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|
"""
A self-contained **pure-Python 3.9+** utility for applying human-readable
“pseudo-diff” patch files to a collection of text files.
"""
from __future__ import annotations
import pathlib
from dataclasses import dataclass, field
from enum import Enum
from typing import (
Callable,
Dict,
List,
Optional,
Tuple,
Union,
)
class ActionType(str, Enum):
ADD = "add"
DELETE = "delete"
UPDATE = "update"
@dataclass
class FileChange:
type: ActionType
old_content: Optional[str] = None
new_content: Optional[str] = None
move_path: Optional[str] = None
@dataclass
class Commit:
changes: Dict[str, FileChange] = field(default_factory=dict)
class DiffError(ValueError):
"""Any problem detected while parsing or applying a patch."""
@dataclass
class Chunk:
orig_index: int = -1
del_lines: List[str] = field(default_factory=list)
ins_lines: List[str] = field(default_factory=list)
@dataclass
class PatchAction:
type: ActionType
new_file: Optional[str] = None
chunks: List[Chunk] = field(default_factory=list)
move_path: Optional[str] = None
@dataclass
class Patch:
actions: Dict[str, PatchAction] = field(default_factory=dict)
@dataclass
class Parser:
current_files: Dict[str, str]
lines: List[str]
index: int = 0
patch: Patch = field(default_factory=Patch)
fuzz: int = 0
def _cur_line(self) -> str:
if self.index >= len(self.lines):
raise DiffError("Unexpected end of input while parsing patch")
return self.lines[self.index]
@staticmethod
def _norm(line: str) -> str:
"""Strip CR so comparisons work for both LF and CRLF input."""
return line.rstrip("\r")
def is_done(self, prefixes: Optional[Tuple[str, ...]] = None) -> bool:
if self.index >= len(self.lines):
return True
if (
prefixes
and len(prefixes) > 0
and self._norm(self._cur_line()).startswith(prefixes)
):
return True
return False
def startswith(self, prefix: Union[str, Tuple[str, ...]]) -> bool:
return self._norm(self._cur_line()).startswith(prefix)
def read_str(self, prefix: str) -> str:
"""
Consume the current line if it starts with *prefix* and return the text
**after** the prefix. Raises if prefix is empty.
"""
if prefix == "":
raise ValueError("read_str() requires a non-empty prefix")
if self._norm(self._cur_line()).startswith(prefix):
text = self._cur_line()[len(prefix) :]
self.index += 1
return text
return ""
def read_line(self) -> str:
"""Return the current raw line and advance."""
line = self._cur_line()
self.index += 1
return line
def parse(self) -> None:
while not self.is_done(("*** End Patch",)):
path = self.read_str("*** Update File: ")
if path:
if path in self.patch.actions:
raise DiffError(f"Duplicate update for file: {path}")
move_to = self.read_str("*** Move to: ")
if path not in self.current_files:
raise DiffError(f"Update File Error - missing file: {path}")
text = self.current_files[path]
action = self._parse_update_file(text)
action.move_path = move_to or None
self.patch.actions[path] = action
continue
path = self.read_str("*** Delete File: ")
if path:
if path in self.patch.actions:
raise DiffError(f"Duplicate delete for file: {path}")
if path not in self.current_files:
raise DiffError(f"Delete File Error - missing file: {path}")
self.patch.actions[path] = PatchAction(type=ActionType.DELETE)
continue
path = self.read_str("*** Add File: ")
if path:
if path in self.patch.actions:
raise DiffError(f"Duplicate add for file: {path}")
if path in self.current_files:
raise DiffError(f"Add File Error - file already exists: {path}")
self.patch.actions[path] = self._parse_add_file()
continue
raise DiffError(f"Unknown line while parsing: {self._cur_line()}")
if not self.startswith("*** End Patch"):
raise DiffError("Missing *** End Patch sentinel")
self.index += 1
def _parse_update_file(self, text: str) -> PatchAction:
action = PatchAction(type=ActionType.UPDATE)
lines = text.split("\n")
index = 0
while not self.is_done(
(
"*** End Patch",
"*** Update File:",
"*** Delete File:",
"*** Add File:",
"*** End of File",
)
):
def_str = self.read_str("@@ ")
section_str = ""
if not def_str and self._norm(self._cur_line()) == "@@":
section_str = self.read_line()
if not (def_str or section_str or index == 0):
raise DiffError(f"Invalid line in update section:\n{self._cur_line()}")
if def_str.strip():
found = False
if def_str not in lines[:index]:
for i, s in enumerate(lines[index:], index):
if s == def_str:
index = i + 1
found = True
break
if not found and def_str.strip() not in [
s.strip() for s in lines[:index]
]:
for i, s in enumerate(lines[index:], index):
if s.strip() == def_str.strip():
index = i + 1
self.fuzz += 1
found = True
break
next_ctx, chunks, end_idx, eof = peek_next_section(self.lines, self.index)
new_index, fuzz = find_context(lines, next_ctx, index, eof)
if new_index == -1:
ctx_txt = "\n".join(next_ctx)
raise DiffError(
f"Invalid {'EOF ' if eof else ''}context at {index}:\n{ctx_txt}"
)
self.fuzz += fuzz
for ch in chunks:
ch.orig_index += new_index
action.chunks.append(ch)
index = new_index + len(next_ctx)
self.index = end_idx
return action
def _parse_add_file(self) -> PatchAction:
lines: List[str] = []
while not self.is_done(
("*** End Patch", "*** Update File:", "*** Delete File:", "*** Add File:")
):
s = self.read_line()
if not s.startswith("+"):
raise DiffError(f"Invalid Add File line (missing '+'): {s}")
lines.append(s[1:])
return PatchAction(type=ActionType.ADD, new_file="\n".join(lines))
def find_context_core(
lines: List[str], context: List[str], start: int
) -> Tuple[int, int]:
if not context:
return start, 0
for i in range(start, len(lines)):
if lines[i : i + len(context)] == context:
return i, 0
for i in range(start, len(lines)):
if [s.rstrip() for s in lines[i : i + len(context)]] == [
s.rstrip() for s in context
]:
return i, 1
for i in range(start, len(lines)):
if [s.strip() for s in lines[i : i + len(context)]] == [
s.strip() for s in context
]:
return i, 100
return -1, 0
def find_context(
lines: List[str], context: List[str], start: int, eof: bool
) -> Tuple[int, int]:
if eof:
new_index, fuzz = find_context_core(lines, context, len(lines) - len(context))
if new_index != -1:
return new_index, fuzz
new_index, fuzz = find_context_core(lines, context, start)
return new_index, fuzz + 10_000
return find_context_core(lines, context, start)
def peek_next_section(
lines: List[str], index: int
) -> Tuple[List[str], List[Chunk], int, bool]:
old: List[str] = []
del_lines: List[str] = []
ins_lines: List[str] = []
chunks: List[Chunk] = []
mode = "keep"
orig_index = index
while index < len(lines):
s = lines[index]
if s.startswith(
(
"@@",
"*** End Patch",
"*** Update File:",
"*** Delete File:",
"*** Add File:",
"*** End of File",
)
):
break
if s == "***":
break
if s.startswith("***"):
raise DiffError(f"Invalid Line: {s}")
index += 1
last_mode = mode
if s == "":
s = " "
if s[0] == "+":
mode = "add"
elif s[0] == "-":
mode = "delete"
elif s[0] == " ":
mode = "keep"
else:
raise DiffError(f"Invalid Line: {s}")
s = s[1:]
if mode == "keep" and last_mode != mode:
if ins_lines or del_lines:
chunks.append(
Chunk(
orig_index=len(old) - len(del_lines),
del_lines=del_lines,
ins_lines=ins_lines,
)
)
del_lines, ins_lines = [], []
if mode == "delete":
del_lines.append(s)
old.append(s)
elif mode == "add":
ins_lines.append(s)
elif mode == "keep":
old.append(s)
if ins_lines or del_lines:
chunks.append(
Chunk(
orig_index=len(old) - len(del_lines),
del_lines=del_lines,
ins_lines=ins_lines,
)
)
if index < len(lines) and lines[index] == "*** End of File":
index += 1
return old, chunks, index, True
if index == orig_index:
raise DiffError("Nothing in this section")
return old, chunks, index, False
def _get_updated_file(text: str, action: PatchAction, path: str) -> str:
if action.type is not ActionType.UPDATE:
raise DiffError("_get_updated_file called with non-update action")
orig_lines = text.split("\n")
dest_lines: List[str] = []
orig_index = 0
for chunk in action.chunks:
if chunk.orig_index > len(orig_lines):
raise DiffError(
f"{path}: chunk.orig_index {chunk.orig_index} exceeds file length"
)
if orig_index > chunk.orig_index:
raise DiffError(
f"{path}: overlapping chunks at {orig_index} > {chunk.orig_index}"
)
dest_lines.extend(orig_lines[orig_index : chunk.orig_index])
orig_index = chunk.orig_index
dest_lines.extend(chunk.ins_lines)
orig_index += len(chunk.del_lines)
dest_lines.extend(orig_lines[orig_index:])
return "\n".join(dest_lines)
def patch_to_commit(patch: Patch, orig: Dict[str, str]) -> Commit:
commit = Commit()
for path, action in patch.actions.items():
if action.type is ActionType.DELETE:
commit.changes[path] = FileChange(
type=ActionType.DELETE, old_content=orig[path]
)
elif action.type is ActionType.ADD:
if action.new_file is None:
raise DiffError("ADD action without file content")
commit.changes[path] = FileChange(
type=ActionType.ADD, new_content=action.new_file
)
elif action.type is ActionType.UPDATE:
new_content = _get_updated_file(orig[path], action, path)
commit.changes[path] = FileChange(
type=ActionType.UPDATE,
old_content=orig[path],
new_content=new_content,
move_path=action.move_path,
)
return commit
def text_to_patch(text: str, orig: Dict[str, str]) -> Tuple[Patch, int]:
lines = text.splitlines()
if (
len(lines) < 2
or not Parser._norm(lines[0]).startswith("*** Begin Patch")
or Parser._norm(lines[-1]) != "*** End Patch"
):
raise DiffError("Invalid patch text - missing sentinels")
parser = Parser(current_files=orig, lines=lines, index=1)
parser.parse()
return parser.patch, parser.fuzz
def identify_files_needed(text: str) -> List[str]:
lines = text.splitlines()
return [
line[len("*** Update File: ") :]
for line in lines
if line.startswith("*** Update File: ")
] + [
line[len("*** Delete File: ") :]
for line in lines
if line.startswith("*** Delete File: ")
]
def identify_files_added(text: str) -> List[str]:
lines = text.splitlines()
return [
line[len("*** Add File: ") :]
for line in lines
if line.startswith("*** Add File: ")
]
def load_files(paths: List[str], open_fn: Callable[[str], str]) -> Dict[str, str]:
return {path: open_fn(path) for path in paths}
def apply_commit(
commit: Commit,
write_fn: Callable[[str, str], None],
remove_fn: Callable[[str], None],
) -> None:
for path, change in commit.changes.items():
if change.type is ActionType.DELETE:
remove_fn(path)
elif change.type is ActionType.ADD:
if change.new_content is None:
raise DiffError(f"ADD change for {path} has no content")
write_fn(path, change.new_content)
elif change.type is ActionType.UPDATE:
if change.new_content is None:
raise DiffError(f"UPDATE change for {path} has no new content")
target = change.move_path or path
write_fn(target, change.new_content)
if change.move_path:
remove_fn(path)
def process_patch(
text: str,
open_fn: Callable[[str], str],
write_fn: Callable[[str, str], None],
remove_fn: Callable[[str], None],
) -> str:
if not text.startswith("*** Begin Patch"):
raise DiffError("Patch text must start with *** Begin Patch")
paths = identify_files_needed(text)
orig = load_files(paths, open_fn)
patch, _fuzz = text_to_patch(text, orig)
commit = patch_to_commit(patch, orig)
apply_commit(commit, write_fn, remove_fn)
return "Done!"
def open_file(path: str) -> str:
with open(path, "rt", encoding="utf-8") as fh:
return fh.read()
def write_file(path: str, content: str) -> None:
target = pathlib.Path(path)
target.parent.mkdir(parents=True, exist_ok=True)
with target.open("wt", encoding="utf-8") as fh:
fh.write(content)
def remove_file(path: str) -> None:
pathlib.Path(path).unlink(missing_ok=True)
def main() -> None:
import sys
patch_text = sys.stdin.read()
if not patch_text:
print("Please pass patch text through stdin", file=sys.stderr)
return
try:
result = process_patch(patch_text, open_file, write_file, remove_file)
except DiffError as exc:
print(exc, file=sys.stderr)
return
print(result)
if __name__ == "__main__":
main()
|
