Zig 0.17.0-dev (Split by item)

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parseInt

This function is specific to how the Win32 RC command line interprets language IDs specified as integers.

Always interpreted as hexadecimal, but explicit 0x prefix is also allowed
Wraps on overflow of u16
Stops parsing on any invalid hexadecimal digits
Errors if a digit is not the first char
- (negative) prefix is allowed

lang.parseInt

pub fn parseInt(str: []const u8) error

File

lib/compiler/resinator/lang.zig:10

Code

pub fn parseInt(str: []const u8) error{InvalidLanguageId}!u16 {
    var result: u16 = 0;
    const radix: u8 = 16;
    var buf = str;

    const Prefix = enum { none, minus };
    var prefix: Prefix = .none;
    switch (buf[0]) {
        '-' => {
            prefix = .minus;
            buf = buf[1..];
        },
        else => {},
    }

    if (buf.len > 2 and buf[0] == '0' and buf[1] == 'x') {
        buf = buf[2..];
    }

    for (buf, 0..) |c, i| {
        const digit = switch (c) {
            // On invalid digit for the radix, just stop parsing but don't fail
            'a'...'f', 'A'...'F', '0'...'9' => std.fmt.charToDigit(c, radix) catch break,
            else => {
                // First digit must be valid
                if (i == 0) {
                    return error.InvalidLanguageId;
                }
                break;
            },
        };

        if (result != 0) {
            result *%= radix;
        }
        result +%= digit;
    }

    switch (prefix) {
        .none => {},
        .minus => result = 0 -% result,
    }

    return result;
}