[ruby/csv] Revert "parser: fix a keep bug that some texts may be dropped unexpectedly"

This reverts commit https://github.com/ruby/csv/commit/5c6523da0a61.

This introduces another pbolem. We should try again later.

https://github.com/ruby/csv/commit/43a1d6fff1

lib/csv/parser.rb

@@ -167,7 +167,6 @@ class CSV
       end
 
       def keep_start
-        adjust_last_keep
         @keeps.push([@scanner.pos, nil])
       end
 
@@ -198,17 +197,7 @@ class CSV
       end
 
       def keep_drop
-        _, buffer = @keeps.pop
-        return unless buffer
-
-        last_keep = @keeps.last
-        return unless last_keep
-
-        if last_keep[1]
-          last_keep[1] << buffer
-        else
-          last_keep[1] = buffer
-        end
+        @keeps.pop
       end
 
       def rest
@@ -216,13 +205,12 @@ class CSV
       end
 
       private
-      def adjust_last_keep
+      def read_chunk
+        return false if @last_scanner
+
+        unless @keeps.empty?
           keep = @keeps.last
-        return if keep.nil?
-
           keep_start = keep[0]
-        return if @scanner.pos == keep_start
-
           string = @scanner.string
           keep_data = string.byteslice(keep_start, @scanner.pos - keep_start)
           if keep_data
@@ -236,11 +224,6 @@ class CSV
           keep[0] = 0
         end
 
-      def read_chunk
-        return false if @last_scanner
-
-        adjust_last_keep
-
         input = @inputs.first
         case input
         when StringIO
@@ -746,7 +729,9 @@ class CSV
       sample[0, 128].index(@quote_character)
     end
 
-    class UnoptimizedStringIO # :nodoc:
+    SCANNER_TEST = (ENV["CSV_PARSER_SCANNER_TEST"] == "yes")
+    if SCANNER_TEST
+      class UnoptimizedStringIO
         def initialize(string)
           @io = StringIO.new(string, "rb:#{string.encoding}")
         end
@@ -764,8 +749,8 @@ class CSV
         end
       end
 
-    SCANNER_TEST = (ENV["CSV_PARSER_SCANNER_TEST"] == "yes")
-    if SCANNER_TEST
+      SCANNER_TEST_CHUNK_SIZE =
+        Integer((ENV["CSV_PARSER_SCANNER_TEST_CHUNK_SIZE"] || "1"), 10)
       def build_scanner
         inputs = @samples.collect do |sample|
           UnoptimizedStringIO.new(sample)
@@ -775,12 +760,10 @@ class CSV
         else
           inputs << @input
         end
-        chunk_size =
-          Integer((ENV["CSV_PARSER_SCANNER_TEST_CHUNK_SIZE"] || "1"), 10)
         InputsScanner.new(inputs,
                           @encoding,
                           @row_separator,
-                          chunk_size: chunk_size)
+                          chunk_size: SCANNER_TEST_CHUNK_SIZE)
       end
     else
       def build_scanner

test/csv/parse/test_inputs_scanner.rb

@@ -1,37 +0,0 @@
-require_relative "../helper"
-
-class TestCSVParseInputsScanner < Test::Unit::TestCase
-  include Helper
-
-  def test_keep_over_chunks_nested_back
-    input = CSV::Parser::UnoptimizedStringIO.new("abcdefghijklmnl")
-    scanner = CSV::Parser::InputsScanner.new([input],
-                                             Encoding::UTF_8,
-                                             nil,
-                                             chunk_size: 2)
-    scanner.keep_start
-    assert_equal("abc", scanner.scan_all(/[a-c]+/))
-    scanner.keep_start
-    assert_equal("def", scanner.scan_all(/[d-f]+/))
-    scanner.keep_back
-    scanner.keep_back
-    assert_equal("abcdefg", scanner.scan_all(/[a-g]+/))
-  end
-
-
-  def test_keep_over_chunks_nested_drop_back
-    input = CSV::Parser::UnoptimizedStringIO.new("abcdefghijklmnl")
-    scanner = CSV::Parser::InputsScanner.new([input],
-                                             Encoding::UTF_8,
-                                             nil,
-                                             chunk_size: 3)
-    scanner.keep_start
-    assert_equal("ab", scanner.scan(/../))
-    scanner.keep_start
-    assert_equal("c", scanner.scan(/./))
-    assert_equal("d", scanner.scan(/./))
-    scanner.keep_drop
-    scanner.keep_back
-    assert_equal("abcdefg", scanner.scan_all(/[a-g]+/))
-  end
-end