Generate IR in a visitor

Rakefile

@@ -4,8 +4,13 @@ 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/*.eln'].flat_map do |test|
+  build = Pathname.new 'build'
+  test_basename = Pathname.new(test).basename('')
+
+  [build + 'riscv' + test_basename].map { |path| path.sub_ext('').to_path }
+end
+
 SOURCES = FileList['source/**/*.d']
 
 directory 'build'
@@ -13,22 +18,27 @@ directory 'build'
 CLEAN.include 'build'
 CLEAN.include '.dub'
 
-rule(/build\/tests\/.+/ => ->(file) { test_for_out(file) }) do |t|
+rule(/build\/riscv\/[^\/\.]+$/ => ->(file) { test_for_out(file, '.o') }) do |t|
+  sh '/opt/riscv/bin/riscv32-unknown-elf-ld',
+    '-o', t.name,
+    '-L/opt/riscv/lib/gcc/riscv32-unknown-elf/11.1.0',
+    '-L/opt/riscv/riscv32-unknown-elf/lib',
+    '/opt/riscv/riscv32-unknown-elf/lib/crt0.o',
+    '/opt/riscv/lib/gcc/riscv32-unknown-elf/11.1.0/crtbegin.o',
+    t.source,
+    '--start-group', '-lgcc', '-lc', '-lgloss', '--end-group',
+    '/opt/riscv/lib/gcc/riscv32-unknown-elf/11.1.0/crtend.o'
+end
+
+rule(/build\/riscv\/.+\.o$/ => ->(file) { test_for_object(file, '.eln') }) 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,  '-']
+  sh BINARY, '-o', t.name, t.source
 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'
@@ -38,20 +48,28 @@ task test: BINARY do
     expected = Pathname
       .new(test)
       .sub_ext('.txt')
-      .sub(/^build\/tests\//, 'tests/expectations/')
-      .read
-      .to_i
+      .sub(/^build\/[[:alpha:]]+\//, 'tests/expectations/')
+      .to_path
 
     puts "Running #{test}"
-    system test
-    actual = $?.exitstatus
+    if test.include? '/riscv/'
+      spike = [
+        '/opt/riscv/bin/spike',
+        '/opt/riscv/riscv32-unknown-elf/bin/pk',
+        test
+      ]
+      diff = ['diff', '-Nur', '--color', expected, '-']
+      tail = ['tail', '-n', '1']
 
-    fail "#{test}: Expected #{expected}, got #{actual}" unless expected == actual
+      last_stdout, wait_threads = Open3.pipeline_r spike, tail, diff
+    else
+      raise 'Unsupported test platform'
+    end
+    print last_stdout.read
+    last_stdout.close
+
+    fail unless wait_threads.last.value.exitstatus.zero?
   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 +77,18 @@ task unittest: SOURCES do |t|
   sh('dub', 'test', '--compiler=gdc-12')
 end
 
-def test_for_out(out_file)
+def test_for_object(out_file, extension)
   test_source = Pathname
     .new(out_file)
-    .sub_ext('.elna')
-    .sub(/^build\//, '')
+    .sub_ext(extension)
+    .sub(/^build\/[[:alpha:]]+\//, 'tests/')
     .to_path
   [test_source, BINARY]
 end
+
+def test_for_out(out_file, extension)
+  Pathname
+    .new(out_file)
+    .sub_ext(extension)
+    .to_path
+end

source/elna/arguments.d

@@ -0,0 +1,154 @@
+/**
+ * Argument parsing.
+ */
+module elna.arguments;
+
+import std.algorithm;
+import std.range;
+import std.sumtype;
+
+struct ArgumentError
+{
+    enum Type
+    {
+        expectedOutputFile,
+        noInput,
+        superfluousArguments,
+    }
+
+    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 inFile_;
+
+    @property string inFile() @nogc nothrow pure @safe
+    {
+        return this.inFile_;
+    }
+
+    /**
+     * 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.inFile is null)
+                {
+                    return ReturnType(ArgumentError(ArgumentError.Type.noInput));
+                }
+                else if (!arguments.empty)
+                {
+                    return ReturnType(ArgumentError(
+                        ArgumentError.Type.superfluousArguments,
+                        arguments.front
+                    ));
+                }
+                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.inFile_ = arguments.front;
+                arguments.popFront;
+                break;
+            }
+            else if (!arguments.front.startsWith("-"))
+            {
+                parsed.inFile_ = arguments.front;
+            }
+            arguments.popFront;
+        }
+        return typeof(return)(parsed);
+    }
+}

source/elna/backend.d

@@ -0,0 +1,100 @@
+module elna.backend;
+
+import core.stdc.stdio;
+import elna.elf;
+import elna.ir;
+import elna.extended;
+import elna.riscv;
+import elna.lexer;
+import elna.parser;
+import elna.result;
+import std.algorithm;
+import std.sumtype;
+import std.typecons;
+import tanya.os.error;
+import tanya.container.array;
+import tanya.container.string;
+import tanya.memory.allocator;
+
+private Nullable!String readSource(string source) @nogc
+{
+    enum size_t bufferSize = 255;
+    auto sourceFilename = String(source);
+
+    return readFile(sourceFilename).match!(
+        (ErrorCode errorCode) {
+            perror(sourceFilename.toStringz);
+            return Nullable!String();
+        },
+        (Array!ubyte contents) => nullable(String(cast(char[]) contents.get))
+    );
+}
+
+int generate(string inFile, ref String outputFilename) @nogc
+{
+    auto sourceText = readSource(inFile);
+    if (sourceText.isNull)
+    {
+        return 3;
+    }
+    auto tokens = lex(sourceText.get.get);
+    if (!tokens.valid)
+    {
+        auto compileError = tokens.error.get;
+        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.message.ptr);
+        return 1;
+    }
+    auto ast = parse(tokens.result);
+    if (!ast.valid)
+    {
+        auto compileError = ast.error.get;
+        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.message.ptr);
+        return 2;
+    }
+    auto transformVisitor = defaultAllocator.make!TransformVisitor();
+    auto ir = transformVisitor.visit(ast.result);
+    defaultAllocator.dispose(transformVisitor);
+
+    auto handle = File.open(outputFilename.toStringz, BitFlags!(File.Mode)(File.Mode.truncate));
+    if (!handle.valid)
+    {
+        return 1;
+    }
+    auto program = writeNext(ir);
+    auto elf = Elf!ELFCLASS32(move(handle));
+    auto readOnlyData = Array!ubyte(cast(const(ubyte)[]) "%d\n".ptr[0 .. 4]); // With \0.
+
+    elf.addReadOnlyData(String(".CL0"), readOnlyData);
+    elf.addCode(program.name, program.text);
+
+    elf.addExternSymbol(String("printf"));
+    foreach (ref reference; program.symbols)
+    {
+        elf.Rela relocationEntry = {
+            r_offset: cast(elf.Addr) reference.offset
+        };
+        elf.Rela relocationSub = {
+            r_offset: cast(elf.Addr) reference.offset,
+            r_info: R_RISCV_RELAX
+        };
+
+        final switch (reference.target)
+        {
+            case Reference.Target.text:
+                relocationEntry.r_info = R_RISCV_CALL;
+                break;
+            case Reference.Target.high20:
+                relocationEntry.r_info = R_RISCV_HI20;
+                break;
+            case Reference.Target.lower12i:
+                relocationEntry.r_info = R_RISCV_LO12_I;
+                break;
+        }
+
+        elf.relocate(reference.name, relocationEntry, relocationSub);
+    }
+
+    elf.finish();
+
+    return 0;
+}

source/elna/extended.d

@@ -3,7 +3,333 @@
  */
 module elna.extended;
 
+import core.stdc.errno;
+import core.stdc.stdio;
+import std.sumtype;
+import std.typecons;
+import tanya.os.error;
+import tanya.container.array;
+import tanya.container.string;
+
+/**
+ * File handle abstraction.
+ */
 struct File
 {
-    @disable this(this);
+    /// Plattform dependent file type.
+    alias Handle = FILE*;
+
+    /// Uninitialized file handle value.
+    enum Handle invalid = null;
+
+    /**
+     * Relative position.
+     */
+    enum Whence
+    {
+        /// Relative to the start of the file.
+        set = SEEK_SET,
+        /// Relative to the current cursor position.
+        currentt = SEEK_CUR,
+        /// Relative from the end of the file.
+        end = SEEK_END,
+    }
+
+    /**
+     * File open modes.
+     */
+    enum Mode
+    {
+        /// Open the file for reading.
+        read = 1 << 0,
+        /// Open the file for writing. The stream is positioned at the beginning
+        /// of the file.
+        write = 1 << 1,
+        /// Open the file for writing and remove its contents.
+        truncate = 1 << 2,
+        /// Open the file for writing. The stream is positioned at the end of
+        /// the file.
+        append = 1 << 3,
+    }
+
+    private enum Status
+    {
+        invalid,
+        owned,
+        borrowed,
+    }
+
+    private union Storage
+    {
+        Handle handle;
+        ErrorCode errorCode;
+    }
+    private Storage storage;
+    private Status status = Status.invalid;
+
+    @disable this(scope return ref File f);
+    @disable this();
+
+    /**
+     * Closes the file.
+     */
+    ~this() @nogc nothrow
+    {
+        if (this.status == Status.owned)
+        {
+            fclose(this.storage.handle);
+        }
+        this.storage.handle = invalid;
+        this.status = Status.invalid;
+    }
+
+    /**
+     * Construct the object with the given system handle. The won't be claused
+     * in the descructor if this constructor is used.
+     *
+     * Params:
+     *   handle = File handle to be wrapped by this structure.
+     */
+    this(Handle handle) @nogc nothrow pure @safe
+    {
+        this.storage.handle = handle;
+        this.status = Status.borrowed;
+    }
+
+    /**
+     * Returns: Plattform dependent file handle.
+     */
+    @property Handle handle() @nogc nothrow pure @trusted
+    {
+        return valid ? this.storage.handle : invalid;
+    }
+
+    /**
+     * Returns: An error code if an error has occurred.
+     */
+    @property ErrorCode errorCode() @nogc nothrow pure @safe
+    {
+        return valid ? ErrorCode() : this.storage.errorCode;
+    }
+
+    /**
+     * Returns: Whether a valid, opened file is represented.
+     */
+    @property bool valid() @nogc nothrow pure @safe
+    {
+        return this.status != Status.invalid;
+    }
+
+    /**
+     * Transfers the file into invalid state.
+     *
+     * Returns: The old file handle.
+     */
+    Handle reset() @nogc nothrow pure @safe
+    {
+        if (!valid)
+        {
+            return invalid;
+        }
+        auto oldHandle = handle;
+
+        this.status = Status.invalid;
+        this.storage.errorCode = ErrorCode();
+
+        return oldHandle;
+    }
+
+    /**
+     * Sets stream position in the file.
+     *
+     * Params:
+     *   offset = File offset.
+     *   whence = File position to add the offset to.
+     *
+     * Returns: Error code if any.
+     */
+    ErrorCode seek(size_t offset, Whence whence) @nogc nothrow
+    {
+        if (!valid)
+        {
+            return ErrorCode(ErrorCode.ErrorNo.badDescriptor);
+        }
+        if (fseek(this.storage.handle, offset, whence))
+        {
+            return ErrorCode(cast(ErrorCode.ErrorNo) errno);
+        }
+        return ErrorCode();
+    }
+
+    /**
+     * Returns: Current offset or an error.
+     */
+    SumType!(ErrorCode, size_t) tell() @nogc nothrow
+    {
+        if (!valid)
+        {
+            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
+        }
+        auto result = ftell(this.storage.handle);
+
+        if (result < 0)
+        {
+            return typeof(return)(ErrorCode(cast(ErrorCode.ErrorNo) errno));
+        }
+        return typeof(return)(cast(size_t) result);
+    }
+
+    /**
+     * Params:
+     *   buffer = Destination buffer.
+     *
+     * Returns: Bytes read. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
+     *          while reading the file an unknown error has occurred.
+     */
+    SumType!(ErrorCode, size_t) read(ubyte[] buffer) @nogc nothrow
+    {
+        if (!valid)
+        {
+            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
+        }
+        const bytesRead = fread(buffer.ptr, 1, buffer.length, this.storage.handle);
+        if (bytesRead == buffer.length || eof())
+        {
+            return typeof(return)(bytesRead);
+        }
+        return typeof(return)(ErrorCode());
+    }
+
+    /**
+     * Params:
+     *   buffer = Source buffer.
+     *
+     * Returns: Bytes written. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
+     *          while reading the file an unknown error has occurred.
+     */
+    SumType!(ErrorCode, size_t) write(const(ubyte)[] buffer) @nogc nothrow
+    {
+        if (!valid)
+        {
+            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
+        }
+        const bytesWritten = fwrite(buffer.ptr, 1, buffer.length, this.storage.handle);
+        if (bytesWritten == buffer.length)
+        {
+            return typeof(return)(buffer.length);
+        }
+        return typeof(return)(ErrorCode());
+    }
+
+    /**
+     * Returns: EOF status of the file.
+     */
+    bool eof() @nogc nothrow
+    {
+        return valid && feof(this.storage.handle) != 0;
+    }
+
+    /**
+     * Constructs a file object that will be closed in the destructor.
+     *
+     * Params:
+     *   filename = The file to open.
+     *
+     * Returns: Opened file or an error.
+     */
+    static File open(const(char)* filename, BitFlags!Mode mode) @nogc nothrow
+    {
+        char[3] modeBuffer = "\0\0\0";
+
+        if (mode.truncate)
+        {
+            modeBuffer[0] = 'w';
+            if (mode.read)
+            {
+                modeBuffer[1] = '+';
+            }
+        }
+        else if (mode.append)
+        {
+            modeBuffer[0] = 'a';
+            if (mode.read)
+            {
+                modeBuffer[1] = '+';
+            }
+        }
+        else if (mode.read)
+        {
+            modeBuffer[0] = 'r';
+            if (mode.write)
+            {
+                modeBuffer[1] = '+';
+            }
+        }
+
+        auto newHandle = fopen(filename, modeBuffer.ptr);
+        auto newFile = File(newHandle);
+
+        if (newHandle is null)
+        {
+            newFile.status = Status.invalid;
+            newFile.storage.errorCode = ErrorCode(cast(ErrorCode.ErrorNo) errno);
+        }
+        else
+        {
+            if (mode == BitFlags!Mode(Mode.write))
+            {
+                rewind(newHandle);
+            }
+            newFile.status = Status.owned;
+        }
+
+        return newFile;
+    }
+}
+
+/**
+ * Reads the whole file and returns its contents.
+ *
+ * Params:
+ *   sourceFilename = Source filename.
+ *
+ * Returns: File contents or an error.
+ *
+ * See_Also: $(D_PSYMBOL File.read)
+ */
+SumType!(ErrorCode, Array!ubyte) readFile(String sourceFilename) @nogc
+{
+    enum size_t bufferSize = 255;
+    auto sourceFile = File.open(sourceFilename.toStringz, BitFlags!(File.Mode)(File.Mode.read));
+
+    if (!sourceFile.valid)
+    {
+        return typeof(return)(sourceFile.errorCode);
+    }
+    Array!ubyte sourceText;
+    size_t totalRead;
+    size_t bytesRead;
+    do
+    {
+        sourceText.length = sourceText.length + bufferSize;
+        const readStatus = sourceFile
+            .read(sourceText[totalRead .. $].get)
+            .match!(
+                (ErrorCode errorCode) => nullable(errorCode),
+                (size_t bytesRead_) {
+                    bytesRead = bytesRead_;
+                    return Nullable!ErrorCode();
+                }
+            );
+        if (!readStatus.isNull)
+        {
+            return typeof(return)(readStatus.get);
+        }
+        totalRead += bytesRead;
+    }
+    while (bytesRead == bufferSize);
+
+    sourceText.length = totalRead;
+
+    return typeof(return)(sourceText);
 }

source/elna/generator.d

@@ -1,660 +0,0 @@
-module elna.generator;
-
-import core.stdc.stdio;
-import core.stdc.stdlib;
-import core.stdc.string;
-import elna.ir;
-import tanya.container.array;
-import tanya.container.string;
-import tanya.memory.mmappool;
-import tanya.format;
-
-/// Unsigned program address.
-alias Elf64_Addr = void*;
-/// Unsigned file offset.
-alias Elf64_Off = ulong;
-/// Unsigned medium integer.
-alias Elf64_Half = ushort;
-/// Unsigned integer.
-alias Elf64_Word = uint;
-/// Signed integer.
-alias Elf64_Sword = int;
-/// Unsigned long integer.
-alias Elf64_Xword = ulong;
-/// Signed long integer.
-alias Elf64_Sxword = long;
-
-enum size_t EI_INDENT = 16;
-
-/**
- * File header.
- */
-struct Elf64_Ehdr
-{
-    /// ELF identification.
-    ubyte[EI_INDENT] e_ident;
-    /// Object file type.
-    Elf64_Half e_type;
-    /// Machine type.
-    Elf64_Half e_machine;
-    /// Object file version
-    Elf64_Word e_version;
-    /// Entry point address.
-    Elf64_Addr e_entry;
-    /// Program header offset.
-    Elf64_Off e_phoff;
-    /// Section header offset.
-    Elf64_Off e_shoff;
-    /// Processor-specific flags.
-    Elf64_Word e_flags;
-    /// ELF header size.
-    Elf64_Half e_ehsize;
-    /// Size of program header entry.
-    Elf64_Half e_phentsize;
-    /// Number of program header entries.
-    Elf64_Half e_phnum;
-    /// Size of section header entry.
-    Elf64_Half e_shentsize;
-    /// Number of section header entries.
-    Elf64_Half e_shnum;
-    /// Section name string table index.
-    Elf64_Half e_shstrndx;
-}
-
-/**
- * Section header.
- */
-struct Elf64_Shdr
-{
-    /// Section name.
-    Elf64_Word sh_name;
-    /// Section type.
-    Elf64_Word sh_type;
-    /// Section attributes.
-    Elf64_Xword sh_flags;
-    /// Virtual address in memory.
-    Elf64_Addr sh_addr;
-    /// Offset in file.
-    Elf64_Off sh_offset;
-    /// Size of section.
-    Elf64_Xword sh_size;
-    /// Link to other section.
-    Elf64_Word sh_link;
-    /// Miscellaneous information.
-    Elf64_Word sh_info;
-    /// Address alignment boundary.
-    Elf64_Xword sh_addralign;
-    /// Size of entries, if section has table.
-    Elf64_Xword sh_entsize;
-}
-
-struct Elf64_Sym
-{
-    /// Symbol name.
-    Elf64_Word st_name;
-    /// Type and Binding attributes.
-    ubyte st_info;
-    /// Reserved.
-    ubyte st_other;
-    /// Section table index.
-    Elf64_Half st_shndx;
-    /// Symbol value.
-    Elf64_Addr st_value;
-    /// Size of object (e.g., common).
-    Elf64_Xword st_size;
-}
-
-/// Section Types, sh_type.
-enum : Elf64_Word
-{
-    /// Marks an unused section header.
-    SHT_NULL = 0,
-    ///  Contains information defined by the program.
-    SHT_PROGBITS = 1,
-    /// Contains a linker symbol table.
-    SHT_SYMTAB = 2,
-    /// Contains a string table.
-    SHT_STRTAB = 3,
-    /// Contains “Rela” type relocation entries.
-    SHT_RELA = 4,
-    /// Contains a symbol hash table
-    SHT_HASH = 5,
-    /// Contains dynamic linking tables
-    SHT_DYNAMIC = 6,
-    /// Contains note information
-    SHT_NOTE = 7,
-    /// Contains uninitialized space; does not occupy any space in the file.
-    SHT_NOBITS = 8,
-    /// Contains "Rel" type relocation entries.
-    SHT_REL = 9,
-    /// Reserved.
-    SHT_SHLIB = 10,
-    /// Contains a dynamic loader symbol table.
-    SHT_DYNSYM = 11,
-    /// Environment-specific use.
-    SHT_LOOS = 0x60000000,
-    SHT_HIOS = 0x6FFFFFFF,
-    /// Processor-specific use.
-    SHT_LOPROC = 0x70000000,
-    SHT_HIPROC = 0x7FFFFFFF,
-}
-
-/**
- * Section Attributes, sh_flags.
- */
-enum : Elf64_Xword
-{
-    /// Section contains writable data.
-    SHF_WRITE = 0x1,
-    /// Section is allocated in memory image of program.
-    SHF_ALLOC = 0x2,
-    /// Section contains executable instructions.
-    SHF_EXECINSTR = 0x4,
-    /// Environment-specific use.
-    SHF_MASKOS = 0x0F000000,
-    /// Processor-specific use.
-    SHF_MASKPROC = 0xF0000000,
-}
-
-enum : Elf64_Word
-{
-    /// Not visible outside the object file.
-    STB_LOCAL = 0,
-    /// Global symbol, visible to all object files.
-    STB_GLOBAL = 1,
-    /// Global scope, but with lower precedence than global symbols.
-    STB_WEAK = 2,
-    /// Environment-specific use.
-    STB_LOOS = 10,
-    STB_HIOS = 12,
-    /// Processor-specific use.
-    STB_LOPROC = 13,
-    STB_HIPROC = 15,
-}
-
-enum : Elf64_Word
-{
-    /// No type specified (e.g., an absolute symbol).
-    STT_NOTYPE = 0,
-    /// Data object.
-    STT_OBJECT = 1,
-    /// Function entry point.
-    STT_FUNC = 2,
-    /// Symbol is associated with a section.
-    STT_SECTION = 3,
-    /// Source file associated with the object file.
-    STT_FILE = 4,
-    /// Environment-specific use.
-    STT_LOOS = 10,
-    STT_HIOS = 12,
-    /// Processor-specific use.
-    STT_LOPROC = 13,
-    STT_HIPROC = 15,
-}
-
-Elf64_Ehdr makeFileHeader(Elf64_Off sectionHeaderOffset,
-        Elf64_Half sectionHeaderCount,
-        Elf64_Half stringIndex) @nogc
-{
-    Elf64_Ehdr header;
-
-    // Magic number.
-    header.e_ident[0] = '\x7f';
-    header.e_ident[1] = 'E';
-    header.e_ident[2] = 'L';
-    header.e_ident[3] = 'F';
-
-    // File class.
-    header.e_ident[4] = EI_CLASS.ELFCLASS64;
-
-    // Data encoding.
-    header.e_ident[5] = EI_DATA.ELFDATA2LSB;
-
-    // Version.
-    header.e_ident[6] = EV_CURRENT;
-
-    // OS/ABI identification.
-    header.e_ident[7] = EI_OSABI.ELFOSABI_SYSV;
-
-    // ABI version.
-    header.e_ident[8] = 0;
-
-    // Size of e_ident[].
-    header.e_ident[15] = 0;
-
-    header.e_type = ET_REL;
-    header.e_machine = 0x3e; // EM_X86_64: AMD x86-64 architecture
-    header.e_version = EV_CURRENT;
-    header.e_entry = null;
-    header.e_phoff = 0;
-    header.e_shoff = sectionHeaderOffset;
-    header.e_flags = 0;
-    header.e_ehsize = Elf64_Ehdr.sizeof;
-    header.e_phentsize = 0;
-    header.e_phnum = 0;
-    header.e_shentsize = Elf64_Shdr.sizeof;
-    header.e_shnum = sectionHeaderCount;
-    header.e_shstrndx = stringIndex;
-
-    return header;
-}
-
-enum char[33] sectionStringTable = "\0.symtab\0.strtab\0.shstrtab\0.text\0";
-
-Elf64_Shdr makeTextHeader(Elf64_Off offset, Elf64_Xword size) @nogc
-{
-    Elf64_Shdr table;
-
-    table.sh_name = 0x1b;
-    table.sh_type = SHT_PROGBITS;
-    table.sh_flags = SHF_EXECINSTR | SHF_ALLOC;
-    table.sh_addr = null;
-    table.sh_offset = offset;
-    table.sh_size = size;
-    table.sh_link = SHN_UNDEF;
-    table.sh_info = 0;
-    table.sh_addralign = 1;
-    table.sh_entsize = 0;
-
-    return table;
-}
-
-Elf64_Shdr makeDataHeader(Elf64_Off offset, Elf64_Xword size) @nogc
-{
-    Elf64_Shdr table;
-
-    table.sh_name = 0x21;
-    table.sh_type = SHT_PROGBITS;
-    table.sh_flags = SHF_WRITE | SHF_ALLOC;
-    table.sh_addr = null;
-    table.sh_offset = offset;
-    table.sh_size = size;
-    table.sh_link = SHN_UNDEF;
-    table.sh_info = 0;
-    table.sh_addralign = 1;
-    table.sh_entsize = 0;
-
-    return table;
-}
-
-Elf64_Shdr makeSymtableHeader(Elf64_Off offset, Elf64_Xword size, Elf64_Word entriesCount) @nogc
-{
-    Elf64_Shdr table;
-
-    table.sh_name = 0x01;
-    table.sh_type = SHT_SYMTAB;
-    table.sh_flags = 0;
-    table.sh_addr = null;
-    table.sh_offset = offset;
-    table.sh_size = size;
-    table.sh_link = 0x03; // String table used by entries in this section.
-    table.sh_info = entriesCount;
-    table.sh_addralign = 8;
-    table.sh_entsize = Elf64_Sym.sizeof;
-
-    return table;
-}
-
-Elf64_Shdr makeStringHeader(Elf64_Word stringIndex, Elf64_Off offset, Elf64_Xword size) @nogc
-{
-    Elf64_Shdr table;
-
-    table.sh_name = stringIndex;
-    table.sh_type = SHT_STRTAB;
-    table.sh_flags = 0;
-    table.sh_addr = null;
-    table.sh_offset = offset;
-    table.sh_size = size;
-    table.sh_link = SHN_UNDEF;
-    table.sh_info = 0;
-    table.sh_addralign = 1;
-    table.sh_entsize = 0;
-
-    return table;
-}
-
-Elf64_Shdr makeInitialHeader() @nogc
-{
-    Elf64_Shdr table;
-
-    table.sh_name = 0;
-    table.sh_type = SHT_NULL;
-    table.sh_flags = 0;
-    table.sh_addr = null;
-    table.sh_offset = 0;
-    table.sh_size = 0;
-    table.sh_link = SHN_UNDEF;
-    table.sh_info = 0;
-    table.sh_addralign = 0;
-    table.sh_entsize = 0;
-
-    return table;
-}
-
-Elf64_Sym makeInitialSymTable() @nogc
-{
-    Elf64_Sym table;
-
-    table.st_name = 0;
-    table.st_info = 0;
-    table.st_other = 0;
-    table.st_shndx = 0;
-    table.st_value = null;
-    table.st_size = 0;
-
-    return table;
-}
-
-Elf64_Sym makeMainSymTable(Elf64_Half textIndex) @nogc
-{
-    Elf64_Sym table;
-
-    table.st_name = 0x01;
-    table.st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC);
-    table.st_other = 0;
-    table.st_shndx = textIndex;
-    table.st_value = null;
-    table.st_size = 0;
-
-    return table;
-}
-
-ubyte ELF32_ST_BIND(ubyte i) @nogc nothrow pure @safe
-{
-    return i >> 4;
-}
-
-ubyte ELF32_ST_TYPE(ubyte i) @nogc nothrow pure @safe
-{
-    return i & 0xf;
-}
-
-ubyte ELF32_ST_INFO(ubyte b, ubyte t) @nogc nothrow pure @safe
-{
-    return cast(ubyte) ((b << 4) + (t & 0xf));
-}
-
-/// Special Section Indices.
-enum : Elf64_Half
-{
-    /// Used to mark an undefined or meaningless section reference.
-    SHN_UNDEF = 0,
-    /// Processor-specific use.
-    SHN_LOPROC = 0xFF00,
-    SHN_HIPROC = 0xFF1F,
-    /// Environment-specific use.
-    SHN_LOOS = 0xFF20,
-    SHN_HIOS = 0xFF3F,
-    /// Indicates that the corresponding reference is an absolute value.
-    SHN_ABS = 0xFFF1,
-    /**
-     * Indicates a symbol that has been declared as a common block (Fortran
-     * COMMON or C tentative declaration).
-     */
-    SHN_COMMON = 0xFFF2,
-}
-
-/**
- * Object File Classes, e_ident[EI_CLASS].
- */
-enum EI_CLASS : ubyte
-{
-    /// 32-bit objects.
-    ELFCLASS32 = 1,
-    /// 64-bit objects.
-    ELFCLASS64 = 2,
-}
-
-enum ubyte EV_CURRENT = 1;
-
-/**
- * Data Encodings, e_ident[EI_DATA].
- */
-enum EI_DATA : ubyte
-{
-    /// Object file data structures are little-endian.
-    ELFDATA2LSB = 1,
-    /// Object file data structures are big-endian.
-    ELFDATA2MSB = 2,
-}
-
-/**
- * Operating System and ABI Identifiers, e_ident[EI_OSABI].
- */
-enum EI_OSABI : ubyte
-{
-    /// System V ABI.
-    ELFOSABI_SYSV = 0,
-    /// HP-UX operating system.
-    ELFOSABI_HPUX = 1,
-    /// Standalone (embedded) application.
-    ELFOSABI_STANDALONE = 255,
-}
-
-enum : Elf64_Half
-{
-    ET_NONE = 0, /// No file type.
-    ET_REL = 1, /// Relocatable object file.
-    ET_EXEC = 2, /// Executable file.
-    ET_DYN = 3, /// Shared object file.
-    ET_CORE = 4, /// Core file.
-    ET_LOOS = 0xFE00, /// Environment-specific use.
-    ET_HIOS = 0xFEFF,
-    ET_LOPROC = 0xFF00, /// Processor-specific use.
-    ET_HIPROC = 0xFFFF,
-}
-
-private size_t pad(size_t value) @nogc
-{
-    return (value / 8 + 1) * 8;
-}
-
-struct Symbol
-{
-    String name;
-    Array!ubyte instructions;
-}
-
-/*
-.text
-    .globl main
-    .type main, @function
-main:
-    movl $3, %eax
-    ret
-*/
-immutable ubyte[] instructions = [
-    // Opcode of pushq is “0x50 + r”, where “r” is the register opcode.
-    // Register opcode of %rbq is 5.
-    0x50 + 5, // push% %rbp
-    0x48, 0x89, 0xe5, // movq %rsp, %rbp
-
-    0xb8, 0x03, 0x00, 0x00, 0x00, // movl $3, %eax
-
-    // Epilogue.
-    0x48, 0x89, 0xec, // movq %rbp, %rsp
-    0x58 + 5, // popq %rbp
-    0xc3, // ret
-];
-
-void writeObject(Definition ast, String outputFilename) @nogc
-{
-    auto handle = fopen(outputFilename.toStringz, "wb");
-
-    if (handle is null)
-    {
-        perror("writing sample");
-        return;
-    }
-    scope (exit)
-    {
-        fclose(handle);
-    }
-
-    size_t currentOffset = Elf64_Ehdr.sizeof;
-    Array!Elf64_Shdr sectionHeaders;
-    Array!Elf64_Sym symbolEntries;
-
-    // Prologue
-    Array!ubyte asmTemplate = Array!ubyte(cast(ubyte[]) [
-        // Opcode of pushq is “0x50 + r”, where “r” is the register opcode.
-        // Register opcode of %rbq is 5.
-        0x50 + 5, // pushq %rbp
-        0x48, 0x89, 0xe5, // movq %rsp, %rbp
-    ]);
-    int i = 1;
-    foreach (statement; ast.statements[])
-    {
-        if ((cast(Number) statement.subroutine.lhs) !is null)
-        {
-            // Opcode of mov is “0xb8 + r”, where “r” is the register opcode.
-            // Register opcode of %eax is 0.
-            asmTemplate.insertBack(cast(ubyte) 0xb8); // movl $x, %eax; where $x is a number.
-            asmTemplate.insertBack((cast(ubyte*) &(cast(Number) statement.subroutine.lhs).value)[0 .. int.sizeof]);
-        }
-        else if ((cast(Variable) statement.subroutine.lhs) !is null)
-        {
-            // movl -x(%rbp), %ebx; where x is a number.
-            asmTemplate.insertBack(cast(ubyte[]) [0x8b, 0x45]);
-            const disposition = (cast(Variable) statement.subroutine.lhs).counter * (-4);
-            asmTemplate.insertBack((cast(ubyte*) &disposition)[0 .. 1]);
-        }
-        if ((cast(Number) statement.subroutine.rhs) !is null)
-        {
-            // Opcode of mov is “0xb8 + r”, where “r” is the register opcode.
-            // Register opcode of %ebx is 3.
-            asmTemplate.insertBack(cast(ubyte) 0xbb); // movl $x, %ebx; where $x is a number.
-            asmTemplate.insertBack((cast(ubyte*) &(cast(Number) statement.subroutine.rhs).value)[0 .. int.sizeof]);
-        }
-        else if ((cast(Variable) statement.subroutine.rhs) !is null)
-        {
-            // movl -x(%rbp), %ebx; where x is a number.
-            asmTemplate.insertBack(cast(ubyte[]) [0x8b, 0x5d]);
-            const disposition = (cast(Variable) statement.subroutine.rhs).counter * (-4);
-            asmTemplate.insertBack((cast(ubyte*) &disposition)[0 .. 1]);
-        }
-        // Calculate the result and assign it to a variable on the stack.
-        asmTemplate.insertBack(cast(ubyte[]) [0x01, 0xd8]); // add %ebx, %eax
-
-        asmTemplate.insertBack(cast(ubyte[]) [0x89, 0x45]); // movl %eax, -x(%rbp); where x is a number.
-        const disposition = i * (-4);
-        asmTemplate.insertBack((cast(ubyte*) &disposition)[0 .. 1]);
-        ++i;
-    }
-    // Epilogue.
-    asmTemplate.insertBack(cast(ubyte[]) [
-        0x48, 0x89, 0xec, // movq %rbp, %rsp
-        0x58 + 5, // popq %rbp
-        0xc3, // ret
-    ]);
-
-    Symbol[1] symbols = [Symbol(String("main"), asmTemplate)];
-
-    sectionHeaders.insertBack(makeInitialHeader());
-    symbolEntries.insertBack(makeInitialSymTable());
-
-    String stringTable = String("\0");
-    foreach (symbol; symbols[])
-    {
-        stringTable.insertBack(symbol.name[]);
-        stringTable.insertBack('\0');
-
-        sectionHeaders.insertBack(makeTextHeader(currentOffset, symbol.instructions.length));
-        currentOffset = pad(currentOffset + symbol.instructions.length);
-
-        symbolEntries.insertBack(makeMainSymTable(cast(Elf64_Half) (sectionHeaders.length - 1)));
-    }
-
-    const symbolTableSize = (symbols.length + 1) * Elf64_Sym.sizeof;
-    sectionHeaders.insertBack(makeSymtableHeader(currentOffset, symbolTableSize, symbols.length));
-    currentOffset += symbolTableSize;
-
-    sectionHeaders.insertBack(makeStringHeader(0x09, currentOffset, stringTable.length));
-    currentOffset += stringTable.length;
-
-    sectionHeaders.insertBack(makeStringHeader(0x11, currentOffset, sectionStringTable.length));
-    currentOffset = pad(currentOffset + sectionStringTable.length);
-
-    auto fileHeader = makeFileHeader(currentOffset, 5, 4);
-
-    version (none)
-    {
-        printf("%.2x\n", cast(uint) currentOffset);
-    }
-    ubyte[8] padding = 0;
-    size_t codeLength = stringTable.length + sectionStringTable.length;
-
-    fwrite(&fileHeader, 8, Elf64_Ehdr.sizeof / 8, handle);
-    foreach (symbol; symbols[])
-    {
-        immutable size_t instructionsLength = pad(symbol.instructions.length);
-        fwrite(symbol.instructions.get.ptr, 1, symbol.instructions.length, handle);
-        fwrite(padding.ptr, 1, instructionsLength - symbol.instructions.length, handle);
-        codeLength += instructionsLength;
-    }
-    fwrite(symbolEntries.get.ptr, Elf64_Sym.sizeof, symbolEntries.length, handle);
-    fwrite(stringTable.get.ptr, 1, stringTable.length, handle);
-    fwrite(sectionStringTable.ptr, 1, sectionStringTable.length, handle);
-    fwrite(padding.ptr, pad(codeLength) - codeLength, 1, handle);
-    fwrite(sectionHeaders.get.ptr, Elf64_Shdr.sizeof, sectionHeaders.length, handle);
-}
-
-String generate(Definition ast) @nogc
-{
-    // Prologue
-    String asmTemplate = ".text
-    .globl main
-    .type main, @function
-main:
-    pushq %rbp
-    movq %rsp, %rbp
-";
-
-    /* Allocate space on the stack for local variables.
-    asmTemplate.insertBack("    sub $");
-    asmTemplate.insertBack(format!"{}"(ast.statements.length)[]);
-    asmTemplate.insertBack(", $esp\n"); */
-
-    int i = 1;
-    foreach (statement; ast.statements[])
-    {
-        if ((cast(Number) statement.subroutine.lhs) !is null)
-        {
-            asmTemplate.insertBack("    movl $");
-            asmTemplate.insertBack(format!"{}"((cast(Number) statement.subroutine.lhs).value)[]);
-            asmTemplate.insertBack(", %eax\n");
-        }
-        else if ((cast(Variable) statement.subroutine.lhs) !is null)
-        {
-            asmTemplate.insertBack("    movl -");
-            asmTemplate.insertBack(format!"{}"((cast(Variable) statement.subroutine.lhs).counter * 4)[]);
-            asmTemplate.insertBack("(%rbp), %eax\n");
-        }
-        if ((cast(Number) statement.subroutine.rhs) !is null)
-        {
-            asmTemplate.insertBack("    movl $");
-            asmTemplate.insertBack(format!"{}"((cast(Number) statement.subroutine.rhs).value)[]);
-            asmTemplate.insertBack(", %ebx\n");
-        }
-        else if ((cast(Variable) statement.subroutine.rhs) !is null)
-        {
-            asmTemplate.insertBack("    movl -");
-            asmTemplate.insertBack(format!"{}"((cast(Variable) statement.subroutine.rhs).counter * 4)[]);
-            asmTemplate.insertBack("(%rbp), %ebx\n");
-        }
-        // Calculate the result and assign it to a variable on the stack.
-        asmTemplate.insertBack("    add %ebx, %eax\n");
-        asmTemplate.insertBack("    movl %eax, -");
-        asmTemplate.insertBack(format!"{}"(i * 4)[]);
-        asmTemplate.insertBack("(%rbp)\n");
-        ++i;
-    }
-
-    // Epilogue.
-    asmTemplate.insertBack("    movq %rbp, %rsp
-    popq %rbp
-    ret
-");
-
-    return asmTemplate;
-}

source/elna/ir.d

@@ -5,140 +5,268 @@ import tanya.container.array;
 import tanya.container.hashtable;
 import tanya.container.string;
 import tanya.memory.allocator;
-import tanya.memory.mmappool;
+public import elna.parser : BinaryOperator;
+
+/**
+ * Mapping between the parser and IR AST.
+ */
+struct ASTMapping
+{
+    alias Node = .Node;
+    alias Definition = .Definition;
+    alias VariableDeclaration = .VariableDeclaration;
+    alias Statement = Array!(.Statement);
+    alias BangStatement = .Expression;
+    alias Block = .Definition;
+    alias Expression = .Expression;
+    alias Number = .Number;
+    alias Variable = .Variable;
+    alias BinaryExpression = .BinaryExpression;
+
+}
+
+/**
+ * IR visitor.
+*/
+interface IRVisitor
+{
+    abstract void visit(Node) @nogc;
+    abstract void visit(Definition) @nogc;
+    abstract void visit(Expression) @nogc;
+    abstract void visit(Statement) @nogc;
+    abstract void visit(Variable) @nogc;
+    abstract void visit(VariableDeclaration) @nogc;
+    abstract void visit(Number) @nogc;
+    abstract void visit(BinaryExpression) @nogc;
+}
+
+/**
+ * AST node.
+ */
+abstract class Node
+{
+    abstract void accept(IRVisitor) @nogc;
+}
 
 /**
  * Definition.
  */
-class Definition
+class Definition : Node
 {
     char[] identifier;
     Array!Statement statements;
     Array!VariableDeclaration variableDeclarations;
+
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
-class Statement
+class Statement : Node
 {
-    Subroutine subroutine;
+    BinaryExpression expression;
+
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
-abstract class Expression
+abstract class Expression : Node
 {
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
 class Number : Expression
 {
     int value;
+
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
 class Variable : Expression
 {
     size_t counter;
+
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
-class VariableDeclaration
+class VariableDeclaration : Node
 {
     String identifier;
+
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
-class Subroutine
+class BinaryExpression : Node
 {
     Expression lhs, rhs;
-}
+    BinaryOperator operator;
 
-private Number transformNumber(parser.Number number) @nogc
-{
-    return MmapPool.instance.make!Number(number.value);
-}
-
-private Variable transformSubroutine(parser.Subroutine subroutine,
-        ref Array!Statement statements,
-        ref HashTable!(String, int) constants) @nogc
-{
-    auto target = MmapPool.instance.make!Subroutine;
-    target.lhs = transformExpression(subroutine.lhs, statements, constants);
-    target.rhs = transformExpression(subroutine.rhs, statements, constants);
-
-    auto newStatement = MmapPool.instance.make!Statement;
-    newStatement.subroutine = target;
-    statements.insertBack(newStatement);
-
-    auto newVariable = MmapPool.instance.make!Variable;
-    newVariable.counter = statements.length;
-
-    return newVariable;
-}
-
-private Expression transformExpression(parser.Expression expression,
-        ref Array!Statement statements,
-        ref HashTable!(String, int) constants) @nogc
-{
-    if ((cast(parser.Number) expression) !is null)
+    this(Expression lhs, Expression rhs, BinaryOperator operator)
+    @nogc
     {
-        auto numberExpression = MmapPool.instance.make!Number;
-        numberExpression.value = (cast(parser.Number) expression).value;
-
-        return numberExpression;
-    }
-    if ((cast(parser.Variable) expression) !is null)
-    {
-        auto numberExpression = MmapPool.instance.make!Number;
-        numberExpression.value = constants[(cast(parser.Variable) expression).identifier];
-
-        return numberExpression;
-    }
-    else if ((cast(parser.Subroutine) expression) !is null)
-    {
-        return transformSubroutine(cast(parser.Subroutine) expression, statements, constants);
-    }
-    return null;
-}
-
-Expression transformStatement(parser.Statement statement,
-        ref Array!Statement statements,
-        ref HashTable!(String, int) constants) @nogc
-{
-    if ((cast(parser.BangStatement) statement) !is null)
-    {
-        return transformExpression((cast(parser.BangStatement) statement).expression, statements, constants);
-    }
-    return null;
-}
-
-HashTable!(String, int) transformConstants(ref Array!(parser.Definition) definitions) @nogc
-{
-    typeof(return) constants;
-
-    foreach (definition; definitions[])
-    {
-        constants[definition.identifier] = definition.number.value;
+        this.lhs = lhs;
+        this.rhs = rhs;
+        this.operator = operator;
     }
 
-    return constants;
+    override void accept(IRVisitor visitor) @nogc
+    {
+        visitor.visit(this);
+    }
 }
 
-Array!VariableDeclaration transformVariableDeclarations(ref Array!(parser.VariableDeclaration) variableDeclarations)
-@nogc
+final class TransformVisitor : parser.ParserVisitor!ASTMapping
 {
-    typeof(return) variables;
+    private HashTable!(String, int) constants;
 
-    foreach (ref variableDeclaration; variableDeclarations)
+    ASTMapping.Node visit(parser.Node node) @nogc
     {
-        auto newDeclaration = MmapPool.instance.make!VariableDeclaration;
-        newDeclaration.identifier = variableDeclaration.identifier;
-        variables.insertBack(newDeclaration);
+        assert(false, "Not implemented");
     }
 
-    return variables;
-}
-
-Definition transform(parser.Block block) @nogc
-{
-    auto target = MmapPool.instance.make!Definition;
-    auto constants = transformConstants(block.definitions);
-
-    transformStatement(block.statement, target.statements, constants);
-    target.variableDeclarations = transformVariableDeclarations(block.variableDeclarations);
-
-    return target;
+    ASTMapping.Definition visit(parser.Definition definition) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.VariableDeclaration visit(parser.VariableDeclaration declaration) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.BangStatement visit(parser.BangStatement statement) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.Block visit(parser.Block block) @nogc
+    {
+        auto target = defaultAllocator.make!Definition;
+        this.constants = transformConstants(block.definitions);
+
+        target.statements = block.statement.accept(this);
+        target.variableDeclarations = transformVariableDeclarations(block.variableDeclarations);
+
+        return target;
+    }
+
+    ASTMapping.Expression visit(parser.Expression expression) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.Number visit(parser.Number number) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.Variable visit(parser.Variable variable) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.BinaryExpression visit(parser.BinaryExpression) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    private Number transformNumber(parser.Number number) @nogc
+    {
+        return defaultAllocator.make!Number(number.value);
+    }
+
+    private Variable binaryExpression(parser.BinaryExpression binaryExpression,
+            ref Array!Statement statements) @nogc
+    {
+        auto target = defaultAllocator.make!BinaryExpression(
+            expression(binaryExpression.lhs, statements),
+            expression(binaryExpression.rhs, statements),
+            binaryExpression.operator
+        );
+
+        auto newStatement = defaultAllocator.make!Statement;
+        newStatement.expression = target;
+        statements.insertBack(newStatement);
+
+        auto newVariable = defaultAllocator.make!Variable;
+        newVariable.counter = statements.length;
+
+        return newVariable;
+    }
+
+    private Expression expression(parser.Expression expression,
+            ref Array!Statement statements) @nogc
+    {
+        if ((cast(parser.Number) expression) !is null)
+        {
+            auto numberExpression = defaultAllocator.make!Number;
+            numberExpression.value = (cast(parser.Number) expression).value;
+
+            return numberExpression;
+        }
+        if ((cast(parser.Variable) expression) !is null)
+        {
+            auto numberExpression = defaultAllocator.make!Number;
+            numberExpression.value = this.constants[(cast(parser.Variable) expression).identifier];
+
+            return numberExpression;
+        }
+        else if ((cast(parser.BinaryExpression) expression) !is null)
+        {
+            return binaryExpression(cast(parser.BinaryExpression) expression, statements);
+        }
+        return null;
+    }
+
+    override Array!Statement visit(parser.Statement statement) @nogc
+    {
+        typeof(return) statements;
+        if ((cast(parser.BangStatement) statement) !is null)
+        {
+            expression((cast(parser.BangStatement) statement).expression, statements);
+        }
+        return statements;
+    }
+
+    private HashTable!(String, int) transformConstants(ref Array!(parser.Definition) definitions) @nogc
+    {
+        typeof(return) constants;
+
+        foreach (definition; definitions[])
+        {
+            constants[definition.identifier] = definition.number.value;
+        }
+
+        return constants;
+    }
+
+    Array!VariableDeclaration transformVariableDeclarations(ref Array!(parser.VariableDeclaration) variableDeclarations)
+    @nogc
+    {
+        typeof(return) variables;
+
+        foreach (ref variableDeclaration; variableDeclarations)
+        {
+            auto newDeclaration = defaultAllocator.make!VariableDeclaration;
+            newDeclaration.identifier = variableDeclaration.identifier;
+            variables.insertBack(newDeclaration);
+        }
+
+        return variables;
+    }
 }

source/elna/lexer.d

@@ -7,14 +7,13 @@ import elna.result;
 import std.range;
 import tanya.container.array;
 import tanya.container.string;
-import tanya.memory.mmappool;
 
 struct Token
 {
     enum Type
     {
         number,
-        subroutine, // Operator.
+        operator,
         let,
         identifier,
         equals,
@@ -54,7 +53,7 @@ struct Token
 
     this()(Type type, auto ref String value, Position position)
     @nogc nothrow pure @trusted
-    in (type == Type.identifier)
+    in (type == Type.identifier || type == Type.operator)
     {
         this(type, position);
         this.value_.identifier = value;
@@ -78,7 +77,7 @@ struct Token
         {
             return this.value_.number;
         }
-        else static if (type == Type.identifier)
+        else static if (type == Type.identifier || type == Type.operator)
         {
             return this.value_.identifier;
         }
@@ -161,7 +160,7 @@ struct Source
     }
 }
 
-Array!Token lex(char[] buffer) @nogc
+Result!(Array!Token) lex(char[] buffer) @nogc
 {
     Array!Token tokens;
     auto source = Source(buffer);
@@ -234,9 +233,12 @@ Array!Token lex(char[] buffer) @nogc
             }
             source.popFrontN(i);
         }
-        else if (source.front == '+') // Multi-character, random special characters.
+        else if (source.front == '+' || source.front == '-')
         {
-            tokens.insertBack(Token(Token.Type.subroutine, source.position));
+            String operator;
+
+            operator.insertBack(source.front);
+            tokens.insertBack(Token(Token.Type.operator, operator, source.position));
             source.popFront;
         }
         else if (source.front == '\n')
@@ -245,8 +247,8 @@ Array!Token lex(char[] buffer) @nogc
         }
         else
         {
-            return typeof(tokens)(); // Error.
+            return typeof(return)("Unexptected next character", source.position);
         }
     }
-    return tokens;
+    return typeof(return)(tokens);
 }

source/elna/parser.d

@@ -5,100 +5,172 @@ import elna.result;
 import tanya.container.array;
 import tanya.container.string;
 import tanya.memory.allocator;
-import tanya.memory.mmappool;
+
+
+/**
+ * Parser visitor.
+ */
+interface ParserVisitor(Mapping)
+{
+    Mapping.Node visit(Node) @nogc;
+    Mapping.Definition visit(Definition) @nogc;
+    Mapping.VariableDeclaration visit(VariableDeclaration) @nogc;
+    Mapping.Statement visit(Statement) @nogc;
+    Mapping.BangStatement visit(BangStatement) @nogc;
+    Mapping.Block visit(Block) @nogc;
+    Mapping.Expression visit(Expression) @nogc;
+    Mapping.Number visit(Number) @nogc;
+    Mapping.Variable visit(Variable) @nogc;
+    Mapping.BinaryExpression visit(BinaryExpression) @nogc;
+}
+
+/**
+ * AST node.
+ */
+abstract class Node
+{
+    Mapping.Node accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
+}
 
 /**
  * Constant definition.
  */
-class Definition
+class Definition : Node
 {
     Number number;
     String identifier;
+
+    Mapping.Definition accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
 /**
  * Variable declaration.
  */
-class VariableDeclaration
+class VariableDeclaration : Node
 {
     String identifier;
+
+    Mapping.VariableDeclaration accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
-abstract class Statement
+abstract class Statement : Node
 {
+    Mapping.Statement accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
 class BangStatement : Statement
 {
     Expression expression;
+
+    Mapping.BangStatement accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
-class Block
+class Block : Node
 {
     Array!Definition definitions;
     Array!VariableDeclaration variableDeclarations;
     Statement statement;
+
+    Mapping.Block accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
-abstract class Expression
+abstract class Expression : Node
 {
+    Mapping.Expression accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
 class Number : Expression
 {
     int value;
+
+    Mapping.Number accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
 class Variable : Expression
 {
     String identifier;
+
+    Mapping.Variable accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
-class Subroutine : Expression
+enum BinaryOperator
+{
+    sum,
+    subtraction
+}
+
+class BinaryExpression : Expression
 {
     Expression lhs, rhs;
+    BinaryOperator operator;
+
+    this(Expression lhs, Expression rhs, String operator) @nogc
+    {
+        this.lhs = lhs;
+        this.rhs = rhs;
+        if (operator == "+")
+        {
+            this.operator = BinaryOperator.sum;
+        }
+        else if (operator == "-")
+        {
+            this.operator = BinaryOperator.subtraction;
+        }
+        else
+        {
+            assert(false, "Invalid binary operator");
+        }
+    }
+
+    Mapping.BinaryExpression accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
 }
 
-private Result!Expression parseExpression(ref Array!(Token).Range tokens) @nogc
-in (!tokens.empty, "Expected expression, got end of stream")
+private Result!Expression parseFactor(ref Array!Token.Range tokens) @nogc
+in (!tokens.empty, "Expected factor, got end of stream")
 {
-    if (tokens.front.ofType(Token.Type.number))
+    if (tokens.front.ofType(Token.Type.identifier))
     {
-        auto number = MmapPool.instance.make!Number;
-        number.value = tokens.front.value!(Token.Type.number);
-        tokens.popFront;
-        return Result!Expression(number);
-    }
-    else if (tokens.front.ofType(Token.Type.identifier))
-    {
-        auto variable = MmapPool.instance.make!Variable;
+        auto variable = defaultAllocator.make!Variable;
         variable.identifier = tokens.front.value!(Token.Type.identifier);
         tokens.popFront;
         return Result!Expression(variable);
     }
-    else if (tokens.front.ofType(Token.Type.subroutine))
+    else if (tokens.front.ofType(Token.Type.number))
     {
-        auto subroutine = MmapPool.instance.make!Subroutine;
+        auto number = defaultAllocator.make!Number;
+        number.value = tokens.front.value!(Token.Type.number);
         tokens.popFront;
-        auto expression = parseExpression(tokens);
-        if (expression.valid)
-        {
-            subroutine.lhs = expression.result;
-        }
-        else
-        {
-            return Result!Expression("Expected left-hand side to be an expression", tokens.front.position);
-        }
-        expression = parseExpression(tokens);
-        if (expression.valid)
-        {
-            subroutine.rhs = expression.result;
-        }
-        else
-        {
-            return Result!Expression("Expected left-hand side to be an expression", tokens.front.position);
-        }
-        return Result!Expression(subroutine);
+        return Result!Expression(number);
     }
     else if (tokens.front.ofType(Token.Type.leftParen))
     {
@@ -109,13 +181,44 @@ in (!tokens.empty, "Expected expression, got end of stream")
         tokens.popFront;
         return expression;
     }
-    return Result!Expression("Expected an expression", tokens.front.position);
+    return Result!Expression("Expected a factor", tokens.front.position);
+}
+
+private Result!Expression parseTerm(ref Array!(Token).Range tokens) @nogc
+{
+    return parseFactor(tokens);
+}
+
+private Result!Expression parseExpression(ref Array!(Token).Range tokens) @nogc
+in (!tokens.empty, "Expected expression, got end of stream")
+{
+    auto term = parseTerm(tokens);
+    if (!term.valid || tokens.empty || !tokens.front.ofType(Token.Type.operator))
+    {
+        return term;
+    }
+    auto operator = tokens.front.value!(Token.Type.operator);
+    tokens.popFront;
+
+    auto expression = parseExpression(tokens);
+
+    if (expression.valid)
+    {
+        auto binaryExpression = defaultAllocator
+            .make!BinaryExpression(term.result, expression.result, operator);
+
+        return Result!Expression(binaryExpression);
+    }
+    else
+    {
+        return Result!Expression("Expected right-hand side to be an expression", tokens.front.position);
+    }
 }
 
 private Result!Definition parseDefinition(ref Array!Token.Range tokens) @nogc
 in (!tokens.empty, "Expected definition, got end of stream")
 {
-    auto definition = MmapPool.instance.make!Definition;
+    auto definition = defaultAllocator.make!Definition;
     definition.identifier = tokens.front.value!(Token.Type.identifier); // Copy.
 
     tokens.popFront();
@@ -123,7 +226,7 @@ in (!tokens.empty, "Expected definition, got end of stream")
 
     if (tokens.front.ofType(Token.Type.number))
     {
-        auto number = MmapPool.instance.make!Number;
+        auto number = defaultAllocator.make!Number;
         number.value = tokens.front.value!(Token.Type.number);
         definition.number = number;
         tokens.popFront;
@@ -138,7 +241,7 @@ in (!tokens.empty, "Expected block, got end of stream")
     if (tokens.front.ofType(Token.Type.bang))
     {
         tokens.popFront;
-        auto statement = MmapPool.instance.make!BangStatement;
+        auto statement = defaultAllocator.make!BangStatement;
         auto expression = parseExpression(tokens);
         if (expression.valid)
         {
@@ -193,7 +296,7 @@ in (!tokens.empty, "Expected variable declarations, got end of stream")
         auto currentToken = tokens.front;
         if (currentToken.ofType(Token.Type.identifier))
         {
-            auto variableDeclaration = MmapPool.instance.make!VariableDeclaration;
+            auto variableDeclaration = defaultAllocator.make!VariableDeclaration;
             variableDeclaration.identifier = currentToken.value!(Token.Type.identifier);
             variableDeclarations.insertBack(variableDeclaration);
             tokens.popFront;
@@ -222,7 +325,7 @@ in (!tokens.empty, "Expected variable declarations, got end of stream")
 private Result!Block parseBlock(ref Array!Token.Range tokens) @nogc
 in (!tokens.empty, "Expected block, got end of stream")
 {
-    auto block = MmapPool.instance.make!Block;
+    auto block = defaultAllocator.make!Block;
     if (tokens.front.ofType(Token.Type.let))
     {
         auto constDefinitions = parseDefinitions(tokens);

source/elna/result.d

@@ -1,6 +1,8 @@
 module elna.result;
 
 import std.typecons;
+import tanya.container.array;
+import tanya.container.string;
 
 /**
  * Position in the source text.
@@ -82,3 +84,24 @@ struct Result(T)
         return error.isNull;
     }
 }
+
+struct Reference
+{
+    enum Target
+    {
+        text,
+        high20,
+        lower12i
+    }
+
+    String name;
+    size_t offset;
+    Target target;
+}
+
+struct Symbol
+{
+    String name;
+    Array!ubyte text;
+    Array!Reference symbols;
+}

source/elna/riscv.d

@@ -0,0 +1,352 @@
+module elna.riscv;
+
+import elna.extended;
+import elna.ir;
+import elna.result;
+import std.algorithm;
+import std.typecons;
+import tanya.container.array;
+import tanya.container.string;
+import tanya.memory.allocator;
+
+enum XRegister : ubyte
+{
+    zero = 0,
+    ra = 1,
+    sp = 2,
+    gp = 3,
+    tp = 4,
+    t0 = 5,
+    t1 = 6,
+    t2 = 7,
+    s0 = 8,
+    s1 = 9,
+    a0 = 10,
+    a1 = 11,
+    a2 = 12,
+    a3 = 13,
+    a4 = 14,
+    a5 = 15,
+    a6 = 16,
+    a7 = 17,
+    s2 = 18,
+    s3 = 19,
+    s4 = 20,
+    s5 = 21,
+    s6 = 22,
+    s7 = 23,
+    s8 = 24,
+    s9 = 25,
+    s10 = 26,
+    s11 = 27,
+    t3 = 28,
+    t4 = 29,
+    t5 = 30,
+    t6 = 31,
+}
+
+enum Funct3 : ubyte
+{
+    addi = 0b000,
+    slti = 0b001,
+    sltiu = 0b011,
+    andi = 0b111,
+    ori = 0b110,
+    xori = 0b100,
+    slli = 0b000,
+    srli = 0b101,
+    srai = 0b101,
+    add = 0b000,
+    slt = 0b010,
+    sltu = 0b011,
+    and = 0b111,
+    or = 0b110,
+    xor = 0b100,
+    sll = 0b001,
+    srl = 0b101,
+    sub = 0b000,
+    sra = 0b101,
+    beq = 0b000,
+    bne = 0b001,
+    blt = 0b100,
+    bltu = 0b110,
+    bge = 0b101,
+    bgeu = 0b111,
+    fence = 0b000,
+    fenceI = 0b001,
+    csrrw = 0b001,
+    csrrs = 0b010,
+    csrrc = 0b011,
+    csrrwi = 0b101,
+    csrrsi = 0b110,
+    csrrci = 0b111,
+    priv = 0b000,
+    sb = 0b000,
+    sh = 0b001,
+    sw = 0b010,
+    lb = 0b000,
+    lh = 0b001,
+    lw = 0b010,
+    lbu = 0b100,
+    lhu = 0b101,
+    jalr = 0b000,
+}
+
+enum Funct12 : ubyte
+{
+    ecall = 0b000000000000,
+    ebreak = 0b000000000001,
+}
+
+enum Funct7 : ubyte
+{
+    none = 0,
+    sub = 0b0100000
+}
+
+enum BaseOpcode : ubyte
+{
+    opImm = 0b0010011,
+    lui = 0b0110111,
+    auipc = 0b0010111,
+    op = 0b0110011,
+    jal = 0b1101111,
+    jalr = 0b1100111,
+    branch = 0b1100011,
+    load = 0b0000011,
+    store = 0b0100011,
+    miscMem = 0b0001111,
+    system = 0b1110011,
+}
+
+struct Instruction
+{
+    private uint instruction;
+
+    this(BaseOpcode opcode) @nogc
+    {
+        this.instruction = opcode;
+    }
+    @disable this();
+
+    ref Instruction i(XRegister rd, Funct3 funct3, XRegister rs1, uint immediate)
+    return scope @nogc
+    {
+        this.instruction |= (rd << 7)
+            | (funct3 << 12)
+            | (rs1 << 15)
+            | (immediate << 20);
+
+        return this;
+    }
+
+    ref Instruction s(uint imm1, Funct3 funct3, XRegister rs1, XRegister rs2, uint imm2 = 0)
+    return scope @nogc
+    {
+        this.instruction |= (imm1 << 7)
+            | (funct3 << 12)
+            | (rs1 << 15)
+            | (rs2 << 20)
+            | (imm2 << 25);
+
+        return this;
+    }
+
+    ref Instruction r(XRegister rd, Funct3 funct3, XRegister rs1, XRegister rs2, Funct7 funct7 = Funct7.none)
+    return scope @nogc
+    {
+        this.instruction |= (rd << 7)
+            | (funct3 << 12)
+            | (rs1 << 15)
+            | (rs2 << 20)
+            | (funct7 << 25);
+
+        return this;
+    }
+
+    ref Instruction u(XRegister rd, uint imm)
+    return scope @nogc
+    {
+        this.instruction |= (rd << 7) | (imm << 12);
+
+        return this;
+    }
+
+    ubyte[] encode() return scope @nogc
+    {
+        return (cast(ubyte*) (&this.instruction))[0 .. uint.sizeof];
+    }
+}
+
+class RiscVVisitor : IRVisitor
+{
+    Array!Instruction instructions;
+    bool registerInUse;
+    uint variableCounter = 1;
+    Array!Reference references;
+
+    override void visit(Node) @nogc
+    {
+    }
+
+    override void visit(Definition definition) @nogc
+    {
+        // Prologue.
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm)
+                .i(XRegister.sp, Funct3.addi, XRegister.sp, cast(uint) -32)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.store)
+                .s(28, Funct3.sw, XRegister.sp, XRegister.s0)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.store)
+                .s(24, Funct3.sw, XRegister.sp, XRegister.ra)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm)
+                .i(XRegister.s0, Funct3.addi, XRegister.sp, 32)
+        );
+
+        foreach (statement; definition.statements[])
+        {
+            statement.accept(this);
+        }
+        foreach (variableDeclaration; definition.variableDeclarations[])
+        {
+            variableDeclaration.accept(this);
+        }
+        // Print the result.
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm)
+                .i(XRegister.a1, Funct3.addi, XRegister.a0, 0)
+        );
+        this.references.insertBack(Reference(String(".CL0"), instructions.length * 4, Reference.Target.high20));
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.lui).u(XRegister.a5, 0)
+        );
+        this.references.insertBack(Reference(String(".CL0"), instructions.length * 4, Reference.Target.lower12i));
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm).i(XRegister.a0, Funct3.addi, XRegister.a5, 0)
+        );
+        this.references.insertBack(Reference(String("printf"), instructions.length * 4, Reference.Target.text));
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.auipc).u(XRegister.ra, 0)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.jalr)
+                .i(XRegister.ra, Funct3.jalr, XRegister.ra, 0)
+        );
+        // Set the return value (0).
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.op)
+                .r(XRegister.a0, Funct3.and, XRegister.zero, XRegister.zero)
+        );
+
+        // Epilogue.
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.load)
+                .i(XRegister.s0, Funct3.lw, XRegister.sp, 28)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.load)
+                .i(XRegister.ra, Funct3.lw, XRegister.sp, 24)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm)
+                .i(XRegister.sp, Funct3.addi, XRegister.sp, 32)
+        );
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.jalr)
+                .i(XRegister.zero, Funct3.jalr, XRegister.ra, 0)
+        );
+    }
+
+    override void visit(Expression) @nogc
+    {
+    }
+
+    override void visit(Statement statement) @nogc
+    {
+        statement.expression.accept(this);
+    }
+
+    override void visit(Variable variable) @nogc
+    {
+        const freeRegister = this.registerInUse ? XRegister.a0 : XRegister.t0;
+
+        // movl -x(%rbp), %eax; where x is a number.
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.load)
+                .i(freeRegister, Funct3.lw, XRegister.sp,
+                    cast(byte) (variable.counter * 4))
+        );
+    }
+
+    override void visit(VariableDeclaration) @nogc
+    {
+    }
+
+    override void visit(Number number) @nogc
+    {
+        const freeRegister = this.registerInUse ? XRegister.a0 : XRegister.t0;
+
+        this.instructions.insertBack(
+            Instruction(BaseOpcode.opImm) // movl $x, %eax; where $x is a number.
+                .i(freeRegister, Funct3.addi, XRegister.zero, number.value)
+        );
+    }
+
+    override void visit(BinaryExpression expression) @nogc
+    {
+        this.registerInUse = true;
+        expression.lhs.accept(this);
+        this.registerInUse = false;
+        expression.rhs.accept(this);
+
+        // Calculate the result and assign it to a variable on the stack.
+        final switch (expression.operator)
+        {
+            case BinaryOperator.sum:
+                this.instructions.insertBack(
+                    Instruction(BaseOpcode.op)
+                        .r(XRegister.a0, Funct3.add, XRegister.a0, XRegister.t0)
+                );
+                break;
+            case BinaryOperator.subtraction:
+                this.instructions.insertBack(
+                    Instruction(BaseOpcode.op)
+                        .r(XRegister.a0, Funct3.sub, XRegister.a0, XRegister.t0, Funct7.sub)
+                );
+                break;
+        }
+        this.instructions.insertBack( // movl %eax, -x(%rbp); where x is a number.
+            Instruction(BaseOpcode.store)
+                .s(cast(uint) (this.variableCounter * 4), Funct3.sw, XRegister.sp, XRegister.a0)
+        );
+
+        ++this.variableCounter;
+    }
+}
+
+Symbol writeNext(Definition ast) @nogc
+{
+    Array!Instruction instructions;
+    Array!Reference references;
+    auto visitor = defaultAllocator.make!RiscVVisitor;
+    scope (exit)
+    {
+        defaultAllocator.dispose(visitor);
+    }
+    visitor.visit(ast);
+
+    auto program = Symbol(String("main"));
+
+    program.symbols = move(visitor.references);
+    foreach (ref instruction; visitor.instructions)
+    {
+        program.text.insertBack(instruction.encode);
+    }
+    return program;
+}

source/main.d

@@ -1,72 +1,33 @@
-import core.stdc.stdio;
-import core.stdc.string;
-import core.stdc.stdlib;
-import elna.lexer;
-import elna.parser;
-import elna.generator;
+import elna.backend;
 import elna.ir;
+import elna.arguments;
+import std.path;
+import std.sumtype;
 import tanya.container.string;
 import tanya.memory.allocator;
 import tanya.memory.mmappool;
 
-private char[] readSource(size_t N)(string source, out char[N] buffer) @nogc
-{
-    memcpy(buffer.ptr, source.ptr, source.length + 1);
-    buffer[source.length] = '\0';
-    auto handle = fopen(buffer.ptr, "r");
-    if (handle is null)
-    {
-        perror(buffer.ptr);
-        return null;
-    }
-    fseek(handle, 0, SEEK_END);
-    size_t fsize = ftell(handle);
-    rewind(handle);
-
-    fread(buffer.ptr, fsize, 1, handle);
-    fclose(handle);
-    buffer[fsize] = '\0';
-
-    return buffer[0 .. fsize];
-}
-
 int main(string[] args)
 {
-    char[255] buffer;
-
     defaultAllocator = MmapPool.instance;
 
-    if (args.length < 2)
-    {
-        return 4;
-    }
-    auto sourceText = readSource(args[1], buffer);
-    if (sourceText is null)
-    {
-        return 3;
-    }
-    auto tokens = lex(sourceText);
-    if (tokens.length == 0)
-    {
-        printf("Lexical analysis failed.\n");
-        return 1;
-    }
-    auto ast = parse(tokens);
-    if (!ast.valid)
-    {
-        auto compileError = ast.error.get;
-        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.message.ptr);
-        return 2;
-    }
-    auto ir = transform(ast.result);
+    return Arguments.parse(args).match!(
+        (ArgumentError argumentError) => 4,
+        (Arguments arguments) {
+            String outputFilename;
+            if (arguments.output is null)
+            {
+                outputFilename = arguments
+                    .inFile
+                    .baseName
+                    .withExtension("o");
+            }
+            else
+            {
+                outputFilename = String(arguments.output);
+            }
 
-    String outputFilename = String("build/");
-    outputFilename.insertBack(args[1][0 .. $ - 4]);
-    outputFilename.insertBack("o");
-    writeObject(ir, outputFilename);
-
-    auto code = generate(ir);
-    printf("%s", code.toStringz());
-
-    return 0;
+            return generate(arguments.inFile, outputFilename);
+        }
+    );
 }

tests/const_list.eln

@@ -1,3 +1,3 @@
 const a = 1, b = 2;
-! + a b
+! a + b
 .

tests/expectations/left_nested_sum.txt

@@ -0,0 +1 @@
+8

tests/expectations/subtraction.txt

@@ -0,0 +1 @@
+1

tests/left_nested_sum.eln

@@ -0,0 +1,2 @@
+! (3 + 4) + 1
+.

tests/subtraction.eln

@@ -0,0 +1,2 @@
+! 5 - 4
+.

tests/sum.eln

@@ -0,0 +1,2 @@
+! 1 + 7
+.

tests/sum.elna

@@ -1,2 +0,0 @@
-! + 1 7
-.

tests/sums.eln

@@ -0,0 +1,2 @@
+! 1 + (3 + 4)
+.

tests/sums.elna

@@ -1,2 +0,0 @@
-! + 1 (+ 3 4)
-.