Print test summary

.gitignore

@@ -2,3 +2,4 @@
 .cache/
 CMakeFiles/
 CMakeCache.txt
+dub.selections.json

CMakeLists.txt

@@ -3,8 +3,7 @@ project(Elna)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
-
+set(CMAKE_CXX_STANDARD 17)
-find_package(Boost COMPONENTS filesystem REQUIRED)
 
 add_executable(tester tests/runner.cpp include/elna/tester.hpp)
 target_include_directories(tester PRIVATE include)
@@ -13,9 +12,14 @@ add_executable(elnsh shell/main.cpp
 	shell/interactive.cpp include/elna/interactive.hpp
 	shell/history.cpp include/elna/history.hpp
 	shell/state.cpp include/elna/state.hpp
-	shell/lexer.cpp include/elna/lexer.hpp
-	shell/result.cpp include/elna/result.hpp)
-target_include_directories(elnsh PRIVATE include)
-target_link_libraries(elnsh PUBLIC
-	${Boost_FILESYSTEM_LIBRARY}
 )
+target_include_directories(elnsh PRIVATE include)
+
+add_library(elna
+	source/lexer.cpp include/elna/lexer.hpp
+	source/result.cpp include/elna/result.hpp
+	source/riscv.cpp include/elna/riscv.hpp
+	source/ir.cpp include/elna/ir.hpp
+	include/elna/parser.hpp
+)
+target_include_directories(elna PRIVATE include)

README

@@ -0,0 +1,37 @@
+# Elna programming language
+
+Elna compiles simple mathematical operations to machine code.
+The compiled program returns the result of the operation.
+
+## File extension
+
+.elna
+
+## Grammar PL/0
+
+program = block "." ;
+
+block = [ "const" ident "=" number {"," ident "=" number} ";"]
+        [ "var" ident {"," ident} ";"]
+        { "procedure" ident ";" block ";" } statement ;
+
+statement = [ ident ":=" expression | "call" ident 
+              | "?" ident | "!" expression 
+              | "begin" statement {";" statement } "end" 
+              | "if" condition "then" statement 
+              | "while" condition "do" statement ];
+
+condition = "odd" expression |
+            expression ("="|"#"|"<"|"<="|">"|">=") expression ;
+
+expression = [ "+"|"-"] term { ("+"|"-") term};
+
+term = factor {("*"|"/") factor};
+
+factor = ident | number | "(" expression ")";
+
+## Operations
+
+"!" - Write a line.
+"?" - Read user input.
+"odd" - The only function, returns whether a number is odd.

Rakefile

@@ -0,0 +1,19 @@
+require 'pathname'
+require 'rake/clean'
+require 'open3'
+
+DFLAGS = ['--warn-no-deprecated', '-L/usr/lib64/gcc-12']
+BINARY = 'build/bin/elna'
+SOURCES = FileList['source/**/*.d']
+
+directory 'build/riscv'
+
+CLEAN.include 'build'
+CLEAN.include '.dub'
+
+file BINARY => SOURCES do |t|
+  sh({ 'DFLAGS' => (DFLAGS * ' ') }, 'dub', 'build', '--compiler=gdc')
+end
+
+task default: 'build/riscv'
+task default: BINARY

TODO

@@ -1,15 +1,23 @@
-- After inserting autocompletion move the cursor to the end of the insertion.
+# Completion
+
+- Configure fzf to show only the current directory files
 - Support multiple selections for insertion in fzf.
-- Vi mode.
 - Don't hardcode fzf binary path.
-- Persist the history.
 - Send the word under the cursor to fzf as initial input.
-- Replace hard coded ANSI codes with constants or functions.
-- Show the hostname in the prompt.
-- Crash if the cd directory doesn't exist.
 - Home directory expansion.
-- Paste pastes only the first character.
+- Show files in the PATH if starting at the beginning of the prompt
-- When we read the key and an error occures how it should be handled?
+
-- Kitty protocol works with UTF8 code points for escape sequences with modifiers.
+# Appearance
-  They can be wider than an unsigned char.
+
-- Add a bar with additional information under the prompt (edit_bar).
+- Add a bar with additional information under the prompt (edit_bar), like the hostname.
+- Show current time in the prompt.
+
+# Input
+
+- DEL handling.
+- Starting long running process and killing it with Ctrl-C kills the shell.
+
+# Other
+
+- Persist the history.
+- Replace hard coded ANSI codes with constants or functions.

dub.json

@@ -0,0 +1,11 @@
+{
+	"dependencies": {
+		"tanya": "~>0.19.0"
+	},
+	"name": "elna",
+	"targetType": "executable",
+	"targetPath": "build/bin",
+	"mainSourceFile": "source/main.d",
+	"libs": ["elna", "stdc++"],
+	"lflags": ["-Lbuild"]
+}

include/elna/interactive.hpp

@@ -5,10 +5,11 @@
 #include <string>
 #include <optional>
 
-#include "elna/lexer.hpp"
 #include "elna/state.hpp"
 #include "elna/history.hpp"
 
+#define BOOST_PROCESS_USE_STD_FS
+
 namespace elna
 {
     /**
@@ -42,15 +43,14 @@ namespace elna
      * \param line The command and arguments.
      * \return Whether the input shoud continued (no exit requested).
      */
-    bool execute(const std::vector<token>& line);
+    bool execute(const std::string& line);
 
     /**
      * Runs the binary specified in its argument.
      *
      * \param program Program name in PATH.
-     * \param arguments Command arguments.
      */
-    void launch(const std::string& program, const std::vector<std::string>& arguments);
+    void launch(const std::string& program);
 
     /**
      * Enables the raw mode.
@@ -74,7 +74,16 @@ namespace elna
     /**
      * Calls autocompletion.
      *
+     * \param User input.
+     * \param Cursor position in the user input.
      * \return Selected item.
      */
-    std::string complete();
+    std::string complete(const std::string& input, const std::size_t position);
+
+    /**
+     * Prints the message from the exception.
+     *
+     * \param exception The exception to print.
+     */
+    void print_exception(const std::exception& exception);
 }

include/elna/ir.hpp

@@ -0,0 +1,95 @@
+#pragma once
+
+#include "elna/parser.hpp"
+#include <cstddef>
+#include <cstdint>
+
+namespace elna::ir
+{
+    class Node;
+    class Definition;
+    class Operand;
+    class BinaryExpression;
+    class Variable;
+    class VariableDeclaration;
+    class Number;
+
+    struct IRVisitor
+    {
+        virtual void visit(Node *) = 0;
+        virtual void visit(Definition *) = 0;
+        virtual void visit(Operand *) = 0;
+        virtual void visit(BinaryExpression *) = 0;
+        virtual void visit(Variable *) = 0;
+        virtual void visit(Number *) = 0;
+    };
+
+    /**
+     * AST node.
+     */
+    class Node
+    {
+    public:
+        virtual void accept(IRVisitor *) = 0;
+    };
+
+    /**
+     * Definition.
+     */
+    class Definition : public Node
+    {
+    public:
+        BinaryExpression **statements;
+        std::size_t statementsLength;
+        Operand *result;
+
+        virtual void accept(IRVisitor *visitor) override;
+    };
+
+    class Statement : public Node
+    {
+    };
+
+    class Operand : public Node
+    {
+    public:
+        virtual void accept(IRVisitor *visitor) override;
+    };
+
+    class Number : public Operand
+    {
+    public:
+        std::int32_t value;
+
+        virtual void accept(IRVisitor *visitor) override;
+    };
+
+    class Variable : public Operand
+    {
+    public:
+        std::size_t counter;
+
+        virtual void accept(IRVisitor *visitor) override;
+    };
+
+    class BinaryExpression : public Statement
+    {
+    public:
+        Operand *lhs, *rhs;
+        BinaryOperator _operator;
+
+        BinaryExpression(Operand *lhs, Operand *rhs, BinaryOperator _operator);
+
+        virtual void accept(IRVisitor *visitor) override;
+    };
+
+    class BangExpression : public Statement
+    {
+        Operand *operand;
+
+    public:
+        BangExpression(Operand *operand);
+
+        virtual void accept(IRVisitor *visitor) override;
+    };
+}

include/elna/lexer.hpp

@@ -16,7 +16,8 @@ namespace elna
             std::string::const_iterator m_buffer;
             Position m_position;
 
-            const_iterator(std::string::const_iterator buffer, const Position& position);
+            const_iterator(std::string::const_iterator buffer,
+                    const Position position = Position());
 
         public:
             using iterator_category = std::forward_iterator_tag;
@@ -42,38 +43,61 @@ namespace elna
         const_iterator end() const;
 
     private:
-        const std::string& m_buffer;
+        const std::string m_buffer;
     };
 
     /**
      * Union type representing a single token.
      */
-    struct token
+    struct Token
     {
         /**
          * Token type.
          */
-        enum class type
+        enum Type : std::uint16_t
         {
-            word,
+            TOKEN_NUMBER = 0,
+            TOKEN_OPERATOR = 1,
+            TOKEN_LET = 2,
+            TOKEN_IDENTIFIER = 3,
+            TOKEN_EQUALS = 4,
+            TOKEN_VAR = 5,
+            TOKEN_SEMICOLON = 6,
+            TOKEN_LEFT_PAREN = 7,
+            TOKEN_RIGHT_PAREN = 8,
+            TOKEN_BANG = 9,
+            TOKEN_DOT = 10,
+            TOKEN_COMMA = 11,
         };
 
-
         /**
          * Type of the token value.
          */
-        using value = std::string;
+        union Value
+        {
+            std::int32_t number;
+            const char *identifier;
+        };
 
-        token(const type of, source::const_iterator begin, source::const_iterator end);
+        Token(Type of, Position position);
+        Token(Type of, std::int32_t value, Position position);
+        Token(Type of, const char *value, Position position);
+        Token(const Token& that);
+        Token(Token&& that);
+        ~Token();
 
-        type of() const noexcept;
+        Token& operator=(const Token& that);
-        const value& identifier() const noexcept;
+        Token& operator=(Token&& that);
+
+        Type of() const noexcept;
+        const char *identifier() const noexcept;
+        std::int32_t number() const noexcept;
         const Position& position() const noexcept;
 
     private:
-        std::string m_value;
+        Type m_type;
+        Value m_value;
         Position m_position;
-        type m_type;
     };
 
     /**
@@ -81,5 +105,5 @@ namespace elna
      *
      * \return Tokens or error.
      */
-    result<std::vector<token>> lex(const std::string& buffer);
+    Token *lex(const char *buffer, CompileError *compile_error, std::size_t *length);
 }

include/elna/parser.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+namespace elna
+{
+    enum class BinaryOperator
+    {
+        sum,
+        subtraction
+    };
+}

include/elna/result.hpp

@@ -23,18 +23,18 @@ namespace elna
     struct CompileError
     {
     private:
-        char const *message_;
+        char const *message;
-        Position position_;
+        Position position;
 
     public:
         /**
          * @param message Error text.
          * @param position Error position in the source text.
          */
-        CompileError(char const *message, Position position) noexcept;
+        CompileError(char const *message, const Position position) noexcept;
 
         /// Error text.
-        char const *message() const noexcept;
+        const char *what() const noexcept;
 
         /// Error line in the source text.
         std::size_t line() const noexcept;
@@ -45,4 +45,18 @@ namespace elna
 
     template<typename T>
     using result = boost::outcome_v2::result<T, CompileError>;
+
+    enum class Target
+    {
+        text,
+        high20,
+        lower12i
+    };
+
+    struct Reference
+    {
+        const char* name;
+        size_t offset;
+        Target target;
+    };
 }

include/elna/riscv.hpp

@@ -0,0 +1,148 @@
+#pragma once
+
+#include <cstdint>
+#include "elna/ir.hpp"
+#include "elna/result.hpp"
+
+namespace elna
+{
+    enum class XRegister : std::uint8_t
+    {
+        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 class Funct3 : std::uint8_t
+    {
+        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 class Funct12 : std::uint8_t
+    {
+        ecall = 0b000000000000,
+        ebreak = 0b000000000001,
+    };
+
+    enum class Funct7 : std::uint8_t
+    {
+        none = 0,
+        sub = 0b0100000
+    };
+
+    enum class BaseOpcode : std::uint8_t
+    {
+        opImm = 0b0010011,
+        lui = 0b0110111,
+        auipc = 0b0010111,
+        op = 0b0110011,
+        jal = 0b1101111,
+        jalr = 0b1100111,
+        branch = 0b1100011,
+        load = 0b0000011,
+        store = 0b0100011,
+        miscMem = 0b0001111,
+        system = 0b1110011,
+    };
+
+    struct Instruction
+    {
+        Instruction(BaseOpcode opcode);
+
+        Instruction& i(XRegister rd, Funct3 funct3, XRegister rs1, std::uint32_t immediate);
+        Instruction& s(std::uint32_t imm1, Funct3 funct3, XRegister rs1, XRegister rs2);
+        Instruction& r(XRegister rd, Funct3 funct3, XRegister rs1, XRegister rs2, Funct7 funct7 = Funct7::none);
+        Instruction& u(XRegister rd, std::uint32_t imm);
+        std::uint8_t *encode();
+
+    private:
+        std::uint32_t instruction{ 0 };
+    };
+
+    class RiscVVisitor : public ir::IRVisitor
+    {
+        Instruction *instructions;
+        std::size_t instructionsLength;
+        bool registerInUse;
+        std::uint32_t variableCounter = 1;
+        Reference references[3];
+
+        virtual void visit(ir::Node *) override;
+        virtual void visit(ir::Definition *definition) override;
+        virtual void visit(ir::Operand *operand) override;
+        virtual void visit(ir::Variable *variable) override;
+        virtual void visit(ir::Number *number) override;
+        virtual void visit(ir::BinaryExpression *expression) override;
+    };
+}

include/elna/state.hpp

@@ -38,30 +38,28 @@ namespace elna
         num_lock = 0b10000000, ///< 128
     };
 
-    class key
+    struct key
     {
-        std::variant<special_key, unsigned char> store;
+        using char_t = std::uint32_t;
-        std::uint8_t modifiers;
 
-    public:
         key();
-        explicit key(const unsigned char c, const std::uint8_t modifiers = 0);
+        explicit key(const char_t c, const std::uint8_t modifiers = 0);
-        explicit key(const unsigned char c, const modifier modifiers);
+        explicit key(const char_t c, const modifier modifiers);
         explicit key(const special_key control, const std::uint8_t modifiers = 0);
         explicit key(const special_key control, const modifier modifiers);
 
-        bool operator==(const unsigned char c) const;
+        bool operator==(const char_t c) const;
-        friend bool operator==(const unsigned char c, const key& that);
+        friend bool operator==(const char_t c, const key& that);
         bool operator==(const special_key control) const;
         friend bool operator==(const special_key control, const key& that);
         bool operator==(const key& that) const;
-        bool operator!=(const unsigned char c) const;
+        bool operator!=(const char_t c) const;
-        friend bool operator!=(const unsigned char c, const key& that);
+        friend bool operator!=(const char_t c, const key& that);
         bool operator!=(const special_key control) const;
         friend bool operator!=(const special_key control, const key& that);
         bool operator!=(const key& that) const;
 
-        unsigned char character() const;
+        char_t character() const;
         special_key control() const;
         bool modified(const std::uint8_t modifiers) const noexcept;
         bool modified(const modifier modifiers) const noexcept;
@@ -69,6 +67,10 @@ namespace elna
         bool is_character() const noexcept;
         bool is_control() const noexcept;
         bool empty() const noexcept;
+
+    private:
+        std::variant<special_key, char_t> store;
+        std::uint8_t modifiers;
     };
 
     /**
@@ -143,12 +145,20 @@ namespace elna
          */
         std::size_t absolute_position() const noexcept;
 
+        /**
+         * Cursor position relative to the start of the user input.
+         *
+         * \returns Cursor position.
+         */
+        std::size_t relative_position() const noexcept;
+
         /**
          * Inserts text at cursor position.
          *
          * \param text Text to insert.
          */
         void insert(const std::string& text);
+        void insert(const key::char_t text);
 
         /**
          * Replaces the user input with the given string.

shell/history.cpp

@@ -9,8 +9,8 @@ namespace elna
 
     void editor_history::push(const std::string& entry)
     {
-        commands.push_front(entry);
+        commands.push_back(entry);
-        current_pointer = commands.cbegin();
+        current_pointer = commands.cend();
     }
 
     void editor_history::clear()
@@ -46,4 +46,9 @@ namespace elna
     {
         return this->commands.cend();
     }
+
+    editor_history::const_iterator editor_history::current() const noexcept
+    {
+        return this->current_pointer;
+    }
 }

shell/interactive.cpp

@@ -1,9 +1,10 @@
+#include "elna/interactive.hpp"
+
+#include <boost/algorithm/string/predicate.hpp>
 #include <boost/process.hpp>
 #include <termios.h>
 #include <filesystem>
 
-#include "elna/interactive.hpp"
-
 namespace elna
 {
     static termios original_termios;
@@ -39,9 +40,8 @@ namespace elna
                 break;
             }
             history.push(line.value().command_line());
-            auto tokens = lex(line.value().command_line());
 
-            if (!execute(tokens.assume_value()))
+            if (!execute(line.value().command_line()))
             {
                 break;
             }
@@ -53,6 +53,7 @@ namespace elna
     {
         editor_state state;
         std::string buffer;
+        std::string saved;
 
         state.draw(std::back_inserter(buffer));
         write(STDOUT_FILENO, buffer.data(), buffer.size());
@@ -81,7 +82,7 @@ namespace elna
                     break;
                 case action::complete:
                     write(STDOUT_FILENO, "\x1b[1E\x1b[2K", 8);
-                    state.insert(complete());
+                    state.insert(complete(state.command_line(), state.relative_position()));
                     write(STDOUT_FILENO, "\x1b[1A", 4);
                     state.draw(std::back_inserter(buffer));
                     write(STDOUT_FILENO, buffer.data(), buffer.size());
@@ -104,18 +105,26 @@ namespace elna
 
                     if (pressed_key == key(special_key::arrow_up, modifier::ctrl))
                     {
-                        history_iterator = history.next();
+                        if (history.current() == history.cend())
+                        {
+                            saved = state.command_line();
+                        }
+                        history_iterator = history.prev();
                     }
                     else if (pressed_key == key(special_key::arrow_down, modifier::ctrl))
                     {
-                        history_iterator = history.prev();
+                        history_iterator = history.next();
+                        if (history_iterator == history.cend())
+                        {
+                            state.load(saved);
+                        }
                     }
                     if (history_iterator != history.cend())
                     {
                         state.load(*history_iterator);
+                    }
                     state.draw(std::back_inserter(buffer));
                     write(STDOUT_FILENO, buffer.data(), buffer.size());
-                    }
                     break;
             }
         }
@@ -137,7 +146,7 @@ namespace elna
         {
             return key();
         }
-        auto [number, last_char] = read_number<unsigned char>();
+        auto [number, last_char] = read_number<key::char_t>();
         std::uint8_t modifiers{ 0 };
 
         if (last_char == ';')
@@ -185,35 +194,51 @@ namespace elna
         return key();
     }
 
-    bool execute(const std::vector<token>& tokens)
+    void print_exception(const std::exception& exception)
     {
-        if (tokens.empty())
+        std::string message{ exception.what()  };
+        message += "\r\n";
+        write(STDERR_FILENO, message.data(), message.size());
+    }
+
+    bool execute(const std::string& line)
+    {
+        if (line.empty())
         {
             return true;
         }
-        std::string program = tokens.front().identifier();
+        if (line == "exit")
-        if (program == "exit")
         {
             return false;
         }
-        else if (program == "cd")
+        else if (boost::starts_with(line, "cd "))
         {
-            std::filesystem::current_path(tokens[1].identifier());
+            try
+            {
+                std::filesystem::current_path(line.substr(strlen("cd ")));
+            }
+            catch (const std::filesystem::filesystem_error& exception)
+            {
+                print_exception(exception);
+            }
 
             return true;
         }
-        std::vector<std::string> arguments;
+        launch(line);
-        for (auto argument = tokens.cbegin() + 1; argument != std::cend(tokens); ++argument)
-        {
-            arguments.push_back(argument->identifier());
-        }
-        launch(program, arguments);
         return true;
     }
 
-    void launch(const std::string& program, const std::vector<std::string>& arguments)
+    void launch(const std::string& program)
     {
-        boost::process::system(boost::process::search_path(program), arguments);
+        try
+        {
+            boost::process::system(program);
+        }
+        catch (const boost::process::process_error& exception)
+        {
+            print_exception(exception);
+        }
+        enable_raw_mode();
     }
 
     bool enable_raw_mode()
@@ -240,10 +265,17 @@ namespace elna
         tcsetattr(STDIN_FILENO, TCSAFLUSH, &original_termios);
     }
 
-    std::string complete()
+    std::string complete(const std::string& input, const std::size_t position)
     {
+        std::filesystem::path program = boost::process::search_path("fzf");
+
+        if (program.empty())
+        {
+            return "";
+        }
         boost::process::ipstream output;
-        boost::process::system("/usr/bin/fzf", "--height=10", "--layout=reverse",
+        boost::process::system(program,
+                "--height=10", "--layout=reverse", "-1", "--no-multi",
                 boost::process::std_out > output);
 
         std::string selections;

shell/lexer.cpp

@@ -1,124 +0,0 @@
-#include "elna/lexer.hpp"
-
-namespace elna
-{
-    source::source(const std::string& buffer)
-        : m_buffer(buffer)
-    {
-    }
-
-    source::const_iterator source::begin() const
-    {
-        return source::const_iterator(std::cbegin(m_buffer), Position());
-    }
-
-    source::const_iterator source::end() const
-    {
-        Position end_position{ 0, 0 };
-
-        return source::const_iterator(std::cend(m_buffer), end_position);
-    }
-
-    source::const_iterator::const_iterator(std::string::const_iterator buffer, const Position& start_position)
-        : m_buffer(buffer), m_position(start_position)
-    {
-    }
-
-    const Position& source::const_iterator::position() const noexcept
-    {
-        return this->m_position;
-    }
-
-    source::const_iterator::reference source::const_iterator::operator*() const noexcept
-    {
-        return *m_buffer;
-    }
-
-    source::const_iterator::pointer source::const_iterator::operator->() const noexcept
-    {
-        return m_buffer.base();
-    }
-
-    source::const_iterator& source::const_iterator::operator++()
-    {
-        if (*this->m_buffer == '\n')
-        {
-            this->m_position.column = 1;
-            ++this->m_position.line;
-        }
-        else
-        {
-            ++this->m_position.column;
-        }
-        std::advance(this->m_buffer, 1);
-
-        return *this;
-    }
-
-    source::const_iterator& source::const_iterator::operator++(int)
-    {
-        auto tmp = *this;
-        ++(*this);
-        return *this;
-    }
-
-    bool source::const_iterator::operator==(const source::const_iterator& that) const noexcept
-    {
-        return this->m_buffer == that.m_buffer;
-    }
-
-    bool source::const_iterator::operator!=(const source::const_iterator& that) const noexcept
-    {
-        return !(*this == that);
-    }
-
-    token::token(const type of, source::const_iterator begin, source::const_iterator end)
-        : m_type(of), m_value(begin, end)
-    {
-    }
-
-    token::type token::of() const noexcept
-    {
-        return m_type;
-    }
-
-    const token::value& token::identifier() const noexcept
-    {
-        return m_value;
-    }
-
-    const Position& token::position() const noexcept
-    {
-        return m_position;
-    }
-
-    result<std::vector<token>> lex(const std::string& buffer)
-    {
-        std::vector<token> tokens;
-        source input{ buffer };
-
-        for (auto iterator = input.begin(); iterator != input.end();)
-        {
-            if (*iterator == ' ' || *iterator == '\n')
-            {
-            }
-            else if (std::isgraph(*iterator))
-            {
-                auto current_position = iterator;
-                do
-                {
-                    ++current_position;
-                }
-                while (current_position != input.end() && std::isgraph(*current_position));
-                token new_token{ token::type::word, iterator, current_position };
-
-                tokens.push_back(new_token);
-                iterator = current_position;
-                continue;
-            }
-            ++iterator;
-        }
-
-        return tokens;
-    }
-}

shell/result.cpp

@@ -1,25 +0,0 @@
-#include "elna/result.hpp"
-
-namespace elna
-{
-    CompileError::CompileError(char const *message, Position position) noexcept
-    {
-        this->message_ = message;
-        this->position_ = position;
-    }
-
-    char const *CompileError::message() const noexcept
-    {
-        return this->message_;
-    }
-
-    std::size_t CompileError::line() const noexcept
-    {
-        return this->position_.line;
-    }
-
-    std::size_t CompileError::column() const noexcept
-    {
-        return this->position_.column;
-    }
-}

shell/state.cpp

@@ -1,3 +1,6 @@
+#include <algorithm>
+#include <boost/endian.hpp>
+
 #include "elna/state.hpp"
 
 namespace elna
@@ -12,16 +15,16 @@ namespace elna
     }
 
     key::key()
-        : store(static_cast<unsigned char>(0x1b))
+        : store(0x1bu)
     {
     }
 
-    key::key(const unsigned char c, const std::uint8_t modifiers)
+    key::key(const char_t c, const std::uint8_t modifiers)
         : store(c), modifiers(modifiers == 0 ? 0 : modifiers - 1)
     {
     }
 
-    key::key(const unsigned char c, const modifier modifiers)
+    key::key(const char_t c, const modifier modifiers)
         : store(c), modifiers(static_cast<uint8_t>(modifiers))
     {
     }
@@ -36,9 +39,9 @@ namespace elna
     {
     }
 
-    unsigned char key::character() const
+    key::char_t key::character() const
     {
-        return std::get<unsigned char>(this->store);
+        return std::get<char_t>(this->store);
     }
 
     special_key key::control() const
@@ -56,10 +59,10 @@ namespace elna
         return this->modifiers == static_cast<std::uint8_t>(modifiers);
     }
 
-    bool key::operator==(const unsigned char c) const
+    bool key::operator==(const char_t c) const
     {
-        return std::holds_alternative<unsigned char>(this->store)
+        return std::holds_alternative<char_t>(this->store)
-            && std::get<unsigned char>(this->store) == c;
+            && std::get<char_t>(this->store) == c;
     }
 
     bool key::operator==(const special_key control) const
@@ -73,7 +76,7 @@ namespace elna
         return this->store == that.store;
     }
 
-    bool key::operator!=(const unsigned char c) const
+    bool key::operator!=(const char_t c) const
     {
         return !(*this == c);
     }
@@ -90,7 +93,7 @@ namespace elna
 
     bool key::is_character() const noexcept
     {
-        return std::holds_alternative<unsigned char>(this->store);
+        return std::holds_alternative<char_t>(this->store);
     }
 
     bool key::is_control() const noexcept
@@ -131,6 +134,7 @@ namespace elna
     void editor_state::load(const std::string& text)
     {
         this->input = text;
+        this->position = this->input.size() + 1;
     }
 
     const std::string& editor_state::command_line() const noexcept
@@ -143,9 +147,36 @@ namespace elna
         return this->prompt.size() + this->position;
     }
 
+    std::size_t editor_state::relative_position() const noexcept
+    {
+        return this->position;
+    }
+
     void editor_state::insert(const std::string& text)
     {
-        this->input.insert(std::end(this->input), std::cbegin(text), std::cend(text));
+        this->input.insert(this->position - 1, text);
+        this->position += text.size();
+    }
+
+    void editor_state::insert(const key::char_t text)
+    {
+        if (text == 0u)
+        {
+            this->input.insert(this->position - 1, '\0', 1);
+            ++this->position;
+            return;
+        }
+        key::char_t buffer = boost::endian::native_to_big<key::char_t>(text);
+
+        const char *begin = reinterpret_cast<char *>(&buffer);
+        const char *end = begin + sizeof(key::char_t);
+        const char *significant = std::find_if(begin, end,
+                [](const char byte) {
+                    return byte != 0;
+                });
+
+        this->input.insert(this->position - 1, significant, end - significant);
+        this->position += end - significant;
     }
 
     action editor_state::process_keypress(const key& press)
@@ -202,13 +233,22 @@ namespace elna
                         this->input.erase(this->position - 1, 1);
                     }
                     return action::redraw;
+                case 9: // Tab.
+                    return action::complete;
                 case '\r':
                     return action::finalize;
                 default:
-                    ++this->position;
+                    if (this->position - 1 < input.size())
-                    this->input.push_back(press.character());
+                    {
+                        insert(press.character());
+                        return action::redraw;
+                    }
+                    else
+                    {
+                        insert(press.character());
                         return action::write;
                     }
             }
         }
+    }
 }

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 +1,114 @@
+module elna.backend;
+
+import core.stdc.stdio;
+import core.stdc.stdlib;
+import core.stdc.string;
+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 char* readSource(string source) @nogc
+{
+    enum size_t bufferSize = 255;
+    auto sourceFilename = String(source);
+
+    return readFile(sourceFilename).match!(
+        (ErrorCode errorCode) {
+            perror(sourceFilename.toStringz);
+            return null;
+        },
+        (Array!ubyte contents) {
+            char* cString = cast(char*) malloc(contents.length + 1);
+            memcpy(cString, contents.get.ptr, contents.length);
+            cString[contents.length] = '\0';
+
+            return cString;
+        }
+    );
+}
+
+int generate(string inFile, ref String outputFilename) @nogc
+{
+    auto sourceText = readSource(inFile);
+    if (sourceText is null)
+    {
+        return 3;
+    }
+    CompileError compileError = void;
+    size_t tokensCount;
+    auto tokens = lex(sourceText, &compileError, &tokensCount);
+    free(sourceText);
+    if (tokens is null)
+    {
+        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.what);
+        return 1;
+    }
+    auto ast = parse(tokens[0 .. tokensCount]);
+    if (!ast.valid)
+    {
+        compileError = ast.error.get;
+        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.what);
+        return 2;
+    }
+    auto transformVisitor = cast(TransformVisitor) malloc(__traits(classInstanceSize, TransformVisitor));
+    (cast(void*) transformVisitor)[0 .. __traits(classInstanceSize, TransformVisitor)] = __traits(initSymbol, TransformVisitor)[];
+
+    auto ir = transformVisitor.visit(ast.result);
+
+    transformVisitor.__xdtor();
+    free(cast(void*) 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 Target.text:
+                relocationEntry.r_info = R_RISCV_CALL;
+                break;
+            case Target.high20:
+                relocationEntry.r_info = R_RISCV_HI20;
+                break;
+            case Target.lower12i:
+                relocationEntry.r_info = R_RISCV_LO12_I;
+                break;
+        }
+
+        elf.relocate(String(reference.name[0 .. strlen(reference.name)]), relocationEntry, relocationSub);
+    }
+
+    elf.finish();
+
+    return 0;
+}

source/elna/extended.d

@@ -0,0 +1,335 @@
+/**
+ * File I/O that can be moved into more generic library when and if finished.
+ */
+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
+{
+    /// 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/ir.d

@@ -0,0 +1,220 @@
+module elna.ir;
+
+import core.stdc.stdlib;
+import parser = elna.parser;
+import tanya.container.array;
+import tanya.container.hashtable;
+import tanya.container.string;
+import tanya.memory.allocator;
+public import elna.parser : BinaryOperator;
+
+/**
+ * Mapping between the parser and IR AST.
+ */
+struct ASTMapping
+{
+    alias Node = .Node;
+    alias Definition = .Definition;
+    alias Statement = .Operand;
+    alias BangStatement = .Operand;
+    alias Block = .Definition;
+    alias Expression = .Operand;
+    alias Number = .Number;
+    alias Variable = .Number;
+    alias BinaryExpression = .Variable;
+
+}
+
+/**
+ * IR visitor.
+*/
+extern(C++, "elna", "ir")
+abstract class IRVisitor
+{
+    abstract void visit(Node) @nogc;
+    abstract void visit(Definition) @nogc;
+    abstract void visit(Operand) @nogc;
+    abstract void visit(BinaryExpression) @nogc;
+    abstract void visit(Variable) @nogc;
+    abstract void visit(Number) @nogc;
+}
+
+/**
+ * AST node.
+ */
+extern(C++, "elna", "ir")
+abstract class Node
+{
+    abstract void accept(IRVisitor) @nogc;
+}
+
+/**
+ * Definition.
+ */
+extern(C++, "elna", "ir")
+class Definition : Node
+{
+    BinaryExpression* statements;
+    size_t statementsLength;
+    Operand result;
+
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+extern(C++, "elna", "ir")
+abstract class Statement : Node
+{
+}
+
+extern(C++, "elna", "ir")
+abstract class Operand : Node
+{
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+extern(C++, "elna", "ir")
+class Number : Operand
+{
+    int value;
+
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+extern(C++, "elna", "ir")
+class Variable : Operand
+{
+    size_t counter;
+
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+extern(C++, "elna", "ir")
+class BinaryExpression : Statement
+{
+    Operand lhs, rhs;
+    BinaryOperator operator;
+
+    this(Operand lhs, Operand rhs, BinaryOperator operator) @nogc;
+
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+extern(C++, "elna", "ir")
+class BangExpression : Statement
+{
+    Operand operand;
+
+    this(Operand operand);
+
+    override void accept(IRVisitor visitor) @nogc;
+}
+
+final class TransformVisitor : parser.ParserVisitor!ASTMapping
+{
+    private HashTable!(String, int) constants;
+    private BinaryExpression* statements;
+    private size_t statementsLength;
+
+    ASTMapping.Node visit(parser.Node node) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.Definition visit(parser.Definition definition) @nogc
+    {
+        assert(false, "Not implemented");
+    }
+
+    ASTMapping.BangStatement visit(parser.BangStatement statement) @nogc
+    {
+        return statement.expression.accept(this);
+    }
+
+    ASTMapping.Block visit(parser.Block block) @nogc
+    {
+        auto target = defaultAllocator.make!Definition;
+        this.constants = transformConstants(block.definitions);
+
+        target.result = block.statement.accept(this);
+        target.statements = this.statements;
+        target.statementsLength = this.statementsLength;
+
+        return target;
+    }
+
+    ASTMapping.Expression visit(parser.Expression expression) @nogc
+    {
+        if ((cast(parser.Number) expression) !is null)
+        {
+            return (cast(parser.Number) expression).accept(this);
+        }
+        if ((cast(parser.Variable) expression) !is null)
+        {
+            return (cast(parser.Variable) expression).accept(this);
+        }
+        else if ((cast(parser.BinaryExpression) expression) !is null)
+        {
+            return (cast(parser.BinaryExpression) expression).accept(this);
+        }
+        assert(false, "Invalid expression type");
+    }
+
+    ASTMapping.Number visit(parser.Number number) @nogc
+    {
+        auto numberExpression = defaultAllocator.make!Number;
+        numberExpression.value = number.value;
+
+        return numberExpression;
+    }
+
+    ASTMapping.Variable visit(parser.Variable variable) @nogc
+    {
+        auto numberExpression = defaultAllocator.make!Number;
+        numberExpression.value = this.constants[variable.identifier];
+
+        return numberExpression;
+    }
+
+    ASTMapping.BinaryExpression visit(parser.BinaryExpression binaryExpression) @nogc
+    {
+        auto target = defaultAllocator.make!BinaryExpression(
+            binaryExpression.lhs.accept(this),
+            binaryExpression.rhs.accept(this),
+            binaryExpression.operator
+        );
+        this.statements = cast(BinaryExpression*)
+            realloc(this.statements, (this.statementsLength + 1) * BinaryExpression.sizeof);
+        this.statements[this.statementsLength++] = target;
+
+        auto newVariable = defaultAllocator.make!Variable;
+        newVariable.counter = this.statementsLength;
+
+        return newVariable;
+    }
+
+    private Number transformNumber(parser.Number number) @nogc
+    {
+        return defaultAllocator.make!Number(number.value);
+    }
+
+    override Operand visit(parser.Statement statement) @nogc
+    {
+        if ((cast(parser.BangStatement) statement) !is null)
+        {
+            return (cast(parser.BangStatement) statement).accept(this);
+        }
+        assert(false, "Invalid statement type");
+    }
+
+    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;
+    }
+}

source/elna/lexer.d

@@ -0,0 +1,117 @@
+module elna.lexer;
+
+import core.stdc.stdlib;
+import core.stdc.ctype;
+import core.stdc.string;
+import elna.result;
+import std.range;
+import tanya.container.array;
+import tanya.container.string;
+
+extern(C++, "elna")
+struct Token
+{
+    enum Type : ushort
+    {
+        number = 0,
+        operator = 1,
+        let = 2,
+        identifier = 3,
+        equals = 4,
+        var = 5,
+        semicolon = 6,
+        leftParen = 7,
+        rightParen = 8,
+        bang = 9,
+        dot = 10,
+        comma = 11,
+    }
+
+    union Value
+    {
+        int number;
+        const(char)* identifier;
+    }
+
+    private Type type;
+    private Value value_;
+    private Position position_;
+
+    @disable this();
+
+    this(Type type, Position position) @nogc nothrow pure @safe;
+    this(Type type, int value, Position position) @nogc nothrow pure @trusted;
+    this(Type type, const(char)* value, Position position) @nogc nothrow;
+
+    /**
+     * Returns: Expected token type.
+     */
+    Type of() const @nogc nothrow pure @safe;
+    const(char)* identifier() const @nogc nothrow pure;
+    int number() const @nogc nothrow pure;
+
+    /**
+     * Returns: The token position in the source text.
+     */
+    @property const(Position) position() const @nogc nothrow pure @safe;
+}
+
+/**
+ * Range over the source text that keeps track of the current position.
+ */
+struct Source
+{
+    const(char)* buffer;
+    Position position;
+
+    this(const(char)* buffer) @nogc nothrow pure @safe
+    {
+        this.buffer = buffer;
+    }
+
+    @disable this();
+
+    bool empty() @nogc nothrow pure @safe
+    {
+        return this.buffer is null || this.buffer[0] == '\0';
+    }
+
+    char front() @nogc nothrow pure @safe
+    in (!empty)
+    {
+        return this.buffer[0];
+    }
+
+    void popFront() @nogc nothrow pure
+    in (!empty)
+    {
+        ++this.buffer;
+        ++this.position.column;
+    }
+
+    void breakLine() @nogc nothrow pure
+    in (!empty)
+    {
+        ++this.buffer;
+        ++this.position.line;
+        this.position.column = 1;
+    }
+
+    @property size_t length() const @nogc nothrow pure
+    {
+        return strlen(this.buffer);
+    }
+
+    char opIndex(size_t index) @nogc nothrow pure
+    {
+        return this.buffer[index];
+    }
+
+    const(char)[] opSlice(size_t i, size_t j) @nogc nothrow pure
+    {
+        return this.buffer[i .. j];
+    }
+}
+
+extern(C++, "elna")
+Token* lex(const(char)* buffer, CompileError* compileError, size_t* length) @nogc;

source/elna/parser.d

@@ -0,0 +1,308 @@
+module elna.parser;
+
+import core.stdc.string;
+import elna.lexer;
+import elna.result;
+import tanya.container.array;
+import tanya.container.string;
+import tanya.memory.allocator;
+import std.array;
+
+/**
+ * Parser visitor.
+ */
+interface ParserVisitor(Mapping)
+{
+    Mapping.Node visit(Node) @nogc;
+    Mapping.Definition visit(Definition) @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 : Node
+{
+    Number number;
+    String identifier;
+
+    Mapping.Definition accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
+}
+
+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 : Node
+{
+    Array!Definition definitions;
+    Statement statement;
+
+    Mapping.Block accept(Mapping)(ParserVisitor!Mapping visitor) @nogc
+    {
+        return visitor.visit(this);
+    }
+}
+
+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);
+    }
+}
+
+extern(C++, "elna")
+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 parseFactor(ref Token[] tokens) @nogc
+in (!tokens.empty, "Expected factor, got end of stream")
+{
+    if (tokens.front.of() == Token.Type.identifier)
+    {
+        auto variable = defaultAllocator.make!Variable;
+        variable.identifier = tokens.front.identifier()[0 .. strlen(tokens.front.identifier())];
+        tokens.popFront;
+        return Result!Expression(variable);
+    }
+    else if (tokens.front.of() == Token.Type.number)
+    {
+        auto number = defaultAllocator.make!Number;
+        number.value = tokens.front.number();
+        tokens.popFront;
+        return Result!Expression(number);
+    }
+    else if (tokens.front.of() == Token.Type.leftParen)
+    {
+        tokens.popFront;
+
+        auto expression = parseExpression(tokens);
+
+        tokens.popFront;
+        return expression;
+    }
+    return Result!Expression("Expected a factor", tokens.front.position);
+}
+
+private Result!Expression parseTerm(ref Token[] tokens) @nogc
+{
+    return parseFactor(tokens);
+}
+
+private Result!Expression parseExpression(ref Token[] tokens) @nogc
+in (!tokens.empty, "Expected expression, got end of stream")
+{
+    auto term = parseTerm(tokens);
+    if (!term.valid || tokens.empty || tokens.front.of() != Token.Type.operator)
+    {
+        return term;
+    }
+    auto operator = String(tokens.front.identifier()[0 .. strlen(tokens.front.identifier())]);
+    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 Token[] tokens) @nogc
+in (!tokens.empty, "Expected definition, got end of stream")
+{
+    auto definition = defaultAllocator.make!Definition;
+    definition.identifier = tokens.front.identifier()[0 .. strlen(tokens.front.identifier())]; // Copy.
+
+    tokens.popFront();
+    tokens.popFront(); // Skip the equals sign.
+
+    if (tokens.front.of() == Token.Type.number)
+    {
+        auto number = defaultAllocator.make!Number;
+        number.value = tokens.front.number();
+        definition.number = number;
+        tokens.popFront;
+        return Result!Definition(definition);
+    }
+    return Result!Definition("Expected a number", tokens.front.position);
+}
+
+private Result!Statement parseStatement(ref Token[] tokens) @nogc
+in (!tokens.empty, "Expected block, got end of stream")
+{
+    if (tokens.front.of() == Token.Type.bang)
+    {
+        tokens.popFront;
+        auto statement = defaultAllocator.make!BangStatement;
+        auto expression = parseExpression(tokens);
+        if (expression.valid)
+        {
+            statement.expression = expression.result;
+        }
+        else
+        {
+            return Result!Statement(expression.error.get);
+        }
+        return Result!Statement(statement);
+    }
+    return Result!Statement("Expected ! statement", tokens.front.position);
+}
+
+private Result!(Array!Definition) parseDefinitions(ref Token[] tokens) @nogc
+in (!tokens.empty, "Expected definition, got end of stream")
+{
+    tokens.popFront; // Skip const.
+
+    Array!Definition definitions;
+
+    while (!tokens.empty)
+    {
+        auto definition = parseDefinition(tokens);
+        if (!definition.valid)
+        {
+            return typeof(return)(definition.error.get);
+        }
+        definitions.insertBack(definition.result);
+        if (tokens.front.of() == Token.Type.semicolon)
+        {
+            break;
+        }
+        if (tokens.front.of() == Token.Type.comma)
+        {
+            tokens.popFront;
+        }
+    }
+
+    return typeof(return)(definitions);
+}
+
+private Result!Block parseBlock(ref Token[] tokens) @nogc
+in (!tokens.empty, "Expected block, got end of stream")
+{
+    auto block = defaultAllocator.make!Block;
+    if (tokens.front.of() == Token.Type.let)
+    {
+        auto constDefinitions = parseDefinitions(tokens);
+        if (constDefinitions.valid)
+        {
+            block.definitions = constDefinitions.result;
+        }
+        else
+        {
+            return Result!Block(constDefinitions.error.get);
+        }
+        tokens.popFront;
+    }
+    auto statement = parseStatement(tokens);
+    if (statement.valid)
+    {
+        block.statement = statement.result;
+    }
+    else
+    {
+        return Result!Block(statement.error.get);
+    }
+
+    return Result!Block(block);
+}
+
+Result!Block parse(Token[] tokenStream) @nogc
+{
+    auto tokens = tokenStream[];
+    return parseBlock(tokens);
+}

source/elna/result.d

@@ -0,0 +1,98 @@
+module elna.result;
+
+import std.typecons;
+import tanya.container.array;
+import tanya.container.string;
+
+/**
+ * Position in the source text.
+ */
+extern(C++, "elna")
+struct Position
+{
+    /// Line.
+    size_t line = 1;
+
+    /// Column.
+    size_t column = 1;
+}
+
+extern(C++, "elna")
+struct CompileError
+{
+    private const(char)* message_;
+
+    private Position position_;
+
+    @disable this();
+
+    /**
+     * Params:
+     *   message = Error text.
+     *   position = Error position in the source text.
+     */
+    this(const(char)* message, const Position position) @nogc nothrow pure @safe;
+
+    /// Error text.
+    @property const(char)* what() const @nogc nothrow pure @safe;
+
+    /// Error line in the source text.
+    @property size_t line() const @nogc nothrow pure @safe;
+
+    /// Error column in the source text.
+    @property size_t column() const @nogc nothrow pure @safe;
+}
+
+struct Result(T)
+{
+    Nullable!CompileError error;
+    T result;
+
+    this(T result)
+    {
+        this.result = result;
+        this.error = typeof(this.error).init;
+    }
+
+    this(const(char)* message, Position position)
+    {
+        this.result = T.init;
+        this.error = CompileError(message, position);
+    }
+
+    this(CompileError compileError)
+    {
+        this.result = null;
+        this.error = compileError;
+    }
+
+    @disable this();
+
+    @property bool valid() const
+    {
+        return error.isNull;
+    }
+}
+
+extern(C++, "elna")
+enum Target
+{
+    text,
+    high20,
+    lower12i
+}
+
+extern(C++, "elna")
+struct Reference
+{
+    const(char)* name;
+    size_t offset;
+    Target target;
+}
+
+struct Symbol
+{
+    String name;
+    Array!ubyte text;
+    Array!Reference symbols;
+}

source/elna/riscv.d

@@ -0,0 +1,183 @@
+module elna.riscv;
+
+import core.stdc.stdlib;
+import elna.ir;
+import elna.result;
+import tanya.container.array;
+import tanya.container.string;
+
+extern(C++, "elna")
+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,
+}
+
+extern(C++, "elna")
+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,
+}
+
+extern(C++, "elna")
+enum Funct12 : ubyte
+{
+    ecall = 0b000000000000,
+    ebreak = 0b000000000001,
+}
+
+extern(C++, "elna")
+enum Funct7 : ubyte
+{
+    none = 0,
+    sub = 0b0100000
+}
+
+extern(C++, "elna")
+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,
+}
+
+extern(C++, "elna")
+struct Instruction
+{
+    private uint instruction;
+
+    this(BaseOpcode opcode) @nogc;
+    @disable this();
+
+    ref Instruction i(XRegister rd, Funct3 funct3, XRegister rs1, uint immediate)
+    return scope @nogc;
+
+    ref Instruction s(uint imm1, Funct3 funct3, XRegister rs1, XRegister rs2)
+    return scope @nogc;
+
+    ref Instruction r(XRegister rd, Funct3 funct3, XRegister rs1, XRegister rs2, Funct7 funct7 = Funct7.none)
+    return scope @nogc;
+
+    ref Instruction u(XRegister rd, uint imm)
+    return scope @nogc;
+
+    ubyte* encode() return scope @nogc;
+}
+
+extern(C++, "elna")
+class RiscVVisitor : IRVisitor
+{
+    Instruction *instructions;
+    size_t instructionsLength;
+    bool registerInUse;
+    uint variableCounter = 1;
+    Reference[3] references;
+
+    override void visit(Node) @nogc;
+    override void visit(Definition definition) @nogc;
+    override void visit(Operand operand) @nogc;
+    override void visit(Variable variable) @nogc;
+    override void visit(Number number) @nogc;
+    override void visit(BinaryExpression expression) @nogc;
+}
+
+Symbol writeNext(Definition ast) @nogc
+{
+    Array!Instruction instructions;
+    auto visitor = cast(RiscVVisitor) malloc(__traits(classInstanceSize, RiscVVisitor));
+    (cast(void*) visitor)[0 .. __traits(classInstanceSize, RiscVVisitor)] = __traits(initSymbol, RiscVVisitor)[];
+    scope (exit)
+    {
+        free(cast(void*) visitor);
+    }
+    visitor.visit(ast);
+
+    auto program = Symbol(String("main"));
+
+    program.symbols = Array!Reference(visitor.references[]);
+    foreach (ref instruction; visitor.instructions[0 .. visitor.instructionsLength])
+    {
+        program.text.insertBack(instruction.encode[0 .. uint.sizeof]);
+    }
+    return program;
+}

source/ir.cpp

@@ -0,0 +1,53 @@
+#include "elna/ir.hpp"
+
+namespace elna::ir
+{
+    /**
+     * AST node.
+     */
+    void Node::accept(IRVisitor *)
+    {
+    }
+
+    void Definition::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    void Operand::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    void Number::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    void Variable::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    BinaryExpression::BinaryExpression(Operand *lhs, Operand *rhs, BinaryOperator _operator)
+    {
+        this->lhs = lhs;
+        this->rhs = rhs;
+        this->_operator = _operator;
+    }
+
+    void BinaryExpression::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    BangExpression::BangExpression(Operand *operand)
+    {
+        this->operand = operand;
+    }
+
+    void BangExpression::accept(IRVisitor *visitor)
+    {
+        visitor->visit(this);
+    }
+}

source/lexer.cpp

@@ -0,0 +1,270 @@
+#include "elna/lexer.hpp"
+
+namespace elna
+{
+    source::source(const std::string& buffer)
+        : m_buffer(buffer)
+    {
+    }
+
+    source::const_iterator source::begin() const
+    {
+        return source::const_iterator(std::cbegin(m_buffer));
+    }
+
+    source::const_iterator source::end() const
+    {
+        Position end_position{ 0, 0 };
+
+        return source::const_iterator(std::cend(m_buffer), end_position);
+    }
+
+    source::const_iterator::const_iterator(std::string::const_iterator buffer,
+            const Position start_position)
+        : m_buffer(buffer), m_position(start_position)
+    {
+    }
+
+    const Position& source::const_iterator::position() const noexcept
+    {
+        return this->m_position;
+    }
+
+    source::const_iterator::reference source::const_iterator::operator*() const noexcept
+    {
+        return *m_buffer;
+    }
+
+    source::const_iterator::pointer source::const_iterator::operator->() const noexcept
+    {
+        return m_buffer.base();
+    }
+
+    source::const_iterator& source::const_iterator::operator++()
+    {
+        if (*this->m_buffer == '\n')
+        {
+            this->m_position.column = 1;
+            ++this->m_position.line;
+        }
+        else
+        {
+            ++this->m_position.column;
+        }
+        std::advance(this->m_buffer, 1);
+
+        return *this;
+    }
+
+    source::const_iterator& source::const_iterator::operator++(int)
+    {
+        auto tmp = *this;
+        ++(*this);
+        return *this;
+    }
+
+    bool source::const_iterator::operator==(const source::const_iterator& that) const noexcept
+    {
+        return this->m_buffer == that.m_buffer;
+    }
+
+    bool source::const_iterator::operator!=(const source::const_iterator& that) const noexcept
+    {
+        return !(*this == that);
+    }
+
+    Token::Token(const Type of, const char *value, Position position)
+        : m_type(of), m_position(position)
+    {
+        std::size_t value_length = strlen(value);
+        char *buffer = reinterpret_cast<char *>(malloc(value_length + 1));
+
+        std::memcpy(buffer, value, value_length);
+        buffer[value_length] = 0;
+
+        m_value.identifier = buffer;
+    }
+
+    Token::Token(const Type of, std::int32_t number, Position position)
+        : m_type(of), m_position(position)
+    {
+        m_value.number = number;
+    }
+
+    Token::Token(const Type of, Position position)
+        : m_type(of), m_position(position)
+    {
+    }
+
+    Token::Token(const Token& that)
+        : m_type(that.of()), m_position(that.position())
+    {
+        *this = that;
+    }
+
+    Token::Token(Token&& that)
+        : m_type(that.of()), m_position(that.position())
+    {
+        *this = std::move(that);
+    }
+
+    Token::~Token()
+    {
+        if (m_type == TOKEN_IDENTIFIER || m_type == TOKEN_OPERATOR)
+        {
+            std::free(const_cast<char*>(m_value.identifier));
+        }
+    }
+
+    Token& Token::operator=(const Token& that)
+    {
+        m_type = that.of();
+        m_position = that.position();
+        if (that.of() == TOKEN_IDENTIFIER || that.of() == TOKEN_OPERATOR)
+        {
+            std::size_t value_length = strlen(that.identifier());
+            char *buffer = reinterpret_cast<char *>(malloc(value_length + 1));
+
+            std::memcpy(buffer, that.identifier(), value_length);
+            buffer[value_length] = 0;
+
+            m_value.identifier = buffer;
+        }
+        else if (that.of() == TOKEN_NUMBER)
+        {
+            m_value.number = that.number();
+        }
+        return *this;
+    }
+
+    Token& Token::operator=(Token&& that)
+    {
+        m_type = that.of();
+        m_position = that.position();
+        if (that.of() == TOKEN_IDENTIFIER || that.of() == TOKEN_OPERATOR)
+        {
+            m_value.identifier = that.identifier();
+            that.m_value.identifier = nullptr;
+        }
+        else if (that.of() == TOKEN_NUMBER)
+        {
+            m_value.number = that.number();
+        }
+        return *this;
+    }
+
+    Token::Type Token::of() const noexcept
+    {
+        return m_type;
+    }
+
+    const char *Token::identifier() const noexcept
+    {
+        return m_value.identifier;
+    }
+
+    std::int32_t Token::number() const noexcept
+    {
+        return m_value.number;
+    }
+
+    const Position& Token::position() const noexcept
+    {
+        return m_position;
+    }
+
+    Token *lex(const char *buffer, CompileError *compile_error, std::size_t *length)
+    {
+        std::vector<Token> tokens;
+        source input{ buffer };
+
+        for (auto iterator = input.begin(); iterator != input.end();)
+        {
+            if (*iterator == ' ' || *iterator == '\n')
+            {
+            }
+            else if (std::isdigit(*iterator))
+            {
+                tokens.emplace_back(
+                        Token::TOKEN_NUMBER,
+                        static_cast<std::int32_t>(*iterator - '0'),
+                        iterator.position()
+                );
+            }
+            else if (*iterator == '=')
+            {
+                tokens.emplace_back(Token::TOKEN_EQUALS, iterator.position());
+            }
+            else if (*iterator == '(')
+            {
+                tokens.emplace_back(Token::TOKEN_LEFT_PAREN, iterator.position());
+            }
+            else if (*iterator == ')')
+            {
+                tokens.emplace_back(Token::TOKEN_RIGHT_PAREN, iterator.position());
+            }
+            else if (*iterator == ';')
+            {
+                tokens.emplace_back(Token::TOKEN_SEMICOLON, iterator.position());
+            }
+            else if (*iterator == ',')
+            {
+                tokens.emplace_back(Token::TOKEN_COMMA, iterator.position());
+            }
+            else if (*iterator == '!')
+            {
+                tokens.emplace_back(Token::TOKEN_BANG, iterator.position());
+            }
+            else if (*iterator == '.')
+            {
+                tokens.emplace_back(Token::TOKEN_DOT, iterator.position());
+            }
+            else if (std::isalpha(*iterator))
+            {
+                std::string word;
+                auto i = iterator;
+                while (i != input.end() && std::isalpha(*i))
+                {
+                    word.push_back(*i);
+                    ++i;
+                }
+                if (word == "const")
+                {
+                    tokens.emplace_back(Token::TOKEN_LET, iterator.position());
+                }
+                else if (word == "var")
+                {
+                    tokens.emplace_back(Token::TOKEN_VAR, iterator.position());
+                }
+                else
+                {
+                    tokens.emplace_back(Token::TOKEN_IDENTIFIER, word.c_str(), iterator.position());
+                }
+                iterator = i;
+                continue;
+            }
+            else if (*iterator == '+' || *iterator == '-')
+            {
+                std::string _operator{ *iterator };
+
+                tokens.emplace_back(Token::TOKEN_OPERATOR, _operator.c_str(), iterator.position());
+            }
+            else
+            {
+                *compile_error = CompileError("Unexpected next character", iterator.position());
+                return nullptr;
+            }
+            ++iterator;
+        }
+        Token *target = reinterpret_cast<Token *>(malloc(tokens.size() * sizeof(Token) + sizeof(Token)));
+        int i = 0;
+        for (auto& token : tokens)
+        {
+            target[i] = std::move(token);
+            ++i;
+        }
+        *length = i;
+
+        return target;
+    }
+}

source/main.d

@@ -0,0 +1,33 @@
+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;
+
+int main(string[] args)
+{
+    defaultAllocator = MmapPool.instance;
+
+    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);
+            }
+
+            return generate(arguments.inFile, outputFilename);
+        }
+    );
+}

source/result.cpp

@@ -0,0 +1,25 @@
+#include "elna/result.hpp"
+
+namespace elna
+{
+    CompileError::CompileError(const char *message, const Position position) noexcept
+    {
+        this->message = message;
+        this->position = position;
+    }
+
+    char const *CompileError::what() const noexcept
+    {
+        return this->message;
+    }
+
+    std::size_t CompileError::line() const noexcept
+    {
+        return this->position.line;
+    }
+
+    std::size_t CompileError::column() const noexcept
+    {
+        return this->position.column;
+    }
+}

source/riscv.cpp

@@ -0,0 +1,191 @@
+#include "elna/parser.hpp"
+#include "elna/riscv.hpp"
+#include <type_traits>
+
+namespace elna
+{
+    Instruction::Instruction(BaseOpcode opcode)
+    {
+        this->instruction = static_cast<std::underlying_type<BaseOpcode>::type>(opcode);
+    }
+
+    Instruction& Instruction::i(XRegister rd, Funct3 funct3, XRegister rs1, std::uint32_t immediate)
+    {
+        this->instruction |= (static_cast<std::underlying_type<XRegister>::type>(rd) << 7)
+            | (static_cast<std::underlying_type<Funct3>::type>(funct3) << 12)
+            | (static_cast<std::underlying_type<XRegister>::type>(rs1) << 15)
+            | (immediate << 20);
+
+        return *this;
+    }
+
+    Instruction& Instruction::s(std::uint32_t imm1, Funct3 funct3, XRegister rs1, XRegister rs2)
+    {
+        this->instruction |= ((imm1 & 0b11111) << 7)
+            | (static_cast<std::underlying_type<Funct3>::type>(funct3) << 12)
+            | (static_cast<std::underlying_type<XRegister>::type>(rs1) << 15)
+            | (static_cast<std::underlying_type<XRegister>::type>(rs2) << 20)
+            | ((imm1 & 0b111111100000) << 20);
+
+        return *this;
+    }
+
+    Instruction& Instruction::r(XRegister rd, Funct3 funct3, XRegister rs1, XRegister rs2, Funct7 funct7)
+    {
+        this->instruction |= (static_cast<std::underlying_type<XRegister>::type>(rd) << 7)
+            | (static_cast<std::underlying_type<Funct3>::type>(funct3) << 12)
+            | (static_cast<std::underlying_type<XRegister>::type>(rs1) << 15)
+            | (static_cast<std::underlying_type<XRegister>::type>(rs2) << 20)
+            | (static_cast<std::underlying_type<Funct7>::type>(funct7) << 25);
+
+        return *this;
+    }
+
+    Instruction& Instruction::u(XRegister rd, std::uint32_t imm)
+    {
+        this->instruction |= (static_cast<std::underlying_type<XRegister>::type>(rd) << 7) | (imm << 12);
+
+        return *this;
+    }
+
+    std::uint8_t *Instruction::encode()
+    {
+        return reinterpret_cast<std::uint8_t *>(&this->instruction);
+    }
+
+    void RiscVVisitor::visit(ir::Node *)
+    {
+    }
+
+    void RiscVVisitor::visit(ir::Definition *definition)
+    {
+        const uint stackSize = static_cast<std::uint32_t>(definition->statementsLength * 4 + 12);
+
+        this->instructionsLength += 4;
+        this->instructions = reinterpret_cast<Instruction *>(
+                realloc(this->instructions, this->instructionsLength * sizeof(Instruction)));
+
+        // Prologue.
+        this->instructions[instructionsLength - 4] = Instruction(BaseOpcode::opImm)
+            .i(XRegister::sp, Funct3::addi, XRegister::sp, -stackSize);
+        this->instructions[instructionsLength - 3] = Instruction(BaseOpcode::store)
+            .s(stackSize - 4, Funct3::sw, XRegister::sp, XRegister::s0);
+        this->instructions[instructionsLength - 2] = Instruction(BaseOpcode::store)
+            .s(stackSize - 8, Funct3::sw, XRegister::sp, XRegister::ra);
+        this->instructions[instructionsLength - 1] = Instruction(BaseOpcode::opImm)
+            .i(XRegister::s0, Funct3::addi, XRegister::sp, stackSize);
+
+        for (std::size_t i = 0; i < definition->statementsLength; ++i)
+        {
+            definition->statements[i]->accept(this);
+        }
+        this->registerInUse = true;
+        definition->result->accept(this);
+        this->registerInUse = false;
+
+        this->instructions = reinterpret_cast<Instruction*>(
+            realloc(this->instructions, (this->instructionsLength + 10) * sizeof(Instruction)));
+
+        // Print the result.
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::opImm)
+            .i(XRegister::a1, Funct3::addi, XRegister::a0, 0);
+        this->references[0] = Reference();
+        this->references[0].name = ".CL0";
+        this->references[0].offset = instructionsLength * 4;
+        this->references[0].target = Target::high20;
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::lui).u(XRegister::a5, 0);
+        this->references[1] = Reference();
+        this->references[1].name = ".CL0";
+        this->references[1].offset = instructionsLength * 4;
+        this->references[1].target = Target::lower12i;
+
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::opImm)
+            .i(XRegister::a0, Funct3::addi, XRegister::a5, 0);
+        this->references[2] = Reference();
+        this->references[2].name = "printf";
+        this->references[2].offset = instructionsLength * 4;
+        this->references[2].target = Target::text;
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::auipc).u(XRegister::ra, 0);
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::jalr)
+            .i(XRegister::ra, Funct3::jalr, XRegister::ra, 0);
+        // Set the return value (0).
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::op)
+            .r(XRegister::a0, Funct3::_and, XRegister::zero, XRegister::zero);
+
+        // Epilogue.
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::load)
+            .i(XRegister::s0, Funct3::lw, XRegister::sp, stackSize - 4);
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::load)
+            .i(XRegister::ra, Funct3::lw, XRegister::sp, stackSize - 8);
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::opImm)
+                .i(XRegister::sp, Funct3::addi, XRegister::sp, stackSize);
+        this->instructions[instructionsLength++] = Instruction(BaseOpcode::jalr)
+            .i(XRegister::zero, Funct3::jalr, XRegister::ra, 0);
+    }
+
+    void RiscVVisitor::visit(ir::Operand *operand)
+    {
+        if (dynamic_cast<ir::Variable *>(operand) != nullptr)
+        {
+            return dynamic_cast<ir::Variable *>(operand)->accept(this);
+        }
+        if (dynamic_cast<ir::Number *>(operand) != nullptr)
+        {
+            return dynamic_cast<ir::Number *>(operand)->accept(this);
+        }
+    }
+
+    void RiscVVisitor::visit(ir::Variable *variable)
+    {
+        const auto freeRegister = this->registerInUse ? XRegister::a0 : XRegister::t0;
+
+        ++this->instructionsLength;
+        this->instructions = reinterpret_cast<Instruction *>(
+                realloc(this->instructions, this->instructionsLength * sizeof(Instruction)));
+        // movl -x(%rbp), %eax; where x is a number.
+        this->instructions[instructionsLength - 1] = Instruction(BaseOpcode::load)
+            .i(freeRegister, Funct3::lw, XRegister::sp,
+                static_cast<std::int8_t>(variable->counter * 4));
+    }
+
+    void RiscVVisitor::visit(ir::Number *number)
+    {
+        const auto freeRegister = this->registerInUse ? XRegister::a0 : XRegister::t0;
+
+        ++this->instructionsLength;
+        this->instructions = reinterpret_cast<Instruction *>(
+                realloc(this->instructions, this->instructionsLength * sizeof(Instruction)));
+        this->instructions[this->instructionsLength - 1] =
+            Instruction(BaseOpcode::opImm) // movl $x, %eax; where $x is a number.
+                .i(freeRegister, Funct3::addi, XRegister::zero, number->value);
+    }
+
+    void RiscVVisitor::visit(ir::BinaryExpression *expression)
+    {
+        this->registerInUse = true;
+        expression->lhs->accept(this);
+        this->registerInUse = false;
+        expression->rhs->accept(this);
+
+        this->instructionsLength += 2;
+        this->instructions = reinterpret_cast<Instruction *>(
+                realloc(this->instructions, this->instructionsLength * sizeof(Instruction)));
+        // Calculate the result and assign it to a variable on the stack.
+        switch (expression->_operator)
+        {
+            case BinaryOperator::sum:
+                this->instructions[instructionsLength - 2] = Instruction(BaseOpcode::op)
+                    .r(XRegister::a0, Funct3::add, XRegister::a0, XRegister::t0);
+                break;
+            case BinaryOperator::subtraction:
+                this->instructions[instructionsLength - 2] = Instruction(BaseOpcode::op)
+                    .r(XRegister::a0, Funct3::sub, XRegister::a0, XRegister::t0, Funct7::sub);
+                break;
+        }
+        this->instructions[instructionsLength - 1] = // movl %eax, -x(%rbp); where x is a number.
+            Instruction(BaseOpcode::store)
+                .s(static_cast<std::uint32_t>(this->variableCounter * 4), Funct3::sw, XRegister::sp, XRegister::a0);
+
+        ++this->variableCounter;
+    }
+}

tests/7_member_sum.eln

@@ -0,0 +1 @@
+! 3 + 4 + 5 + 1 + 2 + 4 + 3

tests/const_list.eln

@@ -0,0 +1,3 @@
+const a = 1, b = 2;
+! a + b
+.

tests/expectations/7_member_sum.txt

@@ -0,0 +1 @@
+22

tests/expectations/const_list.txt

@@ -0,0 +1 @@
+3

tests/expectations/left_nested_sum.txt

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

tests/expectations/print_number.txt

@@ -0,0 +1 @@
+3

tests/expectations/subtraction.txt

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

tests/expectations/sum.txt

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

tests/expectations/sums.txt

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

tests/left_nested_sum.eln

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

tests/print_number.eln

@@ -0,0 +1,2 @@
+! 3
+.

tests/runner.cpp

@@ -35,11 +35,48 @@ namespace elna
         }
     }
 
+    static std::string in_build_directory(const std::filesystem::path& path)
+    {
+        return "build/riscv" / path;
+    }
+
+    static int build_test(const std::filesystem::directory_entry& test_entry)
+    {
+        const std::filesystem::path test_filename = test_entry.path().filename();
+
+        std::filesystem::path test_binary = in_build_directory(test_filename);
+        std::filesystem::path test_object = test_binary;
+        test_binary.replace_extension();
+        test_object.replace_extension(".o");
+
+        std::filesystem::remove(test_binary);
+        std::filesystem::remove(test_object);
+
+        auto status = boost::process::system("./build/bin/elna",
+                "-o", test_object.string(), test_entry.path().string());
+        if (status != 0)
+        {
+            return status;
+        }
+        status = boost::process::system(
+                "/opt/riscv/bin/riscv32-unknown-elf-ld",
+                "-o", test_binary.string(),
+                "-L/opt/riscv/lib/gcc/riscv32-unknown-elf/13.2.0/",
+                "-L/opt/riscv/riscv32-unknown-elf/lib",
+                "/opt/riscv/riscv32-unknown-elf/lib/crt0.o",
+                "/opt/riscv/lib/gcc/riscv32-unknown-elf/13.2.0/crtbegin.o",
+               test_object.string(),
+                "--start-group", "-lgcc", "-lc", "-lgloss", "--end-group",
+                "/opt/riscv/lib/gcc/riscv32-unknown-elf/13.2.0/crtend.o"
+        );
+        return status;
+    }
+
     static int run_test(const std::filesystem::directory_entry& test_entry)
     {
         const std::filesystem::path test_filename = test_entry.path().filename();
 
-        std::filesystem::path test_binary = "build/riscv" / test_filename;
+        std::filesystem::path test_binary = in_build_directory(test_filename);
         test_binary.replace_extension();
 
         std::filesystem::path expectation_path = test_entry.path().parent_path() / "expectations" / test_filename;
@@ -75,7 +112,23 @@ namespace elna
             {
                 continue;
             }
-            results.add_exit_code(run_test(test_entry));
+            int status{ 0 };
+
+            try
+            {
+                status = build_test(test_entry);
+            }
+            catch (const boost::process::process_error& exception)
+            {
+                std::cout << exception.what() << std::endl;
+                status = 3;
+                continue;
+            }
+            if (status == 0)
+            {
+                status = run_test(test_entry);
+            }
+            results.add_exit_code(status);
         }
         return results;
     }

tests/subtraction.eln

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

tests/sum.eln

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

tests/sums.eln

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