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support printing unicode codepoints with {c} #5569

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support printing unicode codepoints with {c} #5569

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f0026e5
support printing codepoints as {c}
pfgithub Jun 9, 2020
175d5bf
{c} codepoint error test
pfgithub Jun 9, 2020
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25 changes: 24 additions & 1 deletion lib/std/fmt.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -530,8 +530,10 @@ pub fn formatIntValue(
} else if (comptime std.mem.eql(u8, fmt, "c")) {
if (@TypeOf(int_value).bit_count <= 8) {
return formatAsciiChar(@as(u8, int_value), options, out_stream);
} else if (@TypeOf(int_value).bit_count <= 32) {
return formatUnicodeCodepoint(@as(u21, int_value), options, out_stream);
} else {
@compileError("Cannot print integer that is larger than 8 bits as a ascii");
@compileError("Cannot print character that is larger than 21 bits as unicode codepoint");
}
} else if (comptime std.mem.eql(u8, fmt, "b")) {
radix = 2;
Expand Down Expand Up @@ -590,6 +592,19 @@ pub fn formatAsciiChar(
return out_stream.writeAll(@as(*const [1]u8, &c));
}

pub fn formatUnicodeCodepoint(
c: u21,
options: FormatOptions,
out_stream: var,
) !void {
var result: [4]u8 = undefined;
const len = std.unicode.utf8Encode(c, &result) catch |e| switch (e) {
error.CodepointTooLarge => return out_stream.writeAll("<codepoint too large>"),
error.Utf8CannotEncodeSurrogateHalf => return out_stream.writeAll("<invalid codepoint>"),
};
return out_stream.writeAll(result[0..len]);
}

pub fn formatBuf(
buf: []const u8,
options: FormatOptions,
Expand Down Expand Up @@ -1197,6 +1212,14 @@ test "int.specifier" {
const value: u8 = 'a';
try testFmt("u8: a\n", "u8: {c}\n", .{value});
}
{
const value: u21 = 'あ';
try testFmt("codepoint: あ\n", "codepoint: {c}\n", .{value});
}
{
const value: u21 = 2097151;
try testFmt("codepoint: <codepoint too large>\n", "codepoint: {c}\n", .{value});
}
{
const value: u8 = 0b1100;
try testFmt("u8: 0b1100\n", "u8: 0b{b}\n", .{value});
Expand Down