Simplify distance conversion (home-assistant#43107)

homeassistant/util/distance.py

@@ -1,5 +1,6 @@
 """Distance util functions."""
 from numbers import Number
+from typing import Callable, Dict
 
 from homeassistant.const import (
     LENGTH,
@@ -25,6 +26,28 @@
     LENGTH_YARD,
 ]
 
+TO_METERS: Dict[str, Callable[[float], float]] = {
+    LENGTH_METERS: lambda meters: meters,
+    LENGTH_MILES: lambda miles: miles * 1609.344,
+    LENGTH_YARD: lambda yards: yards * 0.9144,
+    LENGTH_FEET: lambda feet: feet * 0.3048,
+    LENGTH_INCHES: lambda inches: inches * 0.0254,
+    LENGTH_KILOMETERS: lambda kilometers: kilometers * 1000,
+    LENGTH_CENTIMETERS: lambda centimeters: centimeters * 0.01,
+    LENGTH_MILLIMETERS: lambda millimeters: millimeters * 0.001,
+}
+
+METERS_TO: Dict[str, Callable[[float], float]] = {
+    LENGTH_METERS: lambda meters: meters,
+    LENGTH_MILES: lambda meters: meters * 0.000621371,
+    LENGTH_YARD: lambda meters: meters * 1.09361,
+    LENGTH_FEET: lambda meters: meters * 3.28084,
+    LENGTH_INCHES: lambda meters: meters * 39.3701,
+    LENGTH_KILOMETERS: lambda meters: meters * 0.001,
+    LENGTH_CENTIMETERS: lambda meters: meters * 100,
+    LENGTH_MILLIMETERS: lambda meters: meters * 1000,
+}
+
 
 def convert(value: float, unit_1: str, unit_2: str) -> float:
     """Convert one unit of measurement to another."""
@@ -39,108 +62,6 @@ def convert(value: float, unit_1: str, unit_2: str) -> float:
     if unit_1 == unit_2 or unit_1 not in VALID_UNITS:
         return value
 
-    meters: float = value
-
-    if unit_1 == LENGTH_MILES:
-        meters = __miles_to_meters(value)
-    elif unit_1 == LENGTH_YARD:
-        meters = __yards_to_meters(value)
-    elif unit_1 == LENGTH_FEET:
-        meters = __feet_to_meters(value)
-    elif unit_1 == LENGTH_INCHES:
-        meters = __inches_to_meters(value)
-    elif unit_1 == LENGTH_KILOMETERS:
-        meters = __kilometers_to_meters(value)
-    elif unit_1 == LENGTH_CENTIMETERS:
-        meters = __centimeters_to_meters(value)
-    elif unit_1 == LENGTH_MILLIMETERS:
-        meters = __millimeters_to_meters(value)
-
-    result = meters
-
-    if unit_2 == LENGTH_MILES:
-        result = __meters_to_miles(meters)
-    elif unit_2 == LENGTH_YARD:
-        result = __meters_to_yards(meters)
-    elif unit_2 == LENGTH_FEET:
-        result = __meters_to_feet(meters)
-    elif unit_2 == LENGTH_INCHES:
-        result = __meters_to_inches(meters)
-    elif unit_2 == LENGTH_KILOMETERS:
-        result = __meters_to_kilometers(meters)
-    elif unit_2 == LENGTH_CENTIMETERS:
-        result = __meters_to_centimeters(meters)
-    elif unit_2 == LENGTH_MILLIMETERS:
-        result = __meters_to_millimeters(meters)
-
-    return result
-
-
-def __miles_to_meters(miles: float) -> float:
-    """Convert miles to meters."""
-    return miles * 1609.344
-
-
-def __yards_to_meters(yards: float) -> float:
-    """Convert yards to meters."""
-    return yards * 0.9144
-
-
-def __feet_to_meters(feet: float) -> float:
-    """Convert feet to meters."""
-    return feet * 0.3048
-
-
-def __inches_to_meters(inches: float) -> float:
-    """Convert inches to meters."""
-    return inches * 0.0254
-
-
-def __kilometers_to_meters(kilometers: float) -> float:
-    """Convert kilometers to meters."""
-    return kilometers * 1000
-
-
-def __centimeters_to_meters(centimeters: float) -> float:
-    """Convert centimeters to meters."""
-    return centimeters * 0.01
-
-
-def __millimeters_to_meters(millimeters: float) -> float:
-    """Convert millimeters to meters."""
-    return millimeters * 0.001
-
-
-def __meters_to_miles(meters: float) -> float:
-    """Convert meters to miles."""
-    return meters * 0.000621371
-
-
-def __meters_to_yards(meters: float) -> float:
-    """Convert meters to yards."""
-    return meters * 1.09361
-
-
-def __meters_to_feet(meters: float) -> float:
-    """Convert meters to feet."""
-    return meters * 3.28084
-
-
-def __meters_to_inches(meters: float) -> float:
-    """Convert meters to inches."""
-    return meters * 39.3701
-
-
-def __meters_to_kilometers(meters: float) -> float:
-    """Convert meters to kilometers."""
-    return meters * 0.001
-
-
-def __meters_to_centimeters(meters: float) -> float:
-    """Convert meters to centimeters."""
-    return meters * 100
-
+    meters: float = TO_METERS[unit_1](value)
 
-def __meters_to_millimeters(meters: float) -> float:
-    """Convert meters to millimeters."""
-    return meters * 1000
+    return METERS_TO[unit_2](meters)