#4148 add values_at method for CSV::Row

spec/std/csv/csv_spec.cr

@@ -128,4 +128,32 @@ describe CSV do
       break
     end
   end
+
+  it "returns a Tuple(String, String) for current row with indices" do
+    CSV.new("John,20\nPeter,30") do |csv|
+      csv.values_at(0, -1).should eq({"John", "20"})
+      break
+    end
+  end
+
+  it "returns a Tuple(String, String) for current row with headers" do
+    CSV.new("Name,Age\nJohn,20\nPeter,30", headers: true) do |csv|
+      csv.values_at("Name", "Age").should eq({"John", "20"})
+      break
+    end
+  end
+
+  it "returns a Tuple(String, String) for this row with indices" do
+    CSV.new("John,20\nPeter,30") do |csv|
+      csv.row.values_at(0, -1).should eq({"John", "20"})
+      break
+    end
+  end
+
+  it "returns a Tuple(String, String) for this row with headers" do
+    CSV.new("Name,Age\nJohn,20\nPeter,30", headers: true) do |csv|
+      csv.row.values_at("Name", "Age").should eq({"John", "20"})
+      break
+    end
+  end
 end

src/csv.cr

@@ -254,6 +254,22 @@ class CSV
     row_internal[header_pattern]?
   end
 
+  # Returns a tuple of the current row's values at given indices
+  # A negative index counts from the end.
+  # Raises `IndexError` if any column doesn't exist
+  # The behavior of returning a tuple is similar to `Hash#values_at`
+  def values_at(*columns : Int)
+    columns.map { |column| row_internal[column] }
+  end
+
+  # Returns a tuple of the current row's values corresponding to the given *headers*
+  # Raises `KeyError` if any header doesn't exist.
+  # Raises `CSV::Error` if headers were not requested
+  # The behavior of returning a tuple is similar to `Hash#values_at`
+  def values_at(*headers : String)
+    headers.map { |header| row_internal[header] }
+  end
+
   # Returns the current row as a `Row` instance.
   def row : Row
     Row.new(self, current_row.dup)
@@ -381,6 +397,22 @@ class CSV
       h
     end
 
+    # Returns a tuple of this row's values at given indices
+    # A negative index counts from the end.
+    # Raises `IndexError` if any column doesn't exist
+    # The behavior of returning a tuple is similar to `Hash#values_at`
+    def values_at(*columns : Int)
+      columns.map { |column| self[column] }
+    end
+
+    # Returns a tuple of this row's values corresponding to the given *headers*
+    # Raises `KeyError` if any header doesn't exist.
+    # Raises `CSV::Error` if headers were not requested
+    # The behavior of returning a tuple is similar to `Hash#values_at`
+    def values_at(*headers : String)
+      headers.map { |header| self[header] }
+    end
+
     private def maybe_strip(value)
       csv.strip? ? value.strip : value
     end