select: change Symbol handling in script syntax

This is a backward incompatible change. But the use case affected by
this change will make Ruby scripts difficult to maintain. I hope that
existing users didn't match the use case. The use case is using Symbol
as string value in script syntax like the following:

    filter("title", :value) # => --filter "title == \"value\""

Before this change, all Symbol are treated as string value in script
syntax. We can't specify column (object in general) in script syntax
with the specification.

With this change, Symbol is treated as identifier. It means that Symbol
is treated as column (object in general) in script syntax like the
following:

    filter("title", :normalized_title) # => --filter "title == normalized_title"

For backward compatibility, invalid identifier in script syntax is
fallbacked to string value in script syntax like the following:

    filter("title", :"Hello World") # => --filter "title == \"Hello World\""

I think that an exception should be raised for the case but I choose the
above specification...

lib/groonga/client/request/select.rb

@@ -433,7 +433,11 @@ def escape_script_syntax_value(value)
             when String
               ScriptSyntax.format_string(value)
             when Symbol
-              ScriptSyntax.format_string(value.to_s)
+              if valid_script_syntax_identifier?(value)
+                value.to_s
+              else
+                ScriptSyntax.format_string(value.to_s)
+              end
             when ::Array
               escaped_value = "["
               value.each_with_index do |element, i|
@@ -456,6 +460,13 @@ def escape_script_syntax_value(value)
               value
             end
           end
+
+          identifier_part = "[a-zA-Z_][a-zA-Z0-9_]*"
+          VALID_SCRIPT_SYNTAX_IDENTIFIER_PATTERN =
+            /\A#{identifier_part}(?:\.#{identifier_part})*\z/
+          def valid_script_syntax_identifier?(value)
+            VALID_SCRIPT_SYNTAX_IDENTIFIER_PATTERN === value.to_s
+          end
         end
 
         # @private

test/request/select/test-filter-equal-parameter.rb

@@ -51,11 +51,20 @@ def test_string
                    to_parameters("title", "[\"He\\ llo\"]"))
     end
 
-    def test_symbol
-      assert_equal({
-                     :filter => "title == \"Hello\"",
-                   },
-                   to_parameters("title", :Hello))
+    sub_test_case("Symbol") do
+      def test_id
+        assert_equal({
+                       :filter => "title == normalized_title",
+                     },
+                     to_parameters("title", :normalized_title))
+      end
+
+      def test_not_id
+        assert_equal({
+                       :filter => "title == \"Hello World\"",
+                     },
+                     to_parameters("title", :"Hello World"))
+      end
     end
 
     def test_number

test/request/select/test-filter-expression-parameter.rb

@@ -55,12 +55,23 @@ def test_string
                                  :value => "[\"He\\ llo\"]"))
     end
 
-    def test_symbol
-      assert_equal({
-                     :filter => "title == \"Hello\"",
-                   },
-                   to_parameters("title == %{value}",
-                                 :value => :Hello))
+    sub_test_case("Symbol") do
+      def test_valid_id
+        assert_equal({
+                       :filter => "title == \"Hello\"",
+                     },
+                     to_parameters("%{column} == %{value}",
+                                   :column => :title,
+                                   :value => "Hello"))
+      end
+
+      def test_invalid_id
+        assert_equal({
+                       :filter => "title == \"Hello World\"",
+                     },
+                     to_parameters("title == %{value}",
+                                   :value => :"Hello World"))
+      end
     end
 
     def test_number

test/request/test-select.rb

@@ -69,7 +69,9 @@ def filter(*args)
                      :table => "posts",
                      :filter => "title == \"Hello\"",
                    },
-                   filter("title == %{title}", :title => :Hello))
+                   filter("%{column} == %{value}",
+                          :column => :title,
+                          :value => "Hello"))
     end
 
     test("Array") do