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Fixes floating point alignment in std.fmt.format #6002

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Merged
merged 3 commits into from
Aug 11, 2020
Merged

Fixes floating point alignment in std.fmt.format #6002

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06a1184
Fixes double alignment
ikskuh Aug 9, 2020
ada06e2
Makes formatFloatValue not return error.NoSpaceLeft anymore.
ikskuh Aug 9, 2020
6701046
Uses getWritten instead of .pos + slicing
ikskuh Aug 9, 2020
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30 changes: 28 additions & 2 deletions lib/std/fmt.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -560,13 +560,25 @@ fn formatFloatValue(
options: FormatOptions,
writer: anytype,
) !void {
// this buffer should be enough to display all decimal places of a decimal f64 number.
var buf: [512]u8 = undefined;
var buf_stream = std.io.fixedBufferStream(&buf);

if (fmt.len == 0 or comptime std.mem.eql(u8, fmt, "e")) {
return formatFloatScientific(value, options, writer);
formatFloatScientific(value, options, buf_stream.writer()) catch |err| switch (err) {
error.NoSpaceLeft => unreachable,
else => |e| return e,
};
} else if (comptime std.mem.eql(u8, fmt, "d")) {
return formatFloatDecimal(value, options, writer);
formatFloatDecimal(value, options, buf_stream.writer()) catch |err| switch (err) {
error.NoSpaceLeft => unreachable,
else => |e| return e,
};
} else {
@compileError("Unknown format string: '" ++ fmt ++ "'");
}

return formatBuf(buf_stream.getWritten(), options, writer);
}

pub fn formatText(
Expand Down Expand Up @@ -1791,3 +1803,17 @@ test "padding" {
try testFmt("==================Filled", "{:=>24}", .{"Filled"});
try testFmt(" Centered ", "{:^24}", .{"Centered"});
}

test "decimal float padding" {
var number: f32 = 3.1415;
try testFmt("left-pad: **3.141\n", "left-pad: {d:*>7.3}\n", .{number});
try testFmt("center-pad: *3.141*\n", "center-pad: {d:*^7.3}\n", .{number});
try testFmt("right-pad: 3.141**\n", "right-pad: {d:*<7.3}\n", .{number});
}

test "sci float padding" {
var number: f32 = 3.1415;
try testFmt("left-pad: **3.141e+00\n", "left-pad: {e:*>11.3}\n", .{number});
try testFmt("center-pad: *3.141e+00*\n", "center-pad: {e:*^11.3}\n", .{number});
try testFmt("right-pad: 3.141e+00**\n", "right-pad: {e:*<11.3}\n", .{number});
}