Move command line handling into a module

source/command_line_interface.elna

@@ -0,0 +1,93 @@
+(* This Source Code Form is subject to the terms of the Mozilla Public License,
+  v. 2.0. If a copy of the MPL was not distributed with this file, You can
+  obtain one at https://mozilla.org/MPL/2.0/. *)
+
+(*
+  Command line handling.
+*)
+module;
+
+import cstdlib, cstring, common;
+
+type
+  CommandLine* = record
+    input: ^Char;
+    output: ^Char;
+    lex: Bool;
+    parse: Bool
+  end;
+
+proc parse_command_line*(argc: Int, argv: ^^Char) -> ^CommandLine;
+var
+  parameter: ^Char;
+  i: Int;
+  result: ^CommandLine;
+  parsed: Bool;
+begin
+  i := 1;
+  result := cast(malloc(#size(CommandLine)): ^CommandLine);
+  result^.lex := false;
+  result^.parse := false;
+  result^.input := nil;
+  result^.output := nil;
+
+  while i < argc & result <> nil do
+    parameter := (argv + i)^;
+    parsed := false;
+
+    if strcmp(parameter, "--lex\0".ptr) = 0 then
+      parsed := true;
+      result^.lex := true
+    end;
+    if strcmp(parameter, "--parse\0".ptr) = 0 then
+      parsed := true;
+      result^.parse := true
+    end;
+    if strcmp(parameter, "-o\0".ptr) = 0 then
+      i := i + 1;
+
+      if i = argc then
+        write_s("Fatal error: expecting a file name following -o.");
+        result := nil
+      end;
+      if i < argc then
+        parameter := (argv + i)^;
+        result^.output := parameter
+      end;
+      parsed := true
+    end;
+    if (parameter^ <> '-') & ~parsed then
+      parsed := true;
+
+      if result^.input <> nil then
+        write_s("Fatal error: only one source file can be compiled at once. First given \"");
+        write_z(result^.input);
+        write_s("\", then \"");
+        write_z(parameter);
+        write_s("\".\n");
+        result := nil
+      end;
+      if result <> nil then
+        result^.input := parameter
+      end
+    end;
+    if ~parsed then
+      write_s("Fatal error: unknown command line options: ");
+
+      write_z(parameter);
+      write_s(".\n");
+
+      result := nil
+    end;
+
+    i := i + 1
+  end;
+  if result <> nil & result^.input = nil then
+    write_s("Fatal error: no input files.\n");
+    result := nil
+  end;
+
+  return result
+end;
+
+end.