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std: Make parseInt/parseUnsigned detect the radix

master
LemonBoy 2020-10-31 12:06:42 +01:00 committed by Andrew Kelley
parent 00ceb592ef
commit 35a8d90e55
1 changed files with 62 additions and 3 deletions
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65
lib/std/fmt.zig
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@ -1059,6 +1059,16 @@ pub const ParseIntError = error{
InvalidCharacter,
};
/// Parses the string `buf` as signed or unsigned representation in the
/// specified radix of an integral value of type `T`.
///
/// When `radix` is zero the string prefix is examined to detect the true radix:
/// * A prefix of "0b" implies radix=2,
/// * A prefix of "0o" implies radix=8,
/// * A prefix of "0x" implies radix=16,
/// * Otherwise radix=10 is assumed.
///
/// See also `parseUnsigned`.
pub fn parseInt(comptime T: type, buf: []const u8, radix: u8) ParseIntError!T {
if (buf.len == 0) return error.InvalidCharacter;
if (buf[0] == '+') return parseWithSign(T, buf[1..], radix, .Pos);
@ -1091,6 +1101,20 @@ test "parseInt" {
std.testing.expectError(error.InvalidCharacter, parseInt(i32, "+", 10));
std.testing.expectError(error.InvalidCharacter, parseInt(u32, "-", 10));
std.testing.expectError(error.InvalidCharacter, parseInt(i32, "-", 10));
// autodectect the radix
std.testing.expect((try parseInt(i32, "111", 0)) == 111);
std.testing.expect((try parseInt(i32, "+0b111", 0)) == 7);
std.testing.expect((try parseInt(i32, "+0o111", 0)) == 73);
std.testing.expect((try parseInt(i32, "+0x111", 0)) == 273);
std.testing.expect((try parseInt(i32, "-0b111", 0)) == -7);
std.testing.expect((try parseInt(i32, "-0o111", 0)) == -73);
std.testing.expect((try parseInt(i32, "-0x111", 0)) == -273);
// bare binary/octal/decimal prefix is invalid
std.testing.expectError(error.InvalidCharacter, parseInt(u32, "0b", 0));
std.testing.expectError(error.InvalidCharacter, parseInt(u32, "0o", 0));
std.testing.expectError(error.InvalidCharacter, parseInt(u32, "0x", 0));
}
fn parseWithSign(
@ -1101,6 +1125,31 @@ fn parseWithSign(
) ParseIntError!T {
if (buf.len == 0) return error.InvalidCharacter;
var buf_radix = radix;
var buf_start = buf;
if (radix == 0) {
// Treat is as a decimal number by default.
buf_radix = 10;
// Detect the radix by looking at buf prefix.
if (buf.len > 2 and buf[0] == '0') {
switch (buf[1]) {
'b' => {
buf_radix = 2;
buf_start = buf[2..];
},
'o' => {
buf_radix = 8;
buf_start = buf[2..];
},
'x' => {
buf_radix = 16;
buf_start = buf[2..];
},
else => {},
}
}
}
const add = switch (sign) {
.Pos => math.add,
.Neg => math.sub,
@ -1108,16 +1157,26 @@ fn parseWithSign(
var x: T = 0;
for (buf) |c| {
const digit = try charToDigit(c, radix);
for (buf_start) |c| {
const digit = try charToDigit(c, buf_radix);
if (x != 0) x = try math.mul(T, x, try math.cast(T, radix));
if (x != 0) x = try math.mul(T, x, try math.cast(T, buf_radix));
x = try add(T, x, try math.cast(T, digit));
}
return x;
}
/// Parses the string `buf` as unsigned representation in the specified radix
/// of an integral value of type `T`.
///
/// When `radix` is zero the string prefix is examined to detect the true radix:
/// * A prefix of "0b" implies radix=2,
/// * A prefix of "0o" implies radix=8,
/// * A prefix of "0x" implies radix=16,
/// * Otherwise radix=10 is assumed.
///
/// See also `parseInt`.
pub fn parseUnsigned(comptime T: type, buf: []const u8, radix: u8) ParseIntError!T {
return parseWithSign(T, buf, radix, .Pos);
}