pq connection string parsing from other project

pgLabII.PgUtils/ConnectionStrings/Pq/PqConnectionStringTokenizer.cs

@@ -0,0 +1,118 @@
+using System.Text;
+using static System.Net.Mime.MediaTypeNames;
+
+namespace pgLabII.PgUtils.ConnectionStrings;
+
+public class PqConnectionStringTokenizer : IPqConnectionStringTokenizer
+{
+    private readonly string input;
+    private int position = 0;
+
+    public bool Eof
+    {
+        get
+        {
+            ConsumeWhitespace();
+            return position >= input.Length;
+        }
+    }
+
+    public PqConnectionStringTokenizer(string input)
+    {
+        this.input = input;
+        position = 0;
+    }
+
+    public string GetKeyword()
+    {
+        if (Eof)
+            throw new PqConnectionStringParserException($"Unexpected end of file was expecting a keyword at position {position}");
+
+        return GetString(forKeyword: true);
+    }
+
+    public void ConsumeEquals()
+    {
+        ConsumeWhitespace();
+        if (position < input.Length && input[position] == '=')
+        {
+            position++;
+        }
+        else
+            throw new PqConnectionStringParserException($"Was expecting '=' after keyword at position {position}");
+    }
+
+    public string GetValue()
+    {
+        if (Eof)
+            throw new PqConnectionStringParserException($"Unexpected end of file was expecting a keyword at position {position}");
+
+        return GetString(forKeyword: false);
+    }
+
+    private string GetString(bool forKeyword)
+    {
+        if (forKeyword && input[position] == '=')
+            throw new PqConnectionStringParserException($"Unexpected '=' was expecting keyword at position {position}");
+
+        if (input[position] == '\'')
+            return ParseQuotedText();
+
+        return UnquotedString(forKeyword);
+    }
+
+    private void ConsumeWhitespace()
+    {
+        while (position < input.Length && char.IsWhiteSpace(input[position]))
+            position++;
+    }
+
+    private string UnquotedString(bool forKeyword)
+    {
+        int start = position;
+        while (++position < input.Length && !char.IsWhiteSpace(input[position]) && (!forKeyword || input[position] != '='))
+        { }
+        return input.Substring(start, position - start);
+    }
+
+    private string ParseQuotedText()
+    {
+        bool escape = false;
+        StringBuilder sb = new();
+        int start = position;
+        while (++position < input.Length)
+        {
+            char c = input[position];
+            if (escape)
+            {
+                switch (c)
+                {
+                    case '\'':
+                    case '\\':
+                        sb.Append(c);
+                        escape = false;
+                        break;
+                    default:
+                        throw new PqConnectionStringParserException($"Invalid escape sequence at position {position}");
+                }
+            }
+            else
+            {
+                if (c == '\'')
+                {
+                    ++position;
+                    return sb.ToString();
+                }
+                else if (c == '\\')
+                {
+                    escape = true;
+                }
+                else
+                {
+                    sb.Append(c);
+                }
+            }
+        }
+        throw new PqConnectionStringParserException($"Missing end quote on value starting at {start}");
+    }
+}