Class: Filigree::MatchEnvironment

Inherits:
Object
  • Object
show all
Defined in:
lib/filigree/match.rb

Overview

Match blocks are evaluated inside an instance of MatchEnvironment.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ MatchEnvironment

Returns a new instance of MatchEnvironment.



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# File 'lib/filigree/match.rb', line 231

def initialize
  @patterns = Array.new
  @deferred = Array.new
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args) ⇒ Object

Callback used to generate wildcard and binding patterns



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# File 'lib/filigree/match.rb', line 284

def method_missing(name, *args)
  if args.empty?
    if name == :_ then WildcardPattern.instance else BindingPattern.new(name) end
  else
    super(name, *args)
  end
end

Instance Method Details

#Bind(name) ⇒ BindingPattern

Force binding to the given name

Parameters:

  • name (Symbol) —

    Name to bind the value to

Returns:



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# File 'lib/filigree/match.rb', line 218

def Bind(name)
  BindingPattern.new(name)
end

#find_match(objects) ⇒ Object

Find a match for the given objects among the defined patterns.

Parameters:

Returns:

  • (Object) —

    Result of evaluating the matching pattern’s block

Raises:

  • (MatchError) —

    Raised if no pattern matches the objects



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# File 'lib/filigree/match.rb', line 243

def find_match(objects)
  @patterns.each do |pattern|
    env = OpenStruct.new 
  
    return pattern.(env, objects) if pattern.match?(objects, env)
  end

  # If we didn't find anything we raise a MatchError.
  raise MatchError
end

#Literal(obj) ⇒ LiteralPattern

Force a literal comparison

Parameters:

  • obj (Object) —

    Object to test equality with

Returns:



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# File 'lib/filigree/match.rb', line 227

def Literal(obj)
  LiteralPattern.new(obj)
end

#with(*pattern, &block) ⇒ void Also known as: w

This method returns an undefined value.

Define a pattern in this match call.

Parameters:

  • pattern (Object) —

    Objects defining the pattern

  • block (Proc) —

    Block to be executed if the pattern matches

See Also:

  • Documentation on pattern matching


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# File 'lib/filigree/match.rb', line 262

def with(*pattern, &block)
  guard = if pattern.last.is_a?(Proc) then pattern.pop end 
  
  pattern = Filigree::wrap_pattern_elements(pattern)
  
  @patterns << (mp = OuterPattern.new(pattern, guard, block))

  if block
    @deferred.each { |pattern| pattern.block = block }
    @deferred.clear
  
  else
    @deferred << mp
  end
end