cli: Add a Preprocess Mode

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Sources/Cli/main.swift

@@ -27,7 +27,7 @@ struct Cli: ParsableCommand {
 
   static let configuration = CommandConfiguration(
     abstract: "P4CE compiler, interpreter and debugger.",
-    subcommands: [Compile.self, CodeGen.self])
+    subcommands: [Preprocess.self, Compile.self, CodeGen.self])
 }
 
 struct CliOptions: ParsableArguments {
@@ -38,6 +38,36 @@ struct CliOptions: ParsableArguments {
   var search: [String] = []
 }
 
+extension Cli {
+  struct Preprocess: ParsableCommand {
+    static let configuration = CommandConfiguration(abstract: "Compile P4CE code.")
+
+    @ParentCommand var parent: Cli
+
+    @OptionGroup var options: CliOptions
+
+    mutating func run() {
+      let sm = SourceManager(options.search.map { FilePath($0) })
+      let prep = SourceCodePreprocessor(sm)
+      let file = FilePath(options.path)
+
+      let formatter: any Formattable =
+        if parent.plain != 0 {
+          FormatterPlain()
+        } else {
+          FormatterAnsi()
+        }
+
+      let maybe_source = prep.preprocess(file)
+      guard case .Ok(let source) = maybe_source else {
+        print(ErrorWithLabel("Preprocessor Error", maybe_source.error()!).format(formatter))
+        return
+      }
+
+      print(source.getSource())
+    }
+  }
+}
 extension Cli {
   struct Compile: ParsableCommand {
     static let configuration = CommandConfiguration(abstract: "Compile P4CE code.")