More remarks about Hangul in search collation

unicode-org · May 11, 2022 · ccdec3d · ccdec3d
1 parent d0143bc
commit ccdec3d
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diff --git a/experimental/collator/src/elements.rs b/experimental/collator/src/elements.rs
@@ -1024,6 +1024,11 @@ where
                         // XXX This isn't actually true with the current jamo search
                         // expansions!
 
+                        // TODO: Instead of having different jamo CE32 table for "search"
+                        // collations, we could instead decompose the archaic jamo to
+                        // the modern approximation sequences here and then map those
+                        // by looking up the modern jamo from the normal root.
+
                         // We need to set data to root, because archaic jamo refer to
                         // the root.
                         data = self.root;

diff --git a/experimental/collator/src/lib.rs b/experimental/collator/src/lib.rs
@@ -66,6 +66,19 @@
 //!     the tailored CE32s refer to the expansions table in each collation. To make
 //!     them truly shareable, the archaic jamo expansions need to become self-contained
 //!     the way Latin mini expansions in ICU4C are self-contained.
+//!
+//!     One possible alternative to loading a different table for "search" would be
+//!     performing the mapping of archaic jamo to the modern approximations as a
+//!     special preprocessing step for the incoming characters, which would allow
+//!     the lookup of the resulting modern jamo from the normal root jamo table.
+//!
+//!     "searchjl" is even more problematic than "search", since "searchjl" uses
+//!     prefixes matches with jamo, and currently Hangul is assumed not to participate
+//!     in prefix or contraction matching. Before putting too much effort into "searchjl"
+//!     it would be good to research its usage. The CLDR issue that introduced it,
+//!     https://unicode-org.atlassian.net/browse/CLDR-3560 , said that it was for
+//!     contact search on phones. As of 2022-05-11, I have been unable to find evidence
+//!     of any Open Source app, including Android Contacts, enabling "searchjl".
 
 mod comparison;
 mod elements;
@@ -367,7 +380,7 @@ mod tests {
             "\u{0041}\u{00E1}\u{0063}\u{0064}",
             "\u{0041}\u{00E1}\u{0063}\u{0064}",
             "\u{0061}\u{0062}\u{0063}",
-            "\u{0061}\u{0062}\u{0063}",                                                             
+            "\u{0061}\u{0062}\u{0063}",
             "\u{0054}\u{0043}\u{006F}\u{006D}\u{0070}\u{0061}\u{0072}\u{0065}\u{0050}\u{006C}\u{0061}\u{0069}\u{006E}",
             "\u{0061}\u{0042}\u{0063}",
             "\u{0061}\u{0023}\u{0042}",