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## Copyright (C) 2011-2014, NYU-Poly.
## Copyright (C) 2006-2011, University of Utah. 
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## This file is part of VisTrails.
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###############################################################################
from vistrails.core.modules.vistrails_module import ModuleError
from fold import Fold, FoldWithModule

#################################################################################
## Some useful loop structures

class Map(FoldWithModule):
    """A Map module, that just appends the results in a list."""

    def setInitialValue(self):
        """Defining the initial value..."""

        self.initialValue = []

    def operation(self):
        """Defining the operation..."""

        self.partialResult.append(self.elementResult)


class Filter(FoldWithModule):
    """A Filter module, that returns in a list only the results that satisfy a
    condition."""

    def setInitialValue(self):
        """Defining the initial value..."""

        self.initialValue = []

    def operation(self):
        """Defining the operation..."""

        if not isinstance(self.elementResult, bool):
            raise ModuleError(self,'The function applied to the elements of the\
list must return a boolean result.')

        if self.elementResult:
            self.partialResult.append(self.element)


class Sum(Fold):
    """A Sum module, that computes the sum of the elements in a list."""

    def setInitialValue(self):
        """Defining the initial value..."""

        self.initialValue = 0

    def operation(self):
        """Defining the operation..."""

        self.partialResult += self.element


class And(Fold):
    """An And module, that computes the And result among the elements
    in a list."""

    def setInitialValue(self):
        """Defining the initial value..."""

        self.initialValue = True

    def operation(self):
        """Defining the operation..."""

        self.partialResult = self.partialResult and bool(self.element)


class Or(Fold):
    """An Or module, that computes the Or result among the elements
    in a list."""

    def setInitialValue(self):
        """Defining the initial value..."""

        self.initialValue = False

    def operation(self):
        """Defining the operation..."""

        self.partialResult = self.partialResult or self.element
