From dcf77615c6f1c57bb9100a8dcb26111985d41425 Mon Sep 17 00:00:00 2001
From: Kazuki Tsujimoto <kazuki@callcc.net>
Date: Wed, 4 May 2016 12:52:33 +0900
Subject: [PATCH] * lib/csv.rb (CSV::{Row,Table}#{each,delete_if}): Returns an
 enumerator if no block is given. * test/csv/test_row.rb: add test for above.
 * test/csv/test_table.rb: ditto.

---
 lib/csv.rb             | 20 ++++++++++++++---
 test/csv/test_row.rb   | 25 +++++++++++++++++++--
 test/csv/test_table.rb | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 99 insertions(+), 5 deletions(-)

diff --git a/lib/csv.rb b/lib/csv.rb
index 509e978..5fc7074 100644
--- a/lib/csv.rb
+++ b/lib/csv.rb
@@ -431,7 +431,11 @@ def delete(header_or_index, minimum_index = 0)
     #
     # This method returns the row for chaining.
     #
+    # If no block is given, an Enumerator is returned.
+    #
     def delete_if(&block)
+      block or return enum_for(__method__) { size }
+
       @row.delete_if(&block)
 
       self  # for chaining
@@ -500,13 +504,15 @@ def field?(data)
 
     #
     # Yields each pair of the row as header and field tuples (much like
-    # iterating over a Hash).
+    # iterating over a Hash). This method returns the row for chaining.
     #
-    # Support for Enumerable.
+    # If no block is given, an Enumerator is returned.
     #
-    # This method returns the row for chaining.
+    # Support for Enumerable.
     #
     def each(&block)
+      block or return enum_for(__method__) { size }
+
       @row.each(&block)
 
       self  # for chaining
@@ -822,7 +828,11 @@ def delete(index_or_header)
     #
     # This method returns the table for chaining.
     #
+    # If no block is given, an Enumerator is returned.
+    #
     def delete_if(&block)
+      block or return enum_for(__method__) { @mode == :row or @mode == :col_or_row ? size : headers.size }
+
       if @mode == :row or @mode == :col_or_row  # by index
         @table.delete_if(&block)
       else                                      # by header
@@ -845,7 +855,11 @@ def delete_if(&block)
     #
     # This method returns the table for chaining.
     #
+    # If no block is given, an Enumerator is returned.
+    #
     def each(&block)
+      block or return enum_for(__method__) { @mode == :col ? headers.size : size }
+
       if @mode == :col
         headers.each { |header| block[[header, self[header]]] }
       else
diff --git a/test/csv/test_row.rb b/test/csv/test_row.rb
index 1fa15d3..1cb851b 100755
--- a/test/csv/test_row.rb
+++ b/test/csv/test_row.rb
@@ -209,9 +209,20 @@ def test_delete
     # by header
     assert_equal(["C", 3], @row.delete("C"))
 
-    # using a block
+  end
+
+  def test_delete_if
     assert_equal(@row, @row.delete_if { |h, f| h == "A" and not f.nil? })
-    assert_equal([["A", nil]], @row.to_a)
+    assert_equal([["B", 2], ["C", 3], ["A", nil]], @row.to_a)
+  end
+
+  def test_delete_if_without_block
+    enum = @row.delete_if
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@row.size, enum.size)
+
+    assert_equal(@row, enum.each { |h, f| h == "A" and not f.nil? })
+    assert_equal([["B", 2], ["C", 3], ["A", nil]], @row.to_a)
   end
 
   def test_fields
@@ -281,6 +292,16 @@ def test_each
 
     # verify that we can chain the call
     assert_equal(@row, @row.each { })
+
+    # without block
+    ary = @row.to_a
+    enum = @row.each
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@row.size, enum.size)
+    enum.each do |pair|
+      assert_equal(ary.first.first, pair.first)
+      assert_equal(ary.shift.last, pair.last)
+    end
   end
 
   def test_enumerable
diff --git a/test/csv/test_table.rb b/test/csv/test_table.rb
index 80e553e..25ef11a 100755
--- a/test/csv/test_table.rb
+++ b/test/csv/test_table.rb
@@ -220,6 +220,17 @@ def test_each
     # verify that we can chain the call
     assert_equal(@table, @table.each { })
 
+    # without block
+    enum = @table.each
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@table.size, enum.size)
+
+    i = 0
+    enum.each do |row|
+      assert_equal(@rows[i], row)
+      i += 1
+    end
+
     ###################
     ### Column Mode ###
     ###################
@@ -231,6 +242,17 @@ def test_each
       assert_equal(@table[header], column)
     end
 
+    # without block
+    enum = @table.each
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@table.headers.size, enum.size)
+
+    headers = @table.headers
+    enum.each do |header, column|
+      assert_equal(headers.shift, header)
+      assert_equal(@table[header], column)
+    end
+
     ############################
     ### One Shot Mode Change ###
     ############################
@@ -363,6 +385,24 @@ def test_delete_if_row
     END_RESULT
   end
 
+  def test_delete_if_row_without_block
+    ######################
+    ### Mixed/Row Mode ###
+    ######################
+    enum = @table.delete_if
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@table.size, enum.size)
+
+    # verify that we can chain the call
+    assert_equal(@table, enum.each { |row| (row["B"] % 2).zero? })
+
+    # verify resulting table
+    assert_equal(<<-END_RESULT.gsub(/^\s+/, ""), @table.to_csv)
+    A,B,C
+    4,5,6
+    END_RESULT
+  end
+
   def test_delete_if_column
     ###################
     ### Column Mode ###
@@ -378,6 +418,25 @@ def test_delete_if_column
     END_RESULT
   end
 
+  def test_delete_if_column_without_block
+    ###################
+    ### Column Mode ###
+    ###################
+    @table.by_col!
+
+    enum = @table.delete_if
+    assert_instance_of(Enumerator, enum)
+    assert_equal(@table.headers.size, enum.size)
+
+    assert_equal(@table, enum.each { |h, v| h > "A" })
+    assert_equal(<<-END_RESULT.gsub(/^\s+/, ""), @table.to_csv)
+    A
+    1
+    4
+    7
+    END_RESULT
+  end
+
   def test_values_at
     ##################
     ### Mixed Mode ###
-- 
1.9.1