Added an explicit index type for object IDs.

[didex.git] / didex / index.py

import struct, contextlib, math
from . import db, lib
from .db import bd, txnfun, dloopfun

__all__ = ["maybe", "t_int", "t_uint", "t_dbid", "t_float", "t_str", "ordered"]

deadlock = bd.DBLockDeadlockError
notfound = bd.DBNotFoundError

class simpletype(object):
    def __init__(self, encode, decode):
        self.enc = encode
        self.dec = decode

    def encode(self, ob):
        return self.enc(ob)
    def decode(self, dat):
        return self.dec(dat)
    def compare(self, a, b):
        if a < b:
            return -1
        elif a > b:
            return 1
        else:
            return 0

    @classmethod
    def struct(cls, fmt):
        return cls(lambda ob: struct.pack(fmt, ob),
                   lambda dat: struct.unpack(fmt, dat)[0])

class maybe(object):
    def __init__(self, bk):
        self.bk = bk

    def encode(self, ob):
        if ob is None: return b""
        return b"\0" + self.bk.encode(ob)
    def decode(self, dat):
        if dat == b"": return None
        return self.bk.dec(dat[1:])
    def compare(self, a, b):
        if a is b is None:
            return 0
        elif a is None:
            return -1
        elif b is None:
            return 1
        else:
            return self.bk.compare(a[1:], b[1:])

class compound(object):
    def __init__(self, *parts):
        self.parts = parts

    small = object()
    large = object()
    def minim(self, *parts):
        return parts + tuple([self.small] * (len(self.parts) - len(parts)))
    def maxim(self, *parts):
        return parts + tuple([self.large] * (len(self.parts) - len(parts)))

    def encode(self, obs):
        if len(obs) != len(self.parts):
            raise ValueError("invalid length of compound data: " + str(len(obs)) + ", rather than " + len(self.parts))
        buf = bytearray()
        for ob, part in zip(obs, self.parts):
            if ob is self.small:
                buf.append(0x01)
            elif ob is self.large:
                buf.append(0x02)
            else:
                dat = part.encode(ob)
                if len(dat) < 128:
                    buf.append(0x80 | len(dat))
                    buf.extend(dat)
                else:
                    buf.extend(struct.pack(">BI", 0, len(dat)))
                    buf.extend(dat)
        return bytes(buf)
    def decode(self, dat):
        ret = []
        off = 0
        for part in self.parts:
            fl = dat[off]
            off += 1
            if fl & 0x80:
                ln = fl & 0x7f
            elif fl == 0x01:
                ret.append(self.small)
                continue
            elif fl == 0x02:
                ret.append(self.large)
                continue
            else:
                ln = struct.unpack(">I", dat[off:off + 4])[0]
                off += 4
            ret.append(part.decode(dat[off:off + ln]))
            off += ln
        return tuple(ret)
    def compare(self, al, bl):
        if (len(al) != len(self.parts)) or (len(bl) != len(self.parts)):
            raise ValueError("invalid length of compound data: " + str(len(al)) + ", " + str(len(bl)) + ", rather than " + len(self.parts))
        for a, b, part in zip(al, bl, self.parts):
            if a in (self.small, self.large) or b in (self.small, self.large):
                if a is b:
                    return 0
                if a is self.small:
                    return -1
                elif b is self.small:
                    return 1
                elif a is self.large:
                    return 1
                elif b is self.large:
                    return -1
            c = part.compare(a, b)
            if c != 0:
                return c
        return 0

def floatcmp(a, b):
    if math.isnan(a) and math.isnan(b):
        return 0
    elif math.isnan(a):
        return -1
    elif math.isnan(b):
        return 1
    elif a < b:
        return -1
    elif a > b:
        return 1
    else:
        return 0

t_int = simpletype.struct(">q")
t_uint = simpletype.struct(">Q")
t_dbid = t_uint
t_float = simpletype.struct(">d")
t_float.compare = floatcmp
t_str = simpletype((lambda ob: ob.encode("utf-8")), (lambda dat: dat.decode("utf-8")))

class index(object):
    def __init__(self, db, name, datatype):
        self.db = db
        self.nm = name
        self.typ = datatype

missing = object()

class ordered(index, lib.closable):
    def __init__(self, db, name, datatype, create=True):
        super().__init__(db, name, datatype)
        fl = bd.DB_THREAD | bd.DB_AUTO_COMMIT
        if create: fl |= bd.DB_CREATE
        def initdb(db):
            def compare(a, b):
                if a == b == "": return 0
                return self.typ.compare(self.typ.decode(a), self.typ.decode(b))
            db.set_flags(bd.DB_DUPSORT)
            db.set_bt_compare(compare)
        self.bk = db._opendb("i-" + name, bd.DB_BTREE, fl, initdb)
        self.bk.set_get_returns_none(False)

    def close(self):
        self.bk.close()

    class cursor(lib.closable):
        def __init__(self, idx, fd, fi, ld, li, reverse):
            self.idx = idx
            self.typ = idx.typ
            self.cur = self.idx.bk.cursor()
            self.item = None
            self.fd = fd
            self.fi = fi
            self.ld = ld
            self.li = li
            self.rev = reverse

        def close(self):
            if self.cur is not None:
                self.cur.close()
                self.cur = None

        def __iter__(self):
            return self

        def _decode(self, d):
            k, v = d
            k = self.typ.decode(k)
            v = struct.unpack(">Q", v)[0]
            return k, v

        @dloopfun
        def first(self):
            try:
                if self.fd is missing:
                    self.item = self._decode(self.cur.first())
                else:
                    k, v = self._decode(self.cur.set_range(self.typ.encode(self.fd)))
                    if not self.fi:
                        while self.typ.compare(k, self.fd) == 0:
                            k, v = self._decode(self.cur.next())
                    self.item = k, v
            except notfound:
                self.item = StopIteration

        @dloopfun
        def last(self):
            try:
                if self.ld is missing:
                    self.item = self._decode(self.cur.last())
                else:
                    try:
                        k, v = self._decode(self.cur.set_range(self.typ.encode(self.ld)))
                    except notfound:
                        k, v = self._decode(self.cur.last())
                    if self.li:
                        while self.typ.compare(k, self.ld) == 0:
                            k, v = self._decode(self.cur.next())
                        while self.typ.compare(k, self.ld) > 0:
                            k, v = self._decode(self.cur.prev())
                    else:
                        while self.typ.compare(k, self.ld) >= 0:
                            k, v = self._decode(self.cur.prev())
                    self.item = k, v
            except notfound:
                self.item = StopIteration

        @dloopfun
        def next(self):
            try:
                k, v = self.item = self._decode(self.cur.next())
                if (self.ld is not missing and
                    ((self.li and self.typ.compare(k, self.ld) > 0) or
                     (not self.li and self.typ.compare(k, self.ld) >= 0))):
                    self.item = StopIteration
            except notfound:
                self.item = StopIteration

        @dloopfun
        def prev(self):
            try:
                self.item = self._decode(self.cur.prev())
                if (self.fd is not missing and
                    ((self.fi and self.typ.compare(k, self.fd) < 0) or
                     (not self.fi and self.typ.compare(k, self.fd) <= 0))):
                    self.item = StopIteration
            except notfound:
                self.item = StopIteration

        def __next__(self):
            if self.item is None:
                if not self.rev:
                    self.next()
                else:
                    self.prev()
            if self.item is StopIteration:
                raise StopIteration()
            ret, self.item = self.item, None
            return ret

        def skip(self, n=1):
            try:
                for i in range(n):
                    next(self)
            except StopIteration:
                return

    def get(self, *, match=missing, ge=missing, gt=missing, lt=missing, le=missing, all=False, reverse=False):
        if all:
            cur = self.cursor(self, missing, True, missing, True, reverse)
        elif match is not missing:
            cur = self.cursor(self, match, True, match, True, reverse)
        elif ge is not missing or gt is not missing or lt is not missing or le is not missing:
            if ge is not missing:
                fd, fi = ge, True
            elif gt is not missing:
                fd, fi = gt, False
            else:
                fd, fi = missing, True
            if le is not missing:
                ld, li = le, True
            elif lt is not missing:
                ld, li = lt, False
            else:
                ld, li = missing, True
            cur = self.cursor(self, fd, fi, ld, li, reverse)
        else:
            raise NameError("invalid get() specification")
        done = False
        try:
            if not reverse:
                cur.first()
            else:
                cur.last()
            done = True
            return cur
        finally:
            if not done:
                cur.close()

    @txnfun(lambda self: self.db.env.env)
    def put(self, key, id, *, tx):
        obid = struct.pack(">Q", id)
        if not self.db.ob.has_key(obid, txn=tx.tx):
            raise ValueError("no such object in database: " + str(id))
        try:
            self.bk.put(self.typ.encode(key), obid, txn=tx.tx, flags=bd.DB_NODUPDATA)
        except bd.DBKeyExistError:
            return False
        return True

    @txnfun(lambda self: self.db.env.env)
    def remove(self, key, id, *, tx):
        obid = struct.pack(">Q", id)
        if not self.db.ob.has_key(obid, txn=tx.tx):
            raise ValueError("no such object in database: " + str(id))
        cur = self.bk.cursor(txn=tx.tx)
        try:
            try:
                cur.get_both(self.typ.encode(key), obid)
            except notfound:
                return False
            cur.delete()
        finally:
            cur.close()
        return True