query_parsing.py

from __future__ import annotations

import re
from dataclasses import dataclass, field
from typing import Iterator, List, Optional
from urllib.parse import urlencode

from rich import print


@dataclass(frozen=True)
class Expression:
    VALUE_PATTERN = re.compile(r"\|?(?P<value>\"(?:[^\"]+)\"|(?:\w+))")
    DEFAULT_FIELD = "*"
    DEFAULT_OPERATOR = "=="

    field: str
    operator: str
    values: List[str]

    @classmethod
    def build(cls, match: re.Match) -> Optional[Expression]:
        data = match.groupdict()
        if data["value"]:
            values = [m.groupdict()["value"].strip("\"'") for m in cls.VALUE_PATTERN.finditer(data["value"])]
        elif rem := data["remainder"].strip("\"'"):
            values = [rem]
        else:
            return None
        return cls(
            field=data["field"] or cls.DEFAULT_FIELD,
            operator=data["operator"] or cls.DEFAULT_OPERATOR,
            values=values,
        )


@dataclass(frozen=True)
class Query:
    QUERY_PATTERN = re.compile(
        r"(?P<field>one|two|three|four)(?::(?P<operator>[=~><!]{0,2})"
        r"(?P<value>(?:\".+\")|(?:.+?(?:\s+|$))))|(?P<remainder>(?:\".+\")|(?:[^\s]+))"
    )

    expressions: List[Expression] = field(default_factory=list)

    @classmethod
    def parse(cls, query: str) -> Query:
        if ":" not in query and '"' not in query:
            query = f'"{query}"'
        matches: Iterator[re.Match] = cls.QUERY_PATTERN.finditer(query)
        expressions = [exp for match in matches if (exp := Expression.build(match))]
        if not expressions:
            expressions = [Expression(Expression.DEFAULT_FIELD, Expression.DEFAULT_OPERATOR, [query])]
        return cls(expressions=expressions)


for raw in (
    "search stuff",
    "one:thing",
    '"search everything"',
    '"search partial" stuff',
    "one:item search stuff",
    'one:thing two:~"This has | a bar" three:<6 four:foo|bar',
):
    query = Query.parse(raw)
    print(f"\nPARSING: {raw=}", urlencode({"q": raw}))
    print(query)