fix issue where passing two styles would fail with index error

pydocstringformatter/_formatting/base.py

@@ -278,7 +278,7 @@ def treat_string(
             if first_section:
                 section[0] = section[0].lstrip()
                 first_section = False
-            elif not section[0][0].isspace():
+            elif len(section[0]) > 0 and not section[0][0].isspace():
                 section[0] = f"{' ' * indent_length:s}{section[0]:s}"
 
         # Rejoin sections

tests/data/format/multi_style/numpydoc_parameter_spacing.args

@@ -0,0 +1,2 @@
+--style=numpydoc
+--style=pep257

tests/data/format/multi_style/numpydoc_parameter_spacing.py

@@ -0,0 +1,63 @@
+"""Example module for numpydoc docstring style.
+References
+-----
+NumPy docstring style guide:
+https://numpydoc.readthedocs.io/en/latest/format.html#documenting-modules"""
+import math
+
+EULER_NUMBER = math.e
+"""Euler's number.
+
+Not related to Euler's constant (sometimes called the Euler-Mascheroni
+constant.
+References
+-----
+E (mathematical constant)
+https://en.wikipedia.org/wiki/E_(mathematical_constant)
+Notes
+---
+It is the limit of ``(1 + 1/n)**n`` as n approaches infinity, so it
+is used in the equation for continuously-compouned interest.
+
+It is also the sum of the reciprocals of the whole numbers starting
+with zero, which is related to some calculus-related properties
+mathemeticians find elegant.
+"""
+
+
+def sincos(theta):
+    """Returns
+    ----
+    sin: float
+        the sine of theta
+    cos: float
+        the cosine of theta
+    Raises
+    ---
+    TypeError
+        If `theta` is not a float.
+    Parameters
+    -----
+    theta: float
+        the angle at which to calculate the sine and cosine.
+"""
+    return math.sin(theta), math.cos(theta)
+
+
+def fibbonacci():
+    """Generate the Fibonacci sequence.
+
+    Each term is the sum of the two previous; conventionally starts
+    with two ones.
+    References
+    -----
+    Fibonacci numbers
+    https://en.wikipedia.org/wiki/Fibonacci_number
+    Yields
+    ---
+    int"""
+    curr = 1
+    last = 0
+    while True:
+        yield curr
+        curr, last = curr + last, curr

tests/data/format/multi_style/numpydoc_parameter_spacing.py.out

@@ -0,0 +1,74 @@
+"""Example module for numpydoc docstring style.
+
+References
+----------
+NumPy docstring style guide:
+https://numpydoc.readthedocs.io/en/latest/format.html#documenting-modules
+"""
+import math
+
+EULER_NUMBER = math.e
+"""Euler's number.
+
+Not related to Euler's constant (sometimes called the Euler-Mascheroni
+constant.
+
+Notes
+-----
+It is the limit of ``(1 + 1/n)**n`` as n approaches infinity, so it
+is used in the equation for continuously-compouned interest.
+
+It is also the sum of the reciprocals of the whole numbers starting
+with zero, which is related to some calculus-related properties
+mathemeticians find elegant.
+
+References
+----------
+E (mathematical constant)
+https://en.wikipedia.org/wiki/E_(mathematical_constant)
+"""
+
+
+def sincos(theta):
+    """Returns.
+
+    Parameters
+    ----------
+    theta : float
+        the angle at which to calculate the sine and cosine.
+
+    Raises
+    ------
+    TypeError
+        If `theta` is not a float.
+
+
+
+    sin: float
+        the sine of theta
+    cos: float
+        the cosine of theta
+    """
+    return math.sin(theta), math.cos(theta)
+
+
+def fibbonacci():
+    """Generate the Fibonacci sequence.
+
+    Each term is the sum of the two previous; conventionally starts
+    with two ones.
+
+    Yields
+    ------
+    int
+
+    References
+    ----------
+    Fibonacci numbers
+    https://en.wikipedia.org/wiki/Fibonacci_number
+    """
+    curr = 1
+    last = 0
+    while True:
+        yield curr
+        curr, last = curr + last, curr