normalize to "copyright" and "trademark" rather than single-char variants

This improves matching correctness when trying to match a license file
to the text of a license which includes "copyright" verbatim in the
body of the license text, since the same normalization is not applied
to the original license texts. This includes common licenses such as
the 2- and 3-clause BSD licenses.

Author: taleinat

licensedb/internal/normalize/normalize.go

@@ -75,13 +75,13 @@ var (
 	)
 
 	// 9.1.1 "©", "(c)", or "Copyright" should be considered equivalent and interchangeable.
-	copyrightRe = regexp.MustCompile("copyright|\\(c\\)")
-	trademarkRe = regexp.MustCompile("trademark(s?)|\\(tm\\)")
+	copyrightRe = regexp.MustCompile("©|\\(c\\)")
+	trademarkRe = regexp.MustCompile("trademarks|\\(tm\\)|™")
 
 	// extra cleanup
 	brokenLinkRe    = regexp.MustCompile("http s ://")
 	urlCleanupRe    = regexp.MustCompile("[<(](http(s?)://[^\\s]+)[)>]")
-	copyrightLineRe = regexp.MustCompile("(?m)^((©.*)|(all rights reserved(\\.)?)|(li[cs]en[cs]e))\n")
+	copyrightLineRe = regexp.MustCompile("(?m)^((copyright.*)|(all rights reserved(\\.)?)|(li[cs]en[cs]e))\n")
 	nonAlphaNumRe   = regexp.MustCompile("[^- \\na-z0-9]")
 
 	// used in Split()
@@ -128,8 +128,8 @@ func LicenseText(text string, strictness Strictness) string {
 	text = wordReplacer.Replace(text)
 
 	// 9. Copyright Symbol
-	text = copyrightRe.ReplaceAllString(text, "©")
-	text = trademarkRe.ReplaceAllString(text, "™")
+	text = copyrightRe.ReplaceAllString(text, "copyright")
+	text = trademarkRe.ReplaceAllString(text, "trademark")
 
 	// fix broken URLs in SPDX source texts
 	text = brokenLinkRe.ReplaceAllString(text, "https://")
@@ -155,7 +155,9 @@ func LicenseText(text string, strictness Strictness) string {
 		// there are common mismatches because of trailing dots
 		text = strings.Replace(text, ".", "", -1)
 		// usually copyright lines are custom and occur multiple times
+		text = strings.Replace(text, "copyright notice", "PLACEHOLDER", -1)
 		text = copyrightLineRe.ReplaceAllString(text, "")
+		text = strings.Replace(text, "PLACEHOLDER", "copyright notice", -1)
 	}
 
 	if strictness > Moderate {

licensedb/internal/normalize/normalize_test.go

@@ -23,6 +23,7 @@ permissions granted by this license.`},
 		{"punctuation", "a-‒–—―⁓⸺⸻~˗‐‑⁃⁻₋−∼⎯⏤─➖𐆑֊﹘﹣－", "a-"},
 		{"bullet", "-\n*\n✱\n﹡\n•\n●\n⚫\n⏺\n🞄\n∙\n⋅\n", ""},
 		{"license", "", ""},
+		{"copyright notice", "copyright notice", "copyright notice"},
 	}
 
 	for _, tc := range tt {