lamb/lamb/runner/runner.py

from prompt_toolkit import PromptSession
from prompt_toolkit.formatted_text import FormattedText
from prompt_toolkit import print_formatted_text as printf
import enum
import math
import time

import lamb

from lamb.runner.misc import MacroDef
from lamb.runner.misc import Command
from lamb.runner.misc import StopReason
from lamb.runner import commands as cmd



class Runner:
	def __init__(
		self,
		prompt_session: PromptSession,
		prompt_message
	):
		self.macro_table = {}
		self.prompt_session = prompt_session
		self.prompt_message = prompt_message
		self.parser = lamb.parser.LambdaParser(
			action_func = lamb.nodes.Func.from_parse,
			action_bound = lamb.nodes.Macro.from_parse,
			action_macro = lamb.nodes.Macro.from_parse,
			action_call = lamb.nodes.Call.from_parse,
			action_church = lamb.nodes.Church.from_parse,
			action_macro_def = MacroDef.from_parse,
			action_command = Command.from_parse,
			action_history = lamb.nodes.History.from_parse
		)

		# Maximum amount of reductions.
		# If None, no maximum is enforced.
		# Must be at least 1.
		self.reduction_limit: int | None = 1_000_000

		# Ensure bound variables are unique.
		# This is automatically incremented whenever we make
		# a bound variable.
		self.bound_variable_counter = 0

		# Update iteration after this many iterations
		# Make sure every place value has a non-zero digit
		# so that all digits appear to be changing.
		self.iter_update = 231

		self.history: list[lamb.nodes.Root] = []

	def prompt(self):
		return self.prompt_session.prompt(
			message = self.prompt_message
		)

	def parse(self, line) -> tuple[lamb.nodes.Root | MacroDef | Command, dict]:
		e = self.parser.parse_line(line)

		o = {}
		if isinstance(e, MacroDef):
			e.expr = lamb.nodes.Root(e.expr)
			e.set_runner(self)
			o = lamb.nodes.prepare(e.expr, ban_macro_name = e.label)
		elif isinstance(e, lamb.nodes.Node):
			e = lamb.nodes.Root(e)
			e.set_runner(self)
			o = lamb.nodes.prepare(e)

		return e, o


	def reduce(self, node: lamb.nodes.Root, *, status = {}) -> None:

		warning_text = []

		# Reduction Counter.
		# We also count macro (and church) expansions,
		# and subtract those from the final count.
		k = 0
		macro_expansions = 0

		stop_reason = StopReason.MAX_EXCEEDED
		start_time = time.time()
		out_text = []

		if status["has_history"] and len(self.history) != 0:
			warning_text += [
				("class:code", "$"),
				("class:warn", " will be expanded to "),
				("class:code", str(self.history[-1])),
				("class:warn", "\n")
			]

		only_macro = (
			isinstance(node.left, lamb.nodes.Macro) or
			isinstance(node.left, lamb.nodes.Church)
		)
		if only_macro:
			stop_reason = StopReason.SHOW_MACRO
		m, node = lamb.nodes.expand(node, force_all = only_macro)
		macro_expansions += m


		for i in status["free_variables"]:
			warning_text += [
				("class:warn", "Name "),
				("class:code", i),
				("class:warn", " is a free variable\n"),
			]

		if len(warning_text) != 0:
			printf(FormattedText(warning_text), style = lamb.utils.style)


		while (
				(
					(self.reduction_limit is None) or
					(k < self.reduction_limit)
				) and not only_macro
			):

			# Show reduction count
			if (k >= self.iter_update) and (k % self.iter_update == 0):
				print(f" Reducing... {k:,}", end = "\r")

			try:
				red_type, node = lamb.nodes.reduce(node)
			except KeyboardInterrupt:
				stop_reason = StopReason.INTERRUPT
				break

			# If we can't reduce this expression anymore,
			# it's in beta-normal form.
			if red_type == lamb.nodes.ReductionType.NOTHING:
				stop_reason = StopReason.BETA_NORMAL
				break

			# Count reductions
			k += 1
			if red_type == lamb.nodes.ReductionType.FUNCTION_APPLY:
				macro_expansions += 1

		if k >= self.iter_update:
			# Clear reduction counter if it was printed
			print(" " * round(14 + math.log10(k)), end = "\r")

		if only_macro:
			out_text += [
				("class:ok", f"Displaying macro content")
			]

		else:
			out_text += [
				("class:ok", f"Runtime: "),
				("class:text", f"{time.time() - start_time:.03f} seconds"),

				("class:ok", f"\nExit reason: "),
				stop_reason.value,

				("class:ok", f"\nMacro expansions: "),
				("class:text", f"{macro_expansions:,}"),

				("class:ok", f"\nReductions: "),
				("class:text", f"{k:,}\t"),
				("class:muted", f"(Limit: {self.reduction_limit:,})")
			]

		if (
				stop_reason == StopReason.BETA_NORMAL or
				stop_reason == StopReason.LOOP_DETECTED or
				only_macro
		):
			out_text += [
				("class:ok", "\n\n    => "),
				("class:text", str(node)), # type: ignore
			]

			self.history.append(lamb.nodes.expand(node, force_all = True)[1])


		printf(
			FormattedText(out_text),
			style = lamb.utils.style
		)

	def save_macro(
			self,
			macro: MacroDef,
			*,
			silent = False
		) -> None:
		was_rewritten = macro.label in self.macro_table
		self.macro_table[macro.label] = macro.expr

		if not silent:
			printf(FormattedText([
				("class:text", "Set "),
				("class:code", macro.label),
				("class:text", " to "),
				("class:code", str(macro.expr))
			]), style = lamb.utils.style)

	# Apply a list of definitions
	def run(
			self,
			line: str,
			*,
			silent = False
		) -> None:
		e, o = self.parse(line)

		# If this line is a macro definition, save the macro.
		if isinstance(e, MacroDef):
			self.save_macro(e, silent = silent)

		# If this line is a command, do the command.
		elif isinstance(e, Command):
			if e.name not in cmd.commands:
				printf(
					FormattedText([
						("class:warn", f"Unknown command \"{e.name}\"")
					]),
					style = lamb.utils.style
				)
			else:
				cmd.commands[e.name](e, self)

		# If this line is a plain expression, reduce it.
		elif isinstance(e, lamb.nodes.Node):
			self.reduce(e, status = o)

		# We shouldn't ever get here.
		else:
			raise TypeError(f"I don't know what to do with a {type(e)}")


	def run_lines(self, lines: list[str]):
		for l in lines:
			self.run(l, silent = True)