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Add RocDec.toString

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Jared Ramirez 2021-06-04 19:33:38 -07:00
parent 66a6080f25
commit c7272766fc
1 changed files with 126 additions and 0 deletions
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126
compiler/builtins/bitcode/src/dec.zig
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@ -8,6 +8,7 @@ pub const RocDec = struct {
num: i128,
pub const decimal_places: comptime u32 = 18;
const max_digits: comptime u32 = 39;
pub const min: comptime RocDec = .{ .num = math.minInt(i128) };
pub const max: comptime RocDec = .{ .num = math.maxInt(i128) };
@ -108,6 +109,60 @@ pub const RocDec = struct {
};
}
pub fn toString(self: RocDec) ?RocStr {
var num_bytes: [max_digits]u8 = undefined;
var num_digits = std.fmt.formatIntBuf(num_bytes[0..], self.num, 10, false, .{});
var before_num_digits = num_digits - decimal_places;
var index = decimal_places - 1;
var trim_index: ?usize = null;
var is_consecutive_zero = true;
while (index != 0) {
var digit = num_bytes[before_num_digits + index];
if (digit == '0' and is_consecutive_zero) {
trim_index = index;
} else {
is_consecutive_zero = false;
}
index -= 1;
}
var after_num_digits = if (trim_index) |i| i else decimal_places;
const should_add_prefix_zero = before_num_digits == 0 or (before_num_digits == 1 and num_bytes[0] == '-');
const prefix_zero_len: usize = if (should_add_prefix_zero) 1 else 0;
const dot_len: usize = 1;
var str_len = prefix_zero_len + before_num_digits + dot_len + after_num_digits;
// [max_digits + 2] here to account for '.' and '-'
var str_bytes: [max_digits + 2]u8 = undefined;
var str_bytes_index: usize = 0;
var bytes_index: usize = 0;
if (should_add_prefix_zero) {
if (num_bytes[bytes_index] == '-') {
str_bytes[str_bytes_index] = '-';
str_bytes_index += 1;
bytes_index += 1;
}
str_bytes[str_bytes_index] = '0';
str_bytes_index += 1;
}
while (bytes_index < str_len) {
if (bytes_index == before_num_digits) {
str_bytes[str_bytes_index] = '.';
str_bytes_index += 1;
}
str_bytes[str_bytes_index] = num_bytes[bytes_index];
str_bytes_index += 1;
bytes_index += 1;
}
return RocStr.init(&str_bytes, str_len);
}
pub fn negate(self: RocDec) ?RocDec {
var negated = math.negate(self.num) catch null;
return if (negated) |n| .{ .num = n } else null;
@ -319,6 +374,7 @@ fn mul_u128(a: u128, b: u128) U256 {
const testing = std.testing;
const expectEqual = testing.expectEqual;
const expect = testing.expect;
test "fromU64" {
var dec = RocDec.fromU64(25);
@ -431,6 +487,76 @@ test "fromString: .123.1" {
expectEqual(dec, null);
}
test "toString: 123.45" {
var roc_str = RocStr.init("123.45", 6);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: -123.45" {
var roc_str = RocStr.init("-123.45", 7);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: 123.0" {
var roc_str = RocStr.init("123.0", 5);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: -123.0" {
var roc_str = RocStr.init("-123.0", 6);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: 0.45" {
var roc_str = RocStr.init("0.45", 4);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: -0.45" {
var roc_str = RocStr.init("-0.45", 5);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: -111.123456789" {
var roc_str = RocStr.init("-111.123456789", 14);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: 111.1234567891" {
var roc_str = RocStr.init("111.1234567891", 14);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "toString: 123.111111111111 (big str)" {
var roc_str = RocStr.init("123.111111111111", 16);
var dec = RocDec.fromString(roc_str);
var res_roc_str = dec.?.toString();
expect(RocStr.eq(roc_str, res_roc_str.?));
}
test "add: 0" {
var dec: RocDec = .{ .num = 0 };