From 51e0ce3a103410f1fb03f8305a323a537337ef33 Mon Sep 17 00:00:00 2001
From: Thomas <1258170+ThomasSevestre@users.noreply.github.com>
Date: Wed, 10 May 2023 10:12:15 +0200
Subject: [PATCH] optimize rows_collection_parser (cf. Roo::Utils)

---
 lib/saxlsx/column_name_generator.rb  | 18 --------------
 lib/saxlsx/rows_collection_parser.rb | 37 ++++++++++++++++++++++------
 spec/column_name_generator_spec.rb   | 25 -------------------
 3 files changed, 30 insertions(+), 50 deletions(-)
 delete mode 100644 lib/saxlsx/column_name_generator.rb
 delete mode 100644 spec/column_name_generator_spec.rb

diff --git a/lib/saxlsx/column_name_generator.rb b/lib/saxlsx/column_name_generator.rb
deleted file mode 100644
index e1c9e6d..0000000
--- a/lib/saxlsx/column_name_generator.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-module Saxlsx
-  class ColumnNameGenerator
-    FIRST = 'A'
-    LAST  = 'Z'
-
-    def self.next_to(previous)
-      char = previous ? previous[-1] : nil
-      if char.nil?
-        FIRST
-      elsif char < LAST
-        previous[0..-2] + char.next
-      else
-        next_to(previous[0..-2]) + FIRST
-      end
-    end
-  end
-end
diff --git a/lib/saxlsx/rows_collection_parser.rb b/lib/saxlsx/rows_collection_parser.rb
index 07ef60b..cf3db4a 100644
--- a/lib/saxlsx/rows_collection_parser.rb
+++ b/lib/saxlsx/rows_collection_parser.rb
@@ -54,7 +54,6 @@ def start_element(name)
       case name
       when :row
         @current_row = []
-        @next_column = 'A'
       when :c
         @current_type = nil
         @current_number_format = nil
@@ -74,7 +73,11 @@ def attr(name, value)
         when :t
           @current_type = value
         when :r
-          @current_column = value.gsub(/\d/, '')
+          # fill missing columns with nil values
+          nb_columns = extract_current_column(value) - 1
+          while @current_row.size != nb_columns
+            @current_row << nil
+          end
         when :s
           @current_number_format = detect_format_type(value.to_i)
         end
@@ -83,12 +86,7 @@ def attr(name, value)
 
     def text(value)
       if @current_row && (@current_element == :v || @current_element == :t)
-        while @next_column != @current_column
-          @current_row << nil
-          @next_column = ColumnNameGenerator.next_to(@next_column)
-        end
         @current_row << value_of(value)
-        @next_column = ColumnNameGenerator.next_to(@next_column)
       end
     end
 
@@ -155,5 +153,30 @@ def detect_custom_format_type(code)
         :unsupported
       end
     end
+
+    def char_index(byte)
+      if byte >= 65 && byte <= 90
+        byte - 64
+      elsif byte >= 97 && byte <= 122
+        byte - 96
+      end
+    end
+
+    def extract_current_column(value)
+      letter_num = 0
+
+      value.each_byte do |b|
+        if index = char_index(b)
+          letter_num *= 26
+          letter_num += index
+        else
+          break
+        end
+      end
+
+      raise ArgumentError if letter_num == 0
+
+      letter_num
+    end
   end
 end
diff --git a/spec/column_name_generator_spec.rb b/spec/column_name_generator_spec.rb
deleted file mode 100644
index 9bce426..0000000
--- a/spec/column_name_generator_spec.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-# frozen_string_literal: true
-require 'spec_helper'
-
-describe ColumnNameGenerator do
-
-  it 'First char' do
-    ColumnNameGenerator::FIRST.should eq 'A'
-  end
-
-  it 'Last char' do
-    ColumnNameGenerator::LAST.should eq 'Z'
-  end
-
-  it 'Next value' do
-    ColumnNameGenerator.tap do |g|
-      g.next_to(nil).should eq 'A'
-      g.next_to('F').should eq 'G'
-      g.next_to('DM').should eq 'DN'
-      g.next_to('RZ').should eq 'SA'
-      g.next_to('ZZ').should eq 'AAA'
-      g.next_to('EDT').should eq 'EDU'
-    end
-  end
-
-end