Define from_digits on concrete integer types

Author: andrykonchin

src/int.cr

@@ -670,46 +670,6 @@ struct Int
     ary
   end
 
-  # Returns a number for given digits and base.
-  # The digits are expected as an Enumerable with the least significant digit as the first element.
-  #
-  # Base must not be less than 2.
-  #
-  # All digits must be within 0...base.
-  #
-  # ```
-  # Int.from_digits([5, 4, 3, 2, 1])           # => 12345
-  # Int.from_digits([4, 6, 6, 0, 5], base: 7)  # => 12345
-  # Int.from_digits([45, 23, 1], base: 100)    # => 12345
-  #
-  # Int.from_digits([1], base: -2) # => ArgumentError
-  # Int.from_digits([-1]) # => ArgumentError
-  # Int.from_digits([3], base: 2) # => ArgumentError
-  # ```
-  def self.from_digits(digits : Enumerable(Int), base : Int = 10) : self
-    if base < 2
-      raise ArgumentError.new("Invalid base #{base}")
-    end
-
-    num = 0
-    multiplier = 1
-
-    digits.each do |digit|
-      if digit < 0
-        raise ArgumentError.new("Invalid digit #{digit}")
-      end
-
-      if digit >= base
-        raise ArgumentError.new("Invalid digit #{digit} for base #{base}")
-      end
-
-      num += digit * multiplier
-      multiplier *= base
-    end
-
-    num
-  end
-
   private DIGITS_DOWNCASE = "0123456789abcdefghijklmnopqrstuvwxyz"
   private DIGITS_UPCASE   = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
   private DIGITS_BASE62   = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
@@ -2816,3 +2776,45 @@ struct UInt128
     self
   end
 end
+
+# Returns a number for given digits and base.
+# The digits are expected as an Enumerable with the least significant digit as the first element.
+#
+# Base must not be less than 2.
+#
+# All digits must be within 0...base.
+#
+# ```
+# Int32.from_digits([5, 4, 3, 2, 1])           # => 12345
+# Int32.from_digits([4, 6, 6, 0, 5], base: 7)  # => 12345
+# Int32.from_digits([45, 23, 1], base: 100)    # => 12345
+#
+# Int32.from_digits([1], base: -2) # => ArgumentError
+# Int32.from_digits([-1]) # => ArgumentError
+# Int32.from_digits([3], base: 2) # => ArgumentError
+# ```
+{% for type in %w(Int8 Int16 Int32 Int64 Int128 UInt8 UInt16 UInt32 UInt64 UInt128) %}
+  def {{type.id}}.from_digits(digits : Enumerable(Int), base : Int = 10) : self
+    if base < 2
+      raise ArgumentError.new("Invalid base #{base}")
+    end
+
+    num : {{type.id}} = 0
+    multiplier = 1
+
+    digits.each do |digit|
+      if digit < 0
+        raise ArgumentError.new("Invalid digit #{digit}")
+      end
+
+      if digit >= base
+        raise ArgumentError.new("Invalid digit #{digit} for base #{base}")
+      end
+
+      num += digit * multiplier
+      multiplier *= base
+    end
+
+    num
+  end
+{% end %}