func main()

in html/atom/gen.go [58:218]

• 135 lines of code
• 37 McCabe index (conditional complexity)

func main() {
	flag.Parse()

	var all []string
	all = append(all, elements...)
	all = append(all, attributes...)
	all = append(all, eventHandlers...)
	all = append(all, extra...)
	sort.Strings(all)

	// uniq - lists have dups
	w := 0
	for _, s := range all {
		if w == 0 || all[w-1] != s {
			all[w] = s
			w++
		}
	}
	all = all[:w]

	if *test {
		var buf bytes.Buffer
		fmt.Fprintln(&buf, "// Code generated by go generate gen.go; DO NOT EDIT.\n")
		fmt.Fprintln(&buf, "//go:generate go run gen.go -test\n")
		fmt.Fprintln(&buf, "package atom\n")
		fmt.Fprintln(&buf, "var testAtomList = []string{")
		for _, s := range all {
			fmt.Fprintf(&buf, "\t%q,\n", s)
		}
		fmt.Fprintln(&buf, "}")

		genFile("table_test.go", &buf)
		return
	}

	// Find hash that minimizes table size.
	var best *table
	for i := 0; i < 1000000; i++ {
		if best != nil && 1<<(best.k-1) < len(all) {
			break
		}
		h := rand.Uint32()
		for k := uint(0); k <= 16; k++ {
			if best != nil && k >= best.k {
				break
			}
			var t table
			if t.init(h, k, all) {
				best = &t
				break
			}
		}
	}
	if best == nil {
		fmt.Fprintf(os.Stderr, "failed to construct string table\n")
		os.Exit(1)
	}

	// Lay out strings, using overlaps when possible.
	layout := append([]string{}, all...)

	// Remove strings that are substrings of other strings
	for changed := true; changed; {
		changed = false
		for i, s := range layout {
			if s == "" {
				continue
			}
			for j, t := range layout {
				if i != j && t != "" && strings.Contains(s, t) {
					changed = true
					layout[j] = ""
				}
			}
		}
	}

	// Join strings where one suffix matches another prefix.
	for {
		// Find best i, j, k such that layout[i][len-k:] == layout[j][:k],
		// maximizing overlap length k.
		besti := -1
		bestj := -1
		bestk := 0
		for i, s := range layout {
			if s == "" {
				continue
			}
			for j, t := range layout {
				if i == j {
					continue
				}
				for k := bestk + 1; k <= len(s) && k <= len(t); k++ {
					if s[len(s)-k:] == t[:k] {
						besti = i
						bestj = j
						bestk = k
					}
				}
			}
		}
		if bestk > 0 {
			layout[besti] += layout[bestj][bestk:]
			layout[bestj] = ""
			continue
		}
		break
	}

	text := strings.Join(layout, "")

	atom := map[string]uint32{}
	for _, s := range all {
		off := strings.Index(text, s)
		if off < 0 {
			panic("lost string " + s)
		}
		atom[s] = uint32(off<<8 | len(s))
	}

	var buf bytes.Buffer
	// Generate the Go code.
	fmt.Fprintln(&buf, "// Code generated by go generate gen.go; DO NOT EDIT.\n")
	fmt.Fprintln(&buf, "//go:generate go run gen.go\n")
	fmt.Fprintln(&buf, "package atom\n\nconst (")

	// compute max len
	maxLen := 0
	for _, s := range all {
		if maxLen < len(s) {
			maxLen = len(s)
		}
		fmt.Fprintf(&buf, "\t%s Atom = %#x\n", identifier(s), atom[s])
	}
	fmt.Fprintln(&buf, ")\n")

	fmt.Fprintf(&buf, "const hash0 = %#x\n\n", best.h0)
	fmt.Fprintf(&buf, "const maxAtomLen = %d\n\n", maxLen)

	fmt.Fprintf(&buf, "var table = [1<<%d]Atom{\n", best.k)
	for i, s := range best.tab {
		if s == "" {
			continue
		}
		fmt.Fprintf(&buf, "\t%#x: %#x, // %s\n", i, atom[s], s)
	}
	fmt.Fprintf(&buf, "}\n")
	datasize := (1 << best.k) * 4

	fmt.Fprintln(&buf, "const atomText =")
	textsize := len(text)
	for len(text) > 60 {
		fmt.Fprintf(&buf, "\t%q +\n", text[:60])
		text = text[60:]
	}
	fmt.Fprintf(&buf, "\t%q\n\n", text)

	genFile("table.go", &buf)

	fmt.Fprintf(os.Stdout, "%d atoms; %d string bytes + %d tables = %d total data\n", len(all), textsize, datasize, textsize+datasize)
}