474 lines
15 KiB
Python
474 lines
15 KiB
Python
import argparse
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import bisect
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import importlib
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import inspect
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import enum
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import os
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import select
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import sys
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import termios
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import textwrap
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import time
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import traceback
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import tty
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import types
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import typing
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from dataclasses import dataclass
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import parser
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# from parser import Token, Grammar, rule, seq
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###############################################################################
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# Parsing Stuff
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###############################################################################
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def trace_state(stack, input, input_index, action):
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print(
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"{stack: <20} {input: <50} {action: <5}".format(
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stack=repr([s[0] for s in stack]),
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input=repr(input[input_index : input_index + 4]),
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action=repr(action),
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)
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)
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@dataclass
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class TokenValue:
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kind: str
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start: int
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end: int
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@dataclass
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class Tree:
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name: str | None
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start: int
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end: int
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children: typing.Tuple["Tree | TokenValue", ...]
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def parse(table: parser.ParseTable, tokens, trace=None) -> typing.Tuple[Tree | None, list[str]]:
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"""Parse the input with the generated parsing table and return the
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concrete syntax tree.
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The parsing table can be generated by GenerateLR0.gen_table() or by any
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of the other generators below. The parsing mechanism never changes, only
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the table generation mechanism.
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input is a list of tokens. Don't stick an end-of-stream marker, I'll stick
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one on for you.
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This is not a *great* parser, it's really just a demo for what you can
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do with the table.
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"""
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input_tokens = tokens.tokens()
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input: list[str] = [t.value for (t, _, _) in input_tokens]
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assert "$" not in input
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input = input + ["$"]
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input_index = 0
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# Our stack is a stack of tuples, where the first entry is the state number
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# and the second entry is the 'value' that was generated when the state was
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# pushed.
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stack: list[typing.Tuple[int, TokenValue | Tree | None]] = [(0, None)]
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while True:
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current_state = stack[-1][0]
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current_token = input[input_index]
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action = table.actions[current_state].get(current_token, parser.Error())
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if trace:
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trace(stack, input, input_index, action)
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match action:
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case parser.Accept():
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result = stack[-1][1]
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assert isinstance(result, Tree)
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return (result, [])
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case parser.Reduce(name=name, count=size, transparent=transparent):
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children: list[TokenValue | Tree] = []
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for _, c in stack[-size:]:
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if c is None:
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continue
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elif isinstance(c, Tree) and c.name is None:
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children.extend(c.children)
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else:
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children.append(c)
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value = Tree(
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name=name if not transparent else None,
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start=children[0].start,
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end=children[-1].end,
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children=tuple(children),
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)
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stack = stack[:-size]
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goto = table.gotos[stack[-1][0]].get(name)
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assert goto is not None
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stack.append((goto, value))
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case parser.Shift(state):
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(kind, start, length) = input_tokens[input_index]
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tval = TokenValue(kind=kind.value, start=start, end=start + length)
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stack.append((state, tval))
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input_index += 1
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case parser.Error():
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if input_index >= len(input_tokens):
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message = "Unexpected end of file"
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start = input_tokens[-1][1]
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else:
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message = f"Syntax error: unexpected symbol {current_token}"
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(_, start, _) = input_tokens[input_index]
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line_index = bisect.bisect_left(tokens.lines, start)
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if line_index == 0:
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col_start = 0
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else:
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col_start = tokens.lines[line_index - 1] + 1
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column_index = start - col_start
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line_index += 1
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error = f"{line_index}:{column_index}: {message}"
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return (None, [error])
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case _:
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raise ValueError(f"Unknown action type: {action}")
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###############################################################################
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# Screen Stuff
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###############################################################################
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# https://en.wikipedia.org/wiki/ANSI_escape_code
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# https://gist.github.com/fnky/458719343aabd01cfb17a3a4f7296797
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class CharColor(enum.IntEnum):
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CHAR_COLOR_DEFAULT = 0
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CHAR_COLOR_BLACK = 30
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CHAR_COLOR_RED = enum.auto()
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CHAR_COLOR_GREEN = enum.auto()
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CHAR_COLOR_YELLOW = enum.auto()
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CHAR_COLOR_BLUE = enum.auto()
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CHAR_COLOR_MAGENTA = enum.auto()
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CHAR_COLOR_CYAN = enum.auto()
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CHAR_COLOR_WHITE = enum.auto() # Really light gray
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CHAR_COLOR_BRIGHT_BLACK = 90 # Really dark gray
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CHAR_COLOR_BRIGHT_RED = enum.auto()
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CHAR_COLOR_BRIGHT_GREEN = enum.auto()
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CHAR_COLOR_BRIGHT_YELLOW = enum.auto()
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CHAR_COLOR_BRIGHT_BLUE = enum.auto()
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CHAR_COLOR_BRIGHT_MAGENTA = enum.auto()
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CHAR_COLOR_BRIGHT_CYAN = enum.auto()
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CHAR_COLOR_BRIGHT_WHITE = enum.auto()
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def ESC(x: bytes) -> bytes:
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return b"\033" + x
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def CSI(x: bytes) -> bytes:
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return ESC(b"[" + x)
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CLEAR = CSI(b"H") + CSI(b"J")
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def enter_alt_screen():
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sys.stdout.buffer.write(CSI(b"?1049h"))
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def leave_alt_screen():
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sys.stdout.buffer.write(CSI(b"?1049l"))
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###############################################################################
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# Dynamic Modules: Detect and Reload Modules when they Change
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###############################################################################
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class DynamicModule:
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file_name: str
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member_name: str | None
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last_time: float | None
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module: types.ModuleType | None
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def __init__(self, file_name, member_name):
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self.file_name = file_name
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self.member_name = member_name
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self.last_time = None
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self.module = None
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self.value = None
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def _predicate(self, member) -> bool:
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if not inspect.isclass(member):
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return False
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assert self.module is not None
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if member.__module__ != self.module.__name__:
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return False
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return True
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def _transform(self, value):
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return value
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def get(self):
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st = os.stat(self.file_name)
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if self.last_time == st.st_mtime:
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assert self.value is not None
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return self.value
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self.value = None
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if self.module is None:
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mod_name = inspect.getmodulename(self.file_name)
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if mod_name is None:
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raise Exception(f"{self.file_name} does not seem to be a module")
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self.module = importlib.import_module(mod_name)
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else:
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importlib.reload(self.module)
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if self.member_name is None:
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classes = inspect.getmembers(self.module, self._predicate)
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if len(classes) == 0:
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raise Exception(f"No grammars found in {self.file_name}")
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if len(classes) > 1:
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raise Exception(
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f"{len(classes)} grammars found in {self.file_name}: {', '.join(c[0] for c in classes)}"
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)
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cls = classes[0][1]
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else:
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cls = getattr(self.module, self.member_name)
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if cls is None:
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raise Exception(f"Cannot find {self.member_name} in {self.file_name}")
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if not self._predicate(cls):
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raise Exception(f"{self.member_name} in {self.file_name} is not suitable")
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self.value = self._transform(cls)
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self.last_time = st.st_mtime
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return self.value
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class DynamicGrammarModule(DynamicModule):
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def __init__(self, file_name, member_name, start_rule, generator):
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super().__init__(file_name, member_name)
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self.start_rule = start_rule
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self.generator = generator
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def _predicate(self, member) -> bool:
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if not super()._predicate(member):
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return False
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if getattr(member, "build_table", None):
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return True
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return False
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def _transform(self, value):
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return value().build_table(start=self.start_rule, generator=self.generator)
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class DynamicLexerModule(DynamicModule):
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def _predicate(self, member) -> bool:
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if not super()._predicate(member):
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return False
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if getattr(member, "tokens", None):
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return True
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return False
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class Harness:
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grammar_file: str
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grammar_member: str | None
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lexer_file: str
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lexer_member: str | None
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start_rule: str | None
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source: str | None
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table: parser.ParseTable | None
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tree: Tree | None
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def __init__(
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self, grammar_file, grammar_member, lexer_file, lexer_member, start_rule, source_path
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):
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self.grammar_file = grammar_file
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self.grammar_member = grammar_member
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self.lexer_file = lexer_file or grammar_file
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self.lexer_member = lexer_member
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self.start_rule = start_rule
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self.source_path = source_path
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self.source = None
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self.table = None
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self.tokens = None
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self.tree = None
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self.errors = []
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self.state_count = 0
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self.average_entries = 0
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self.max_entries = 0
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self.grammar_module = DynamicGrammarModule(
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self.grammar_file, self.grammar_member, self.start_rule, generator=parser.GenerateLALR
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)
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self.lexer_module = DynamicLexerModule(self.lexer_file, self.lexer_member)
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def run(self):
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while True:
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i, _, _ = select.select([sys.stdin], [], [], 1)
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if i:
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k = sys.stdin.read(1)
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print(f"Key {k}\r")
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return
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self.update()
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self.render()
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def load_grammar(self) -> parser.ParseTable:
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return self.grammar_module.get()
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def update(self):
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start_time = time.time()
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try:
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table = self.load_grammar()
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lexer_func = self.lexer_module.get()
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with open(self.source_path, "r", encoding="utf-8") as f:
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self.source = f.read()
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self.tokens = lexer_func(self.source)
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lex_time = time.time()
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# print(f"{tokens.lines}")
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# tokens.dump(end=5)
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(tree, errors) = parse(table, self.tokens, trace=None)
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parse_time = time.time()
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self.tree = tree
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self.errors = errors
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self.parse_elapsed = parse_time - lex_time
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states = table.actions
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self.state_count = len(states)
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self.average_entries = sum(len(row) for row in states) / len(states)
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self.max_entries = max(len(row) for row in states)
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except Exception as e:
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self.tree = None
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self.errors = ["Error loading grammar:"] + [
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" " + l.rstrip() for fl in traceback.format_exception(e) for l in fl.splitlines()
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]
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self.parse_elapsed = time.time() - start_time
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self.state_count = 0
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self.average_entries = 0
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self.max_entries = 0
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def render(self):
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sys.stdout.buffer.write(CLEAR)
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rows, cols = termios.tcgetwinsize(sys.stdout.fileno())
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if self.state_count > 0:
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print(
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f"{self.state_count} states - {self.average_entries:.3} average, {self.max_entries} max - {self.parse_elapsed:.3}s\r"
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)
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else:
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print(f"No table\r")
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print(("\u2500" * cols) + "\r")
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if self.tree is not None:
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lines = []
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self.format_node(lines, self.tree)
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for line in lines[: rows - 3]:
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print(line[:cols] + "\r")
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else:
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wrapper = textwrap.TextWrapper(width=cols)
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lines = [line for error in self.errors for line in wrapper.wrap(error)]
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for line in lines[: rows - 3]:
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print(line + "\r")
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sys.stdout.flush()
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sys.stdout.buffer.flush()
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def format_node(self, lines, node: Tree | TokenValue, indent=0):
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"""Print out an indented concrete syntax tree, from parse()."""
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match node:
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case Tree(name=name, start=start, end=end, children=children):
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lines.append((" " * indent) + f"{name or '???'} [{start}, {end})")
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for child in children:
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self.format_node(lines, child, indent + 2)
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case TokenValue(kind=kind, start=start, end=end):
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assert self.source is not None
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value = self.source[start:end]
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lines.append((" " * indent) + f"{kind}:'{value}' [{start}, {end})")
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def main(args: list[str]):
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parser = argparse.ArgumentParser(description="An interactive debugging harness for grammars")
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parser.add_argument("grammar", help="Path to a python file containing the grammar to load")
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parser.add_argument("source_path", help="Path to an input file to parse")
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parser.add_argument(
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"--grammar-member",
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type=str,
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default=None,
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help="The name of the member in the grammar module to load. The default is to search "
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"the module for a class that looks like a Grammar. You should only need to specify "
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"this if you have more than one grammar in your module, or if it's hidden somehow.",
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)
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parser.add_argument(
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"--start-rule",
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type=str,
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default=None,
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help="The name of the production to start parsing with. The default is the one "
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"specified by the grammar.",
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)
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parser.add_argument(
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"--lexer",
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type=str,
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default=None,
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help="Path to a python file containing the lexer to load. The default is to use the "
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"grammar file.",
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)
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parser.add_argument(
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"--lexer-member",
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type=str,
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default=None,
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help="The name of the lexer in the lexer module to load. The default is to search "
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"the module for a class that looks like a lexer. You should only need to specify this "
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"if you have more than one Lexer in the file, or if your lexer is hidden somehow.",
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)
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parsed = parser.parse_args(args[1:])
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fd = sys.stdin.fileno()
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old_settings = termios.tcgetattr(fd)
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try:
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tty.setraw(fd)
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enter_alt_screen()
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h = Harness(
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grammar_file=parsed.grammar,
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grammar_member=parsed.grammar_member,
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lexer_file=parsed.lexer,
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lexer_member=parsed.lexer_member,
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start_rule=parsed.start_rule,
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source_path=parsed.source_path,
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)
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h.run()
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finally:
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leave_alt_screen()
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termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
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if __name__ == "__main__":
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main(sys.argv)
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