whatcanGOwrong

go/pkg/mod/mvdan.cc/xurls/v2@v2.5.0/generate/unicodegen/main.go

@@ -0,0 +1,152 @@
+// Copyright (c) 2015, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package main
+
+import (
+	"log"
+	"os"
+	"strconv"
+	"strings"
+	"text/template"
+	"unicode"
+)
+
+const path = "unicode.go"
+
+var tmpl = template.Must(template.New("tlds").Parse(`// Generated by unicodegen
+
+package xurls
+
+const allowedUcsChar = {{.withPunc}}
+
+const allowedUcsCharMinusPunc = {{.withoutPunc}}
+`))
+
+func visit(rt *unicode.RangeTable, fn func(rune)) {
+	for _, r16 := range rt.R16 {
+		for r := rune(r16.Lo); r <= rune(r16.Hi); r += rune(r16.Stride) {
+			fn(r)
+		}
+	}
+	for _, r32 := range rt.R32 {
+		for r := rune(r32.Lo); r <= rune(r32.Hi); r += rune(r32.Stride) {
+			fn(r)
+		}
+	}
+}
+
+func writeUnicode() error {
+	// rfc3987Ranges contains the ranges of valid code points specified by RFC 3987.
+	rfc3987Ranges := [][2]rune{
+		{0xA0, 0xD7FF},
+		{0xF900, 0xFDCF},
+		{0xFDF0, 0xFFEF},
+		{0x10000, 0x1FFFD},
+		{0x20000, 0x2FFFD},
+		{0x30000, 0x3FFFD},
+		{0x40000, 0x4FFFD},
+		{0x50000, 0x5FFFD},
+		{0x60000, 0x6FFFD},
+		{0x70000, 0x7FFFD},
+		{0x80000, 0x8FFFD},
+		{0x90000, 0x9FFFD},
+		{0xA0000, 0xAFFFD},
+		{0xB0000, 0xBFFFD},
+		{0xC0000, 0xCFFFD},
+		{0xD0000, 0xDFFFD},
+		{0xE1000, 0xEFFFD},
+	}
+
+	// removeRune accepts a slice of inclusive code point ranges (in ascending order)
+	// and returns a new slice that is equivalent except for excluding a specified rune
+	// by removing/replacing/splitting any range containing it.
+	// Its linear searches over the ranges (including those added by previous invocations)
+	// are inefficient, but acceptable because this code runs only at build time.
+	removeRune := func(ranges [][2]rune, cp rune) [][2]rune {
+		for i, r := range ranges {
+			// Ranges are in ascending order. Skip any that precede `cp`,
+			// and bail out upon reaching one that follows `cp`.
+			if r[1] < cp {
+				continue
+			} else if cp < r[0] {
+				break
+			}
+
+			// `cp` is in this range and must be removed from it.
+			if cp == r[0] && cp == r[1] {
+				// Remove this single-element range.
+				return append(ranges[0:i], ranges[i+1:]...)
+			} else if cp == r[0] {
+				// Remove the first element of this range.
+				newRange := [2]rune{r[0] + 1, r[1]}
+				newTail := append([][2]rune{newRange}, ranges[i+1:]...)
+				return append(ranges[0:i], newTail...)
+			} else if cp == r[1] {
+				// Remove the last element of this range.
+				newRange := [2]rune{r[0], r[1] - 1}
+				newTail := append([][2]rune{newRange}, ranges[i+1:]...)
+				return append(ranges[0:i], newTail...)
+			} else {
+				// Split this range.
+				newTail := append(
+					[][2]rune{
+						{r[0], cp - 1},
+						{cp + 1, r[1]},
+					},
+					ranges[i+1:]...)
+				return append(ranges[0:i], newTail...)
+			}
+		}
+		return ranges
+	}
+
+	// sepFreeRanges excludes separators from rfc3987Ranges.
+	sepFreeRanges := append([][2]rune{}, rfc3987Ranges...)
+	visit(unicode.Z, func(cp rune) {
+		sepFreeRanges = removeRune(sepFreeRanges, cp)
+	})
+
+	// puncFreeRanges excludes punctuation from sepFreeRanges.
+	puncFreeRanges := append([][2]rune{}, sepFreeRanges...)
+	visit(unicode.Po, func(cp rune) {
+		puncFreeRanges = removeRune(puncFreeRanges, cp)
+	})
+
+	// Build the corresponding regular expression character class contents.
+	characterClassContents := func(ranges [][2]rune) strings.Builder {
+		var builder strings.Builder
+		for _, r := range ranges {
+			// regexp.QuoteMeta is not necessary because all metacharacters are ASCII.
+			// cf. https://golang.org/s/re2syntax and
+			// https://cs.opensource.google/go/go/+/refs/tags/go1.17.6:src/regexp/regexp.go;l=721
+			builder.WriteRune(r[0])
+			if r[0] == r[1] {
+				continue
+			}
+			builder.WriteRune('-')
+			builder.WriteRune(r[1])
+		}
+		return builder
+	}
+	allowedUcsChar := characterClassContents(sepFreeRanges)
+	allowedUcsCharMinusPunc := characterClassContents(puncFreeRanges)
+
+	// Write to file.
+	f, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return tmpl.Execute(f, map[string]string{
+		"withPunc":    strconv.Quote(allowedUcsChar.String()),
+		"withoutPunc": strconv.Quote(allowedUcsCharMinusPunc.String()),
+	})
+}
+
+func main() {
+	log.Printf("Generating %s...", path)
+	if err := writeUnicode(); err != nil {
+		log.Fatalf("Could not write path: %v", err)
+	}
+}