From 6ef3352fb81970f925dd33eac52b20d035bc1051 Mon Sep 17 00:00:00 2001
From: Zeljko Predjeskovic <Zeljko.Predjeskovic@opti-q.com>
Date: Mon, 9 Dec 2024 20:11:13 +0100
Subject: [PATCH] added updated parser_to_h and added test cases

---
 spec/std/csv/csv_parse_spec.cr | 31 +++++++++++++++++++++++++++----
 src/csv/lexer.cr               |  3 +++
 src/csv/parser.cr              | 20 +++++++++++++-------
 3 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/spec/std/csv/csv_parse_spec.cr b/spec/std/csv/csv_parse_spec.cr
index c93ae5be2b53..3e505cd349ea 100644
--- a/spec/std/csv/csv_parse_spec.cr
+++ b/spec/std/csv/csv_parse_spec.cr
@@ -50,16 +50,39 @@ describe CSV do
     end
 
     it "parses to hashes" do
-      csv_text = "Index,Customer Id,First Name,Last Name
-              1,DD37Cf93aecA6Dc,Sheryl,Baxter
-              2,1Ef7b82A4CAAD10,Preston,Lozano
-              3,6F94879bDAfE5a6,,Berry"
+      csv_text = "Index,Customer Id,First Name,Last Name\n\n1,DD37Cf93aecA6Dc,Sheryl,Baxter\n2,1Ef7b82A4CAAD10,Preston,Lozano\n3,6F94879bDAfE5a6,,Berry, Jerry, \n"
 
       CSV.parse_to_h(csv_text).should eq([{"Index" => "1", "Customer Id" => "DD37Cf93aecA6Dc", "First Name" => "Sheryl", "Last Name" => "Baxter"},
                                           {"Index" => "2", "Customer Id" => "1Ef7b82A4CAAD10", "First Name" => "Preston", "Last Name" => "Lozano"},
                                           {"Index" => "3", "Customer Id" => "6F94879bDAfE5a6", "First Name" => "", "Last Name" => "Berry"}])
     end
 
+    it "parses to hashes with no headers" do
+      csv_text = "\n1,DD37Cf93aecA6Dc,Sheryl,Baxter\n2,1Ef7b82A4CAAD10,Preston,Lozano\n3,6F94879bDAfE5a6,,Berry"
+
+      actual = [{} of String => String, {} of String => String, {} of String => String]
+
+      CSV.parse_to_h(csv_text).should eq(actual)
+    end
+
+    it "parses to hashes with only headers" do
+      csv_text = "Index,Customer Id,First Name,Last Name"
+
+      CSV.parse_to_h(csv_text).should eq([] of Hash(String, String))
+    end
+
+    it "parses to hashes remaining rows" do
+      csv_text = "Index,Customer Id,First Name,Last Name\n1,DD37Cf93aecA6Dc,Sheryl,Baxter\n2,1Ef7b82A4CAAD10,Preston,Lozano\n3,6F94879bDAfE5a6,,Berry"
+      parser = CSV::Parser.new(csv_text)
+      # skip header
+      parser.next_row
+      # skip rows
+      parser.next_row
+      parser.next_row
+
+      parser.parse_to_h.should eq([{"Index" => "3", "Customer Id" => "6F94879bDAfE5a6", "First Name" => "", "Last Name" => "Berry"}])
+    end
+
     it "raises if single quote in the middle" do
       expect_raises CSV::MalformedCSVError, "Unexpected quote at line 1, column 4" do
         CSV.parse(%(hel"lo))
diff --git a/src/csv/lexer.cr b/src/csv/lexer.cr
index 9d3d04c68c0f..5109f630a7e0 100644
--- a/src/csv/lexer.cr
+++ b/src/csv/lexer.cr
@@ -29,6 +29,9 @@ abstract class CSV::Lexer
   getter separator : Char
   getter quote_char : Char
 
+  # :nodoc:
+  protected getter line_number : Int32
+
   # :nodoc:
   def initialize(@separator : Char = DEFAULT_SEPARATOR, @quote_char : Char = DEFAULT_QUOTE_CHAR)
     @token = Token.new
diff --git a/src/csv/parser.cr b/src/csv/parser.cr
index 32d0931d921e..a3460b302fe7 100644
--- a/src/csv/parser.cr
+++ b/src/csv/parser.cr
@@ -21,9 +21,17 @@ class CSV::Parser
 
   def parse_to_h : Array(Hash(String, String))
     rows = [] of Hash(String, String)
+    row_number = @lexer.line_number
+
+    rewind
     if headers = next_row
-      while row = next_row
-        rows << parse_row_to_h_internal(headers, row)
+      while @lexer.line_number < row_number
+        next_row
+      end
+      each_row do |row|
+        if parsed_row = parse_row_to_h_internal(headers, row)
+          rows << parsed_row
+        end
       end
     end
     rows
@@ -81,12 +89,10 @@ class CSV::Parser
     end
   end
 
-  private def parse_row_to_h_internal(headers : Array(String), row : Array(String)) : Hash(String, String)
+  private def parse_row_to_h_internal(headers : Array(String), row : Array(String)) : Hash(String, String) | Nil
     h = {} of String => String
-    headers.each_with_index do |header, i|
-      h[header] = row[i].strip || ""
-    end
-    h
+    row.empty? ? return nil : headers.each_with_index { |header, i| h[header] = row[i] }
+    return h
   end
 
   private struct RowIterator