Add Nimble Parsed based arithmetic expression evaluator

lib/intcode/assembler.ex

@@ -1,28 +1,31 @@
 defmodule Assembler do
   @asm """
-    in #30
-    clt 30 #8 #31
-    jnz 31 #lessThan
-    ceq 30 #8 #31
-    jnz 31 #equal
-    out #1001
+    in res
+    clt $res, 8 cmpRes
+    jnz $cmpRes, lessThan
+    ceq $res, 8, cmpRes
+    jnz $cmpRes, equal
+    out 1001
     hlt
 
   lessThan:
-    out #999
+    out 999
     hlt
 
   equal:
-    out #1000
+    out 1000
     hlt
+
+  res: 0
+  cmpRes: 0
   """
   def test do
     @asm
     |> IO.inspect()
-    |> assemble(32)
+    |> assemble()
   end
 
-  def assemble(asm, pad_length \\ 0) do
+  def assemble(asm) do
     {memory, labels} =
       asm
       |> String.split("\n")
@@ -44,109 +47,239 @@ defmodule Assembler do
               Map.put(labels, String.slice(line, 0..-2), length(memory))
             }
 
+          Regex.match?(~r/^\w+: \d+$/, line) ->
+            [name, value] = String.split(line, ": ")
+            value = String.to_integer(value)
+
+            {
+              [value | memory],
+              Map.put(labels, name, length(memory))
+            }
+
           true ->
             IO.inspect("Ignoring line: #{line}")
         end
       end)
 
-    memory =
-      Enum.map(memory, fn
-        {:label, name} -> Map.fetch!(labels, name)
-        it -> it
-      end)
+    # IO.inspect(labels)
 
-    memory =
-      if pad_length > length(memory) do
-        repeat(0, pad_length - length(memory)) ++ memory
-      else
-        memory
-      end
-
-    IO.inspect(labels)
-    Enum.reverse(memory)
+    memory
+    |> Enum.reverse()
+    |> Enum.with_index()
+    |> Enum.map(fn
+      {{:label, name}, index} -> get_label(name, index, labels)
+      {it, _} -> it
+    end)
   end
 
-  def repeat(_, 0), do: []
-  def repeat(n, count), do: [n | repeat(n, count - 1)]
+  @doc """
+  Get the address of a label.
 
+  `_self` is a special label that resolves to the address of where it's being inserted into the program.
+
+  ## Examples
+    iex> Assembler.get_label("test", 1, %{"test" => 14})
+    14
+    iex> Assembler.get_label("_self", 1, %{})
+    1
+  """
+  def get_label(name, index, labels)
+
+  def get_label("_self", index, _) do
+    index
+  end
+
+  def get_label(name, _, labels) do
+    Map.fetch!(labels, name)
+  end
+
+  @doc """
+  Raises the base to to the given power.
+
+  ## Examples
+    iex> Assembler.pow(10, 3)
+    1000
+    iex> Assembler.pow(5, 4)
+    625
+  """
   def pow(base, 1), do: base
   def pow(base, exp), do: base * pow(base, exp - 1)
 
+  @doc """
+  Parses assembly instruction parameter values and modes.
+
+  ## Examples
+    iex> Assembler.parse_params("1, 2, 3", [:read, :read, :read])
+    {[1, 2, 3], 11100}
+    iex> Assembler.parse_params("1, 2, 3", [:read, :read, :write])
+    {[1, 2, 3], 1100}
+    iex> Assembler.parse_params("1, 2, $3", [:read, :read, :write])
+    {[1, 2, 3], 1100}
+    iex> Assembler.parse_params("$1, 2, 3", [:read, :read, :write])
+    {[1, 2, 3], 1000}
+    iex> Assembler.parse_params("$label, 2, 3", [:read, :read, :write])
+    {[{:label, "label"}, 2, 3], 1000}
+    iex> Assembler.parse_params("1, label, 3", [:read, :read, :write])
+    {[1, {:label, "label"}, 3], 1100}
+  """
   def parse_params(params, param_types) do
     params
-    |> String.split(" ")
+    |> String.split(",")
+    |> Enum.map(&String.trim/1)
     |> Enum.zip(param_types)
     |> Enum.with_index()
     |> Enum.map_reduce(0, fn {{param, type}, index}, modes ->
       val =
-        case Regex.run(~r/^#?(\d+)$/, param) do
+        case Regex.run(~r/^\$?(\d+)$/, param) do
           [_, digits] ->
             String.to_integer(digits)
 
           _ ->
-            [_, name] = Regex.run(~r/^#(\w+)$/, param)
+            [_, name] = Regex.run(~r/^\$?(\w+)$/, param)
             {:label, name}
         end
 
       modes =
-        if type == :read && String.starts_with?(param, "#") do
-          modes + pow(10, index + 2)
-        else
-          modes
+        case type do
+          :read ->
+            if String.starts_with?(param, "$") do
+              modes
+            else
+              modes + pow(10, index + 2)
+            end
+
+          _ ->
+            modes
         end
 
       {val, modes}
     end)
   end
 
+  @doc """
+  Assembles the given instruction and adds it to the memory (in reverse order).
+  """
   def assemble_instruction(insn, memory \\ [])
 
+  @doc """
+  Assemble add instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("add 1, 2, 3")
+    [3, 2, 1, 1101]
+  """
   def assemble_instruction("add " <> params, memory) do
     {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
 
     [dest, b, a, 1 + modes | memory]
   end
 
+  @doc """
+  Assemble multiply instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("mul 1, 2, 3")
+    [3, 2, 1, 1102]
+  """
   def assemble_instruction("mul " <> params, memory) do
     {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
 
     [dest, b, a, 2 + modes | memory]
   end
 
+  @doc """
+  Assemble halt instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("hlt")
+    [99]
+  """
   def assemble_instruction("hlt", memory) do
     [99 | memory]
   end
 
+  @doc """
+  Assemble input instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("in 7")
+    [7, 3]
+  """
   def assemble_instruction("in " <> params, memory) do
     {[dest], modes} = parse_params(params, [:write])
 
     [dest, 3 + modes | memory]
   end
 
+  @doc """
+  Assemble input instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("out 7")
+    [7, 104]
+    iex> Assembler.assemble_instruction("out $7")
+    [7, 4]
+  """
   def assemble_instruction("out " <> params, memory) do
     {[val], modes} = parse_params(params, [:read])
 
     [val, 4 + modes | memory]
   end
 
+  @doc """
+  Assemble jump-if-non-zero instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("jnz 1, 2")
+    [2, 1, 105]
+    iex> Assembler.assemble_instruction("jnz $var, 2")
+    [2, {:label, "var"}, 5]
+  """
   def assemble_instruction("jnz " <> params, memory) do
     {[target, dest], modes} = parse_params(params, [:read, :read])
 
     [dest, target, 5 + modes | memory]
   end
 
+  @doc """
+  Assemble jump-if-zero instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("jez 1, 2")
+    [2, 1, 106]
+    iex> Assembler.assemble_instruction("jez $var, 2")
+    [2, {:label, "var"}, 6]
+  """
   def assemble_instruction("jez " <> params, memory) do
     {[target, dest], modes} = parse_params(params, [:read, :read])
 
     [dest, target, 6 + modes | memory]
   end
 
+  @doc """
+  Assemble compare-less-than instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("clt 1, 2, 3")
+    [3, 2, 1, 1107]
+    iex> Assembler.assemble_instruction("clt $1, $2, 3")
+    [3, 2, 1, 7]
+  """
   def assemble_instruction("clt " <> params, memory) do
     {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
 
     [dest, b, a, 7 + modes | memory]
   end
 
+  @doc """
+  Assemble compare-equal instruction.
+
+  ## Examples
+    iex> Assembler.assemble_instruction("ceq 1, 2, 3")
+    [3, 2, 1, 1108]
+    iex> Assembler.assemble_instruction("ceq $1, $2, 3")
+    [3, 2, 1, 8]
+  """
   def assemble_instruction("ceq " <> params, memory) do
     {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
 

lib/intcode/expression_evaluator.ex

@@ -0,0 +1,98 @@
+defmodule ExpressionEvaluator do
+  import NimbleParsec
+
+  number = integer(min: 1)
+
+  variable = ascii_string([?a..?z, ?_], min: 1)
+
+  whitespace = ascii_string([?\s], min: 1)
+
+  factor =
+    choice([
+      ignore(ascii_char([?(]))
+      |> concat(parsec(:expr))
+      |> ignore(ascii_char([?)])),
+      number,
+      variable,
+      ignore(ascii_char([?-]))
+      |> concat(number)
+      |> tag(:neg),
+      ignore(ascii_char([?-]))
+      |> concat(variable)
+      |> tag(:neg)
+    ])
+
+  defcombinatorp(
+    :term,
+    choice([
+      factor
+      |> optional(ignore(whitespace))
+      |> ignore(ascii_char([?*]))
+      |> optional(ignore(whitespace))
+      |> concat(parsec(:term))
+      |> tag(:mul),
+      factor
+      |> optional(ignore(whitespace))
+      |> ignore(ascii_char([?/]))
+      |> optional(ignore(whitespace))
+      |> concat(parsec(:term))
+      |> tag(:div),
+      factor
+    ])
+  )
+
+  defcombinatorp(
+    :expr,
+    choice([
+      parsec(:term)
+      |> optional(ignore(whitespace))
+      |> ignore(ascii_char([?+]))
+      |> optional(ignore(whitespace))
+      |> concat(parsec(:expr))
+      |> tag(:add),
+      parsec(:term)
+      |> optional(ignore(whitespace))
+      |> ignore(ascii_char([?-]))
+      |> optional(ignore(whitespace))
+      |> concat(parsec(:expr))
+      |> tag(:sub),
+      parsec(:term)
+    ])
+  )
+
+  defparsec(:parse, parsec(:expr))
+
+  def eval(expr, vars \\ %{}) do
+    {:ok, expr, _, _, _, _} = parse(expr)
+    do_eval(expr, vars)
+  end
+
+  def do_eval([{op, [a, b]}], vars) do
+    do_op(op, do_eval_single(a, vars), do_eval_single(b, vars))
+  end
+
+  def do_eval([it], vars) do
+    do_eval_single(it, vars)
+  end
+
+  def do_eval_single({:neg, [it]}, vars) do
+    -1 * do_eval_single(it, vars)
+  end
+
+  def do_eval_single(it, _) when is_integer(it) do
+    it
+  end
+
+  def do_eval_single(it, vars) when is_binary(it) do
+    Map.fetch!(vars, it)
+  end
+
+  def do_eval_single(it, vars) do
+    do_eval([it], vars)
+  end
+
+  def do_op(:add, a, b), do: a + b
+  def do_op(:sub, a, b), do: a - b
+  def do_op(:mul, a, b), do: a * b
+  def do_op(:div, a, b), do: floor(a / b)
+end

mix.exs

@@ -21,6 +21,7 @@ defmodule Aoc19.MixProject do
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     [
+      {:nimble_parsec, "~> 0.5.2"}
       # {:dep_from_hexpm, "~> 0.3.0"},
       # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
     ]

mix.lock

@@ -0,0 +1,3 @@
+%{
+  "nimble_parsec": {:hex, :nimble_parsec, "0.5.2", "1d71150d5293d703a9c38d4329da57d3935faed2031d64bc19e77b654ef2d177", [:mix], [], "hexpm"},
+}

test/intcode/assembler_test.exs

@@ -0,0 +1,79 @@
+defmodule AssemblerTest do
+  use ExUnit.Case
+  doctest Assembler
+
+  test "assembles empty program" do
+    assert Assembler.assemble("") == []
+  end
+
+  test "assembles simple program" do
+    program = """
+      add 1, 2, 10
+      mul 2, 3, 11
+      add $10, $11, 12
+      hlt
+    """
+
+    assert Assembler.assemble(program) == [
+             1101,
+             1,
+             2,
+             10,
+             1102,
+             2,
+             3,
+             11,
+             1,
+             10,
+             11,
+             12,
+             99
+           ]
+  end
+
+  test "assembles simple program with a label" do
+    program = """
+      add 1, 2, 10
+      jnz $10, nonZero
+    nonZero:
+      hlt
+    """
+
+    assert Assembler.assemble(program) == [
+             1101,
+             1,
+             2,
+             10,
+             1005,
+             10,
+             7,
+             99
+           ]
+  end
+
+  test "assembles a simple program with a data label" do
+    program = """
+      add 1, 2, var
+      out $var
+    var: 0
+    """
+
+    assert Assembler.assemble(program) == [
+             1101,
+             1,
+             2,
+             6,
+             4,
+             6,
+             0
+           ]
+  end
+
+  test "assembles a program with a _self label" do
+    program = """
+      add 1, 2, _self
+    """
+
+    assert Assembler.assemble(program) == [1101, 1, 2, 3]
+  end
+end

test/intcode/expr_test.exs

@@ -0,0 +1,48 @@
+defmodule ExpressionEvaluatorTest do
+  use ExUnit.Case
+  doctest ExpressionEvaluator
+  import ExpressionEvaluator
+
+  test "evaluates individual numbers" do
+    assert eval("1") == 1
+  end
+
+  test "evaluates negated numbers" do
+    assert eval("-1") == -1
+  end
+
+  test "evaluates variables" do
+    assert eval("x", %{"x" => 3}) == 3
+  end
+
+  test "evaluates negated variables" do
+    assert eval("-x", %{"x" => 3}) == -3
+    assert eval("-x", %{"x" => -3}) == 3
+  end
+
+  test "evaluates binary operations" do
+    assert eval("1 + 2") == 3
+    assert eval("3 - 2") == 1
+    assert eval("3 * 2") == 6
+    assert eval("10 / 2") == 5
+  end
+
+  test "floors division" do
+    assert eval("3 / 2") == 1
+  end
+
+  test "obeys operator precedence" do
+    assert eval("1 + 2 * 3") == 7
+    assert eval("(1 + 2) * 3") == 9
+    assert eval("12 - 6 / 2") == 9
+    assert eval("(12 - 6) / 2") == 3
+  end
+
+  test "evaluates complex expressions" do
+    assert eval("1 + 2 * (3 - ((4 / 2 + 5) * 6))") == -77
+  end
+
+  test "evaluates complex expressions with variables" do
+    assert eval("x * ((4 - y) / 6 + z))", %{"x" => 2, "y" => -8, "z" => 5}) == 14
+  end
+end