Support Proc passed to option setup_regexp_function in sqlite adapter

CHANGELOG

@@ -24,7 +24,7 @@
 
 * Add auto_cast_date_and_time extension, for casting date and time values using SQL standard functions (jeremyevans)
 
-* Cache regexp objects in the sqlite adapter to improve performance (paddor)
+* Improve performance and flexibility of regexp matching in sqlite adapter (paddor)
 
 === 5.75.0 (2023-12-01)
 

doc/opening_databases.rdoc

@@ -389,7 +389,9 @@ The following additional options are supported:
 :timeout :: the busy timeout to use in milliseconds (default: 5000).
 :setup_regexp_function :: Whether to setup a REGEXP function in the underlying SQLite3::Database object. Doing so
                           allows you to use regexp support in dataset expressions.  If ':cached', caches each
-                          unique regex (risk of memory leak).
+                          unique regex (more efficient but risk of memory leak). If a Proc like 
+                          +proc{|regex_str,str| ...}+ is provided, it is used to determine whether the string
+                          in question matches.
 
 Note that SQLite memory databases are restricted to a single connection by
 default.  This is because SQLite does not allow multiple connections to

lib/sequel/adapters/sqlite.rb

@@ -112,7 +112,9 @@ def initialize(opts = OPTS)
       # :timeout :: how long to wait for the database to be available if it
       #             is locked, given in milliseconds (default is 5000)
       # :setup_regexp_function :: enable use of Regexp objects with SQL
-      #             'REGEXP' operator (with regexp cache if ':cached')
+      #             'REGEXP' operator (with regexp cache if ':cached', or
+      #             custom behavior if it's a Proc like
+      #             +proc{|regex_str,str| ...}+)
       def connect(server)
         opts = server_opts(server)
         opts[:database] = ':memory:' if blank_object?(opts[:database])
@@ -208,6 +210,8 @@ def setup_regexp_function(db, how)
         when :cached
           cache = Hash.new{|h,k| h[k] = Regexp.new(k)}
           cb = proc { |func, regexp_str, str| func.result = cache[regexp_str].match(str) ? 1 : 0 }
+        when Proc
+          cb = proc { |func, regexp_str, str| func.result = how.call(regexp_str, str) ? 1 : 0 }
         else
           cb = proc { |func, regexp_str, str| func.result = Regexp.new(regexp_str).match(str) ? 1 : 0 }
         end