  start(
    :empty => 0.6,
    :monster => 0.1,
    :monster_treasure => 0.15,
    :special => 0.05,
    :trick_trap => 0.05,
    :treasure => 0.05
  )
  empty 'Empty'
  monster 'Monster Only'
  monster_treasure 'Monster and Treasure'
  special 'Special'
  trick_trap 'Trick/Trap.'
  treasure 'Treasure'
end

String Modifiers

Dot-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.

greeting = Calyx::Grammar.new do
  start '{hello.capitalize} there.', 'Why, {hello} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "Hello there."
# => "Hi there."
# => "Why, hello there."
# => "Why, hi there."

You can also extend the grammar with custom modifiers that provide useful formatting functions.

Filters

Filters accept an input string and return the transformed output:

greeting = Calyx::Grammar.new do
  filter :shoutycaps do |input|
    input.upcase
  end

  start '{hello.shoutycaps} there.', 'Why, {hello.shoutycaps} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "HELLO there."
# => "HI there."
# => "Why, HELLO there."
# => "Why, HI there."

Mappings

The mapping shortcut allows you to specify a map of regex patterns pointing to their resulting substitution strings:

green_bottle = Calyx::Grammar.new do
  mapping :pluralize, /(.+)/ => '\\1s'
  start 'One green {bottle}.', 'Two green {bottle.pluralize}.'
  bottle 'bottle'
end

2.times { green_bottle.generate }
# => "One green bottle."
# => "Two green bottles."

Modifier Mixins

In order to use more intricate rewriting and formatting methods in a modifier chain, you can add methods to a module and embed it in a grammar using the modifier classmethod.

Modifier methods accept a single argument representing the input string from the previous step in the expression chain and must return a string, representing the modified output.

module FullStop
  def full_stop(input)
    input << '.'
  end
end

hello = Calyx::Grammar.new do
  modifier FullStop
  start '{hello.capitalize.full_stop}'
  hello 'hello'
end

hello.generate
# => "Hello."

To share custom modifiers across multiple grammars, you can include the module in Calyx::Modifiers. This will make the methods available to all subsequent instances:

module FullStop
  def full_stop(input)
    input << '.'
  end
end

class Calyx::Modifiers
  include FullStop
end

Monkeypatching String

Alternatively, you can combine methods from existing Gems that monkeypatch String:

require 'indefinite_article'

module FullStop
  def full_stop
    self << '.'
  end
end

class String
  include FullStop
end

noun_articles = Calyx::Grammar.new do
  start '{fruit.with_indefinite_article.capitalize.full_stop}'
  fruit 'apple', 'orange', 'banana', 'pear'
end

4.times { noun_articles.generate }
# => "An apple."
# => "An orange."
# => "A banana."
# => "A pear."

Memoized Rules

Rule expansions can be ‘memoized’ so that multiple references to the same rule return the same value. This is useful for picking a noun from a list and reusing it in multiple places within a text.

The @ sigil is used to mark memoized rules. This evaluates the rule and stores it in memory the first time it’s referenced. All subsequent references to the memoized rule use the same stored value.

# Without memoization
grammar = Calyx::Grammar.new do
  start '{name} <{name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Daenerys <jon>
# => Tyrion <daenerys>
# => Jon <tyrion>

# With memoization
grammar = Calyx::Grammar.new do
  start '{@name} <{@name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Tyrion <tyrion>
# => Daenerys <daenerys>
# => Jon <jon>

Note that the memoization symbol can only be used on the right hand side of a production rule.

Unique Rules

Rule expansions can be marked as ‘unique’, meaning that multiple references to the same rule always return a different value. This is useful for situations where the same result appearing twice would appear awkward and messy.

Unique rules are marked by the $ sigil.

grammar = Calyx::Grammar.new do
  start "{$medal}, {$medal}, {$medal}"
  medal 'Gold', 'Silver', 'Bronze'
end

grammar.generate
# => Silver, Bronze, Gold

Dynamically Constructing Rules

Template expansions can be dynamically constructed at runtime by passing a context map of rules to the #generate method:

class AppGreeting < Calyx::Grammar
  start 'Hi {username}!', 'Welcome back {username}...', 'Hola {username}'
end

context = {
  username: UserModel.username
}

greeting = AppGreeting.new
greeting.generate(context)

External File Formats

In addition to defining grammars in pure Ruby, you can load them from external JSON and YAML files:

hello = Calyx::Grammar.load('hello.yml')
hello.generate

The format requires a flat map with keys representing the left-hand side named symbols and the values representing the right hand side substitution rules.

In JSON:

{
  "start": "{greeting} world.",
  "greeting": ["Hello", "Hi", "Hey", "Yo"]
}

In YAML:

---
start: "{greeting} world."
greeting:
  - Hello
  - Hi
  - Hey
  - Yo

Accessing the Raw Generated Tree

Calling #evaluate on the grammar instance will give you access to the raw generated tree structure before it gets flattened into a string.

The tree is encoded as an array of nested arrays, with the leading symbols labeling the choices and rules selected, and the trailing terminal leaves encoding string values.

This may not make a lot of sense unless you’re familiar with the concept of s-expressions. It’s a fairly speculative feature at this stage, but it leads to some interesting possibilities.

grammar = Calyx::Grammar.new do
  start 'Riddle me ree.'
end

grammar.evaluate
# => [:start, [:choice, [:concat, [[:atom, "Riddle me ree."]]]]]

Roadmap

Rough plan for stabilising the API and features for a 1.0 release.

VersionFeatures planned
0.6block constructor
0.7support for template context map passed to generate
0.8method missing metaclass API
0.9return grammar tree from #evaluate, with flattened string from #generate being separate
0.10inject custom string functions for parameterised rules, transforms and mappings
0.11support YAML format (and JSON?)
0.12API documentation
0.13Support for unique rules
0.14Support for Ruby 2.4
0.15Options config and ‘strict mode’ error handling
0.16Improve representation of weighted probability selection
0.17Return result object from #generate calls

Credits

Author & Maintainer

Contributors

Author: Maetl
Source Code: https://github.com/maetl/calyx 
License: MIT license

#ruby #text 

Navigating Between DOM Nodes in JavaScript

In the previous chapters you've learnt how to select individual elements on a web page. But there are many occasions where you need to access a child, parent or ancestor element. See the JavaScript DOM nodes chapter to understand the logical relationships between the nodes in a DOM tree.

DOM node provides several properties and methods that allow you to navigate or traverse through the tree structure of the DOM and make changes very easily. In the following section we will learn how to navigate up, down, and sideways in the DOM tree using JavaScript.

Accessing the Child Nodes

You can use the firstChild and lastChild properties of the DOM node to access the first and last direct child node of a node, respectively. If the node doesn't have any child element, it returns null.

Example

<div id="main">
    <h1 id="title">My Heading</h1>
    <p id="hint"><span>This is some text.</span></p>
</div>

<script>
var main = document.getElementById("main");
console.log(main.firstChild.nodeName); // Prints: #text

var hint = document.getElementById("hint");
console.log(hint.firstChild.nodeName); // Prints: SPAN
</script>

Note: The nodeName is a read-only property that returns the name of the current node as a string. For example, it returns the tag name for element node, #text for text node, #comment for comment node, #document for document node, and so on.

If you notice the above example, the nodeName of the first-child node of the main DIV element returns #text instead of H1. Because, whitespace such as spaces, tabs, newlines, etc. are valid characters and they form #text nodes and become a part of the DOM tree. Therefore, since the <div> tag contains a newline before the <h1> tag, so it will create a #text node.

To avoid the issue with firstChild and lastChild returning #text or #comment nodes, you could alternatively use the firstElementChild and lastElementChild properties to return only the first and last element node, respectively. But, it will not work in IE 9 and earlier.

Example

<div id="main">
    <h1 id="title">My Heading</h1>
    <p id="hint"><span>This is some text.</span></p>
</div>

<script>
var main = document.getElementById("main");
alert(main.firstElementChild.nodeName); // Outputs: H1
main.firstElementChild.style.color = "red";

var hint = document.getElementById("hint");
alert(hint.firstElementChild.nodeName); // Outputs: SPAN
hint.firstElementChild.style.color = "blue";
</script>

Similarly, you can use the childNodes property to access all child nodes of a given element, where the first child node is assigned index 0. Here's an example:

Example

<div id="main">
    <h1 id="title">My Heading</h1>
    <p id="hint"><span>This is some text.</span></p>
</div>

<script>
var main = document.getElementById("main");

// First check that the element has child nodes 
if(main.hasChildNodes()) {
    var nodes = main.childNodes;
    
    // Loop through node list and display node name
    for(var i = 0; i < nodes.length; i++) {
        alert(nodes[i].nodeName);
    }
}
</script>

The childNodes returns all child nodes, including non-element nodes like text and comment nodes. To get a collection of only elements, use children property instead.

Example

<div id="main">
    <h1 id="title">My Heading</h1>
    <p id="hint"><span>This is some text.</span></p>
</div>

<script>
var main = document.getElementById("main");

// First check that the element has child nodes 
if(main.hasChildNodes()) {
    var nodes = main.children;
    
    // Loop through node list and display node name
    for(var i = 0; i < nodes.length; i++) {
        alert(nodes[i].nodeName);
    }
}
</script>

#javascript 

Fancy Font Generator - Fancy Text Generator - Cool & Stylish Text Fonts

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Cool and Fancy Text Generator that converts Normal Text To Cool And Fancy. PUBG Mobile Fonts. Cursive Fancy Texts and Emojis. Stylish and Cool Text.

  1. Enter Your Text To Contert it In Fancy Text.
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1613440398

How To Create Stylish Text Generator Website On Blogger.

Create “Stylish text generator website” on Blogger for free, using (stylish front text scripts). Fb page, Instagram, Twitter, style text and Emoji script code.
Friends, how are you all? I hope you are well. Today I will share with you how to create stylish fancy text generator websites for blogger.com Facebook page, Instagram, Twitter, etc social media.

Currently Instagram stylish text generator is playing a very important role. Moreover, this keyword is very high. If you work smartly, then your life chance is ranked by ranking your keywords on Google Fast Page. Because you don’t have to post here every day. Just create a website and create backlinks according to some needs. But the work is done, this site will earn you money in life time.

Because these crazy texts are very nice to look at and use any social media. This makes your followers attractive. Basically, for this, everyone comes to Google and searches by typing symbol generetor, text generator and uses this assorted color front text for its necessary work.

You can make thousands of rupees a month by creating a fancy text generator one page websites. You don’t have to work very hard on such a website, you don’t have to publish articles every day.

You can easily create a beautiful colorful website using this fancy text generator scripts code given by me. Let’s find out how to create your own stylish front text generator one page websites

How To Create Stylish Text Generator Website -

First you login to Blogger.com with your Gmail account. Now click on “Create New Blog”. Enter the keyword of your choice here, you must make sure that the keyword you use is valuable.

For example, the keyword “fancy text generator” is searched on Google every month. This is how you can use a high volume search keyword.

E.g.
“Free fancy text generator” Monthly search 1.8m cpc $ 33.20 per click

“Text front for Instagram” monthly search 1.2 m cpc $ 23.50 per click.

“Stylish text generator” monthly search 100k cpc & 12.30 per click.
“Font copy and paste” monthly search 500k cpc 5.90

Choose such low CPC or high search volume keywords. This will allow you to easily reach the fast page of Google.

And you will be able to earn good money by getting more traffic.

Once the blog is created you need to click on your dashboard “Theme” option.

Then scroll down and click “Revert classic theme”.

Now open it in HTML format, delete it with ctrl + a then paste the following code given by us here.

And click the blue button at the top of the theme options. Tick the “Off” option. Then save your theme by clicking “Theme”.

Bach has created your fancy text generator websites.

Below are two types of scripts.

Visit (Onlinekaj.com) to download the script.

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