Skip to content

Commit

Permalink
std.fmt: use SI prefixes for printing bytes
Browse files Browse the repository at this point in the history 
closes #1015
  • Loading branch information
@andrewrk
andrewrk committed May 16, 2018
1 parent ee5f9ff commit 4a3d689
Showing 1 changed file with 58 additions and 29 deletions.
87 changes: 58 additions & 29 deletions std/fmt/index.zig
View file
Expand Up @@ -28,6 +28,7 @@ pub fn format(context: var, comptime Errors: type, output: fn(@typeOf(context),
Buf,
BufWidth,
Bytes,
BytesBase,
BytesWidth,
};

Expand Down Expand Up @@ -99,6 +100,7 @@ pub fn format(context: var, comptime Errors: type, output: fn(@typeOf(context),
},
'B' => {
width = 0;
radix = 1000;
state = State.Bytes;
},
else => @compileError("Unknown format character: " ++ []u8{c}),
Expand Down Expand Up @@ -214,7 +216,24 @@ pub fn format(context: var, comptime Errors: type, output: fn(@typeOf(context),
},
State.Bytes => switch (c) {
'}' => {
try formatBytes(args[next_arg], 0, context, Errors, output);
try formatBytes(args[next_arg], 0, radix, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'i' => {
radix = 1024;
state = State.BytesBase;
},
'0' ... '9' => {
width_start = i;
state = State.BytesWidth;
},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.BytesBase => switch (c) {
'}' => {
try formatBytes(args[next_arg], 0, radix, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
Expand All @@ -228,7 +247,7 @@ pub fn format(context: var, comptime Errors: type, output: fn(@typeOf(context),
State.BytesWidth => switch (c) {
'}' => {
width = comptime (parseUnsigned(usize, fmt[width_start..i], 10) catch unreachable);
try formatBytes(args[next_arg], width, context, Errors, output);
try formatBytes(args[next_arg], width, radix, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
Expand Down Expand Up @@ -550,24 +569,34 @@ pub fn formatFloatDecimal(value: var, maybe_precision: ?usize, context: var, com
}
}

pub fn formatBytes(value: var, width: ?usize,
pub fn formatBytes(value: var, width: ?usize, comptime radix: usize,
context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void
{
if (value == 0) {
return output(context, "0B");
}

const mags = " KMGTPEZY";
const magnitude = math.min(math.log2(value) / 10, mags.len - 1);
const new_value = f64(value) / math.pow(f64, 1024, f64(magnitude));
const magnitude = switch (radix) {
1000 => math.min(math.log2(value) / comptime math.log2(1000), mags.len - 1),
1024 => math.min(math.log2(value) / 10, mags.len - 1),
else => unreachable,
};
const new_value = f64(value) / math.pow(f64, f64(radix), f64(magnitude));
const suffix = mags[magnitude];

try formatFloatDecimal(new_value, width, context, Errors, output);

if (suffix != ' ') {
try output(context, (&suffix)[0..1]);
if (suffix == ' ') {
return output(context, "B");
}
return output(context, "B");

const buf = switch (radix) {
1000 => []u8 { suffix, 'B' },
1024 => []u8 { suffix, 'i', 'B' },
else => unreachable,
};
return output(context, buf);
}

pub fn formatInt(value: var, base: u8, uppercase: bool, width: usize,
Expand Down Expand Up @@ -787,41 +816,27 @@ test "parse unsigned comptime" {

test "fmt.format" {
{
var buf1: [32]u8 = undefined;
const value: ?i32 = 1234;
const result = try bufPrint(buf1[0..], "nullable: {}\n", value);
assert(mem.eql(u8, result, "nullable: 1234\n"));
try testFmt("nullable: 1234\n", "nullable: {}\n", value);
}
{
var buf1: [32]u8 = undefined;
const value: ?i32 = null;
const result = try bufPrint(buf1[0..], "nullable: {}\n", value);
assert(mem.eql(u8, result, "nullable: null\n"));
try testFmt("nullable: null\n", "nullable: {}\n", value);
}
{
var buf1: [32]u8 = undefined;
const value: error!i32 = 1234;
const result = try bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: 1234\n"));
try testFmt("error union: 1234\n", "error union: {}\n", value);
}
{
var buf1: [32]u8 = undefined;
const value: error!i32 = error.InvalidChar;
const result = try bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: error.InvalidChar\n"));
try testFmt("error union: error.InvalidChar\n", "error union: {}\n", value);
}
{
var buf1: [32]u8 = undefined;
const value: u3 = 0b101;
const result = try bufPrint(buf1[0..], "u3: {}\n", value);
assert(mem.eql(u8, result, "u3: 5\n"));
}
{
var buf1: [32]u8 = undefined;
const value: usize = 63 * 1024 * 1024;
const result = try bufPrint(buf1[0..], "file size: {B}\n", value);
assert(mem.eql(u8, result, "file size: 63MB\n"));
try testFmt("u3: 5\n", "u3: {}\n", value);
}
try testFmt("file size: 63MiB\n", "file size: {Bi}\n", usize(63 * 1024 * 1024));
try testFmt("file size: 66.06MB\n", "file size: {B2}\n", usize(63 * 1024 * 1024));
{
// Dummy field because of https://github.com/zig-lang/zig/issues/557.
const Struct = struct {
Expand Down Expand Up @@ -1041,6 +1056,20 @@ test "fmt.format" {
}
}

fn testFmt(expected: []const u8, comptime template: []const u8, args: ...) !void {
var buf: [100]u8 = undefined;
const result = try bufPrint(buf[0..], template, args);
if (mem.eql(u8, result, expected))
return;

std.debug.warn("\n====== expected this output: =========\n");
std.debug.warn("{}", expected);
std.debug.warn("\n======== instead found this: =========\n");
std.debug.warn("{}", result);
std.debug.warn("\n======================================\n");
return error.TestFailed;
}

pub fn trim(buf: []const u8) []const u8 {
var start: usize = 0;
while (start < buf.len and isWhiteSpace(buf[start])) : (start += 1) { }
Expand Down

0 comments on commit 4a3d689

Please sign in to comment.