Intcode assembler: replace parser with Nimble Parsec

lib/day5/day5.ex

@@ -98,7 +98,7 @@ defmodule Day5 do
     # IO.inspect(memory)
 
     case eval(Enum.drop(memory, ip), memory, parent) do
-      {memory, :halt} ->
+      {_memory, :halt} ->
         send(parent, {:halt, self()})
 
       {memory, :cont, offset} ->
@@ -109,7 +109,7 @@ defmodule Day5 do
     end
   end
 
-  def run(memory, parent, _) do
+  def run(_memory, parent, _) do
     send(parent, {:ok, self()})
   end
 

lib/intcode/assembler.ex

@@ -1,155 +1,227 @@
 defmodule Assembler do
+  import NimbleParsec
+
+  label =
+    ascii_string([?a..?z, ?A..?Z, ?_], min: 1)
+    |> ignore(ascii_char([?:]))
+    |> ignore(repeat(ascii_char([?\s])))
+
+  data_label =
+    label
+    |> choice([
+      integer(min: 1),
+      ignore(ascii_char([?-]))
+      |> integer(min: 1)
+      |> tag(:neg)
+    ])
+    |> tag(:data_label)
+
+  param =
+    optional(ignore(ascii_string([?\s], min: 1)))
+    |> ascii_string([{:not, ?,}], min: 1)
+
+  instruction =
+    ignore(ascii_string([?\s], 2))
+    |> ascii_string([?a..?z], min: 1)
+    |> repeat(param |> ignore(ascii_char([?,])))
+    |> optional(param)
+    |> tag(:insn)
+
+  defparsec(
+    :parse_line,
+    choice([
+      data_label,
+      label |> tag(:label),
+      instruction,
+      eos()
+    ])
+  )
+
   @asm """
-    in #30
-    clt 30 #8 #31
-    jnz 31 #lessThan
-    ceq 30 #8 #31
-    jnz 31 #equal
-    out #1001
+    in res
+    clt $res, _self + 1, 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(@asm)
   end
 
-  def assemble(asm, pad_length \\ 0) do
+  def assemble(asm) do
     {memory, labels} =
       asm
+      |> String.trim_trailing("\n")
       |> String.split("\n")
-      |> Enum.reject(&(String.length(&1) == 0))
-      |> Enum.reduce({[], %{}}, fn line, {memory, labels} ->
-        cond do
-          Regex.match?(~r/^\s+$/, line) ->
-            {memory, labels}
+      |> Enum.map(fn line ->
+        case parse_line(line) do
+          {:ok, res, _, _, _, _} ->
+            res
 
-          String.starts_with?(line, "  ") ->
-            {
-              assemble_instruction(String.slice(line, 2..-1), memory),
-              labels
-            }
-
-          String.ends_with?(line, ":") ->
-            {
-              memory,
-              Map.put(labels, String.slice(line, 0..-2), length(memory))
-            }
-
-          true ->
-            IO.inspect("Ignoring line: #{line}")
+          err ->
+            raise "Unable to parse line: '#{line}':\n#{inspect(err)}"
         end
       end)
+      |> Enum.reduce({[], %{}}, &assemble_line/2)
 
-    memory =
-      Enum.map(memory, fn
-        {:label, name} -> Map.fetch!(labels, name)
-        it -> it
-      end)
+    memory
+    |> Enum.reverse()
+    |> Enum.with_index()
+    |> Enum.map(fn
+      {{:expr, expr}, index} ->
+        ExpressionEvaluator.eval(expr, fn
+          "_self" -> index
+          name -> Map.fetch!(labels, name)
+        end)
 
-    memory =
-      if pad_length > length(memory) do
-        repeat(0, pad_length - length(memory)) ++ memory
-      else
-        memory
-      end
-
-    IO.inspect(labels)
-    Enum.reverse(memory)
+      {it, _} ->
+        it
+    end)
   end
 
-  def repeat(_, 0), do: []
-  def repeat(n, count), do: [n | repeat(n, count - 1)]
+  def assemble_line([], acc), do: acc
 
+  def assemble_line([label: [name]], {memory, labels}) do
+    {
+      memory,
+      Map.put(labels, name, length(memory))
+    }
+  end
+
+  def assemble_line([data_label: [name, value]], {memory, labels}) do
+    {
+      [value | memory],
+      Map.put(labels, name, length(memory))
+    }
+  end
+
+  def assemble_line([insn: insn], {memory, labels}) do
+    {
+      assemble_insn(insn, memory),
+      labels
+    }
+  end
+
+  def assemble_insn(["add" | params], memory) when length(params) == 3 do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+    [dest, b, a, 1 + modes | memory]
+  end
+
+  def assemble_insn(["mul" | params], memory) when length(params) == 3 do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+    [dest, b, a, 2 + modes | memory]
+  end
+
+  def assemble_insn(["in", dest], memory) do
+    {[dest], modes} = parse_params([dest], [:write])
+    [dest, 3 + modes | memory]
+  end
+
+  def assemble_insn(["out", src], memory) do
+    {[src], modes} = parse_params([src], [:read])
+    [src, 4 + modes | memory]
+  end
+
+  def assemble_insn(["jnz" | params], memory) when length(params) == 2 do
+    {[target, dest], modes} = parse_params(params, [:read, :read])
+    [dest, target, 5 + modes | memory]
+  end
+
+  def assemble_insn(["jez" | params], memory) when length(params) == 2 do
+    {[target, dest], modes} = parse_params(params, [:read, :read])
+    [dest, target, 6 + modes | memory]
+  end
+
+  def assemble_insn(["clt" | params], memory) when length(params) == 3 do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+    [dest, b, a, 7 + modes | memory]
+  end
+
+  def assemble_insn(["ceq" | params], memory) when length(params) == 3 do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+    [dest, b, a, 8 + modes | memory]
+  end
+
+  def assemble_insn(["hlt"], memory) do
+    [99 | memory]
+  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])
+    {[{:expr, "label"}, 2, 3], 1000}
+    iex> Assembler.parse_params(["1", "label", "3"], [:read, :read, :write])
+    {[1, {:expr, "label"}, 3], 1100}
+  """
   def parse_params(params, param_types) do
     params
-    |> String.split(" ")
     |> 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+)$/, param)
-            {:label, name}
+            case param do
+              "$" <> param ->
+                {:expr, param}
+
+              _ ->
+                {:expr, param}
+            end
         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
-
-  def assemble_instruction(insn, memory \\ [])
-
-  def assemble_instruction("add " <> params, memory) do
-    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
-
-    [dest, b, a, 1 + modes | memory]
-  end
-
-  def assemble_instruction("mul " <> params, memory) do
-    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
-
-    [dest, b, a, 2 + modes | memory]
-  end
-
-  def assemble_instruction("hlt", memory) do
-    [99 | memory]
-  end
-
-  def assemble_instruction("in " <> params, memory) do
-    {[dest], modes} = parse_params(params, [:write])
-
-    [dest, 3 + modes | memory]
-  end
-
-  def assemble_instruction("out " <> params, memory) do
-    {[val], modes} = parse_params(params, [:read])
-
-    [val, 4 + modes | memory]
-  end
-
-  def assemble_instruction("jnz " <> params, memory) do
-    {[target, dest], modes} = parse_params(params, [:read, :read])
-
-    [dest, target, 5 + modes | memory]
-  end
-
-  def assemble_instruction("jez " <> params, memory) do
-    {[target, dest], modes} = parse_params(params, [:read, :read])
-
-    [dest, target, 6 + modes | memory]
-  end
-
-  def assemble_instruction("clt " <> params, memory) do
-    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
-
-    [dest, b, a, 7 + modes | memory]
-  end
-
-  def assemble_instruction("ceq " <> params, memory) do
-    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
-
-    [dest, b, a, 8 + modes | memory]
-  end
 end

lib/intcode/expression_evaluator.ex

@@ -0,0 +1,106 @@
+defmodule ExpressionEvaluator do
+  import NimbleParsec
+
+  number = integer(min: 1)
+
+  variable = ascii_string([?a..?z, ?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 \\ %{})
+
+  def eval(expr, vars) when is_map(vars) do
+    eval(expr, fn name ->
+      Map.fetch!(vars, name)
+    end)
+  end
+
+  def eval(expr, get_var) when is_function(get_var) do
+    {:ok, expr, _, _, _, _} = parse(expr)
+    do_eval(expr, get_var)
+  end
+
+  def do_eval([{op, [a, b]}], get_var) do
+    do_op(op, do_eval_single(a, get_var), do_eval_single(b, get_var))
+  end
+
+  def do_eval([it], get_var) do
+    do_eval_single(it, get_var)
+  end
+
+  def do_eval_single({:neg, [it]}, get_var) do
+    -1 * do_eval_single(it, get_var)
+  end
+
+  def do_eval_single(it, _) when is_integer(it) do
+    it
+  end
+
+  def do_eval_single(it, get_var) when is_binary(it) do
+    get_var.(it)
+  end
+
+  def do_eval_single(it, get_var) do
+    do_eval([it], get_var)
+  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 +1,112 @@
+defmodule AssemblerTest do
+  use ExUnit.Case
+  doctest Assembler
+  import Assembler
+
+  test "assembles empty program" do
+    assert assemble("") == []
+  end
+
+  test "assembles instructions correctly" do
+    assert assemble("  add 1, 2, 3") == [1101, 1, 2, 3]
+    assert assemble("  mul 1, 2, 3") == [1102, 1, 2, 3]
+    assert assemble("  in 7") == [3, 7]
+    assert assemble("  out 7") == [104, 7]
+    assert assemble("  out $7") == [4, 7]
+    assert assemble("  jnz 1, 2") == [1105, 1, 2]
+    assert assemble("  jnz $1, 2") == [1005, 1, 2]
+    assert assemble("  jez 1, 2") == [1106, 1, 2]
+    assert assemble("  jez $1, 2") == [1006, 1, 2]
+    assert assemble("  clt 1, 2, 3") == [1107, 1, 2, 3]
+    assert assemble("  clt $1, $2, $3") == [7, 1, 2, 3]
+    assert assemble("  ceq 1, 2, 3") == [1108, 1, 2, 3]
+    assert assemble("  ceq $1, $2, $3") == [8, 1, 2, 3]
+    assert assemble("  hlt") == [99]
+  end
+
+  test "assembles simple program" do
+    program = """
+      add 1, 2, 10
+      mul 2, 3, 11
+      add $10, $11, 12
+      hlt
+    """
+
+    assert 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 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 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 assemble(program) == [1101, 1, 2, 3]
+  end
+
+  test "assembles parameters with expressions" do
+    assert assemble("  add 1, _self + 1, 3") == [1101, 1, 3, 3]
+    assert assemble("  add 1, $(_self + 1), 3") == [101, 1, 3, 3]
+
+    assert assemble("""
+             add 1, label + 4 - 2, 3
+           label: 42
+           """) == [1101, 1, 6, 3, 42]
+
+    assert assemble("""
+             add 1, $(label + 4 - 2), 3
+           label: 42
+           """) == [101, 1, 6, 3, 42]
+  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