Source code for pychord.utils

# -*- coding: utf-8 -*-

from .constants import NOTE_VAL_DICT, SCALE_VAL_DICT


def note_to_val(note):
    """ Convert note to int

    >>> note_to_val("C")
    0
    >>> note_to_val("B")
    11

    :type note: str
    :rtype: int
    """
    if note not in NOTE_VAL_DICT:
        raise ValueError("Unknown note {}".format(note))
    return NOTE_VAL_DICT[note]


def val_to_note(val, scale="C"):
    """ Convert int to note

    >>> val_to_note(0)
    "C"
    >>> val_to_note(11, "D")
    "D#"

    :type val: int
    :param str scale: key scale
    :rtype: str
    """
    val %= 12
    return SCALE_VAL_DICT[scale][val]


def transpose_note(note, transpose, scale="C"):
    """ Transpose a note

    :param str note: note to transpose
    :type transpose: int
    :param str scale: key scale
    :rtype: str
    :return: transposed note
    """
    val = note_to_val(note)
    val += transpose
    return val_to_note(val, scale)


def display_appended(appended):
    # TODO: Implement this
    return ""


def display_on(on_note):
    if on_note:
        return "/{}".format(on_note)
    return ""