feat(ufmt): enhance printf functionnalities by adding flags #4136

paulogarithm · 2025-04-14T14:51:35Z

Fixes

ufmt/printf
- added flag parsing, such as %.number, %#, %0, and others
- cf 5d71b3a
- new features has been tested using unit tests (see tests)

* includes gnominers * includes home * include pure packages

* reorganise gnominers into submodules * create the dao submodule * add the tofix folder with all broken features * create the minerdao /!\ DAO DOESNT WORK RN BECAUSE OF CYCLE DEPENDANCIES /!\

* i didnt use subfolders

* add precisision flag ("%.2f") * add 0 & ' ' flags ("%03d", "% 3d") * add length parsing (not used rn) * add # for hex ("%#02x") * add %i & %X (%i is just %d, %X is big hex) * change the home * ass some tests to handle what ive done

* also changed my home page so it displays a number

Format -> FormatRound because it rounds...

* cause of major issue because it was reading to far

* better messages * better formatting * use `p/moun/md` for md formatting in users.gno

paulogarithm · 2025-04-15T13:46:21Z

tell me if i need to add anything else !

notJoon

I've confirmed that all the requested changes have been reflected and all tests have passed.

It's a minor point related to policy, but the "resolve conversation" button should not be pressed until the reviewer has checked it. Please refer to this document for more details.

Anyway, except for this, everything else looks good.

remove: review/triage-pending flag

notJoon · 2025-04-16T10:26:54Z

@paulogarithm

Hmm... When using ufmt (especially, using Sprintf function), gas consumption increases causing "out of gas" errors and test failures. The other CI failure issues will likely be resolved with a branch update, but this one seems to require code modifications.

I'll check this problem today. If it's okay, may I modify this code together with you?

paulogarithm · 2025-04-16T16:30:06Z

totally fine for me, @notJoon ! but maybe it's because of the maps, so when you'll test, can you try putting the maps in the scope like i did, even if it's more greedy on memory ?

notJoon · 2025-04-17T00:56:05Z

can you try putting the maps in the scope like i did, even if it's more greedy on memory ?

I'm testing by directly checking the gas consumption with txtar. It seems rather than map usage, we also need to improve parts related to memory allocation within the ufmt package overall.

notJoon · 2025-04-17T02:27:53Z

@paulogarithm I couldn't push directly to this PR #4174, so I created a separate PR. Please check it and feel free to cherry-pick if needed. thank you 👍

gfanton

Nice ! this is something really welcome !

Could you please update documentation above Sprintf as well as indicating all currently supported flags ? (you can take inspiration from https://pkg.go.dev/fmt)

While we are here we could support padding as well ? (could be done in another PR)

I've tried your code against some go/fmt test code, and the output differs in many formatting cases.

		// advanced int (from go/fmt)
		{"%.d", []any{0}, ""},
		{"%.0d", []any{0}, ""},
		{"% d", []any{12345}, " 12345"},
		{"%+d", []any{12345}, "+12345"},
		{"%+d", []any{-12345}, "-12345"},
		{"%#X", []any{0}, "0X0"},
		{"%x", []any{0x12abcdef}, "12abcdef"},
		{"%X", []any{0x12abcdef}, "12ABCDEF"},
		{"%x", []any{^uint32(0)}, "ffffffff"},
		{"%X", []any{^uint64(0)}, "FFFFFFFFFFFFFFFF"},
		// {"%010d", []any{12345}, "0000012345"},
		// {"%010d", []any{-12345}, "-000012345"}, // weird behaviors

		// advanced float (from go/fmt)
		{"%+.3e", []any{0.0}, "+0.000e+00"},
		{"%+.3e", []any{1.0}, "+1.000e+00"},
		{"%+.3x", []any{0.0}, "+0x0.000p+00"},
		{"%+.3x", []any{1.0}, "+0x1.000p+00"},
		{"%+.3f", []any{-1.0}, "-1.000"},
		{"%+.3F", []any{-1.0}, "-1.000"},
		{"%+.3F", []any{float32(-1.0)}, "-1.000"},
		{"% .3E", []any{-1.0}, "-1.000E+00"},
		{"% .3e", []any{1.0}, " 1.000e+00"},
		{"% .3X", []any{-1.0}, "-0X1.000P+00"},
		{"% .3x", []any{1.0}, " 0x1.000p+00"},
		{"%+.3g", []any{0.0}, "+0"},
		{"%+.3g", []any{1.0}, "+1"},
		{"%+.3g", []any{-1.0}, "-1"},
		{"% .3g", []any{-1.0}, "-1"},
		{"% .3g", []any{1.0}, " 1"},
		// Test sharp flag used with floats.
		{"%#g", []any{1e-323}, "1.00000e-323"},
		{"%#g", []any{-1.0}, "-1.00000"},
		{"%#g", []any{1.1}, "1.10000"},
		{"%#g", []any{123456.0}, "123456."},
		{"%#g", []any{1234567.0}, "1.234567e+06"},
		{"%#g", []any{1230000.0}, "1.23000e+06"},
		{"%#g", []any{1000000.0}, "1.00000e+06"},
		{"%#.0f", []any{1.0}, "1."},
		{"%#.0e", []any{1.0}, "1.e+00"},
		{"%#.0x", []any{1.0}, "0x1.p+00"},
		{"%#.0g", []any{1.0}, "1."},
		{"%#.0g", []any{1100000.0}, "1.e+06"},
		{"%#.4f", []any{1.0}, "1.0000"},
		{"%#.4e", []any{1.0}, "1.0000e+00"},
		{"%#.4x", []any{1.0}, "0x1.0000p+00"},
		{"%#.4g", []any{1.0}, "1.000"},
		{"%#.4g", []any{100000.0}, "1.000e+05"},
		{"%#.4g", []any{1.234}, "1.234"},
		{"%#.4g", []any{0.1234}, "0.1234"},
		{"%#.4g", []any{1.23}, "1.230"},
		{"%#.4g", []any{0.123}, "0.1230"},
		{"%#.4g", []any{1.2}, "1.200"},
		{"%#.4g", []any{0.12}, "0.1200"},
		{"%#.4g", []any{10.2}, "10.20"},
		{"%#.4g", []any{0.0}, "0.000"},
		{"%#.4g", []any{0.012}, "0.01200"},
		{"%#.0f", []any{123.0}, "123."},
		{"%#.0e", []any{123.0}, "1.e+02"},
		{"%#.0x", []any{123.0}, "0x1.p+07"},
		{"%#.0g", []any{123.0}, "1.e+02"},
		{"%#.4f", []any{123.0}, "123.0000"},
		{"%#.4e", []any{123.0}, "1.2300e+02"},
		{"%#.4x", []any{123.0}, "0x1.ec00p+06"},
		{"%#.4g", []any{123.0}, "123.0"},
		{"%#.4g", []any{123000.0}, "1.230e+05"},

Even if minimalist, this library should follow the output of go/fmt to be consistent with Go behaviors. Don't hesitate to follow / copy the fmt library code in Go to match the behavior.

Also i got some weird behaviours from %010d with -12345 -> 0000-12345

I will also check the gas issue. Since many projects import this package, we should take extra precautions regarding performance, but please do not compromise readability.

gfanton · 2025-04-18T14:34:03Z

examples/gno.land/p/demo/ufmt/ufmt.gno

@@ -170,14 +295,14 @@ func (p *printer) doPrintf(format string, args []any) {
 			writeString(p, verb, arg)
 		case 'c':
 			writeChar(p, verb, arg)
-		case 'd':
+		case 'd', 'i':


%i doesn't seems to exist in go, I don't think we should port it in gno

examples/gno.land/p/demo/ufmt/ufmt.gno

gfanton · 2025-04-18T14:39:23Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+	}
+	stop := false
+	for {
+		x, ok := c2f[runes[*index]]


Hiding the reference inside a map complicates readability and performance. Why not use a direct switch case like this:

switch *index { case '+' case '-': ... }

because it's special characters, just after checking if it exists, i use the internal value of the flag to set it as the flag

x, ok := c2f[runes[*index]] switch { case ok: p.meta.flags |= x // here ptrForward(index, runes, 1)

so with map, i can check

if it's a flag modifier character

which flag do i need to trigger in the bit mask

maybe i can use a switch but idk if it will be better imo, what do you think ?

thehowl · 2025-05-14T14:20:15Z

@paulogarithm did you have a chance to read guilhem's feedback?

* E & e precision

* from: 6.41E+01 to: 6.410000E+01, this is go behavior

paulogarithm · 2025-06-17T21:11:59Z

I'm so sorry i was putting all my efforts on Flamegraphs & EVM, I did not made any updates, but I'm back !

@thehowl yep i'm reading each reviews
@gfanton i will add the new tests + improve the Sprintf doc + check your reviews
@notJoon ill cherry pick mostly everything because from what i seen, it seems that everything improves ufmt in a better way !

@gfanton

Co-authored-by: Guilhem Fanton <[email protected]> * the tests are from @gfanton recommandation

* 45+ test fails -> 39 test fails * todo: g flag, sign for scientific notations

ps: idk how to cherry pick so i copy pasted Co-authored-by: notJoon <[email protected]>

paulogarithm · 2025-06-19T14:38:25Z

alright so i added the tests from the real printf (the ones that @gfanton shared here) + i cherry picked (more like manually copy-pasted and put notJoon as co authored) the @notJoon 's code parts for optimization.
the only things that are mostly left on the tests are the G flag

thehowl · 2025-06-26T12:51:11Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+type flag uint8
+
+const (
+	flagHashtag flag = 1 << iota


Suggested change

flagHashtag flag = 1 << iota

flagHash flag = 1 << iota

thehowl · 2025-06-26T12:51:26Z

examples/gno.land/p/demo/ufmt/ufmt.gno

@@ -32,13 +34,215 @@ func (b *buffer) writeRune(r rune) {
 	*b = utf8.AppendRune(*b, r)
 }

+// the different flags


Suggested change

// the different flags

// bitmap representing different flags

thehowl · 2025-06-26T12:51:44Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+	lenH
+	lenL
+	lenLL
+	lenZ


comments would be good, maybe even full names.

thehowl · 2025-06-26T12:56:03Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+	i := 0
+	for i < len(s) && unicode.IsDigit(rune(s[i])) {
+		i++
+	}


Suggested change

i := 0

for i < len(s) && unicode.IsDigit(rune(s[i])) {

i++

}

var i int

for idx, c := range s {

if c < '0' || c > '9' {

i = idx

return

}

}

Handles UTF-8 properly and more efficiently.

unicode.IsDigit considers many more digits: https://www.fileformat.info/info/unicode/category/Nd/list.htm

thehowl · 2025-06-26T13:22:10Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+	return num, i, true
+}
+
+var flagMap = [256]flag{


This would maybe be better adjacent to their types.

thehowl · 2025-06-26T13:23:28Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+var lenMap = map[string]lengthModifier{
+	"ll": lenLL,
+	"l":  lenL,
+	"h":  lenH,
+	"hh": lenHH,
+	"z":  lenZ,
+}


thehowl · 2025-06-26T13:44:58Z

examples/gno.land/p/demo/ufmt/ufmt.gno

+		case 'h', 'l', 'z':
+			// Use lookahead to check for double-character length modifiers
+			// like 'hh' (char) or 'll' (long long) without iterating through options
+			if *index+1 < end {
+				next := runes[*index+1]
+				if c == 'h' && next == 'h' {
+					p.meta.length = lenHH
+					*index += 2 // Skip both characters
+					continue
+				} else if c == 'l' && next == 'l' {
+					p.meta.length = lenLL
+					*index += 2 // Skip both characters
+					continue
+				}
+			}
+
+			// Handle single-character length modifiers
+			switch c {
+			case 'h':
+				p.meta.length = lenH
+			case 'l':
+				p.meta.length = lenL
+			case 'z':
+				p.meta.length = lenZ
+			}
+			*index++


The length flags don't really seem to be doing anything now, but I don't think they should anywaY

paulogarithm and others added 30 commits April 7, 2025 18:47

feat(examples): add 'pol' example page

502c85b

* includes gnominers * includes home * include pure packages

chore: remove the unusep p/pol/gnomining package

f72fd4c

feat(gnominers): nerf opal price & spawn rate

10c4960

Merge branch 'gnolang:master' into master

30780d2

feat(gnominers): begin dao impl in gnominers

d935be7

* reorganise gnominers into submodules * create the dao submodule * add the tofix folder with all broken features * create the minerdao /!\ DAO DOESNT WORK RN BECAUSE OF CYCLE DEPENDANCIES /!\

fix(gnominers): finish impl dao

966de11

* i didnt use subfolders

feat(gnominers): now you can generate a DAO request

4923018

fix(gnominers): bad formatting

80bf496

feat: add uufmt (with printf with flags) + nfmt (number format)

20260f7

Merge branch 'gnolang:master' into master

5455127

feat: add flag parsing in ufmt.printf

5d71b3a

* add precisision flag ("%.2f") * add 0 & ' ' flags ("%03d", "% 3d") * add length parsing (not used rn) * add # for hex ("%#02x") * add %i & %X (%i is just %d, %X is big hex) * change the home * ass some tests to handle what ive done

fix(nfmt): number format fix .2f instead of .1f

f396fe4

* also changed my home page so it displays a number

fix(nfmt): number format func name

a91aac5

Format -> FormatRound because it rounds...

fix(ufmt)!: flag parsing using []rune instead of string

efb7a3e

* cause of major issue because it was reading to far

feat(gnominers): add nfmt to shop

c5d0400

chore: remove tofix folder remotely

9451a3b

fix(gnolang#4109): html escape string global realm error

8289230

chore: add some gno-columns everywhere so its cleaner

f2359c8

feat(gnominers): add the leaderboard system

ce15ebf

feat(ux): improved user experience + use md lib

9755a09

* better messages * better formatting * use `p/moun/md` for md formatting in users.gno

feat(gnominers): change everything to use md lib

6decc3f

feat: add releases to gnominers

6b914d3

feat: implement gnominers releases in home

d83de10

chore: fixup render gno unused packages

6ea1081

feat(home): make my home page use md lib

76d2680

Merge branch 'master' into master

67b2a21

fix: remove uufmt

d172d78

test(ufmt/sprintf): add more tests to printf

feaffc2

feat(ufmt/printf): add %x features for []uint8{}

fd9e9fb

chore: remove r/pol & p/pol for clean PR

442a327

chore: move map to upvalues for better memory efficiency

6353239

notJoon approved these changes Apr 16, 2025

View reviewed changes

notJoon removed the review/triage-pending PRs opened by external contributors that are waiting for the 1st review label Apr 16, 2025

leohhhn removed this from 💪 Bounties & Worx Apr 16, 2025

leohhhn added this to 🧑‍🎓Student contributors Apr 16, 2025

leohhhn moved this to In Progress in 🧑‍🎓Student contributors Apr 16, 2025

leohhhn moved this from In Progress to In Review in 🧑‍🎓Student contributors Apr 16, 2025

fix: remove test on leon's home

1d29c1c

notJoon mentioned this pull request Apr 17, 2025

feat(p/ufmt): Optimize ufmt package #4174

Open

Kouteki moved this from Triage to In Review in 🧙‍♂️gno.land core team Apr 17, 2025

gfanton requested changes Apr 18, 2025

View reviewed changes

jaekwon force-pushed the master branch from d3e0886 to 705e0df Compare May 3, 2025 20:18

paulogarithm added 3 commits June 17, 2025 22:57

Merge remote-tracking branch 'upstream/master' into ufmt-enhancement

a6cbd14

fix(ufmt): fix float bad test precision

d6ad9e8

* E & e precision

fix(ufmt): bad test with %e

7555b3a

* from: 6.41E+01 to: 6.410000E+01, this is go behavior

paulogarithm and others added 5 commits June 17, 2025 23:13

fix(ufmt): lengthModifier and flag type

f2517db

test(ufmt): add more tests (go/fmt tests)

0197930

Co-authored-by: Guilhem Fanton <[email protected]> * the tests are from @gfanton recommandation

fix(ufmt): make more tests pass

426f92c

* 45+ test fails -> 39 test fails * todo: g flag, sign for scientific notations

fix(ufmt): handle the sign in %f, %e, ...

1787606

perf(ufmt): add @notJoon optimisations

d5f1fc3

ps: idk how to cherry pick so i copy pasted Co-authored-by: notJoon <[email protected]>

paulogarithm requested a review from gfanton June 20, 2025 22:27

thehowl reviewed Jun 26, 2025

View reviewed changes

	// the different flags
	// bitmap representing different flags

-	i := 0
-	for i < len(s) && unicode.IsDigit(rune(s[i])) {
-		i++
-	}
+	var i int
+	for idx, c := range s {
+		if c < '0' || c > '9' {
+			i = idx
+			return
+		}
+	}

feat(ufmt): enhance printf functionnalities by adding flags #4136

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