in-house bytes pkgbuild parser

src/ahriman/core/alpm/bytes_pkgbuild_parser.py

@@ -0,0 +1,183 @@
+#
+# Copyright (c) 2021-2025 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+from __future__ import annotations
+
+from collections import defaultdict
+from collections.abc import Iterator
+from dataclasses import dataclass
+from enum import ReprEnum
+from types import SimpleNamespace
+from typing import Generator, IO, Self
+
+from ahriman.models.pkgbuild_patch import PkgbuildPatch
+
+
+class PkgbuildToken(bytes, ReprEnum):
+
+    Comment = b"#"
+    Assignment = b"="
+    SingleQuote = b"'"
+    DoubleQuote = b"\""
+    Space = b" "
+    NewLine = b"\n"
+
+    ParenthesisOpen = b"("
+    ParenthesisClose = b")"
+
+    FunctionStarts = b"function"
+    FunctionDeclaration = b"()"
+    BraceOpen = b"{"
+    BraceClose = b"}"
+
+
+@dataclass
+class PkgbuildWord:
+
+    word: bytes
+    quote: bytes | None
+
+    @property
+    def closing(self) -> PkgbuildToken | None:
+        if self.quote:
+            return None
+        match self.word:
+            case PkgbuildToken.ParenthesisOpen:
+                return PkgbuildToken.ParenthesisClose
+            case PkgbuildToken.BraceOpen:
+                return PkgbuildToken.BraceClose
+        return None
+
+    @property
+    def original(self) -> bytes:
+        quote = self.quote or b""
+        return quote + self.word + quote
+
+    def __bool__(self) -> bool:
+        return bool(self.original)
+
+
+class BytesPkgbuildParser(Iterator[PkgbuildPatch]):
+
+    def __init__(self, stream: IO[bytes]) -> None:
+        self._io = stream
+
+    def _next(self, *, declaration: bool) -> bytes:
+        while not (token := self._next_token(declaration=declaration)):
+            continue
+        return token
+
+    def _next_token(self, *, declaration: bool) -> bytes:
+        buffer = b""
+        while word := self._next_word():
+            match word:
+                case PkgbuildWord(PkgbuildToken.Comment, None):
+                    self._io.readline()
+
+                case PkgbuildWord(PkgbuildToken.NewLine, None):
+                    if declaration:
+                        buffer = b""
+                    return buffer
+
+                case PkgbuildWord(PkgbuildToken.Assignment, None) if declaration:
+                    return buffer
+
+                case PkgbuildWord(PkgbuildToken.Space, None) if declaration:
+                    if buffer.endswith(PkgbuildToken.FunctionDeclaration):
+                        return buffer
+                    buffer = b""
+                    continue
+
+                case PkgbuildWord(PkgbuildToken.Space, None):
+                    return buffer
+
+                case PkgbuildWord(PkgbuildToken.ParenthesisOpen, None):
+                    buffer += PkgbuildToken.ParenthesisOpen
+                    buffer += b"".join(self._next_words_until(PkgbuildWord(PkgbuildToken.ParenthesisClose, None)))
+
+                case PkgbuildWord(PkgbuildToken.BraceOpen, None):
+                    buffer += PkgbuildToken.BraceOpen
+                    buffer += b"".join(self._next_words_until(PkgbuildWord(PkgbuildToken.BraceClose, None)))
+
+                case PkgbuildWord(token, _):
+                    buffer += token
+
+        raise StopIteration
+
+    def _next_word(self) -> PkgbuildWord:
+        # pass SimpleNamespace as an argument to implement side effects
+        def generator(quote: SimpleNamespace) -> Generator[bytes, None, None]:
+            while token := self._io.read(1):
+                match token:
+                    case (PkgbuildToken.SingleQuote | PkgbuildToken.DoubleQuote) if quote.open is None:
+                        quote.open = token
+                    case closing_quote if closing_quote == quote.open:
+                        return
+                    case part:
+                        yield part
+                        if quote.open is None:
+                            return
+
+            if quote.open is not None:
+                raise ValueError("No closing quotation")
+
+        open_quote = SimpleNamespace(open=None)
+        value = b"".join(generator(open_quote))
+
+        return PkgbuildWord(value, open_quote.open)
+
+    def _next_words_until(self, ending: PkgbuildWord) -> Generator[bytes, None, None]:
+        braces = defaultdict(int)
+        while element := self._next_word():
+            yield element.original
+            match element:
+                case PkgbuildWord(token, None) if braces[token] > 0:
+                    braces[token] -= 1
+                case with_closure if (closing := with_closure.closing) is not None:
+                    braces[closing] += 1
+                case _ if element == ending:
+                    return
+
+        if any(brace for brace in braces.values() if brace > 0):
+            raise ValueError("Unclosed parenthesis and/or braces found")
+        raise ValueError(f"No matching ending element {ending.word} found")
+
+    def parse(self) -> Generator[PkgbuildPatch, None, None]:
+        """
+        parse source stream and yield parsed entries
+
+        Yields:
+            PkgbuildPatch: extracted a PKGBUILD node
+        """
+        yield from self
+
+    def __iter__(self) -> Self:
+        """
+        base iterator method
+
+        Returns:
+            Self: iterator instance
+        """
+        return self
+
+    def __next__(self) -> PkgbuildPatch:
+        key = self._next(declaration=True)
+        value = self._next(declaration=False)
+
+        return PkgbuildPatch(key.decode(encoding="utf8"), value.decode(encoding="utf8"))