Add an argument parser

Rakefile

@@ -4,8 +4,12 @@ require 'open3'
 
 DFLAGS = ['--warn-no-deprecated', '-L/usr/lib64/gcc-12']
 BINARY = 'build/bin/elna'
-TESTS = FileList['tests/*.elna']
-  .map { |test| (Pathname.new('build') + test).sub_ext('').to_path }
+TESTS = FileList['tests/*.elna'].flat_map do |test|
+  build = Pathname.new 'build'
+  asm_test = build + 'asm' + Pathname.new(test).basename('')
+
+  [build + test, asm_test].map { |path| path.sub_ext('').to_path }
+end
 SOURCES = FileList['source/**/*.d']
 
 directory 'build'
@@ -13,22 +17,24 @@ directory 'build'
 CLEAN.include 'build'
 CLEAN.include '.dub'
 
-rule(/build\/tests\/.+/ => ->(file) { test_for_out(file) }) do |t|
+rule(/build\/tests\/[^\/\.]+$/ => ->(file) { test_for_out(file) }) do |t|
+  sh 'gcc', '-o', t.name, "#{t.name}.o"
+end
+
+rule(/build\/asm\/[^\/\.]+$/ => ->(file) { test_for_object(file) }) do |t|
+  Pathname.new(t.name).dirname.mkpath
+  Open3.pipeline [BINARY, t.source], ['gcc', '-x', 'assembler', '-o', t.name,  '-']
+end
+
+rule(/build\/tests\/.+\.o$/ => ->(file) { test_for_object(file) }) do |t|
   Pathname.new(t.name).dirname.mkpath
   sh BINARY, t.source
-  sh 'gcc', '-o', t.name, "#{t.name}.o"
-  # Open3.pipeline [BINARY, t.source], ['gcc', '-x', 'assembler', '-o', t.name,  '-']
 end
 
 file BINARY => SOURCES do |t|
   sh({ 'DFLAGS' => (DFLAGS * ' ') }, 'dub', 'build', '--compiler=gdc-12')
 end
 
-file 'build/tests/sample' => BINARY do |t|
-  sh t.source
-  sh 'gcc', '-o', t.name, 'build/tests/sample.o'
-end
-
 task default: BINARY
 
 desc 'Run all tests and check the results'
@@ -38,7 +44,7 @@ task test: BINARY do
     expected = Pathname
       .new(test)
       .sub_ext('.txt')
-      .sub(/^build\/tests\//, 'tests/expectations/')
+      .sub(/^build\/[[:alpha:]]+\//, 'tests/expectations/')
       .read
       .to_i
 
@@ -48,10 +54,6 @@ task test: BINARY do
 
     fail "#{test}: Expected #{expected}, got #{actual}" unless expected == actual
   end
-
-  # system './build/tests/sample'
-  # actual = $?.exitstatus
-  # fail "./build/tests/sample: Expected 3, got #{actual}" unless 3 == actual
 end
 
 desc 'Run unittest blocks'
@@ -59,11 +61,18 @@ task unittest: SOURCES do |t|
   sh('dub', 'test', '--compiler=gdc-12')
 end
 
-def test_for_out(out_file)
+def test_for_object(out_file)
   test_source = Pathname
     .new(out_file)
     .sub_ext('.elna')
-    .sub(/^build\//, '')
+    .sub(/^build\/[[:alpha:]]+\//, 'tests/')
     .to_path
   [test_source, BINARY]
 end
+
+def test_for_out(out_file)
+  Pathname
+    .new(out_file)
+    .sub_ext('.o')
+    .to_path
+end

source/elna/arguments.d

@@ -0,0 +1,146 @@
+/**
+ * Argument parsing.
+ */
+module elna.arguments;
+
+import std.algorithm;
+import std.range;
+import std.sumtype;
+
+struct ArgumentError
+{
+    enum Type
+    {
+        expectedOutputFile,
+        noInput,
+    }
+
+    private Type type_;
+    private string argument_;
+
+    @property Type type() const @nogc nothrow pure @safe
+    {
+        return this.type_;
+    }
+
+    @property string argument() const @nogc nothrow pure @safe
+    {
+        return this.argument_;
+    }
+
+    void toString(OR)(OR range)
+    if (isOutputRage!OR)
+    {
+        final switch (Type)
+        {
+            case Type.expectedOutputFile:
+                put(range, "Expected an output filename after -o");
+                break;
+            case Type.noInput:
+                put(range, "No input files specified");
+                break;
+        }
+    }
+}
+
+/**
+ * Supported compiler arguments.
+ */
+struct Arguments
+{
+    private bool assembler_;
+    private string output_;
+    private string[] inFiles_;
+
+    @property string[] inFiles() @nogc nothrow pure @safe
+    {
+        return this.inFiles_;
+    }
+
+    /**
+     * Returns: Whether to generate assembly instead of an object file.
+     */
+    @property bool assembler() const @nogc nothrow pure @safe
+    {
+        return this.assembler_;
+    }
+
+    /**
+     * Returns: Output file.
+     */
+    @property string output() const @nogc nothrow pure @safe
+    {
+        return this.output_;
+    }
+
+    /**
+     * Parse command line arguments.
+     *
+     * The first argument is expected to be the program name (and it is
+     * ignored).
+     *
+     * Params:
+     *   arguments = Command line arguments.
+     *
+     * Returns: Parsed arguments or an error.
+     */
+    static SumType!(ArgumentError, Arguments) parse(string[] arguments)
+    @nogc nothrow pure @safe
+    {
+        if (!arguments.empty)
+        {
+            arguments.popFront;
+        }
+        alias ReturnType = typeof(return);
+
+        return parseArguments(arguments).match!(
+            (Arguments parsed) {
+                if (parsed.inFiles.empty)
+                {
+                    return ReturnType(ArgumentError(ArgumentError.Type.noInput));
+                }
+                return ReturnType(parsed);
+            },
+            (ArgumentError argumentError) => ReturnType(argumentError)
+        );
+    }
+
+    private static SumType!(ArgumentError, Arguments) parseArguments(ref string[] arguments)
+    @nogc nothrow pure @safe
+    {
+        Arguments parsed;
+
+        while (!arguments.empty)
+        {
+            if (arguments.front == "-s")
+            {
+                parsed.assembler_ = true;
+            }
+            else if (arguments.front == "-o")
+            {
+                if (arguments.empty)
+                {
+                    return typeof(return)(ArgumentError(
+                        ArgumentError.Type.expectedOutputFile,
+                        arguments.front
+                    ));
+                }
+                arguments.popFront;
+                parsed.output_ = arguments.front;
+            }
+            else if (arguments.front == "--")
+            {
+                arguments.popFront;
+                parsed.inFiles_ = arguments;
+                break;
+            }
+            else if (!arguments.front.startsWith("-"))
+            {
+                parsed.inFiles_ = arguments;
+                break;
+            }
+            arguments.popFront;
+        }
+        return typeof(return)(parsed);
+    }
+}