Class: TaskJuggler::LogicalOperation

Inherits:
Object
  • Object
show all
Defined in:
lib/taskjuggler/LogicalOperation.rb

Overview

A LogicalOperation is the basic building block for a LogicalExpression. A logical operation has one or two operands and an operator. The operands can be LogicalOperation objects, fixed values or references to project data. The LogicalOperation can be evaluated in a certain context. This contexts determines the actual values of the project data references. The evaluation is done by calling LogicalOperation#eval. The result must be of a type that responds to all the operators that are used in the eval method.

Direct Known Subclasses

LogicalAttribute, LogicalFlag

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opnd1, operator = nil, opnd2 = nil) ⇒ LogicalOperation

Create a new LogicalOperation object. opnd1 is the mandatory operand. The @operand2 and the @operator can be set later.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 35

def initialize(opnd1, operator = nil, opnd2 = nil)
  @operand1 = opnd1
  @operand2 = opnd2
  @operator = operator
end

Instance Attribute Details

#operand1 ⇒ Object (readonly)

Returns the value of attribute operand1.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 30

def operand1
  @operand1
end

#operand2 ⇒ Object

Returns the value of attribute operand2.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 31

def operand2
  @operand2
end

#operator ⇒ Object

Returns the value of attribute operator.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 31

def operator
  @operator
end

Instance Method Details

#eval(expr) ⇒ Object

Evaluate the expression in a given context represented by expr of type LogicalExpression. The result must be of a type that responds to all the operators of this function.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 44

def eval(expr)
  case @operator
  when nil
    if @operand1.respond_to?(:eval)
      # An operand can be a fixed value or another term. This could be a
      # LogicalOperation, LogicalFunction or anything else that provides
      # an appropriate eval() method.
      return @operand1.eval(expr)
    else
      return @operand1
    end
  when '~'
    return !coerceBoolean(@operand1.eval(expr), expr)
  when '>', '>=', '=', '<', '<=', '!='
    # Evaluate the operation for all 2 operand operations that can be
    # either interpreted as date, numbers or Strings.
    opnd1 = @operand1.eval(expr)
    opnd2 = @operand2.eval(expr)
    if opnd1.is_a?(TjTime)
      res= evalBinaryOperation(opnd1, operator, opnd2) do |o|
        coerceTime(o, expr)
      end
      return res
    elsif opnd1.is_a?(Integer) || opnd1.is_a?(Float)
      return evalBinaryOperation(opnd1, operator, opnd2) do |o|
        coerceNumber(o, expr)
      end
    elsif opnd1.is_a?(RichTextIntermediate)
      return evalBinaryOperation(opnd1.to_s, operator, opnd2) do |o|
        coerceString(o, expr)
      end
    elsif opnd1.is_a?(String)
      return evalBinaryOperation(opnd1, operator, opnd2) do |o|
        coerceString(o, expr)
      end
    else
      expr.error("First operand of a binary operation must be a date, " +
                 "a number or a string: #{opnd1.class}")
    end
  when '&'
    return coerceBoolean(@operand1.eval(expr), expr) &&
           coerceBoolean(@operand2.eval(expr), expr)
  when '|'
    return coerceBoolean(@operand1.eval(expr), expr) ||
           coerceBoolean(@operand2.eval(expr), expr)
  else
    expr.error("Unknown operator #{@operator} in logical expression")
  end
end

#to_s(query) ⇒ Object

Convert the operation into a textual representation.



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# File 'lib/taskjuggler/LogicalOperation.rb', line 95

def to_s(query)
  if @operator.nil?
    operand_to_s(@operand1, query)
  elsif @operand2.nil?
    @operator + operand_to_s(@operand1, query)
  else
    "(#{operand_to_s(@operand1, query)} #{@operator} " +
    "#{operand_to_s(@operand2, query)})"
  end
end