lib/icu/CaseFold: rename to IcuCanonicalize() and add flag parameter

Prepare for adding more transformations.

src/lib/icu/Canonicalize.cxx

@@ -17,10 +17,10 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "CaseFold.hxx"
+#include "Canonicalize.hxx"
 #include "config.h"
 
-#ifdef HAVE_ICU_CASE_FOLD
+#ifdef HAVE_ICU_CANONICALIZE
 
 #include "util/AllocatedString.hxx"
 
@@ -32,18 +32,19 @@
 #endif
 
 AllocatedString
-IcuCaseFold(std::string_view src) noexcept
+IcuCanonicalize(std::string_view src, bool fold_case) noexcept
 try {
 #ifdef HAVE_ICU
 	auto u = UCharFromUTF8(src);
 	if (u.data() == nullptr)
 		return {src};
 
-	auto folded = IcuFoldCase(ToStringView(std::span{u}));
-	if (folded == nullptr)
-		return {src};
+	if (fold_case)
+		if (auto folded = IcuFoldCase(ToStringView(std::span{u}));
+		    folded != nullptr)
+			u = std::move(folded);
 
-	return UCharToUTF8(ToStringView(std::span{folded}));
+	return UCharToUTF8(ToStringView(std::span{u}));
 #else
 #error not implemented
 #endif
@@ -51,4 +52,4 @@ try {
 	return {src};
 }
 
-#endif /* HAVE_ICU_CASE_FOLD */
+#endif /* HAVE_ICU_CANONICALIZE */

src/lib/icu/Canonicalize.hxx

@@ -17,21 +17,25 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef MPD_ICU_CASE_FOLD_HXX
-#define MPD_ICU_CASE_FOLD_HXX
+#pragma once
 
 #include "config.h"
 
 #ifdef HAVE_ICU
-#define HAVE_ICU_CASE_FOLD
+#define HAVE_ICU_CANONICALIZE
 
 #include <string_view>
 
 class AllocatedString;
 
+/**
+ * Transform the given string to "canonical" form to allow fuzzy
+ * string comparisons.  The full set of features (if ICU is being
+ * used):
+ *
+ * - case folding (optional)
+ */
 AllocatedString
-IcuCaseFold(std::string_view src) noexcept;
-
-#endif
+IcuCanonicalize(std::string_view src, bool fold_case) noexcept;
 
 #endif

src/lib/icu/Compare.cxx

@@ -18,7 +18,7 @@
  */
 
 #include "Compare.hxx"
-#include "CaseFold.hxx"
+#include "Canonicalize.hxx"
 #include "util/StringAPI.hxx"
 #include "util/StringCompare.hxx"
 #include "config.h"
@@ -28,10 +28,10 @@
 #include <windows.h>
 #endif
 
-#ifdef HAVE_ICU_CASE_FOLD
+#ifdef HAVE_ICU_CANONICALIZE
 
 IcuCompare::IcuCompare(std::string_view _needle) noexcept
-	:needle(IcuCaseFold(_needle)) {}
+	:needle(IcuCanonicalize(_needle, true)) {}
 
 #elif defined(_WIN32)
 
@@ -54,8 +54,8 @@ IcuCompare::IcuCompare(std::string_view _needle) noexcept
 bool
 IcuCompare::operator==(const char *haystack) const noexcept
 {
-#ifdef HAVE_ICU_CASE_FOLD
-	return StringIsEqual(IcuCaseFold(haystack).c_str(), needle.c_str());
+#ifdef HAVE_ICU_CANONICALIZE
+	return StringIsEqual(IcuCanonicalize(haystack, true).c_str(), needle.c_str());
 #elif defined(_WIN32)
 	if (needle == nullptr)
 		/* the MultiByteToWideChar() call in the constructor
@@ -80,8 +80,8 @@ IcuCompare::operator==(const char *haystack) const noexcept
 bool
 IcuCompare::IsIn(const char *haystack) const noexcept
 {
-#ifdef HAVE_ICU_CASE_FOLD
-	return StringFind(IcuCaseFold(haystack).c_str(),
+#ifdef HAVE_ICU_CANONICALIZE
+	return StringFind(IcuCanonicalize(haystack, true).c_str(),
 			  needle.c_str()) != nullptr;
 #elif defined(_WIN32)
 	if (needle == nullptr)
@@ -117,8 +117,9 @@ IcuCompare::IsIn(const char *haystack) const noexcept
 bool
 IcuCompare::StartsWith(const char *haystack) const noexcept
 {
-#ifdef HAVE_ICU_CASE_FOLD
-	return StringStartsWith(IcuCaseFold(haystack).c_str(), needle);
+#ifdef HAVE_ICU_CANONICALIZE
+	return StringStartsWith(IcuCanonicalize(haystack, true).c_str(),
+				needle);
 #elif defined(_WIN32)
 	if (needle == nullptr)
 		/* the MultiByteToWideChar() call in the constructor

src/lib/icu/meson.build

@@ -2,7 +2,7 @@ icu_dep = dependency('icu-i18n', version: '>= 50', required: get_option('icu'))
 conf.set('HAVE_ICU', icu_dep.found())
 
 icu_sources = [
-  'CaseFold.cxx',
+  'Canonicalize.cxx',
   'Compare.cxx',
   'Collate.cxx',
   'Converter.cxx',