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

@@ -1,7 +1,45 @@
 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 res
-    clt $res, 8 cmpRes
+    clt $res, _self + 1, cmpRes
     jnz $cmpRes, lessThan
     ceq $res, 8, cmpRes
     jnz $cmpRes, equal
@@ -20,77 +58,105 @@ defmodule Assembler do
   cmpRes: 0
   """
   def test do
-    @asm
+    assemble(@asm)
-    |> IO.inspect()
-    |> assemble()
   end
 
   def assemble(asm) do
     {memory, labels} =
       asm
+      |> String.trim_trailing("\n")
       |> String.split("\n")
-      |> Enum.reject(&(String.length(&1) == 0))
+      |> Enum.map(fn line ->
-      |> Enum.reduce({[], %{}}, fn line, {memory, labels} ->
+        case parse_line(line) do
-        cond do
+          {:ok, res, _, _, _, _} ->
-          Regex.match?(~r/^\s+$/, line) ->
+            res
-            {memory, labels}
 
-          String.starts_with?(line, "  ") ->
+          err ->
-            {
+            raise "Unable to parse line: '#{line}':\n#{inspect(err)}"
-              assemble_instruction(String.slice(line, 2..-1), memory),
-              labels
-            }
-
-          String.ends_with?(line, ":") ->
-            {
-              memory,
-              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)
-
+      |> Enum.reduce({[], %{}}, &assemble_line/2)
-    # IO.inspect(labels)
 
     memory
     |> Enum.reverse()
     |> Enum.with_index()
     |> Enum.map(fn
-      {{:label, name}, index} -> get_label(name, index, labels)
+      {{:expr, expr}, index} ->
-      {it, _} -> it
+        ExpressionEvaluator.eval(expr, fn
+          "_self" -> index
+          name -> Map.fetch!(labels, name)
+        end)
+
+      {it, _} ->
+        it
     end)
   end
 
-  @doc """
+  def assemble_line([], acc), do: acc
-  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.
+  def assemble_line([label: [name]], {memory, labels}) do
-
+    {
-  ## Examples
+      memory,
-    iex> Assembler.get_label("test", 1, %{"test" => 14})
+      Map.put(labels, name, length(memory))
-    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
+  def assemble_line([data_label: [name, value]], {memory, labels}) do
-    Map.fetch!(labels, name)
+    {
+      [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 """
@@ -109,23 +175,21 @@ defmodule Assembler do
   Parses assembly instruction parameter values and modes.
 
   ## Examples
-    iex> Assembler.parse_params("1, 2, 3", [:read, :read, :read])
+    iex> Assembler.parse_params(["1", "2", "3"], [:read, :read, :read])
     {[1, 2, 3], 11100}
-    iex> Assembler.parse_params("1, 2, 3", [:read, :read, :write])
+    iex> Assembler.parse_params(["1", "2", "3"], [:read, :read, :write])
     {[1, 2, 3], 1100}
-    iex> Assembler.parse_params("1, 2, $3", [:read, :read, :write])
+    iex> Assembler.parse_params(["1", "2", "$3"], [:read, :read, :write])
     {[1, 2, 3], 1100}
-    iex> Assembler.parse_params("$1, 2, 3", [:read, :read, :write])
+    iex> Assembler.parse_params(["$1", "2", "3"], [:read, :read, :write])
     {[1, 2, 3], 1000}
-    iex> Assembler.parse_params("$label, 2, 3", [:read, :read, :write])
+    iex> Assembler.parse_params(["$label", "2", "3"], [:read, :read, :write])
-    {[{:label, "label"}, 2, 3], 1000}
+    {[{:expr, "label"}, 2, 3], 1000}
-    iex> Assembler.parse_params("1, label, 3", [:read, :read, :write])
+    iex> Assembler.parse_params(["1", "label", "3"], [:read, :read, :write])
-    {[1, {:label, "label"}, 3], 1100}
+    {[1, {:expr, "label"}, 3], 1100}
   """
   def parse_params(params, param_types) do
     params
-    |> String.split(",")
-    |> Enum.map(&String.trim/1)
     |> Enum.zip(param_types)
     |> Enum.with_index()
     |> Enum.map_reduce(0, fn {{param, type}, index}, modes ->
@@ -135,8 +199,13 @@ defmodule Assembler do
             String.to_integer(digits)
 
           _ ->
-            [_, name] = Regex.run(~r/^\$?(\w+)$/, param)
+            case param do
-            {:label, name}
+              "$" <> param ->
+                {:expr, param}
+
+              _ ->
+                {:expr, param}
+            end
         end
 
       modes =
@@ -155,134 +224,4 @@ defmodule Assembler do
       {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])
-
-    [dest, b, a, 8 + modes | memory]
-  end
 end

lib/intcode/expression_evaluator.ex

@@ -3,7 +3,7 @@ defmodule ExpressionEvaluator do
 
   number = integer(min: 1)
 
-  variable = ascii_string([?a..?z, ?_], min: 1)
+  variable = ascii_string([?a..?z, ?A..?Z, ?_], min: 1)
 
   whitespace = ascii_string([?\s], min: 1)
 
@@ -62,33 +62,41 @@ defmodule ExpressionEvaluator do
 
   defparsec(:parse, parsec(:expr))
 
-  def eval(expr, vars \\ %{}) do
+  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, vars)
+    do_eval(expr, get_var)
   end
 
-  def do_eval([{op, [a, b]}], vars) do
+  def do_eval([{op, [a, b]}], get_var) do
-    do_op(op, do_eval_single(a, vars), do_eval_single(b, vars))
+    do_op(op, do_eval_single(a, get_var), do_eval_single(b, get_var))
   end
 
-  def do_eval([it], vars) do
+  def do_eval([it], get_var) do
-    do_eval_single(it, vars)
+    do_eval_single(it, get_var)
   end
 
-  def do_eval_single({:neg, [it]}, vars) do
+  def do_eval_single({:neg, [it]}, get_var) do
-    -1 * do_eval_single(it, vars)
+    -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, vars) when is_binary(it) do
+  def do_eval_single(it, get_var) when is_binary(it) do
-    Map.fetch!(vars, it)
+    get_var.(it)
   end
 
-  def do_eval_single(it, vars) do
+  def do_eval_single(it, get_var) do
-    do_eval([it], vars)
+    do_eval([it], get_var)
   end
 
   def do_op(:add, a, b), do: a + b

test/intcode/assembler_test.exs

@@ -1,9 +1,27 @@
 defmodule AssemblerTest do
   use ExUnit.Case
   doctest Assembler
+  import Assembler
 
   test "assembles empty program" do
-    assert Assembler.assemble("") == []
+    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
@@ -14,7 +32,7 @@ defmodule AssemblerTest do
       hlt
     """
 
-    assert Assembler.assemble(program) == [
+    assert assemble(program) == [
              1101,
              1,
              2,
@@ -39,7 +57,7 @@ defmodule AssemblerTest do
       hlt
     """
 
-    assert Assembler.assemble(program) == [
+    assert assemble(program) == [
              1101,
              1,
              2,
@@ -58,7 +76,7 @@ defmodule AssemblerTest do
     var: 0
     """
 
-    assert Assembler.assemble(program) == [
+    assert assemble(program) == [
              1101,
              1,
              2,
@@ -74,6 +92,21 @@ defmodule AssemblerTest do
       add 1, 2, _self
     """
 
-    assert Assembler.assemble(program) == [1101, 1, 2, 3]
+    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