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# to you under the Apache License, Version 2.0 (the
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#
#   http://www.apache.org/licenses/LICENSE-2.0
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import tvm
import tvm.testing
from tvm import te


def test_basic():
    a = te.var("a")
    b = te.var("b")
    m = tvm.arith.detect_linear_equation(a * 4 + b * 6 + 7, [a])
    assert m[0].value == 4
    tvm.testing.assert_prim_expr_equal(m[1], b * 6 + 7)

    m = tvm.arith.detect_linear_equation(a * 4 * (a + 1) + b * 6 + 7, [a])
    assert len(m) == 0

    m = tvm.arith.detect_linear_equation(a * 4 + (a + 1) + b * 6 + 7, [a])
    assert m[0].value == 5
    tvm.testing.assert_prim_expr_equal(m[1], b * 6 + 7 + 1)

    m = tvm.arith.detect_linear_equation(a * b + 7, [a])
    assert m[0] == b

    m = tvm.arith.detect_linear_equation(b * 7, [a])
    assert m[0].value == 0

    m = tvm.arith.detect_linear_equation(b * 7, [])
    assert len(m) == 1
    tvm.testing.assert_prim_expr_equal(m[0], b * 7)


def test_multivariate():
    v = [te.var("v%d" % i) for i in range(4)]
    b = te.var("b")
    m = tvm.arith.detect_linear_equation(v[0] * (b + 4) + v[0] + v[1] * 8, v)

    tvm.testing.assert_prim_expr_equal(m[0], b + 5)

    assert m[1].value == 8

    m = tvm.arith.detect_linear_equation(v[0] * (b + 4) + v[0] + v[1] * 8 * v[2], v)
    assert len(m) == 0

    m = tvm.arith.detect_linear_equation(v[0] * (b + 4) + v[0] + v[1] * 8 * v[1] + v[3], v)
    assert len(m) == 0

    m = tvm.arith.detect_linear_equation(((v[0] * b + v[1]) * 8 + v[2] + 1) * 2, v)
    assert m[1].value == 16
    assert m[2].value == 2
    assert m[len(m) - 1].value == 2

    m = tvm.arith.detect_linear_equation((v[0] - v[1]), [v[2]])
    assert m[0].value == 0

    tvm.testing.assert_prim_expr_equal(m[1], v[0] - v[1])

    m = tvm.arith.detect_linear_equation((v[0] - v[1]), [])
    assert len(m) == 1
    tvm.testing.assert_prim_expr_equal(m[0], v[0] - v[1])


if __name__ == "__main__":
    test_basic()
    test_multivariate()