gno.land/r/moul/x/daily/rledemo/v0⧉

1// Package rledemo is a small gnoweb demo of the run-length codec provided by2// the [p/moul/x/daily/rle](/p/moul/x/daily/rle/v0) library: it encodes a few3// sample strings, round-trips them, and reports the size ratio — including the4// case where the "compression" makes things bigger.5//6// It contains no codec logic of its own. Stateless, so Render is deterministic.7package rledemo89import (10	"strconv"11	"strings"1213	"gno.land/p/moul/x/daily/rle/v0"14)1516// samples are picked to show both outcomes: runny data compresses, data17// without runs expands.18var samples = []string{19	"aaaaaaaaaabbbbbbbbbb",20	"aaabbc",21	"abcdef",22}2324// Render renders the demo for gnoweb.25//26//	Render("")        / Render("/") -> the samples table27//	Render("/<text>")               -> encode that text28func Render(path string) string {29	var b strings.Builder30	b.WriteString("# Run-Length Encoding\n\n")31	b.WriteString("`<count><char>` pairs, demoing the ")32	b.WriteString("[`p/moul/x/daily/rle`](/p/moul/x/daily/rle/v0) library.\n\n")3334	if in := parseArg(path); in != "" {35		return b.String() + one(in)36	}3738	b.WriteString("| input | encoded | size | round-trips |\n|---|---|---|---|\n")39	for _, s := range samples {40		enc, err := rle.Encode(s)41		if err != nil {42			continue43		}44		dec, _ := rle.Decode(enc)45		b.WriteString("| `")46		b.WriteString(s)47		b.WriteString("` | `")48		b.WriteString(enc)49		b.WriteString("` | ")50		b.WriteString(strconv.Itoa(rle.Ratio(s, enc)))51		b.WriteString("% | ")52		if dec == s {53			b.WriteString("✅")54		} else {55			b.WriteString("❌")56		}57		b.WriteString(" |\n")58	}59	b.WriteString("\n> Over 100% means the encoding made the data **bigger**. ")60	b.WriteString("RLE only wins on runny input, and `abcdef` is the honest counter-example.\n\n")61	b.WriteString("> Append text to the path to encode it — digits are rejected, ")62	b.WriteString("since they would be ambiguous with a run count.\n")63	return b.String()64}6566func one(in string) string {67	var b strings.Builder68	b.WriteString("## `")69	b.WriteString(in)70	b.WriteString("`\n\n")71	enc, err := rle.Encode(in)72	if err != nil {73		b.WriteString("_")74		b.WriteString(err.Error())75		b.WriteString("_\n")76		return b.String()77	}78	dec, _ := rle.Decode(enc)79	b.WriteString("- encoded: `")80	b.WriteString(enc)81	b.WriteString("`\n- size: **")82	b.WriteString(strconv.Itoa(rle.Ratio(in, enc)))83	b.WriteString("%**\n- round-trips: ")84	if dec == in {85		b.WriteString("✅\n")86	} else {87		b.WriteString("❌\n")88	}89	return b.String()90}9192func parseArg(path string) string {93	s := strings.TrimSpace(path)94	s = strings.TrimPrefix(s, "/")95	if i := strings.IndexByte(s, '/'); i >= 0 {96		s = s[:i]97	}98	return s99}100