path: root/src/smp/macro_processor.py

import smp.builtins
import traceback
import inspect

from typing import Any
from enum import Enum
from io import StringIO
from contextlib import redirect_stdout


class ParserState(Enum):
    NORMAL = 1
    IN_QUOTES = 2
    IN_MACRO = 3
    IN_MACRO_ARGS = 4
    IN_SPECIAL_MACRO = 5
    IN_SPECIAL_MACRO_EXPRESSION = 6
    IN_CODE = 7
    DNL = 8


def macro_is_whitespace_deleting(s: str) -> bool:
    if len(s) == 0:
        return False
    return s[-1] == "_"


def macro_name_clean(macro_name: str) -> str:
    if macro_is_whitespace_deleting(macro_name):
        macro_name = macro_name[:-1]
    return macro_name


def seek(input: str, start: int, target: str) -> int | None:
    """Seek for a value in a string, consider using startswith instead"""
    from warnings import warn

    warn(
        "seek should be considered replaced with str.startswith",
        DeprecationWarning,
        stacklevel=2,
    )
    input_end = len(input)
    target_end = len(target)

    if input_end < start + target_end:
        return None

    i = 0
    while i < len(target):
        if input[start + i] != target[i]:
            return None
        i += 1

    return start + target_end


class MacroProcessor:
    """All currently defined macros in this MacroProcessor"""

    macros: dict[str, Any]
    """ All macro invocations that has happened """
    macro_invocations: list[tuple[str, list[str]]]
    """ Emitted warnings """
    warnings: list[Any]
    """ Global environment for python execution """
    py_global_env: dict
    py_local_env_alt: dict
    py_local_env_current: dict

    special_macros: dict[str, tuple[Any, Any]]

    start_quote: str = '%"'
    end_quote: str = '"%'

    def __init__(self, prefix=""):
        self.macros = dict()
        self.macro_invocations = list()
        self.warnings = list()
        self.py_global_env = dict()
        self.py_local_env_alt = dict()
        self.py_local_env_current = self.macros
        self.indent_level = ""

        self._define_builtins(self.macros, prefix=prefix)
        self._define_builtins(self.py_local_env_alt, prefix=prefix)

    def _define_builtins(self, env, prefix=""):
        env[f"{prefix}macro_processor"] = self
        env[f"{prefix}define"] = smp.builtins.smp_builtin_define
        env[f"{prefix}undefine"] = smp.builtins.smp_builtin_undefine
        env[f"{prefix}define_array"] = smp.builtins.smp_builtin_define_array
        env[f"{prefix}ifdef"] = smp.builtins.smp_builtin_ifdef
        env[f"{prefix}ifndef"] = smp.builtins.smp_builtin_ifndef
        env[f"{prefix}ifeq"] = smp.builtins.smp_builtin_ifeq
        env[f"{prefix}ifneq"] = smp.builtins.smp_builtin_ifneq
        env[f"{prefix}include"] = smp.builtins.smp_builtin_include
        env[f"{prefix}include_verbatim"] = smp.builtins.smp_builtin_include_verbatim
        env[f"{prefix}shell"] = smp.builtins.smp_builtin_shell
        env[f"{prefix}dumpenv"] = smp.builtins.smp_builtin_dumpenv
        env[f"{prefix}eval"] = smp.builtins.smp_builtin_eval
        env[f"{prefix}array_push"] = smp.builtins.smp_builtin_array_push
        env[f"{prefix}array_each"] = smp.builtins.smp_builtin_array_each
        env[f"{prefix}array_size"] = smp.builtins.smp_builtin_array_size
        env[f"{prefix}explode"] = smp.builtins.smp_builtin_explode
        env[f"{prefix}format_time"] = smp.builtins.smp_builtin_format_time
        env[f"{prefix}html_from_markdown"] = smp.builtins.smp_builtin_html_from_markdown
        env[f"{prefix}wodl"] = smp.builtins.smp_builtin_wodl

    def define_macro_string(self, macro_name, macro_value):
        self.define_macro(macro_name, str(macro_value))

    def define_macro(self, macro_name, macro_value):
        self.macros[macro_name] = macro_value

    def expand_macro(self, macro_name: str, args: list[str] = list()) -> str:
        # Ignore trailing underscore in macro name, the parser will pop a space in front if
        # present, but we should ignore it for finding the macro.
        macro_name = macro_name_clean(macro_name)
        if macro_name not in self.macros:
            if len(args) == 0:
                return macro_name
            out = f"{macro_name}("
            for i, arg in enumerate(args):
                out += self.process_input(arg)
                if i < (len(args) - 1):
                    out += ","
            out += ")"
            return out

        # Strip leading whitespace from arguments
        for arg in args:
            arg = arg.strip()

        # Log macro invokation
        # The fact that we are here, does not ensure that the macro is actually expanded into
        # something useful, just that it exists, and was invoked
        self.macro_invocations.append((macro_name, args))

        macro = self.macros.get(macro_name)

        if callable(macro):
            signature = inspect.signature(macro)
            macro_args: list[Any] = []
            if (
                "macro_processor" in signature.parameters
                or "smp" in signature.parameters
            ):
                macro_args.append(self)
            macro_args.extend(args)
            try:
                return str(macro(*macro_args))
            except Exception as e:
                s = f"{macro_name}({','.join([repr(x) for x in args])})"
                self.warnings.append(f"Error expanding macro {s} ({e})")
                return s
        if isinstance(macro, str):
            expanded = macro
            for i, arg in enumerate(args):
                placeholder = f"${i}"
                expanded = macro.replace(placeholder, arg)
            return self.process_input(expanded)
        return f"{repr(macro)}"

    def process_input(self, input: str):
        """
        I also want to add special syntax for "special blocks",
        I am thinking of two main options, either some macro_names are intercepted, _or_ a special kind of macro can exist like
        These will be on a line-basis, so they simply end on newline
        @if <python-expression>

        @else <python-expression>

        @endif

        @for <python-expression>
        @endfor
        """
        output = ""
        state = ParserState.NORMAL
        macro_name = ""
        macro_args = []
        argument = ""
        py_expr = ""

        skip_next_line_ending = False

        # We should keep track of filename, linenumber, and character number on line here
        # So we can give sensible error messages
        # Probably add to python stack trace?

        quote_level = 0
        parens_level = 0

        i = 0
        while i < len(input):
            c = input[i]
            peek = None if i + 1 >= len(input) else input[i + 1]
            # import sys
            # print(f"[{i:4}] {repr(c):4} -> {repr(peek):4} [{state}] = {repr(output)}", file=sys.stderr)

            if state == ParserState.DNL:
                if c == "\n":
                    state = ParserState.NORMAL
            elif state == ParserState.NORMAL:
                if skip_next_line_ending and (c == "\n"):
                    skip_next_line_ending = False
                    i += 1
                    continue

                if c == "%" and peek == "(":
                    state = ParserState.IN_CODE
                    i += 2
                    continue

                if c == "%" and peek == '"':
                    state = ParserState.IN_QUOTES
                    quote_level += 1
                    i += 1
                elif c.isalnum():
                    state = ParserState.IN_MACRO
                    macro_name += c
                else:
                    output += c

            elif state == ParserState.IN_QUOTES:
                if c == "%" and peek == '"':
                    quote_level += 1
                    i += 1
                    output += '%"'
                elif c == '"' and peek == "%":
                    quote_level -= 1
                    if quote_level == 0:
                        state = ParserState.NORMAL
                    else:
                        output += '"%'
                    i += 1
                else:
                    output += c
            elif state == ParserState.IN_MACRO:
                if c.isalnum() or c == "_":
                    macro_name += c
                elif c == "(":
                    parens_level += 1
                    state = ParserState.IN_MACRO_ARGS
                else:
                    if macro_is_whitespace_deleting(macro_name):
                        if output[-1] == " ":
                            output = output[:-1]
                        macro_name = macro_name_clean(macro_name)

                    if macro_name == "SNNL":
                        skip_next_line_ending = c != "\n"
                    elif macro_name == "DNL":
                        if c != "\n":
                            state = ParserState.DNL
                        macro_name = ""
                        i += 1
                        continue
                    else:
                        expanded = self.expand_macro(macro_name)
                        output += expanded
                        output += c
                    macro_name = ""
                    state = ParserState.NORMAL
            elif state == ParserState.IN_MACRO_ARGS:
                if c == "%" and peek == '"':
                    quote_level += 1
                    i += 2
                    argument += '%"'
                    continue
                elif c == '"' and peek == "%":
                    quote_level -= 1
                    i += 2
                    argument += '"%'
                    continue
                elif quote_level > 0:
                    argument += c
                    i += 1
                    continue

                if (c == ")") and (parens_level == 1):
                    if macro_is_whitespace_deleting(macro_name):
                        if output[-1] == " ":
                            output = output[:-1]
                        macro_name = macro_name_clean(macro_name)
                    parens_level = 0
                    macro_args.append(argument.strip())
                    expanded = self.expand_macro(macro_name, macro_args)
                    output += expanded
                    state = ParserState.NORMAL
                    macro_name = ""
                    macro_args = []
                    argument = ""
                elif (c == ",") and (parens_level == 1):
                    macro_args.append(argument.strip())
                    argument = ""
                else:
                    if c == "(":
                        parens_level += 1
                    if c == ")":
                        parens_level -= 1
                    argument += c
            elif state == ParserState.IN_CODE:
                if c == ")" and peek == "%":
                    try:
                        f = StringIO()
                        with redirect_stdout(f):
                            exec(py_expr, self.py_global_env, self.py_local_env_current)
                        s = f.getvalue()
                        if s != "":
                            output += s
                    except Exception:
                        traceback.print_exc()
                    py_expr = ""
                    state = ParserState.NORMAL
                    i += 1
                else:
                    py_expr += c
            i += 1

        # Handle cases where the text ends with a macro without arguments
        if macro_name != "":
            if macro_is_whitespace_deleting(macro_name):
                if output[-1] == " ":
                    output = output[:-1]
                macro_name = macro_name_clean(macro_name)
            output += self.expand_macro(macro_name)
        return output