From 09a7e8c9d013f13a1aa1ef4e9b7f397647b79967 Mon Sep 17 00:00:00 2001
From: Martin Czygan <martin.czygan@gmail.com>
Date: Sun, 21 Mar 2021 01:17:38 +0100
Subject: initial import of skate

---
 skate/cluster.go | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 skate/cluster.go

(limited to 'skate/cluster.go')

diff --git a/skate/cluster.go b/skate/cluster.go
new file mode 100644
index 0000000..bec8154
--- /dev/null
+++ b/skate/cluster.go
@@ -0,0 +1,131 @@
+package skate
+
+import (
+	"regexp"
+	"strings"
+
+	jsoniter "github.com/json-iterator/go"
+	"golang.org/x/text/unicode/norm"
+)
+
+// IdentifierKeyFunc returns the id and some key from a given blob.
+type IdentifierKeyFunc func([]byte) (string, string, error)
+
+var (
+	json       = jsoniter.ConfigCompatibleWithStandardLibrary
+	wsReplacer = strings.NewReplacer("\t", " ", "\n", " ")
+	repeatedWs = regexp.MustCompile(`[ ]{2,}`)
+	nonWord    = regexp.MustCompile(`[\W]+`)
+
+	SandcrawlerCharMap = map[string]string{
+		"\u00c6": "AE",
+		"\u00e6": "ae",
+		"\u00d0": "D",
+		"\u00f0": "d",
+		"\u00d8": "O",
+		"\u00f8": "o",
+		"\u00de": "Th",
+		"\u00fe": "th",
+		"\u00df": "s",
+		"\u0110": "D",
+		"\u0111": "d",
+		"\u0126": "H",
+		"\u0127": "h",
+		"\u0131": "i",
+		"\u0138": "k",
+		"\u0141": "L",
+		"\u0142": "l",
+		"\u014a": "N",
+		"\u014b": "n",
+		"\u0152": "Oe",
+		"\u0153": "oe",
+		"\u0166": "T",
+		"\u0167": "t",
+		"\u00b5": "u",
+		"c":      "c",
+		"\u0192": "f",
+		"\u2202": "",
+		"\u0296": "",
+		"\u2211": "",
+		"\u220f": "",
+		"\u02c6": "",
+		"\u2603": "",
+		"\u02c7": "",
+	}
+	SandcrawlerPrefixRemove = []string{
+		"original article: ", "original article ", "article: ", "title: ",
+	}
+	// SandcrawlerPrefixRemove does not have:
+	// InCombiningDiacriticalMarks (assume it's in "M"),
+	// https://unicodebook.readthedocs.io/unicode.html,
+	// https://stackoverflow.com/q/5697171/89391,
+	// https://github.com/google/re2/wiki/Syntax.
+	SandcrawlerRemoveCharRegex = regexp.MustCompile("[\\s\\p{P}\\p{M}\u2000-\u206F\u2E00-\u2E7F’\u0060·“”‘’“”«»「」¿–±§_°ʖ©®¤=<>|+$^~≈√∫≤≥÷ƒ∆¬£¢∞¥◊€]")
+)
+
+// IdentTitleDoc is a minimal subset of fields, we can work with.
+type IdentTitleDoc struct {
+	Ident string `json:"ident"`
+	Title string `json:"title"`
+}
+
+// KeyTitle is extract the title, and slight cleaning.
+func KeyTitle(p []byte) (ident string, key string, err error) {
+	var doc IdentTitleDoc
+	if err = json.Unmarshal(p, &doc); err != nil {
+		return ident, key, err
+	}
+	title := wsReplacer.Replace(strings.TrimSpace(doc.Title))
+	return doc.Ident, title, nil
+}
+
+// KeyTitleNormalized applies further normalization.
+func KeyTitleNormalized(p []byte) (ident string, key string, err error) {
+	ident, key, err = KeyTitle(p)
+	if err != nil {
+		return
+	}
+	key = strings.ToLower(key)
+	key = repeatedWs.ReplaceAllString(key, " ")
+	key = nonWord.ReplaceAllString(key, "")
+	return ident, key, nil
+}
+
+// KeyTitleNysiis returns the New York State Identification and Intelligence
+// System phonetic code for the title.
+func KeyTitleNysiis(p []byte) (ident string, key string, err error) {
+	ident, key, err = KeyTitle(p)
+	if err != nil {
+		return
+	}
+	return ident, NYSIIS(key), nil
+}
+
+// KeyTitleSandcrawler applies more sophisticated title cleanup.
+func KeyTitleSandcrawler(p []byte) (ident string, key string, err error) {
+	ident, key, err = KeyTitle(p)
+	if err != nil {
+		return
+	}
+	return ident, sandcrawlerSlugify(key), nil
+}
+
+// sandcrawlerSlugify normalizes a string.
+func sandcrawlerSlugify(s string) string {
+	slug := strings.ToLower(strings.TrimSpace(s))
+	for _, prefix := range SandcrawlerPrefixRemove {
+		if strings.HasPrefix(slug, prefix) {
+			slug = slug[:len(prefix)]
+		}
+	}
+	slug = strings.ReplaceAll(slug, "&apos;", "'")
+	for k, v := range SandcrawlerCharMap {
+		slug = strings.ReplaceAll(slug, k, v)
+	}
+	if len(slug) == 0 {
+		return slug
+	}
+	slug = norm.NFKD.String(slug)
+	slug = SandcrawlerRemoveCharRegex.ReplaceAllString(slug, "")
+	return strings.ToLower(slug)
+}
-- 
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