Class: Janeway::AST::Expression

Inherits:
Object
  • Object
show all
Defined in:
lib/janeway/ast/expression.rb

Overview

Base class for jsonpath expressions.

Every AST node is a subclass of this. This includes selectors, root and child identifiers, descendant segments, and the nodes that occur within a filter selector such as the current node identifier, operators and literals.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(val = nil) ⇒ Expression

Returns a new instance of Expression.



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# File 'lib/janeway/ast/expression.rb', line 28

def initialize(val = nil)
  # don't set the instance variable if unused, because it makes the
  # "#inspect" output cleaner in rspec test failures
  @value = val unless val.nil? # literal false must be stored though!
end

Instance Attribute Details

#next ⇒ Object

Next expression in the AST, if any. Writable so the parser can link nodes as it constructs the chain, and so Query#dup / #pop can rewire the top-level chain.



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# File 'lib/janeway/ast/expression.rb', line 26

def next
  @next
end

#value ⇒ Object

Value provided by subclass constructor.



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# File 'lib/janeway/ast/expression.rb', line 21

def value
  @value
end

Class Method Details

.type_name ⇒ String

Cached camelcase→underscore transform of the class name. Same value on every instance of the class — compute once per class.

Returns:

  • (String) 


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# File 'lib/janeway/ast/expression.rb', line 43

def self.type_name
  @type_name ||=
    Helpers.camelcase_to_underscore(name.split('::').last).freeze
end

Instance Method Details

#chain_of?(*allowed_classes) ⇒ Boolean

True if every selector in the @next chain is one of the allowed classes. An empty chain (no @next) returns true. Extracted from the identical implementations that used to live in CurrentNode and RootNode.

Parameters:

  • allowed_classes (Array<Class>)

Returns:



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# File 'lib/janeway/ast/expression.rb', line 83

def chain_of?(*allowed_classes)
  selector = @next
  while selector
    return false unless allowed_classes.include?(selector.class)

    selector = selector.next
  end
  true
end

#indented(level, msg) ⇒ String

Return the given message, indented

Parameters:

  • level (Integer)
  • msg (String)

Returns:

  • (String) 


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# File 'lib/janeway/ast/expression.rb', line 53

def indented(level, msg)
  (INDENTS[level] || (INDENT * level)) + msg
end

#literal? ⇒ Boolean

Return true if this is a literal expression

Returns:



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# File 'lib/janeway/ast/expression.rb', line 65

def literal?
  false
end

#singular_query? ⇒ Boolean

True if this is the root of a singular-query.

Returns:

See Also:



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# File 'lib/janeway/ast/expression.rb', line 73

def singular_query?
  false
end

#tree(level) ⇒ Array

Parameters:

  • level (Integer)

Returns:

  • (Array) 


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# File 'lib/janeway/ast/expression.rb', line 59

def tree(level)
  [indented(level, to_s)]
end

#type ⇒ String

Returns:

  • (String) 


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# File 'lib/janeway/ast/expression.rb', line 35

def type
  self.class.type_name
end