Add DuckDB adapter supporting modules

- Add quoting.rb for proper SQL quoting and escaping
- Add explain_pretty_printer.rb for formatted EXPLAIN output
- Add tasks.rb for Rails database tasks (db:create, db:drop, etc.)

Author: eddietejeda

lib/active_record/connection_adapters/duckdb/explain_pretty_printer.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module ConnectionAdapters
+    module Duckdb
+      class ExplainPrettyPrinter # :nodoc:
+        # @note Pretty prints the result of an EXPLAIN QUERY PLAN in a way that resembles the output of the SQLite shell
+        # @example Output format
+        #   0|0|0|SEARCH TABLE users USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)
+        #   0|1|1|SCAN TABLE posts (~100000 rows)
+        # @param [ActiveRecord::Result] result Query result containing explain output
+        # @return [String] Pretty-printed explanation with newlines
+        def pp(result)
+          result.rows.map do |row|
+            row.join("|")
+          end.join("\n") + "\n"
+        end
+      end
+    end
+  end
+end

lib/active_record/connection_adapters/duckdb/quoting.rb

@@ -0,0 +1,166 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module ConnectionAdapters
+    module Duckdb
+      module Quoting # :nodoc:
+        extend ActiveSupport::Concern
+
+        QUOTED_COLUMN_NAMES = Concurrent::Map.new # :nodoc:
+        QUOTED_TABLE_NAMES = Concurrent::Map.new # :nodoc:
+
+        module ClassMethods # :nodoc:
+          # @note regex pattern for column name matching
+          # @return [Regexp] Regular expression for matching column names
+          def column_name_matcher
+            /
+              \A
+              (
+                (?:
+                  # "table_name"."column_name" | function(one or no argument)
+                  ((?:\w+\.|"\w+"\.)?(?:\w+|"\w+") | \w+\((?:|\g<2>)\))
+                )
+                (?:(?:\s+AS)?\s+(?:\w+|"\w+"))?
+              )
+              (?:\s*,\s*\g<1>)*
+              \z
+            /ix
+          end
+
+          # @note regex pattern for column name with order matching
+          # @return [Regexp] Regular expression for matching column names with order
+          def column_name_with_order_matcher
+            /
+              \A
+              (
+                (?:
+                  # "table_name"."column_name" | function(one or no argument)
+                  ((?:\w+\.|"\w+"\.)?(?:\w+|"\w+") | \w+\((?:|\g<2>)\))
+                )
+                (?:\s+COLLATE\s+(?:\w+|"\w+"))?
+                (?:\s+ASC|\s+DESC)?
+              )
+              (?:\s*,\s*\g<1>)*
+              \z
+            /ix
+          end
+
+          # @override
+          # @note Implements AbstractAdapter interface method
+          # @param [String, Symbol] name Column name to quote
+          # @return [String] Quoted column name
+          def quote_column_name(name)
+            QUOTED_COLUMN_NAMES[name] ||= %Q("#{name.to_s.gsub('"', '""')}").freeze
+          end
+
+          # @override
+          # @note Implements AbstractAdapter interface method
+          # @param [String, Symbol] name Table name to quote
+          # @return [String] Quoted table name
+          def quote_table_name(name)
+            QUOTED_TABLE_NAMES[name] ||= %Q("#{name.to_s.gsub('"', '""').gsub(".", "\".\"")}").freeze
+          end
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [String] s String to quote
+        # @return [String] Quoted string with escaped single quotes
+        def quote_string(s)
+          s.gsub("'", "''")  # Escape single quotes by doubling them
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [String] table Table name (unused)
+        # @param [String] attr Attribute name
+        # @return [String] Quoted column name
+        def quote_table_name_for_assignment(table, attr)
+          quote_column_name(attr)
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [Time] value Time value to quote
+        # @return [String] Quoted time string
+        def quoted_time(value)
+          value = value.change(year: 2000, month: 1, day: 1)
+          quoted_date(value).sub(/\A\d\d\d\d-\d\d-\d\d /, "2000-01-01 ")
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [String] value Binary value to quote
+        # @return [String] Quoted binary string in hex format
+        def quoted_binary(value)
+          "x'#{value.hex}'"
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @return [String] Quoted true value for DuckDB
+        def quoted_true
+          "1"
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @return [Integer] Unquoted true value for DuckDB
+        def unquoted_true
+          1
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @return [String] Quoted false value for DuckDB
+        def quoted_false
+          "0"
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @return [Integer] Unquoted false value for DuckDB
+        def unquoted_false
+          0
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [Object] value Default value to quote
+        # @param [ActiveRecord::ConnectionAdapters::Column] column Column object
+        # @return [String] Quoted default expression
+        def quote_default_expression(value, column) # :nodoc:
+          if value.is_a?(Proc)
+            value = value.call
+            # Don't wrap nextval() calls in extra parentheses
+            value
+          elsif value.is_a?(String) && value.match?(/\Anextval\(/i)
+            # Handle nextval function calls for sequences - don't quote them
+            value
+          else
+            super
+          end
+        end
+
+        # @override
+        # @note Implements AbstractAdapter interface method
+        # @param [Object] value Value to type cast
+        # @return [Object] Type-cast value
+        def type_cast(value) # :nodoc:
+          case value
+          when BigDecimal, Rational
+            value.to_f
+          when String
+            if value.encoding == Encoding::ASCII_8BIT
+              super(value.encode(Encoding::UTF_8))
+            else
+              super
+            end
+          else
+            super
+          end
+        end
+      end
+    end
+  end
+end