Allow underscores in the String passed to Big* constructors

spec/std/big/big_decimal_spec.cr

@@ -21,6 +21,9 @@ describe BigDecimal do
     BigDecimal.new("42.0123")
       .should eq(BigDecimal.new(BigInt.new(420123), 4))
 
+    BigDecimal.new("42_42_42_24.0123_456_789")
+      .should eq(BigDecimal.new(BigInt.new(424242240123456789), 10))
+
     BigDecimal.new("0.0")
       .should eq(BigDecimal.new(BigInt.new(0)))
 

spec/std/big/big_float_spec.cr

@@ -13,6 +13,7 @@ describe "BigFloat" do
       bigfloat_of_float_value.to_s.should eq(string_of_float_value)
       BigFloat.new("+#{string_of_integer_value}").to_s.should eq(string_of_integer_value)
       BigFloat.new("-#{string_of_integer_value}").to_s.should eq("-#{string_of_integer_value}")
+      BigFloat.new("123_456_789.123_456_789").to_s.should eq("123456789.123456789")
     end
 
     it "raises an ArgumentError unless string denotes valid float" do

spec/std/big/big_int_spec.cr

@@ -22,6 +22,7 @@ describe "BigInt" do
 
   it "creates from string" do
     BigInt.new("12345678").to_s.should eq("12345678")
+    BigInt.new("123_456_78").to_s.should eq("12345678")
     BigInt.new("+12345678").to_s.should eq("12345678")
     BigInt.new("-12345678").to_s.should eq("-12345678")
   end

src/big/big_decimal.cr

@@ -63,6 +63,8 @@ struct BigDecimal < Number
   def initialize(str : String)
     # Strip leading '+' char to smooth out cases with strings like "+123"
     str = str.lchop('+')
+    # Strip '_' to make it compatible with int literals like "1_000_000"
+    str = str.delete('_')
 
     raise InvalidBigDecimalException.new(str, "Zero size") if str.bytesize == 0
 

src/big/big_float.cr

@@ -16,6 +16,8 @@ struct BigFloat < Float
   def initialize(str : String)
     # Strip leading '+' char to smooth out cases with strings like "+123"
     str = str.lchop('+')
+    # Strip '_' to make it compatible with int literals like "1_000_000"
+    str = str.delete('_')
     if LibGMP.mpf_init_set_str(out @mpf, str, 10) == -1
       raise ArgumentError.new("Invalid BigFloat: #{str.inspect}")
     end

src/big/big_int.cr

@@ -27,11 +27,14 @@ struct BigInt < Int
   #
   # ```
   # BigInt.new("123456789123456789123456789123456789") # => 123456789123456789123456789123456789
+  # BigInt.new("123_456_789_123_456_789_123_456_789")  # => 123456789012345678901234567890
   # BigInt.new("1234567890ABCDEF", base: 16)           # => 1311768467294899695
   # ```
   def initialize(str : String, base = 10)
     # Strip leading '+' char to smooth out cases with strings like "+123"
     str = str.lchop('+')
+    # Strip '_' to make it compatible with int literals like "1_000_000"
+    str = str.delete('_')
     err = LibGMP.init_set_str(out @mpz, str, base)
     if err == -1
       raise ArgumentError.new("Invalid BigInt: #{str}")