python/moz/l10n/formats/properties/parse.py

# Copyright Mozilla Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

from enum import Enum
from re import Match, compile
from typing import Callable

from ...model import Comment, Entry, LinePos, Message, PatternMessage, Resource, Section
from ...util.printf import parse_printf_pattern
from .. import Format


class LineKind(Enum):
    EMPTY = 0
    COMMENT = 1
    KEY = 2
    VALUE = 3


esc_re = compile("\\\\(u[0-9A-Fa-f]{1,4}|.)")


def esc_parse(match: Match[str]) -> str:
    esc = match.group(1)
    if len(esc) > 1 and esc[0] == "u":
        n = int(esc[1:], 16)
        return chr(n)
    elif esc == "t":
        return "\t"
    elif esc == "n":
        return "\n"
    elif esc == "f":
        return "\f"
    elif esc == "r":
        return "\r"
    else:
        return esc


def properties_parse(
    source: bytes | str,
    encoding: str = "utf-8",
    parse_message: Callable[[str], Message] | None = None,
) -> Resource[Message]:
    """
    Parse a .properties file into a message resource.

    By default, all messages are parsed as PatternMessage([str]).
    To customize that, define an appropriate `parse_message(str) -> Message`.

    The parsed resource will not include any metadata.
    """
    if not isinstance(source, str):
        source = source.decode(encoding)
    parser = PropertiesParser(source)
    entries: list[Entry[Message] | Comment] = []
    resource = Resource(Format.properties, [Section((), entries)])

    start_line = 0
    comment = ""
    comment_linepos: LinePos | None = None
    prev_linepos: LinePos | None = None
    entry: Entry[Message] | None = None
    for kind, line, value in parser:
        if kind == LineKind.VALUE:
            assert entry
            if parse_message:
                entry.value = parse_message(value)
            else:
                assert isinstance(entry.value, PatternMessage)
                entry.value.pattern.append(value)
            if entry.linepos and line > entry.linepos.key:
                entry.linepos.value = line
                entry.linepos.end = line + 1
            entry = None
        else:
            if prev_linepos:
                prev_linepos.end = max(prev_linepos.end, line)
                prev_linepos = None
            entry = None
            if kind == LineKind.KEY:
                entry = Entry(
                    id=(value,),
                    value=PatternMessage([]),
                    comment=comment,
                    linepos=LinePos(start_line or line, line, line, line + 1),
                )
                prev_linepos = entry.linepos
                entries.append(entry)
                comment = ""
                comment_linepos = None
                start_line = 0
            elif kind == LineKind.COMMENT:
                if comment:
                    comment += "\n" + value
                    assert comment_linepos
                    comment_linepos.end = line + 1
                else:
                    comment = value
                    start_line = line
                    comment_linepos = LinePos(line, line, line, line + 1)
            elif comment:
                # empty line or EOF after a comment
                if entries or resource.comment:
                    entries.append(Comment(comment=comment, linepos=comment_linepos))
                else:
                    resource.comment = comment
                comment = ""
                comment_linepos = None
                start_line = 0
    return resource


def properties_parse_message(
    source: str, *, printf_placeholders: bool = False
) -> PatternMessage:
    """
    Parse a .properties message value.

    If `printf_placeholders` is enabled,
    printf specifiers are parsed as variables.
    """
    parser = PropertiesParser(source)
    parser.at_value = True
    (kind, _, value), *rest = parser
    if kind != LineKind.VALUE or not all(kind == LineKind.EMPTY for kind, _, _ in rest):
        raise ValueError("Source is not a .properties value")
    if printf_placeholders:
        return PatternMessage(list(parse_printf_pattern(source)))
    return PatternMessage([value])


class PropertiesParser:
    def __init__(self, source: str) -> None:
        self.source = source
        self.pos = 0
        self.line_pos = 1
        self.at_value = False
        self.done = False

    def __iter__(self) -> PropertiesParser:
        return self

    def __next__(self) -> tuple[LineKind, int, str]:
        if self.done:
            raise StopIteration

        lp = self.line_pos
        self.ws()
        if self.pos == len(self.source):
            self.done = True
            return LineKind.EMPTY, lp, ""

        if self.nl():
            self.at_value = False
            return LineKind.EMPTY, lp, ""

        if self.at_value:
            # value
            self.at_value = False
            line_start = start = self.pos
            at_escape = False
            at_cr = False
            idx = -1
            lines: list[str] = []
            for idx, ch in enumerate(self.source[start:]):
                if ch == "\n" or ch == "\r":
                    if at_escape:
                        at_escape = False
                        self.line_pos += 1
                        end = start + idx - 1
                        lines.append(self.source[line_start:end])
                        at_cr = ch == "\r"
                        line_start = start + idx + 1
                    elif ch == "\n" and at_cr:
                        at_cr = False
                        line_start = start + idx + 1
                    else:
                        idx -= 1
                        break
                else:
                    if at_cr:
                        at_cr = False
                    if at_escape:
                        at_escape = False
                    elif ch == "\\":
                        at_escape = True
            self.pos = end = start + idx + 1
            lines.append(self.source[line_start:end])
            self.nl()
            value = "".join(
                esc_re.sub(esc_parse, line.lstrip("\f\t ")) for line in lines
            )
            return LineKind.VALUE, lp, value

        if self.source.startswith(("#", "!"), self.pos):
            # comment
            self.pos += 1
            if self.source.startswith(" ", self.pos):
                # Ignore one space after #, if present.
                self.pos += 1
            start = self.pos
            idx = -1
            for idx, ch in enumerate(self.source[start:]):
                if ch == "\n" or ch == "\r":
                    idx -= 1
                    break
            end = self.pos = start + idx + 1
            self.nl()
            return LineKind.COMMENT, lp, self.source[start:end]

        # key
        start = self.pos
        at_escape = False
        idx = -1
        for idx, ch in enumerate(self.source[start:]):
            if at_escape:
                at_escape = False
            elif ch == "\\":
                at_escape = True
            elif ch in {"\n", "\r", "\t", "\f", " ", "=", ":"}:
                idx -= 1
                break
        end = self.pos = start + idx + 1
        self.ws()
        if self.source.startswith(("=", ":"), self.pos):
            self.pos += 1
        self.at_value = True
        return LineKind.KEY, lp, esc_re.sub(esc_parse, self.source[start:end])

    def nl(self) -> bool:
        if self.source.startswith("\n", self.pos):
            self.pos += 1
            self.line_pos += 1
            return True
        elif self.source.startswith("\r", self.pos):
            self.pos += 1
            self.line_pos += 1
            if self.source.startswith("\n", self.pos):
                self.pos += 1
            return True
        return False

    def ws(self) -> None:
        for ch in self.source[self.pos :]:
            if ch in {" ", "\t", "\f"}:
                self.pos += 1
            else:
                break