1 files changed, 59 insertions, 0 deletions
diff --git a/Compiler/Preprocessor.cs b/Compiler/Preprocessor.cs
new file mode 100644
index 0000000..01c14ab
--- /dev/null
+++ b/Compiler/Preprocessor.cs
@@ -0,0 +1,59 @@
+namespace Q1.Compiler;
+
+using System.Text.RegularExpressions;
+
+public static class Preprocessor
+{
+    private static readonly Dictionary<string, string> Defines = new();
+
+    public static string Process(string filePath)
+    {
+        List<string> lines = [];
+        ProcessFile(filePath, lines, []);
+        return string.Join(Environment.NewLine, lines);
+    }
+
+    private static void ProcessFile(string filePath, List<string> output, HashSet<string> includeGuard)
+    {
+        if (includeGuard.Contains(Path.GetFullPath(filePath)))
+            return; // prevent recursive includes
+        
+        includeGuard.Add(Path.GetFullPath(filePath));
+
+        foreach (string rawLine in File.ReadAllLines(filePath))
+        {
+            string line = rawLine.Trim();
+
+            if (line.StartsWith("#include"))
+            {
+                // simple format: #include "file"
+                Match match = Regex.Match(line, "#include\\s+\"([^\"]+)\"");
+                if (match.Success)
+                {
+                    string includePath = Path.Combine(Path.GetDirectoryName(filePath)!, match.Groups[1].Value);
+                    ProcessFile(includePath, output, includeGuard);
+                }
+                continue;
+            }
+            else if (line.StartsWith("#define"))
+            {
+                // simple format: #define NAME VALUE
+                Match match = Regex.Match(line, "#define\\s+(\\w+)\\s+(.*)");
+                if (match.Success)
+                    Defines[match.Groups[1].Value] = match.Groups[2].Value;
+                continue;
+            }
+            else if (line.StartsWith("#load"))
+            {
+                output.Add(line.Replace("#load", "#.include"));
+                continue;
+            }
+
+            // expand macros
+            foreach (KeyValuePair<string, string> kvp in Defines)
+                line = line.Replace(kvp.Key, kvp.Value);
+
+            output.Add(line);
+        }
+    }
+}
+\ No newline at end of file