# mode: run
# tag: readonly, const, numpy

import numpy as np

def new_array():
    return np.arange(10).astype('float')

ARRAY = new_array()


cdef getmax(const double[:] x):
    """Example code, should work with both ro and rw memoryviews"""
    cdef double max_val = -float('inf')
    for val in x:
        if val > max_val:
            max_val = val
    return max_val


cdef update_array(double [:] x):
    """Modifying a ro memoryview should raise an error"""
    x[0] = 23.


cdef getconst(const double [:] x):
    """Should accept ro memoryviews"""
    return x[0]


def test_mmview_rw(x):
    """
    >>> test_mmview_rw(ARRAY)
    9.0
    """
    return getmax(x)


def test_mmview_ro(x):
    """
    >>> test_mmview_ro(new_array())
    9.0
    """
    x.setflags(write=False)
    assert x.flags.writeable is False
    return getmax(x)


def test_update_mmview_rw(x):
    """
    >>> test_update_mmview_rw(new_array())
    23.0
    """
    update_array(x)
    return x[0]


def test_update_mmview_ro(x):
    """
    >>> test_update_mmview_ro(new_array())
    0.0
    """
    x.setflags(write=False)
    assert x.flags.writeable is False
    try:
        update_array(x)
    except ValueError: pass
    else:
        assert False, "RO error not raised!"
    return getconst(x)


def test_rw_call_getmax(double[:] x):
    """
    >>> test_rw_call_getmax(new_array())
    23.0
    """
    update_array(x)
    assert getconst(x) == 23
    return getmax(x)


def test_const_mmview_ro(x):
    """
    >>> test_const_mmview_ro(new_array())
    0.0
    """
    x.setflags(write=False)
    assert x.flags.writeable is False
    return getconst(x)


def test_two_views(x):
    """
    >>> test_two_views(new_array())
    23.0
    """
    cdef double[:] rw = x
    cdef const double[:] ro = rw
    rw[0] = 23
    return ro[0]


def test_assign_ro_to_rw(x):
    """
    >>> test_assign_ro_to_rw(new_array())
    2.0
    """
    cdef const double[:] ro = x
    cdef double[:] rw = np.empty_like(ro)
    rw[:] = ro
    return rw[2]