Add a toCSV to go along with the fromCSV

processor/processor.go

@@ -223,7 +223,7 @@ end
 ---
 --- Returns:
 --- - A table (array) of rows; each row is a table (array) of string fields.
-local function parseCSV(csv)
+function fromCSV(csv)
 	local rows = {}
 	local fields = {}
 	local field = {}
@@ -305,6 +305,45 @@ local function parseCSV(csv)
 	return rows
 end
 
+--- Converts a table of rows back to CSV text format (RFC 4180 compliant).
+---
+--- Requirements:
+--- - Input is a table (array) of rows, where each row is a table (array) of field values.
+--- - Field values are converted to strings using tostring().
+--- - Fields are quoted if they contain commas, newlines, or double quotes.
+--- - Double quotes inside quoted fields are doubled ("").
+--- - Fields are joined with commas; rows are joined with newlines.
+---
+--- @param rows table Array of rows, where each row is an array of field values.
+--- @return string CSV-formatted text.
+function toCSV(rows)
+	local rowStrings = {}
+
+	for _, row in ipairs(rows) do
+		local fieldStrings = {}
+
+		for _, field in ipairs(row) do
+			local fieldStr = tostring(field)
+			local needsQuoting = false
+
+			if fieldStr:find(',') or fieldStr:find('\n') or fieldStr:find('\r') or fieldStr:find('"') then
+				needsQuoting = true
+			end
+
+			if needsQuoting then
+				fieldStr = fieldStr:gsub('"', '""')
+				fieldStr = '"' .. fieldStr .. '"'
+			end
+
+			table.insert(fieldStrings, fieldStr)
+		end
+
+		table.insert(rowStrings, table.concat(fieldStrings, ','))
+	end
+
+	return table.concat(rowStrings, '\n')
+end
+
 -- String to number conversion helper
 function num(str)
     return tonumber(str) or 0
@@ -599,8 +638,8 @@ func EvalRegex(L *lua.LState) int {
 	if len(matches) > 0 {
 		matchesTable := L.NewTable()
 		for i, match := range matches {
-			matchesTable.RawSetString(fmt.Sprintf("%d", i), lua.LString(match))
-			evalRegexLogger.Debug("Set table[%d] = %q", i, match)
+			matchesTable.RawSetInt(i+1, lua.LString(match))
+			evalRegexLogger.Debug("Set table[%d] = %q", i+1, match)
 		}
 		L.Push(matchesTable)
 	} else {
@@ -629,7 +668,8 @@ STRING FUNCTIONS:
   format(s, ...)          - Formats string using Lua string.format
   trim(s)                 - Removes leading/trailing whitespace
   strsplit(inputstr, sep) - Splits string by separator (default: whitespace)
-  parseCSV(csv)           - Parses CSV text into rows of fields
+  fromCSV(csv)            - Parses CSV text into rows of fields
+  toCSV(rows)             - Converts table of rows to CSV text format
   num(str)                - Converts string to number (returns 0 if invalid)
   str(num)                - Converts number to string
   is_number(str)          - Returns true if string is numeric

processor/processor_test.go

@@ -1,7 +1,6 @@
 package processor_test
 
 import (
-	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -30,8 +29,8 @@ func TestEvalRegex_CaptureGroupsReturned(t *testing.T) {
 	}
 	expected := []string{"test-42", "test", "42"}
 	for i, v := range expected {
-		val := tbl.RawGetString(fmt.Sprintf("%d", i))
-		assert.Equal(t, lua.LString(v), val, "Expected index %d to be %q", i, v)
+		val := tbl.RawGetInt(i + 1)
+		assert.Equal(t, lua.LString(v), val, "Expected index %d to be %q", i+1, v)
 	}
 }
 
@@ -67,9 +66,9 @@ func TestEvalRegex_NoCaptureGroups(t *testing.T) {
 	if !ok {
 		t.Fatalf("Expected Lua table, got %T", out)
 	}
-	fullMatch := tbl.RawGetString("0")
+	fullMatch := tbl.RawGetInt(1)
 	assert.Equal(t, lua.LString("foo123"), fullMatch)
-	// There should be only the full match (index 0)
+	// There should be only the full match (index 1)
 	count := 0
 	tbl.ForEach(func(k, v lua.LValue) {
 		count++