trs/tests/test_rules_powers.py

from src.rules.powers import match_add_exponents, add_exponents, \
        match_subtract_exponents, subtract_exponents, \
        match_multiply_exponents, multiply_exponents, \
        match_duplicate_exponent, duplicate_exponent, \
        match_remove_negative_exponent, remove_negative_exponent, \
        match_exponent_to_root, exponent_to_root
from src.possibilities import Possibility as P
from src.node import ExpressionNode as N
from tests.rulestestcase import RulesTestCase, tree


class TestRulesPowers(RulesTestCase):

    def test_match_add_exponents_binary(self):
        a, p, q = tree('a,p,q')
        n0, n1 = root = a ** p * a ** q

        possibilities = match_add_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, add_exponents, (n0, n1, a, p, q))])

    def test_match_add_exponents_ternary(self):
        a, p, q, r = tree('a,p,q,r')
        (n0, n1), n2 = root = a ** p * a ** q * a ** r

        possibilities = match_add_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, add_exponents, (n0, n1, a, p, q)),
                 P(root, add_exponents, (n0, n2, a, p, r)),
                 P(root, add_exponents, (n1, n2, a, q, r))])

    def test_match_add_exponents_multiple_identifiers(self):
        a, b, p, q = tree('a,b,p,q')
        ((a0, b0), a1), b1 = root = a ** p * b ** p * a ** q * b ** q

        possibilities = match_add_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, add_exponents, (a0, a1, a, p, q)),
                 P(root, add_exponents, (b0, b1, b, p, q))])

    def test_match_subtract_exponents_powers(self):
        a, p, q = tree('a,p,q')
        root = a ** p / a ** q

        possibilities = match_subtract_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, subtract_exponents, (a, p, q))])

    def test_match_subtract_power_id(self):
        a, p = tree('a,p')
        root = a ** p / a

        possibilities = match_subtract_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, subtract_exponents, (a, p, 1))])

    def test_match_subtract_id_power(self):
        a, q = tree('a,q')
        root = a / a ** q

        possibilities = match_subtract_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, subtract_exponents, (a, 1, q))])

    def test_match_multiply_exponents(self):
        a, p, q = tree('a,p,q')
        root = (a ** p) ** q

        possibilities = match_multiply_exponents(root)
        self.assertEqualPos(possibilities,
                [P(root, multiply_exponents, (a, p, q))])

    def test_match_duplicate_exponent(self):
        a, b, p = tree('a,b,p')
        root = (a * b) ** p

        possibilities = match_duplicate_exponent(root)
        self.assertEqualPos(possibilities,
                [P(root, duplicate_exponent, ([a, b], p))])

    def test_match_remove_negative_exponent(self):
        a, p = tree('a,p')
        root = a ** -p

        possibilities = match_remove_negative_exponent(root)
        self.assertEqualPos(possibilities,
                [P(root, remove_negative_exponent, (a, -p))])

    def test_match_exponent_to_root(self):
        a, n, m, l1 = tree('a,n,m,1')

        root = a ** (n / m)
        possibilities = match_exponent_to_root(root)
        self.assertEqualPos(possibilities,
                [P(root, exponent_to_root, (a, n, m))])

        root = a ** (l1 / m)
        possibilities = match_exponent_to_root(root)
        self.assertEqualPos(possibilities,
                [P(root, exponent_to_root, (a, 1, m))])

    def test_add_exponents(self):
        a, p, q = tree('a,p,q')
        n0, n1 = root = a ** p * a ** q

        self.assertEqualNodes(add_exponents(root, (n0, n1, a, p, q)),
                              a ** (p + q))

    def test_subtract_exponents(self):
        a, p, q = tree('a,p,q')
        root = a ** p / a ** q

        self.assertEqualNodes(subtract_exponents(root, (a, p, q)),
                              a ** (p - q))

    def test_multiply_exponents(self):
        a, p, q = tree('a,p,q')
        root = (a ** p) ** q

        self.assertEqualNodes(multiply_exponents(root, (a, p, q)),
                              a ** (p * q))

    def test_duplicate_exponent(self):
        a, b, c, p = tree('a,b,c,p')

        root = (a * b) ** p
        self.assertEqualNodes(duplicate_exponent(root, ([a, b], p)),
                              a ** p * b ** p)

        root = (a * b * c) ** p
        self.assertEqualNodes(duplicate_exponent(root, ([a, b, c], p)),
                              a ** p * b ** p * c ** p)

    def test_remove_negative_exponent(self):
        a, p, l1 = tree('a,-p,1')
        root = a ** p

        self.assertEqualNodes(remove_negative_exponent(root, (a, p)),
                              l1 / a ** +p)

    def test_exponent_to_root(self):
        a, n, m, l1 = tree('a,n,m,1')
        root = a ** (n / m)

        self.assertEqualNodes(exponent_to_root(root, (a, n, m)),
                              N('sqrt', a ** n, m))

        self.assertEqualNodes(exponent_to_root(root, (a, l1, m)),
                              N('sqrt', a, m))