strconv: add 0b, 0o integer prefixes in ParseInt, ParseUint
This CL modifies ParseInt and ParseUint to recognize
0b and 0o as binary and octal base prefixes when base == 0.
See golang.org/design/19308-number-literals for background.
For #19308.
For #12711.
Change-Id: I8efe067f415aa517bdefbff7e230d3fa1694d530
Reviewed-on: https://go-review.googlesource.com/c/160244
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/src/strconv/atoi.go b/src/strconv/atoi.go
index ecbc9f4..31774d0 100644
--- a/src/strconv/atoi.go
+++ b/src/strconv/atoi.go
@@ -71,18 +71,22 @@
case base == 0:
// Look for octal, hex prefix.
- switch {
- case s[0] == '0' && len(s) >= 3 && lower(s[1]) == 'x':
- if len(s) < 3 {
- return 0, syntaxError(fnParseUint, s0)
+ base = 10
+ if s[0] == '0' {
+ switch {
+ case len(s) >= 3 && lower(s[1]) == 'b':
+ base = 2
+ s = s[2:]
+ case len(s) >= 3 && lower(s[1]) == 'o':
+ base = 8
+ s = s[2:]
+ case len(s) >= 3 && lower(s[1]) == 'x':
+ base = 16
+ s = s[2:]
+ default:
+ base = 8
+ s = s[1:]
}
- base = 16
- s = s[2:]
- case s[0] == '0':
- base = 8
- s = s[1:]
- default:
- base = 10
}
default:
@@ -149,13 +153,14 @@
// bit size (0 to 64) and returns the corresponding value i.
//
// If base == 0, the base is implied by the string's prefix:
-// base 16 for "0x", base 8 for "0", and base 10 otherwise.
-// For bases 1, below 0 or above 36 an error is returned.
+// base 2 for "0b", base 8 for "0" or "0o", base 16 for "0x",
+// and base 10 otherwise.
+// If base is below 0, is 1, or is above 36, an error is returned.
//
// The bitSize argument specifies the integer type
// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
// correspond to int, int8, int16, int32, and int64.
-// For a bitSize below 0 or above 64 an error is returned.
+// If bitSize is below 0 or above 64, an error is returned.
//
// The errors that ParseInt returns have concrete type *NumError
// and include err.Num = s. If s is empty or contains invalid
diff --git a/src/strconv/atoi_test.go b/src/strconv/atoi_test.go
index ec0542ab..8b0576b 100644
--- a/src/strconv/atoi_test.go
+++ b/src/strconv/atoi_test.go
@@ -65,42 +65,69 @@
{"01777777777777777777778", 0, 0, ErrSyntax},
{"02000000000000000000000", 0, 1<<64 - 1, ErrRange},
{"0200000000000000000000", 0, 1 << 61, nil},
+ {"0b", 0, 0, ErrSyntax},
+ {"0B", 0, 0, ErrSyntax},
+ {"0b101", 0, 5, nil},
+ {"0B101", 0, 5, nil},
+ {"0o", 0, 0, ErrSyntax},
+ {"0O", 0, 0, ErrSyntax},
+ {"0o377", 0, 255, nil},
+ {"0O377", 0, 255, nil},
// underscores allowed with base == 0 only
- {"1_2_3_4_5", 0, 12345, nil},
+ {"1_2_3_4_5", 0, 12345, nil}, // base 0 => 10
{"_12345", 0, 0, ErrSyntax},
{"1__2345", 0, 0, ErrSyntax},
{"12345_", 0, 0, ErrSyntax},
- {"1_2_3_4_5", 10, 0, ErrSyntax},
+ {"1_2_3_4_5", 10, 0, ErrSyntax}, // base 10
{"_12345", 10, 0, ErrSyntax},
{"1__2345", 10, 0, ErrSyntax},
{"12345_", 10, 0, ErrSyntax},
- {"0x_1_2_3_4_5", 0, 0x12345, nil},
+ {"0x_1_2_3_4_5", 0, 0x12345, nil}, // base 0 => 16
{"_0x12345", 0, 0, ErrSyntax},
{"0x__12345", 0, 0, ErrSyntax},
{"0x1__2345", 0, 0, ErrSyntax},
{"0x1234__5", 0, 0, ErrSyntax},
{"0x12345_", 0, 0, ErrSyntax},
- {"1_2_3_4_5", 16, 0, ErrSyntax},
+ {"1_2_3_4_5", 16, 0, ErrSyntax}, // base 16
{"_12345", 16, 0, ErrSyntax},
{"1__2345", 16, 0, ErrSyntax},
{"1234__5", 16, 0, ErrSyntax},
{"12345_", 16, 0, ErrSyntax},
- {"0_1_2_3_4_5", 0, 012345, nil},
+ {"0_1_2_3_4_5", 0, 012345, nil}, // base 0 => 8 (0377)
{"_012345", 0, 0, ErrSyntax},
{"0__12345", 0, 0, ErrSyntax},
{"01234__5", 0, 0, ErrSyntax},
{"012345_", 0, 0, ErrSyntax},
- {"0_1_2_3_4_5", 8, 0, ErrSyntax},
+ {"0o_1_2_3_4_5", 0, 012345, nil}, // base 0 => 8 (0o377)
+ {"_0o12345", 0, 0, ErrSyntax},
+ {"0o__12345", 0, 0, ErrSyntax},
+ {"0o1234__5", 0, 0, ErrSyntax},
+ {"0o12345_", 0, 0, ErrSyntax},
+
+ {"0_1_2_3_4_5", 8, 0, ErrSyntax}, // base 8
{"_012345", 8, 0, ErrSyntax},
{"0__12345", 8, 0, ErrSyntax},
{"01234__5", 8, 0, ErrSyntax},
{"012345_", 8, 0, ErrSyntax},
+
+ {"0b_1_0_1", 0, 5, nil}, // base 0 => 2 (0b101)
+ {"_0b101", 0, 0, ErrSyntax},
+ {"0b__101", 0, 0, ErrSyntax},
+ {"0b1__01", 0, 0, ErrSyntax},
+ {"0b10__1", 0, 0, ErrSyntax},
+ {"0b101_", 0, 0, ErrSyntax},
+
+ {"1_0_1", 2, 0, ErrSyntax}, // base 2
+ {"_101", 2, 0, ErrSyntax},
+ {"1_01", 2, 0, ErrSyntax},
+ {"10_1", 2, 0, ErrSyntax},
+ {"101_", 2, 0, ErrSyntax},
}
type parseInt64Test struct {
