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defmodule ElixirMathParser do
@moduledoc """
Documentation for `ElixirMathParser`.
"""
alias ElixirMathParser.Math.Rational
alias ElixirMathParser.Math.Calc
alias ElixirMathParser.Math.Conversion
alias ElixirMathParser.Math.Function
defp reduce_to_value({:int, _line, value}, _state), do: {:ok, Rational.new(value)}
defp reduce_to_value({:float, _line, value}, _state) do
{:ok, to_string(value) |> Conversion.literal_float_to_rational()}
end
defp reduce_to_value({:var, line, var}, state) do
if !Map.has_key?(state, var) do
{:error, line, "value not found for " <> to_string(var)}
else
{:ok, state[var]}
end
end
defp reduce_to_value({:add_op, lhs, rhs}, state) do
with {:ok, op1} <- reduce_to_value(lhs, state),
{:ok, op2} <- reduce_to_value(rhs, state) do
{:ok, Rational.add(op1, op2)}
end
end
defp reduce_to_value({:sub_op, lhs, rhs}, state) do
with {:ok, op1} <- reduce_to_value(lhs, state),
{:ok, op2} <- reduce_to_value(rhs, state) do
{:ok, Rational.sub(op1, op2)}
end
end
defp reduce_to_value({:mul_op, lhs, rhs}, state) do
with {:ok, op1} <- reduce_to_value(lhs, state),
{:ok, op2} <- reduce_to_value(rhs, state) do
{:ok, Rational.mult(op1, op2)}
end
end
defp reduce_to_value({:div_op, lhs, rhs}, state) do
with {:ok, op1} <- reduce_to_value(lhs, state),
{:ok, op2} <- reduce_to_value(rhs, state) do
{:ok, Rational.div(op1, op2)}
end
end
defp reduce_to_value({:factor_op, lhs}, state) do
with {:ok, op} <- reduce_to_value(lhs, state),
true <- Rational.denominator(op) == 1,
true <- Rational.numerator(op) >= 0 do
{:ok, Calc.factorial(Rational.numerator(op)) |> Rational.new()}
else
{:error, line, reason} -> {:error, line, reason}
{:error, reason} -> {:error, reason}
false -> {:error, "must have a positive integer for the factorial"}
end
end
defp reduce_to_value({:exp_op, lhs, rhs}, state) do
with {:ok, op1} <- reduce_to_value(lhs, state),
{:ok, op2} <- reduce_to_value(rhs, state) do
{:ok,
Calc.pow(
op1,
if Rational.denominator(op2) == 1 do
Rational.numerator(op2)
else
op2
end
)}
end
end
defp reduce_to_value({:eval_func, {:var, line, var}, params}, state) do
if !Map.has_key?(state, var) do
{:error, line, "function " <> to_string(var) <> " not found"}
else
v = state[var]
# check if the mult is implicit
if Rational.is_rational(v) do
[head | _] = params
reduce_to_value({:mul_op, {:var, line, var}, head}, state)
else
params = Enum.map(params, fn v -> with {:ok, v} <- reduce_to_value(v, state), do: v end)
with {:ok, val} <- Function.eval(v, params) do
{:ok, val}
else
{:error, reason} -> {:error, line, reason}
{:error, line, reason} -> {:error, line, reason}
end
end
end
end
defp evaluate_tree([{:assign, {:var, line, lhs}, rhs} | tail], state) do
with {:ok, val} <- reduce_to_value(rhs, state) do
evaluate_tree(tail, Map.merge(state, %{lhs => val}))
else
{:error, reason} -> {:error, line, reason}
{:error, line, reason} -> {:error, line, reason}
end
end
defp evaluate_tree([{:eval, expr} | tail], state) do
with {:ok, expr} <- reduce_to_value(expr, state) do
IO.puts(expr)
evaluate_tree(tail, state)
end
end
defp evaluate_tree([{:assign_func, {:var, _line, name}, vars, expr} | tail], state) do
fun =
Function.new(
fn params, given ->
state =
Enum.reduce(given, state, fn {v, id}, acc -> Map.merge(acc, %{params[id] => v}) end)
reduce_to_value(expr, state)
end,
Enum.map(vars, fn {:var, _line, name} -> name end)
)
evaluate_tree(tail, Map.merge(state, %{name => fun}))
end
defp evaluate_tree([], state), do: {:ok, state}
def process_tree(tree), do: evaluate_tree(tree, %{})
def parse_file(filename) do
text = File.read!(filename)
with {:ok, tokens, _line} <- :elixir_math_parser_lexer.string(String.to_charlist(text)),
{:ok, tree} <- :elixir_math_parser.parse(tokens) do
process_tree(tree)
end
end
end
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