From edb8ce37d94021b45347f282fd93ba72e8a96de5 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 31 May 2025 11:28:24 +0200
Subject: [PATCH] Add a command line parsing procedure

---
 Rakefile                         |  17 +-
 source/CommandLineInterface.def  |  15 ++
 source/CommandLineInterface.elna |  75 ++++++
 source/Common.def                |   6 +
 source/Common.elna               |   3 +
 source/Compiler.elna             |  43 ++-
 source/Lexer.elna                |   6 +-
 source/Parser.def                |   3 +
 source/Parser.elna               |   3 +
 source/Transpiler.def            |  12 +-
 source/Transpiler.elna           | 450 +++++++++++++++----------------
 11 files changed, 386 insertions(+), 247 deletions(-)
 create mode 100644 source/CommandLineInterface.def
 create mode 100644 source/CommandLineInterface.elna
 create mode 100644 source/Common.def
 create mode 100644 source/Common.elna
 create mode 100644 source/Parser.def
 create mode 100644 source/Parser.elna

diff --git a/Rakefile b/Rakefile
index 774a3e7..ba6063a 100644
--- a/Rakefile
+++ b/Rakefile
@@ -44,11 +44,12 @@ end
       .partition { |f| f.end_with? '.elna' }
 
     File.open t.name, 'w' do |output|
-      puts
-      puts(compiler * ' ')
+      compiler_command = compiler + sources
 
-      Open3.popen2(*compiler) do |cl_in, cl_out|
-        cl_in.write File.read(*sources)
+      puts
+      puts(compiler_command * ' ')
+
+      Open3.popen2(*compiler_command) do |cl_in, cl_out|
         cl_in.close
 
         IO.copy_stream cl_out, output
@@ -87,11 +88,11 @@ task default: 'source/Compiler.elna'
 task :default do |t|
   exe, previous_output, source = t.prerequisites
 
-  cat_arguments = ['cat', source]
+  exe_arguments = [exe, source]
   diff_arguments = ['diff', '-Nur', '--text', previous_output, '-']
 
-  puts [cat_arguments * ' ', exe, diff_arguments * ' '].join(' | ')
-  Open3.pipeline(cat_arguments, exe, diff_arguments)
+  puts [exe, diff_arguments * ' '].join(' | ')
+  Open3.pipeline exe_arguments, diff_arguments
 end
 
 task :backport do
@@ -104,7 +105,7 @@ task :backport do
     source
       .gsub(/^(var|type|const|begin)/) { |match| match.upcase }
       .gsub(/^[[:alnum:]]* ?module/) { |match| match.upcase }
-      .gsub(/\b(record|nil|or)\b/) { |match| match.upcase }
+      .gsub(/\b(record|nil|or|false|true)\b/) { |match| match.upcase }
       .gsub(/proc\(/, 'PROCEDURE(')
       .gsub(/ & /, ' AND ')
       .gsub(/ -> /, ': ')
diff --git a/source/CommandLineInterface.def b/source/CommandLineInterface.def
new file mode 100644
index 0000000..85be324
--- /dev/null
+++ b/source/CommandLineInterface.def
@@ -0,0 +1,15 @@
+DEFINITION MODULE CommandLineInterface;
+
+FROM Common IMPORT ShortString;
+
+TYPE
+  CommandLine = RECORD
+    input: ShortString;
+    lex: BOOLEAN;
+    parse: BOOLEAN
+  END;
+  PCommandLine = POINTER TO CommandLine;
+
+PROCEDURE parse_command_line(): PCommandLine;
+
+END CommandLineInterface.
diff --git a/source/CommandLineInterface.elna b/source/CommandLineInterface.elna
new file mode 100644
index 0000000..eb16b4f
--- /dev/null
+++ b/source/CommandLineInterface.elna
@@ -0,0 +1,75 @@
+implementation module CommandLineInterface;
+
+from SYSTEM import ADR, TSIZE;
+
+from Args import GetArg, Narg;
+from FIO import WriteString, WriteChar, WriteLine, StdErr;
+from Storage import ALLOCATE;
+from Strings import CompareStr, Length;
+from MemUtils import MemZero;
+
+from Common import ShortString;
+
+proc parse_command_line() -> PCommandLine;
+var
+  parameter: ShortString;
+  i: CARDINAL;
+  result: PCommandLine;
+  parsed: BOOLEAN;
+begin
+  i := 1;
+  ALLOCATE(result, TSIZE(CommandLine));
+  result^.lex := false;
+  result^.parse := false;
+  MemZero(ADR(result^.input), 256);
+
+  while (i < Narg()) & (result <> nil) do
+    parsed := GetArg(parameter, i);
+    parsed := false;
+
+    if CompareStr(parameter, '--lex') = 0 then
+      parsed := true;
+      result^.lex := true
+    end;
+    if CompareStr(parameter, '--parse') = 0 then
+      parsed := true;
+      result^.parse := true
+    end;
+    if parameter[0] <> '-' then
+      parsed := true;
+
+      if Length(result^.input) > 0 then
+        WriteString(StdErr, 'Fatal error: only one source file can be compiled at once. First given "');
+        WriteString(StdErr, result^.input);
+        WriteString(StdErr, '", then "');
+        WriteString(StdErr, parameter);
+        WriteString(StdErr, '".');
+        WriteLine(StdErr);
+        result := nil
+      end;
+      if result <> nil then
+        result^.input := parameter
+      end
+    end;
+    if parsed = false then
+      WriteString(StdErr, 'Fatal error: unknown command line options: ');
+
+      WriteString(StdErr, parameter);
+      WriteChar(StdErr, '.');
+      WriteLine(StdErr);
+
+      result := nil
+    end;
+
+    i := i + 1
+  end;
+  if (result <> nil) & (Length(result^.input) = 0) then
+    WriteString(StdErr, 'Fatal error: no input files.');
+    WriteLine(StdErr);
+    result := nil
+  end;
+
+  return result
+end;
+
+end CommandLineInterface.
diff --git a/source/Common.def b/source/Common.def
new file mode 100644
index 0000000..5925cbf
--- /dev/null
+++ b/source/Common.def
@@ -0,0 +1,6 @@
+DEFINITION MODULE Common;
+
+TYPE
+  ShortString = ARRAY[0..255] OF CHAR;
+
+END Common.
diff --git a/source/Common.elna b/source/Common.elna
new file mode 100644
index 0000000..7b8d623
--- /dev/null
+++ b/source/Common.elna
@@ -0,0 +1,3 @@
+implementation module Common;
+
+end Common.
diff --git a/source/Compiler.elna b/source/Compiler.elna
index 4e6ea19..4ee052b 100644
--- a/source/Compiler.elna
+++ b/source/Compiler.elna
@@ -1,18 +1,51 @@
 module Compiler;
 
-from FIO import StdIn;
+from FIO import Close, IsNoError, File, OpenToRead, StdErr, WriteLine, WriteString;
 from SYSTEM import ADR;
+from M2RTS import HALT, ExitOnHalt;
 
 from Lexer import Lexer, lexer_destroy, lexer_initialize;
 from Transpiler import transpile;
+from CommandLineInterface import PCommandLine, parse_command_line;
 
+var
+  command_line: PCommandLine;
+
+proc compile_from_stream();
 var
   lexer: Lexer;
+  source_input: File;
+begin
+  source_input := OpenToRead(command_line^.input);
+
+  if IsNoError(source_input) = false then
+    WriteString(StdErr, 'Fatal error: failed to read the input file "');
+    WriteString(StdErr, command_line^.input);
+    WriteString(StdErr, '".');
+    WriteLine(StdErr);
+
+    ExitOnHalt(2)
+  end;
+  if IsNoError(source_input) then
+    lexer_initialize(ADR(lexer), source_input);
+
+    transpile(ADR(lexer));
+
+    lexer_destroy(ADR(lexer));
+
+    Close(source_input)
+  end
+end;
 
 begin
-  lexer_initialize(ADR(lexer), StdIn);
+  ExitOnHalt(0);
+  command_line := parse_command_line();
 
-  transpile(ADR(lexer));
-
-  lexer_destroy(ADR(lexer))
+  if command_line <> nil then
+    compile_from_stream()
+  end;
+  if command_line = nil then
+    ExitOnHalt(1)
+  end;
+  HALT()
 end Compiler.
diff --git a/source/Lexer.elna b/source/Lexer.elna
index 902e93a..19cfd34 100644
--- a/source/Lexer.elna
+++ b/source/Lexer.elna
@@ -217,7 +217,7 @@ var
   index: CARDINAL;
 begin
   index := 0;
-  result := TRUE;
+  result := true;
 
   while (index < Length(Keyword)) & (TokenStart <> TokenEnd) & result DO
     result := (Keyword[index] = TokenStart^) or (Lower(Keyword[index]) = TokenStart^);
@@ -409,11 +409,11 @@ begin
   end;
   if compare_keyword('TRUE', lexer^.Start, lexer^.Current) then
     token^.kind := lexerKindBoolean;
-    token^.booleanKind := TRUE
+    token^.booleanKind := true
   end;
   if compare_keyword('FALSE', lexer^.Start, lexer^.Current) then
     token^.kind := lexerKindBoolean;
-    token^.booleanKind := FALSE
+    token^.booleanKind := false
   end
 end;
 
diff --git a/source/Parser.def b/source/Parser.def
new file mode 100644
index 0000000..5b016de
--- /dev/null
+++ b/source/Parser.def
@@ -0,0 +1,3 @@
+DEFINITION MODULE Parser;
+
+END Parser.
diff --git a/source/Parser.elna b/source/Parser.elna
new file mode 100644
index 0000000..edd30e5
--- /dev/null
+++ b/source/Parser.elna
@@ -0,0 +1,3 @@
+module Parser;
+
+end Parser.
diff --git a/source/Transpiler.def b/source/Transpiler.def
index c3cd8a7..d9a65cf 100644
--- a/source/Transpiler.def
+++ b/source/Transpiler.def
@@ -1,6 +1,16 @@
 DEFINITION MODULE Transpiler;
 
-FROM Lexer IMPORT PLexer;
+FROM FIO IMPORT File;
+
+FROM Lexer IMPORT PLexer, Lexer;
+
+TYPE
+  TranspilerContext = RECORD
+    indentation: CARDINAL;
+    output: File;
+    lexer: PLexer
+  END;
+  PTranspilerContext = POINTER TO TranspilerContext;
 
 PROCEDURE transpile(ALexer: PLexer);
 
diff --git a/source/Transpiler.elna b/source/Transpiler.elna
index 9820193..0e79df4 100644
--- a/source/Transpiler.elna
+++ b/source/Transpiler.elna
@@ -1,17 +1,11 @@
 implementation module Transpiler;
 
-from FIO import WriteNBytes, StdOut;
+from FIO import WriteNBytes, StdOut, WriteLine, WriteChar;
 from SYSTEM import ADR, ADDRESS;
 
 from Terminal import Write, WriteLn, WriteString;
 from Lexer import Lexer, LexerToken, lexer_current, lexer_lex, LexerKind;
 
-type
-  PTranspilerContext = ^TranspilerContext;
-  TranspilerContext = record
-    Indentation: CARDINAL
-  end;
-
 (* Calls lexer_lex() but skips the comments. *)
 proc transpiler_lex(lexer: PLexer) -> LexerToken;
 var
@@ -27,413 +21,403 @@ begin
 end;
 
 (* Write a semicolon followed by a newline. *)
-proc write_semicolon();
+proc write_semicolon(output: File);
 begin
-  WriteString(';');
-  WriteLn()
+  WriteChar(output, ';');
+  WriteLine(output)
 end;
 
-proc transpile_import(context: PTranspilerContext,  lexer: PLexer);
+proc write_current(lexer: PLexer);
+var
+  written_bytes: CARDINAL;
+begin
+  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start)
+end;
+
+proc transpile_import(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('FROM ');
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-
-  token := transpiler_lex(lexer);
+  write_current(context^.lexer);
+  token := transpiler_lex(context^.lexer);
   WriteString(' IMPORT ');
 
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   while token.kind <> lexerKindSemicolon do
     WriteString(', ');
-    token := transpiler_lex(lexer);
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer);
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer)
   end;
-  write_semicolon();
-  token := transpiler_lex(lexer)
+  write_semicolon(context^.output);
+  token := transpiler_lex(context^.lexer)
 end;
 
-proc transpile_import_part(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_import_part(context: PTranspilerContext);
 var
   token: LexerToken;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
 
   while token.kind = lexerKindFrom do
-    transpile_import(context, lexer);
-    token := lexer_current(lexer)
+    transpile_import(context);
+    token := lexer_current(context^.lexer)
   end;
   WriteLn()
 end;
 
-proc transpile_constant(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_constant(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  ');
-  token := lexer_current(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := lexer_current(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   WriteString(' = ');
 
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
-  write_semicolon()
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output)
 end;
 
-proc transpile_constant_part(context: PTranspilerContext,  lexer: PLexer) -> BOOLEAN;
+proc transpile_constant_part(context: PTranspilerContext) -> BOOLEAN;
 var
   token: LexerToken;
   result: BOOLEAN;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
   result := token.kind = lexerKindConst;
 
   if result then
     WriteString('CONST');
     WriteLn();
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
 
     while token.kind = lexerKindIdentifier do
-      transpile_constant(context, lexer);
-      token := transpiler_lex(lexer)
+      transpile_constant(context);
+      token := transpiler_lex(context^.lexer)
     end
   end;
   return result
 end;
 
-proc transpile_module(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_module(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   if token.kind = lexerKindDefinition then
     WriteString('DEFINITION ');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   if token.kind = lexerKindImplementation then
     WriteString('IMPLEMENTATION ');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   WriteString('MODULE ');
 
   (* Write the module name and end the line with a semicolon and newline. *)
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
-  write_semicolon();
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output);
   WriteLn();
 
   (* Write the module body. *)
-  token := transpiler_lex(lexer);
-  transpile_import_part(context, lexer);
-  if transpile_constant_part(context, lexer) then
+  token := transpiler_lex(context^.lexer);
+  transpile_import_part(context);
+  if transpile_constant_part(context) then
     WriteLn()
   end;
-  transpile_type_part(context, lexer);
-  if transpile_variable_part(context, lexer) then
+  transpile_type_part(context);
+  if transpile_variable_part(context) then
     WriteLn()
   end;
-  transpile_procedure_part(context, lexer);
-  transpile_statement_part(context, lexer);
+  transpile_procedure_part(context);
+  transpile_statement_part(context);
 
   WriteString('END ');
 
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   Write('.');
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   WriteLn()
 end;
 
-proc transpile_type_fields(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_type_fields(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   while token.kind <> lexerKindEnd do
     WriteString('    ');
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer);
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer);
     WriteString(': ');
-    transpile_type_expression(context, lexer);
-    token := transpiler_lex(lexer);
+    transpile_type_expression(context);
+    token := transpiler_lex(context^.lexer);
 
     if token.kind = lexerKindSemicolon then
-      token := transpiler_lex(lexer);
+      token := transpiler_lex(context^.lexer);
       Write(';')
     end;
     WriteLn()
   end
 end;
 
-proc transpile_record_type(context: PTranspilerContext,  lexer: PLexer);
-var
-  token: LexerToken;
+proc transpile_record_type(context: PTranspilerContext);
 begin
   WriteString('RECORD');
   WriteLn();
-  transpile_type_fields(context, lexer);
+  transpile_type_fields(context);
   WriteString('  END')
 end;
 
-proc transpile_pointer_type(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_pointer_type(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
   WriteString('POINTER TO ');
   if token.kind = lexerKindPointer then
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
-  transpile_type_expression(context, lexer)
+  transpile_type_expression(context)
 end;
 
-proc transpile_array_type(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_array_type(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('ARRAY');
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
 
   if token.kind = lexerKindArray then
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   if token.kind <> lexerKindOf then
     WriteString('[1..');
-    token := transpiler_lex(lexer);
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer);
     Write(']')
   end;
   WriteString(' OF ');
-  transpile_type_expression(context, lexer)
+  transpile_type_expression(context)
 end;
 
-proc transpile_enumeration_type(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_enumeration_type(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('(');
   WriteLn();
   WriteString('    ');
 
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   while token.kind = lexerKindComma do
     Write(',');
     WriteLn();
     WriteString('    ');
-    token := transpiler_lex(lexer);
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+    token := transpiler_lex(context^.lexer);
+    write_current(context^.lexer);
 
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   WriteLn();
   WriteString('  )')
 end;
 
-proc transpile_union_type(context: PTranspilerContext,  lexer: PLexer);
-var
-  token: LexerToken;
+proc transpile_union_type(context: PTranspilerContext);
 end;
 
-proc transpile_procedure_type(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_procedure_type(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   WriteString('PROCEDURE(');
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   while token.kind <> lexerKindRightParen do
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+    write_current(context^.lexer);
 
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
     if token.kind = lexerKindComma then
-      token := transpiler_lex(lexer);
+      token := transpiler_lex(context^.lexer);
       WriteString(', ')
     end
   end;
   Write(')')
 end;
 
-proc transpile_type_expression(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_type_expression(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   if token.kind = lexerKindRecord then
-    transpile_record_type(context, lexer)
+    transpile_record_type(context)
   end;
   if token.kind = lexerKindLeftParen then
-    transpile_enumeration_type(context, lexer)
+    transpile_enumeration_type(context)
   end;
   if (token.kind = lexerKindArray) or (token.kind = lexerKindLeftSquare) then
-    transpile_array_type(context, lexer)
+    transpile_array_type(context)
   end;
   if token.kind = lexerKindHat then
-    transpile_pointer_type(context, lexer)
+    transpile_pointer_type(context)
   end;
   if token.kind = lexerKindProc then
-    transpile_procedure_type(context, lexer)
+    transpile_procedure_type(context)
   end;
   if token.kind = lexerKindIdentifier then
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start)
+    write_current(context^.lexer)
   end
 end;
 
-proc transpile_type_declaration(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_type_declaration(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  ');
-  token := lexer_current(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := lexer_current(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   WriteString(' = ');
-  transpile_type_expression(context, lexer);
-  token := transpiler_lex(lexer);
-  write_semicolon();
+  transpile_type_expression(context);
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output);
 end;
 
-proc transpile_type_part(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_type_part(context: PTranspilerContext);
 var
   token: LexerToken;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
 
   if token.kind = lexerKindType then
     WriteString('TYPE');
     WriteLn();
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
 
     while token.kind = lexerKindIdentifier do
-      transpile_type_declaration(context, lexer);
-      token := transpiler_lex(lexer)
+      transpile_type_declaration(context);
+      token := transpiler_lex(context^.lexer)
     end;
     WriteLn()
   end
 end;
 
-proc transpile_variable_declaration(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_variable_declaration(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  ');
-  token := lexer_current(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  token := lexer_current(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   WriteString(': ');
-  transpile_type_expression(context, lexer);
-  token := transpiler_lex(lexer);
-  write_semicolon()
+  transpile_type_expression(context);
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output)
 end;
 
-proc transpile_variable_part(context: PTranspilerContext,  lexer: PLexer) -> BOOLEAN;
+proc transpile_variable_part(context: PTranspilerContext) -> BOOLEAN;
 var
   token: LexerToken;
   result: BOOLEAN;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
   result := token.kind = lexerKindVar;
 
   if result then
     WriteString('VAR');
     WriteLn();
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
 
     while token.kind = lexerKindIdentifier do
-      transpile_variable_declaration(context, lexer);
-      token := transpiler_lex(lexer)
+      transpile_variable_declaration(context);
+      token := transpiler_lex(context^.lexer)
     end
   end;
   return result
 end;
 
-proc transpile_procedure_heading(context: PTranspilerContext, lexer: PLexer) -> LexerToken;
+proc transpile_procedure_heading(context: PTranspilerContext) -> LexerToken;
 var
   token: LexerToken;
   result: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('PROCEDURE ');
 
-  result := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+  result := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   Write('(');
 
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
   while token.kind <> lexerKindRightParen do
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+    write_current(context^.lexer);
 
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
     WriteString(': ');
 
-    transpile_type_expression(context, lexer);
+    transpile_type_expression(context);
 
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
     if (token.kind = lexerKindSemicolon) or (token.kind = lexerKindComma) then
       WriteString('; ');
-      token := transpiler_lex(lexer)
+      token := transpiler_lex(context^.lexer)
     end
   end;
   WriteString(')');
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   (* Check for the return type and write it. *)
   if token.kind = lexerKindArrow then
     WriteString(': ');
-    token := transpiler_lex(lexer);
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer);
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer)
   end;
-  token := transpiler_lex(lexer);
-  write_semicolon();
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output);
 
   return result
 end;
 
-proc transpile_expression(context: PTranspilerContext,  lexer: PLexer, trailing_token: LexerKind);
+proc transpile_expression(context: PTranspilerContext, trailing_token: LexerKind);
 var
   token: LexerToken;
   written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   while (token.kind <> trailing_token) & (token.kind <> lexerKindEnd) do
     written_bytes := 0;
@@ -441,6 +425,14 @@ begin
       WriteString('NIL ');
       written_bytes := 1
     end;
+    if (token.kind = lexerKindBoolean) & token.booleanKind then
+      WriteString('TRUE ');
+      written_bytes := 1
+    end;
+    if (token.kind = lexerKindBoolean) & (~token.booleanKind) then
+      WriteString('FALSE ');
+      written_bytes := 1
+    end;
     if token.kind = lexerKindOr then
       WriteString('OR ');
       written_bytes := 1
@@ -454,157 +446,151 @@ begin
       written_bytes := 1
     end;
     if written_bytes = 0 then
-      written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
+      write_current(context^.lexer);
       Write(' ')
     end;
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end
 end;
 
-proc transpile_if_statement(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_if_statement(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  IF ');
-  transpile_expression(context, lexer, lexerKindThen);
+  transpile_expression(context, lexerKindThen);
 
   WriteString('THEN');
   WriteLn();
-  transpile_statements(context, lexer);
+  transpile_statements(context);
   WriteString('  END');
-  token := transpiler_lex(lexer)
+  token := transpiler_lex(context^.lexer)
 end;
 
-proc transpile_while_statement(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_while_statement(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  WHILE ');
-  transpile_expression(context, lexer, lexerKindDo);
+  transpile_expression(context, lexerKindDo);
 
   WriteString('DO');
   WriteLn();
-  transpile_statements(context, lexer);
+  transpile_statements(context);
   WriteString('  END');
-  token := transpiler_lex(lexer)
+  token := transpiler_lex(context^.lexer)
 end;
 
-proc transpile_assignment_statement(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_assignment_statement(context: PTranspilerContext);
 begin
   WriteString(' := ');
-  transpile_expression(context, lexer, lexerKindSemicolon);
+  transpile_expression(context, lexerKindSemicolon);
 end;
 
-proc transpile_call_statement(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_call_statement(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('(');
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   while (token.kind <> lexerKindSemicolon) & (token.kind <> lexerKindEnd) do
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer)
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer)
   end
 end;
 
-proc transpile_designator_expression(context: PTranspilerContext, lexer: PLexer);
+proc transpile_designator_expression(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  ');
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-  token := transpiler_lex(lexer);
+  write_current(context^.lexer);
+  token := transpiler_lex(context^.lexer);
 
   while token.kind = lexerKindLeftSquare do
     Write('[');
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
     while token.kind <> lexerKindRightSquare do
-      written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-      token := transpiler_lex(lexer)
+      write_current(context^.lexer);
+      token := transpiler_lex(context^.lexer)
     end;
     Write(']');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   if token.kind = lexerKindHat then
     Write('^');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   if token.kind = lexerKindDot then
     Write('.');
-    token := transpiler_lex(lexer);
-    written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer);
+    write_current(context^.lexer);
+    token := transpiler_lex(context^.lexer)
   end;
   if token.kind = lexerKindHat then
     Write('^');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end;
   while token.kind = lexerKindLeftSquare do
     Write('[');
-    token := transpiler_lex(lexer);
+    token := transpiler_lex(context^.lexer);
     while token.kind <> lexerKindRightSquare do
-      written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-      token := transpiler_lex(lexer)
+      write_current(context^.lexer);
+      token := transpiler_lex(context^.lexer)
     end;
     Write(']');
-    token := transpiler_lex(lexer)
+    token := transpiler_lex(context^.lexer)
   end
 end;
 
-proc transpile_return_statement(context: PTranspilerContext, lexer: PLexer);
+proc transpile_return_statement(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
   WriteString('  RETURN ');
-  token := transpiler_lex(lexer);
-  written_bytes := WriteNBytes(StdOut, ADDRESS(lexer^.Current - lexer^.Start), lexer^.Start);
-  token := transpiler_lex(lexer)
+  token := transpiler_lex(context^.lexer);
+  write_current(context^.lexer);
+  token := transpiler_lex(context^.lexer)
 end;
 
-proc transpile_statement(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_statement(context: PTranspilerContext);
 var
   token: LexerToken;
-  written_bytes: CARDINAL;
 begin
-  token := transpiler_lex(lexer);
+  token := transpiler_lex(context^.lexer);
 
   if token.kind = lexerKindIf then
-    transpile_if_statement(context, lexer)
+    transpile_if_statement(context)
   end;
   if token.kind = lexerKindWhile then
-    transpile_while_statement(context, lexer)
+    transpile_while_statement(context)
   end;
   if token.kind = lexerKindReturn then
-    transpile_return_statement(context, lexer)
+    transpile_return_statement(context)
   end;
   if token.kind = lexerKindIdentifier then
-    transpile_designator_expression(context, lexer);
-    token := lexer_current(lexer);
+    transpile_designator_expression(context);
+    token := lexer_current(context^.lexer);
 
     if token.kind = lexerKindAssignment then
-      transpile_assignment_statement(context, lexer)
+      transpile_assignment_statement(context)
     end;
     if token.kind = lexerKindLeftParen then
-      transpile_call_statement(context, lexer)
+      transpile_call_statement(context)
     end
   end
 end;
 
-proc transpile_statements(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_statements(context: PTranspilerContext);
 var
   token: LexerToken;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
 
   while token.kind <> lexerKindEnd do
-    transpile_statement(context, lexer);
-    token := lexer_current(lexer);
+    transpile_statement(context);
+    token := lexer_current(context^.lexer);
 
     if token.kind = lexerKindSemicolon then
       Write(';')
@@ -613,46 +599,46 @@ begin
   end
 end;
 
-proc transpile_statement_part(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_statement_part(context: PTranspilerContext);
 var
   token: LexerToken;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
   if token.kind = lexerKindBegin then
     WriteString('BEGIN');
     WriteLn();
-    transpile_statements(context, lexer)
+    transpile_statements(context)
   end
 end;
 
-proc transpile_procedure_declaration(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_procedure_declaration(context: PTranspilerContext);
 var
   token: LexerToken;
   seen_part: BOOLEAN;
   written_bytes: CARDINAL;
 begin
-  token := transpile_procedure_heading(context, lexer);
-  seen_part := transpile_constant_part(context, lexer);
-  seen_part := transpile_variable_part(context, lexer);
-  transpile_statement_part(context, lexer);
+  token := transpile_procedure_heading(context);
+  seen_part := transpile_constant_part(context);
+  seen_part := transpile_variable_part(context);
+  transpile_statement_part(context);
 
   WriteString('END ');
   written_bytes := WriteNBytes(StdOut, ORD(token.identifierKind[1]), ADR(token.identifierKind[2]));
 
-  token := transpiler_lex(lexer);
-  write_semicolon();
-  token := transpiler_lex(lexer)
+  token := transpiler_lex(context^.lexer);
+  write_semicolon(context^.output);
+  token := transpiler_lex(context^.lexer)
 end;
 
-proc transpile_procedure_part(context: PTranspilerContext,  lexer: PLexer);
+proc transpile_procedure_part(context: PTranspilerContext);
 var
   token: LexerToken;
 begin
-  token := lexer_current(lexer);
+  token := lexer_current(context^.lexer);
 
   while token.kind = lexerKindProc do
-    transpile_procedure_declaration(context, lexer);
-    token := lexer_current(lexer);
+    transpile_procedure_declaration(context);
+    token := lexer_current(context^.lexer);
     WriteLn()
   end
 end;
@@ -663,7 +649,11 @@ var
   written_bytes: CARDINAL;
   context: TranspilerContext;
 begin
-  transpile_module(ADR(context), lexer)
+  context.indentation := 0;
+  context.output := StdOut;
+  context.lexer := lexer;
+
+  transpile_module(ADR(context))
 end;
 
 end Transpiler.