implement search builder

nominatim/api/search/db_search_builder.py

@@ -0,0 +1,322 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Convertion from token assignment to an abstract DB search.
+"""
+from typing import Optional, List, Tuple, Iterator
+import heapq
+
+from nominatim.api.types import SearchDetails, DataLayer
+from nominatim.api.search.query import QueryStruct, TokenType, TokenRange, BreakType
+from nominatim.api.search.token_assignment import TokenAssignment
+import nominatim.api.search.db_search_fields as dbf
+import nominatim.api.search.db_searches as dbs
+from nominatim.api.logging import log
+
+class SearchBuilder:
+    """ Build the abstract search queries from token assignments.
+    """
+
+    def __init__(self, query: QueryStruct, details: SearchDetails) -> None:
+        self.query = query
+        self.details = details
+
+
+    @property
+    def configured_for_country(self) -> bool:
+        """ Return true if the search details are configured to
+            allow countries in the result.
+        """
+        return self.details.min_rank <= 4 and self.details.max_rank >= 4 \
+               and self.details.layer_enabled(DataLayer.ADDRESS)
+
+
+    @property
+    def configured_for_postcode(self) -> bool:
+        """ Return true if the search details are configured to
+            allow postcodes in the result.
+        """
+        return self.details.min_rank <= 5 and self.details.max_rank >= 11\
+               and self.details.layer_enabled(DataLayer.ADDRESS)
+
+
+    @property
+    def configured_for_housenumbers(self) -> bool:
+        """ Return true if the search details are configured to
+            allow addresses in the result.
+        """
+        return self.details.max_rank >= 30 \
+               and self.details.layer_enabled(DataLayer.ADDRESS)
+
+
+    def build(self, assignment: TokenAssignment) -> Iterator[dbs.AbstractSearch]:
+        """ Yield all possible abstract searches for the given token assignment.
+        """
+        sdata = self.get_search_data(assignment)
+        if sdata is None:
+            return
+
+        categories = self.get_search_categories(assignment)
+
+        if assignment.name is None:
+            if categories and not sdata.postcodes:
+                sdata.qualifiers = categories
+                categories = None
+                builder = self.build_poi_search(sdata)
+            else:
+                builder = self.build_special_search(sdata, assignment.address,
+                                                    bool(categories))
+        else:
+            builder = self.build_name_search(sdata, assignment.name, assignment.address,
+                                             bool(categories))
+
+        if categories:
+            penalty = min(categories.penalties)
+            categories.penalties = [p - penalty for p in categories.penalties]
+            for search in builder:
+                yield dbs.NearSearch(penalty, categories, search)
+        else:
+            yield from builder
+
+
+    def build_poi_search(self, sdata: dbf.SearchData) -> Iterator[dbs.AbstractSearch]:
+        """ Build abstract search query for a simple category search.
+            This kind of search requires an additional geographic constraint.
+        """
+        if not sdata.housenumbers \
+           and ((self.details.viewbox and self.details.bounded_viewbox) or self.details.near):
+            yield dbs.PoiSearch(sdata)
+
+
+    def build_special_search(self, sdata: dbf.SearchData,
+                             address: List[TokenRange],
+                             is_category: bool) -> Iterator[dbs.AbstractSearch]:
+        """ Build abstract search queries for searches that do not involve
+            a named place.
+        """
+        if sdata.qualifiers or sdata.housenumbers:
+            # No special searches over housenumbers or qualifiers supported.
+            return
+
+        if sdata.countries and not address and not sdata.postcodes \
+           and self.configured_for_country:
+            yield dbs.CountrySearch(sdata)
+
+        if sdata.postcodes and (is_category or self.configured_for_postcode):
+            if address:
+                sdata.lookups = [dbf.FieldLookup('nameaddress_vector',
+                                                 [t.token for r in address
+                                                  for t in self.query.get_partials_list(r)],
+                                                 'restrict')]
+            yield dbs.PostcodeSearch(0.4, sdata)
+
+
+    def build_name_search(self, sdata: dbf.SearchData,
+                          name: TokenRange, address: List[TokenRange],
+                          is_category: bool) -> Iterator[dbs.AbstractSearch]:
+        """ Build abstract search queries for simple name or address searches.
+        """
+        if is_category or not sdata.housenumbers or self.configured_for_housenumbers:
+            sdata.rankings.append(self.get_name_ranking(name))
+            name_penalty = sdata.rankings[-1].normalize_penalty()
+            for penalty, count, lookup in self.yield_lookups(name, address):
+                sdata.lookups = lookup
+                yield dbs.PlaceSearch(penalty + name_penalty, sdata, count)
+
+
+    def yield_lookups(self, name: TokenRange, address: List[TokenRange])\
+                          -> Iterator[Tuple[float, int, List[dbf.FieldLookup]]]:
+        """ Yield all variants how the given name and address should best
+            be searched for. This takes into account how frequent the terms
+            are and tries to find a lookup that optimizes index use.
+        """
+        penalty = 0.0 # extra penalty currently unused
+
+        name_partials = self.query.get_partials_list(name)
+        exp_name_count = min(t.count for t in name_partials)
+        addr_partials = []
+        for trange in address:
+            addr_partials.extend(self.query.get_partials_list(trange))
+        addr_tokens = [t.token for t in addr_partials]
+        partials_indexed = all(t.is_indexed for t in name_partials) \
+                           and all(t.is_indexed for t in addr_partials)
+
+        if (len(name_partials) > 3 or exp_name_count < 1000) and partials_indexed:
+            # Lookup by name partials, use address partials to restrict results.
+            lookup = [dbf.FieldLookup('name_vector',
+                                  [t.token for t in name_partials], 'lookup_all')]
+            if addr_tokens:
+                lookup.append(dbf.FieldLookup('nameaddress_vector', addr_tokens, 'restrict'))
+            yield penalty, exp_name_count, lookup
+            return
+
+        exp_addr_count = min(t.count for t in addr_partials) if addr_partials else exp_name_count
+        if exp_addr_count < 1000 and partials_indexed:
+            # Lookup by address partials and restrict results through name terms.
+            yield penalty, exp_addr_count,\
+                  [dbf.FieldLookup('name_vector', [t.token for t in name_partials], 'restrict'),
+                   dbf.FieldLookup('nameaddress_vector', addr_tokens, 'lookup_all')]
+            return
+
+        # Partial term to frequent. Try looking up by rare full names first.
+        name_fulls = self.query.get_tokens(name, TokenType.WORD)
+        rare_names = list(filter(lambda t: t.count < 1000, name_fulls))
+        # At this point drop unindexed partials from the address.
+        # This might yield wrong results, nothing we can do about that.
+        if not partials_indexed:
+            addr_tokens = [t.token for t in addr_partials if t.is_indexed]
+            log().var_dump('before', penalty)
+            penalty += 1.2 * sum(t.penalty for t in addr_partials if not t.is_indexed)
+            log().var_dump('after', penalty)
+        if rare_names:
+            # Any of the full names applies with all of the partials from the address
+            lookup = [dbf.FieldLookup('name_vector', [t.token for t in rare_names], 'lookup_any')]
+            if addr_tokens:
+                lookup.append(dbf.FieldLookup('nameaddress_vector', addr_tokens, 'restrict'))
+            yield penalty, sum(t.count for t in rare_names), lookup
+
+        # To catch remaining results, lookup by name and address
+        if all(t.is_indexed for t in name_partials):
+            lookup = [dbf.FieldLookup('name_vector',
+                                      [t.token for t in name_partials], 'lookup_all')]
+        else:
+            # we don't have the partials, try with the non-rare names
+            non_rare_names = [t.token for t in name_fulls if t.count >= 1000]
+            if not non_rare_names:
+                return
+            lookup = [dbf.FieldLookup('name_vector', non_rare_names, 'lookup_any')]
+        if addr_tokens:
+            lookup.append(dbf.FieldLookup('nameaddress_vector', addr_tokens, 'lookup_all'))
+        yield penalty + 0.1 * max(0, 5 - len(name_partials) - len(addr_tokens)),\
+              min(exp_name_count, exp_addr_count), lookup
+
+
+    def get_name_ranking(self, trange: TokenRange) -> dbf.FieldRanking:
+        """ Create a ranking expression for a name term in the given range.
+        """
+        name_fulls = self.query.get_tokens(trange, TokenType.WORD)
+        ranks = [dbf.RankedTokens(t.penalty, [t.token]) for t in name_fulls]
+        ranks.sort(key=lambda r: r.penalty)
+        # Fallback, sum of penalty for partials
+        name_partials = self.query.get_partials_list(trange)
+        default = sum(t.penalty for t in name_partials) + 0.2
+        return dbf.FieldRanking('name_vector', default, ranks)
+
+
+    def get_addr_ranking(self, trange: TokenRange) -> dbf.FieldRanking:
+        """ Create a list of ranking expressions for an address term
+            for the given ranges.
+        """
+        todo: List[Tuple[int, int, dbf.RankedTokens]] = []
+        heapq.heappush(todo, (0, trange.start, dbf.RankedTokens(0.0, [])))
+        ranks: List[dbf.RankedTokens] = []
+
+        while todo: # pylint: disable=too-many-nested-blocks
+            neglen, pos, rank = heapq.heappop(todo)
+            for tlist in self.query.nodes[pos].starting:
+                if tlist.ttype in (TokenType.PARTIAL, TokenType.WORD):
+                    if tlist.end < trange.end:
+                        chgpenalty = PENALTY_WORDCHANGE[self.query.nodes[tlist.end].btype]
+                        if tlist.ttype == TokenType.PARTIAL:
+                            penalty = rank.penalty + chgpenalty \
+                                      + max(t.penalty for t in tlist.tokens)
+                            heapq.heappush(todo, (neglen - 1, tlist.end,
+                                                  dbf.RankedTokens(penalty, rank.tokens)))
+                        else:
+                            for t in tlist.tokens:
+                                heapq.heappush(todo, (neglen - 1, tlist.end,
+                                                      rank.with_token(t, chgpenalty)))
+                    elif tlist.end == trange.end:
+                        if tlist.ttype == TokenType.PARTIAL:
+                            ranks.append(dbf.RankedTokens(rank.penalty
+                                                          + max(t.penalty for t in tlist.tokens),
+                                                          rank.tokens))
+                        else:
+                            ranks.extend(rank.with_token(t, 0.0) for t in tlist.tokens)
+                        if len(ranks) >= 10:
+                            # Too many variants, bail out and only add
+                            # Worst-case Fallback: sum of penalty of partials
+                            name_partials = self.query.get_partials_list(trange)
+                            default = sum(t.penalty for t in name_partials) + 0.2
+                            ranks.append(dbf.RankedTokens(rank.penalty + default, []))
+                            # Bail out of outer loop
+                            todo.clear()
+                            break
+
+        ranks.sort(key=lambda r: len(r.tokens))
+        default = ranks[0].penalty + 0.3
+        del ranks[0]
+        ranks.sort(key=lambda r: r.penalty)
+
+        return dbf.FieldRanking('nameaddress_vector', default, ranks)
+
+
+    def get_search_data(self, assignment: TokenAssignment) -> Optional[dbf.SearchData]:
+        """ Collect the tokens for the non-name search fields in the
+            assignment.
+        """
+        sdata = dbf.SearchData()
+        sdata.penalty = assignment.penalty
+        if assignment.country:
+            tokens = self.query.get_tokens(assignment.country, TokenType.COUNTRY)
+            if self.details.countries:
+                tokens = [t for t in tokens if t.lookup_word in self.details.countries]
+                if not tokens:
+                    return None
+            sdata.set_strings('countries', tokens)
+        elif self.details.countries:
+            sdata.countries = dbf.WeightedStrings(self.details.countries,
+                                                  [0.0] * len(self.details.countries))
+        if assignment.housenumber:
+            sdata.set_strings('housenumbers',
+                              self.query.get_tokens(assignment.housenumber,
+                                                    TokenType.HOUSENUMBER))
+        if assignment.postcode:
+            sdata.set_strings('postcodes',
+                              self.query.get_tokens(assignment.postcode,
+                                                    TokenType.POSTCODE))
+        if assignment.qualifier:
+            sdata.set_qualifiers(self.query.get_tokens(assignment.qualifier,
+                                                       TokenType.QUALIFIER))
+
+        if assignment.address:
+            sdata.set_ranking([self.get_addr_ranking(r) for r in assignment.address])
+        else:
+            sdata.rankings = []
+
+        return sdata
+
+
+    def get_search_categories(self,
+                              assignment: TokenAssignment) -> Optional[dbf.WeightedCategories]:
+        """ Collect tokens for category search or use the categories
+            requested per parameter.
+            Returns None if no category search is requested.
+        """
+        if assignment.category:
+            tokens = [t for t in self.query.get_tokens(assignment.category,
+                                                       TokenType.CATEGORY)
+                      if not self.details.categories
+                         or t.get_category() in self.details.categories]
+            return dbf.WeightedCategories([t.get_category() for t in tokens],
+                                          [t.penalty for t in tokens])
+
+        if self.details.categories:
+            return dbf.WeightedCategories(self.details.categories,
+                                          [0.0] * len(self.details.categories))
+
+        return None
+
+
+PENALTY_WORDCHANGE = {
+    BreakType.START: 0.0,
+    BreakType.END: 0.0,
+    BreakType.PHRASE: 0.0,
+    BreakType.WORD: 0.1,
+    BreakType.PART: 0.2,
+    BreakType.TOKEN: 0.4
+}

nominatim/api/search/db_search_fields.py

@@ -0,0 +1,167 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Data structures for more complex fields in abstract search descriptions.
+"""
+from typing import List, Tuple, cast
+import dataclasses
+
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ARRAY
+
+from nominatim.typing import SaFromClause, SaColumn
+from nominatim.api.search.query import Token
+
+@dataclasses.dataclass
+class WeightedStrings:
+    """ A list of strings together with a penalty.
+    """
+    values: List[str]
+    penalties: List[float]
+
+    def __bool__(self) -> bool:
+        return bool(self.values)
+
+
+@dataclasses.dataclass
+class WeightedCategories:
+    """ A list of class/type tuples together with a penalty.
+    """
+    values: List[Tuple[str, str]]
+    penalties: List[float]
+
+    def __bool__(self) -> bool:
+        return bool(self.values)
+
+
+@dataclasses.dataclass(order=True)
+class RankedTokens:
+    """ List of tokens together with the penalty of using it.
+    """
+    penalty: float
+    tokens: List[int]
+
+    def with_token(self, t: Token, transition_penalty: float) -> 'RankedTokens':
+        """ Create a new RankedTokens list with the given token appended.
+            The tokens penalty as well as the given transision penalty
+            are added to the overall penalty.
+        """
+        return RankedTokens(self.penalty + t.penalty + transition_penalty,
+                            self.tokens + [t.token])
+
+
+@dataclasses.dataclass
+class FieldRanking:
+    """ A list of rankings to be applied sequentially until one matches.
+        The matched ranking determines the penalty. If none matches a
+        default penalty is applied.
+    """
+    column: str
+    default: float
+    rankings: List[RankedTokens]
+
+    def normalize_penalty(self) -> float:
+        """ Reduce the default and ranking penalties, such that the minimum
+            penalty is 0. Return the penalty that was subtracted.
+        """
+        if self.rankings:
+            min_penalty = min(self.default, min(r.penalty for r in self.rankings))
+        else:
+            min_penalty = self.default
+        if min_penalty > 0.0:
+            self.default -= min_penalty
+            for ranking in self.rankings:
+                ranking.penalty -= min_penalty
+        return min_penalty
+
+
+    def sql_penalty(self, table: SaFromClause) -> SaColumn:
+        """ Create an SQL expression for the rankings.
+        """
+        assert self.rankings
+
+        col = table.c[self.column]
+
+        return sa.case(*((col.contains(r.tokens),r.penalty) for r in self.rankings),
+                       else_=self.default)
+
+
+@dataclasses.dataclass
+class FieldLookup:
+    """ A list of tokens to be searched for. The column names the database
+        column to search in and the lookup_type the operator that is applied.
+        'lookup_all' requires all tokens to match. 'lookup_any' requires
+        one of the tokens to match. 'restrict' requires to match all tokens
+        but avoids the use of indexes.
+    """
+    column: str
+    tokens: List[int]
+    lookup_type: str
+
+    def sql_condition(self, table: SaFromClause) -> SaColumn:
+        """ Create an SQL expression for the given match condition.
+        """
+        col = table.c[self.column]
+        if self.lookup_type == 'lookup_all':
+            return col.contains(self.tokens)
+        if self.lookup_type == 'lookup_any':
+            return cast(SaColumn, col.overlap(self.tokens))
+
+        return sa.func.array_cat(col, sa.text('ARRAY[]::integer[]'),
+                                 type_=ARRAY(sa.Integer())).contains(self.tokens)
+
+
+class SearchData:
+    """ Search fields derived from query and token assignment
+        to be used with the SQL queries.
+    """
+    penalty: float
+
+    lookups: List[FieldLookup] = []
+    rankings: List[FieldRanking]
+
+    housenumbers: WeightedStrings = WeightedStrings([], [])
+    postcodes: WeightedStrings = WeightedStrings([], [])
+    countries: WeightedStrings = WeightedStrings([], [])
+
+    qualifiers: WeightedCategories = WeightedCategories([], [])
+
+
+    def set_strings(self, field: str, tokens: List[Token]) -> None:
+        """ Set on of the WeightedStrings properties from the given
+            token list. Adapt the global penalty, so that the
+            minimum penalty is 0.
+        """
+        if tokens:
+            min_penalty = min(t.penalty for t in tokens)
+            self.penalty += min_penalty
+            wstrs = WeightedStrings([t.lookup_word for t in tokens],
+                                    [t.penalty - min_penalty for t in tokens])
+
+            setattr(self, field, wstrs)
+
+
+    def set_qualifiers(self, tokens: List[Token]) -> None:
+        """ Set the qulaifier field from the given tokens.
+        """
+        if tokens:
+            min_penalty = min(t.penalty for t in tokens)
+            self.penalty += min_penalty
+            self.qualifiers = WeightedCategories([t.get_category() for t in tokens],
+                                                 [t.penalty - min_penalty for t in tokens])
+
+
+    def set_ranking(self, rankings: List[FieldRanking]) -> None:
+        """ Set the list of rankings and normalize the ranking.
+        """
+        self.rankings = []
+        for ranking in rankings:
+            if ranking.rankings:
+                self.penalty += ranking.normalize_penalty()
+                self.rankings.append(ranking)
+            else:
+                self.penalty += ranking.default

nominatim/api/search/db_searches.py

@@ -0,0 +1,115 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Implementation of the acutal database accesses for forward search.
+"""
+import abc
+
+from nominatim.api.connection import SearchConnection
+from nominatim.api.types import SearchDetails
+import nominatim.api.results as nres
+from nominatim.api.search.db_search_fields import SearchData, WeightedCategories
+
+class AbstractSearch(abc.ABC):
+    """ Encapuslation of a single lookup in the database.
+    """
+
+    def __init__(self, penalty: float) -> None:
+        self.penalty = penalty
+
+    @abc.abstractmethod
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+
+
+class NearSearch(AbstractSearch):
+    """ Category search of a place type near the result of another search.
+    """
+    def __init__(self, penalty: float, categories: WeightedCategories,
+                 search: AbstractSearch) -> None:
+        super().__init__(penalty)
+        self.search = search
+        self.categories = categories
+
+
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+        return nres.SearchResults([])
+
+
+class PoiSearch(AbstractSearch):
+    """ Category search in a geographic area.
+    """
+    def __init__(self, sdata: SearchData) -> None:
+        super().__init__(sdata.penalty)
+        self.categories = sdata.qualifiers
+        self.countries = sdata.countries
+
+
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+        return nres.SearchResults([])
+
+
+class CountrySearch(AbstractSearch):
+    """ Search for a country name or country code.
+    """
+    def __init__(self, sdata: SearchData) -> None:
+        super().__init__(sdata.penalty)
+        self.countries = sdata.countries
+
+
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+        return nres.SearchResults([])
+
+
+class PostcodeSearch(AbstractSearch):
+    """ Search for a postcode.
+    """
+    def __init__(self, extra_penalty: float, sdata: SearchData) -> None:
+        super().__init__(sdata.penalty + extra_penalty)
+        self.countries = sdata.countries
+        self.postcodes = sdata.postcodes
+        self.lookups = sdata.lookups
+        self.rankings = sdata.rankings
+
+
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+        return nres.SearchResults([])
+
+
+class PlaceSearch(AbstractSearch):
+    """ Generic search for an address or named place.
+    """
+    def __init__(self, extra_penalty: float, sdata: SearchData, expected_count: int) -> None:
+        super().__init__(sdata.penalty + extra_penalty)
+        self.countries = sdata.countries
+        self.postcodes = sdata.postcodes
+        self.housenumbers = sdata.housenumbers
+        self.qualifiers = sdata.qualifiers
+        self.lookups = sdata.lookups
+        self.rankings = sdata.rankings
+        self.expected_count = expected_count
+
+
+    async def lookup(self, conn: SearchConnection,
+                     details: SearchDetails) -> nres.SearchResults:
+        """ Find results for the search in the database.
+        """
+        return nres.SearchResults([])

nominatim/api/search/query.py

@@ -169,7 +169,10 @@ class QueryNode:
             and ending at the node 'end'. Returns 'None' if no such
             tokens exist.
         """
-        return next((t.tokens for t in self.starting if t.end == end and t.ttype == ttype), None)
+        for tlist in self.starting:
+            if tlist.end == end and tlist.ttype == ttype:
+                return tlist.tokens
+        return None
 
 
 @dataclasses.dataclass

nominatim/api/types.py

@@ -7,13 +7,18 @@
 """
 Complex datatypes used by the Nominatim API.
 """
-from typing import Optional, Union, Tuple, NamedTuple, TypeVar, Type, Dict, Any
+from typing import Optional, Union, Tuple, NamedTuple, TypeVar, Type, Dict, \
+                   Any, List, Sequence
+from collections import abc
 import dataclasses
 import enum
+import math
 from struct import unpack
 
 from nominatim.errors import UsageError
 
+# pylint: disable=no-member,too-many-boolean-expressions,too-many-instance-attributes
+
 @dataclasses.dataclass
 class PlaceID:
     """ Reference an object by Nominatim's internal ID.
@@ -85,6 +90,36 @@ class Point(NamedTuple):
         return Point(x, y)
 
 
+    @staticmethod
+    def from_param(inp: Any) -> 'Point':
+        """ Create a point from an input parameter. The parameter
+            may be given as a point, a string or a sequence of
+            strings or floats. Raises a UsageError if the format is
+            not correct.
+        """
+        if isinstance(inp, Point):
+            return inp
+
+        seq: Sequence[str]
+        if isinstance(inp, str):
+            seq = inp.split(',')
+        elif isinstance(inp, abc.Sequence):
+            seq = inp
+
+        if len(seq) != 2:
+            raise UsageError('Point parameter needs 2 coordinates.')
+        try:
+            x, y = filter(math.isfinite, map(float, seq))
+        except ValueError as exc:
+            raise UsageError('Point parameter needs to be numbers.') from exc
+
+        if x < -180.0 or x > 180.0 or y < -90.0 or y > 90.0:
+            raise UsageError('Point coordinates invalid.')
+
+        return Point(x, y)
+
+
+
 AnyPoint = Union[Point, Tuple[float, float]]
 
 WKB_BBOX_HEADER_LE = b'\x01\x03\x00\x00\x20\xE6\x10\x00\x00\x01\x00\x00\x00\x05\x00\x00\x00'
@@ -128,6 +163,12 @@ class Bbox:
         return self.coords[2]
 
 
+    def contains(self, pt: Point) -> bool:
+        """ Check if the point is inside or on the boundary of the box.
+        """
+        return self.coords[0] <= pt[0] and self.coords[1] <= pt[1]\
+               and self.coords[2] >= pt[0] and self.coords[3] >= pt[1]
+
     @staticmethod
     def from_wkb(wkb: Optional[bytes]) -> 'Optional[Bbox]':
         """ Create a Bbox from a bounding box polygon as returned by
@@ -156,6 +197,38 @@ class Bbox:
                     pt[0] + buffer, pt[1] + buffer)
 
 
+    @staticmethod
+    def from_param(inp: Any) -> 'Bbox':
+        """ Return a Bbox from an input parameter. The box may be
+            given as a Bbox, a string or a list or strings or integer.
+            Raises a UsageError if the format is incorrect.
+        """
+        if isinstance(inp, Bbox):
+            return inp
+
+        seq: Sequence[str]
+        if isinstance(inp, str):
+            seq = inp.split(',')
+        elif isinstance(inp, abc.Sequence):
+            seq = inp
+
+        if len(seq) != 4:
+            raise UsageError('Bounding box parameter needs 4 coordinates.')
+        try:
+            x1, y1, x2, y2 = filter(math.isfinite, map(float, seq))
+        except ValueError as exc:
+            raise UsageError('Bounding box parameter needs to be numbers.') from exc
+
+        if x1 < -180.0 or x1 > 180.0 or y1 < -90.0 or y1 > 90.0 \
+           or x2 < -180.0 or x2 > 180.0 or y2 < -90.0 or y2 > 90.0:
+            raise UsageError('Bounding box coordinates invalid.')
+
+        if x1 == x2 or y1 == y2:
+            raise UsageError('Bounding box with invalid parameters.')
+
+        return Bbox(min(x1, x2), min(y1, y2), max(x1, x2), max(y1, y2))
+
+
 class GeometryFormat(enum.Flag):
     """ Geometry output formats supported by Nominatim.
     """
@@ -176,6 +249,47 @@ class DataLayer(enum.Flag):
     NATURAL = enum.auto()
 
 
+def format_country(cc: Any) -> List[str]:
+    """ Extract a list of country codes from the input which may be either
+        a string or list of strings. Filters out all values that are not
+        a two-letter string.
+    """
+    clist: Sequence[str]
+    if isinstance(cc, str):
+        clist = cc.split(',')
+    elif isinstance(cc, abc.Sequence):
+        clist = cc
+    else:
+        raise UsageError("Parameter 'country' needs to be a comma-separated list "
+                         "or a Python list of strings.")
+
+    return [cc.lower() for cc in clist if isinstance(cc, str) and len(cc) == 2]
+
+
+def format_excluded(ids: Any) -> List[int]:
+    """ Extract a list of place ids from the input which may be either
+        a string or a list of strings or ints. Ignores empty value but
+        throws a UserError on anything that cannot be converted to int.
+    """
+    plist: Sequence[str]
+    if isinstance(ids, str):
+        plist = ids.split(',')
+    elif isinstance(ids, abc.Sequence):
+        plist = ids
+    else:
+        raise UsageError("Parameter 'excluded' needs to be a comma-separated list "
+                         "or a Python list of numbers.")
+    if any(not isinstance(i, int) or (isinstance(i, str) and not i.isdigit()) for i in plist):
+        raise UsageError("Parameter 'excluded' only takes place IDs.")
+
+    return [int(id) for id in plist if id]
+
+
+def format_categories(categories: List[Tuple[str, str]]) -> List[Tuple[str, str]]:
+    """ Extract a list of categories. Currently a noop.
+    """
+    return categories
+
 TParam = TypeVar('TParam', bound='LookupDetails') # pylint: disable=invalid-name
 
 @dataclasses.dataclass
@@ -244,3 +358,92 @@ class ReverseDetails(LookupDetails):
     layers: DataLayer = DataLayer.ADDRESS | DataLayer.POI
     """ Filter which kind of data to include.
     """
+
+@dataclasses.dataclass
+class SearchDetails(LookupDetails):
+    """ Collection of parameters for the search call.
+    """
+    max_results: int = 10
+    """ Maximum number of results to be returned. The actual number of results
+        may be less.
+    """
+    min_rank: int = dataclasses.field(default=0,
+                                      metadata={'transform': lambda v: max(0, min(v, 30))}
+                                     )
+    """ Lowest address rank to return.
+    """
+    max_rank: int = dataclasses.field(default=30,
+                                      metadata={'transform': lambda v: max(0, min(v, 30))}
+                                     )
+    """ Highest address rank to return.
+    """
+    layers: Optional[DataLayer] = None
+    """ Filter which kind of data to include. When 'None' (the default) then
+        filtering by layers is disabled.
+    """
+    countries: List[str] = dataclasses.field(default_factory=list,
+                                             metadata={'transform': format_country})
+    """ Restrict search results to the given countries. An empty list (the
+        default) will disable this filter.
+    """
+    excluded: List[int] = dataclasses.field(default_factory=list,
+                                            metadata={'transform': format_excluded})
+    """ List of OSM objects to exclude from the results. Currenlty only
+        works when the internal place ID is given.
+        An empty list (the default) will disable this filter.
+    """
+    viewbox: Optional[Bbox] = dataclasses.field(default=None,
+                                                metadata={'transform': Bbox.from_param})
+    """ Focus the search on a given map area.
+    """
+    bounded_viewbox: bool = False
+    """ Use 'viewbox' as a filter and restrict results to places within the
+        given area.
+    """
+    near: Optional[Point] = dataclasses.field(default=None,
+                                              metadata={'transform': Point.from_param})
+    """ Order results by distance to the given point.
+    """
+    near_radius: Optional[float] = None
+    """ Use near point as a filter and drop results outside the given
+        radius. Radius is given in degrees WSG84.
+    """
+    categories: List[Tuple[str, str]] = dataclasses.field(default_factory=list,
+                                                          metadata={'transform': format_categories})
+    """ Restrict search to places with one of the given class/type categories.
+        An empty list (the default) will disable this filter.
+    """
+
+    def __post_init__(self) -> None:
+        if self.viewbox is not None:
+            xext = (self.viewbox.maxlon - self.viewbox.minlon)/2
+            yext = (self.viewbox.maxlat - self.viewbox.minlat)/2
+            self.viewbox_x2 = Bbox(self.viewbox.minlon - xext, self.viewbox.maxlon - yext,
+                                   self.viewbox.maxlon + xext, self.viewbox.maxlat + yext)
+
+
+    def restrict_min_max_rank(self, new_min: int, new_max: int) -> None:
+        """ Change the min_rank and max_rank fields to respect the
+            given boundaries.
+        """
+        assert new_min <= new_max
+        self.min_rank = max(self.min_rank, new_min)
+        self.max_rank = min(self.max_rank, new_max)
+
+
+    def is_impossible(self) -> bool:
+        """ Check if the parameter configuration is contradictionary and
+            cannot yield any results.
+        """
+        return (self.min_rank > self.max_rank
+                or (self.bounded_viewbox
+                    and self.viewbox is not None and self.near is not None
+                    and self.viewbox.contains(self.near))
+                or self.layers is not None and not self.layers)
+
+
+    def layer_enabled(self, layer: DataLayer) -> bool:
+        """ Check if the given layer has been choosen. Also returns
+            true when layer restriction has been disabled completely.
+        """
+        return self.layers is None or bool(self.layers & layer)

test/python/api/search/test_db_search_builder.py

@@ -0,0 +1,395 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Tests for creating abstract searches from token assignments.
+"""
+import pytest
+
+from nominatim.api.search.query import Token, TokenRange, BreakType, PhraseType, TokenType, QueryStruct, Phrase
+from nominatim.api.search.db_search_builder import SearchBuilder
+from nominatim.api.search.token_assignment import TokenAssignment
+from nominatim.api.types import SearchDetails
+import nominatim.api.search.db_searches as dbs
+
+class MyToken(Token):
+    def get_category(self):
+        return 'this', 'that'
+
+
+def make_query(*args):
+    q = None
+
+    for tlist in args:
+        if q is None:
+            q = QueryStruct([Phrase(PhraseType.NONE, '')])
+        else:
+            q.add_node(BreakType.WORD, PhraseType.NONE)
+
+        start = len(q.nodes) - 1
+        for end, ttype, tinfo in tlist:
+            for tid, word in tinfo:
+                q.add_token(TokenRange(start, end), ttype,
+                            MyToken(0.5 if ttype == TokenType.PARTIAL else 0.0, tid, 1, word, True))
+
+    q.add_node(BreakType.END, PhraseType.NONE)
+
+    return q
+
+
+def test_country_search():
+    q = make_query([(1, TokenType.COUNTRY, [(2, 'de'), (3, 'en')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(country=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+
+    search = searches[0]
+
+    assert isinstance(search, dbs.CountrySearch)
+    assert set(search.countries.values) == {'de', 'en'}
+
+
+def test_country_search_with_country_restriction():
+    q = make_query([(1, TokenType.COUNTRY, [(2, 'de'), (3, 'en')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs({'countries': 'en,fr'}))
+
+    searches = list(builder.build(TokenAssignment(country=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+
+    search = searches[0]
+
+    assert isinstance(search, dbs.CountrySearch)
+    assert set(search.countries.values) == {'en'}
+
+
+def test_country_search_with_confllicting_country_restriction():
+    q = make_query([(1, TokenType.COUNTRY, [(2, 'de'), (3, 'en')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs({'countries': 'fr'}))
+
+    searches = list(builder.build(TokenAssignment(country=TokenRange(0, 1))))
+
+    assert len(searches) == 0
+
+
+def test_postcode_search_simple():
+    q = make_query([(1, TokenType.POSTCODE, [(34, '2367')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(postcode=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PostcodeSearch)
+    assert search.postcodes.values == ['2367']
+    assert not search.countries.values
+    assert not search.lookups
+    assert not search.rankings
+
+
+def test_postcode_with_country():
+    q = make_query([(1, TokenType.POSTCODE, [(34, '2367')])],
+                   [(2, TokenType.COUNTRY, [(1, 'xx')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(postcode=TokenRange(0, 1),
+                                                  country=TokenRange(1, 2))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PostcodeSearch)
+    assert search.postcodes.values == ['2367']
+    assert search.countries.values == ['xx']
+    assert not search.lookups
+    assert not search.rankings
+
+
+def test_postcode_with_address():
+    q = make_query([(1, TokenType.POSTCODE, [(34, '2367')])],
+                   [(2, TokenType.PARTIAL, [(100, 'word')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(postcode=TokenRange(0, 1),
+                                                  address=[TokenRange(1, 2)])))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PostcodeSearch)
+    assert search.postcodes.values == ['2367']
+    assert not search.countries
+    assert search.lookups
+    assert not search.rankings
+
+
+def test_postcode_with_address_with_full_word():
+    q = make_query([(1, TokenType.POSTCODE, [(34, '2367')])],
+                   [(2, TokenType.PARTIAL, [(100, 'word')]),
+                    (2, TokenType.WORD, [(1, 'full')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(postcode=TokenRange(0, 1),
+                                                  address=[TokenRange(1, 2)])))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PostcodeSearch)
+    assert search.postcodes.values == ['2367']
+    assert not search.countries
+    assert search.lookups
+    assert len(search.rankings) == 1
+
+
+@pytest.mark.parametrize('kwargs', [{'viewbox': '0,0,1,1', 'bounded_viewbox': True},
+                                    {'near': '10,10'}])
+def test_category_only(kwargs):
+    q = make_query([(1, TokenType.CATEGORY, [(2, 'foo')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs(kwargs))
+
+    searches = list(builder.build(TokenAssignment(category=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+
+    search = searches[0]
+
+    assert isinstance(search, dbs.PoiSearch)
+    assert search.categories.values == [('this', 'that')]
+
+
+@pytest.mark.parametrize('kwargs', [{'viewbox': '0,0,1,1'},
+                                    {}])
+def test_category_skipped(kwargs):
+    q = make_query([(1, TokenType.CATEGORY, [(2, 'foo')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs(kwargs))
+
+    searches = list(builder.build(TokenAssignment(category=TokenRange(0, 1))))
+
+    assert len(searches) == 0
+
+
+def test_name_only_search():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert not search.countries.values
+    assert not search.housenumbers.values
+    assert not search.qualifiers.values
+    assert len(search.lookups) == 1
+    assert len(search.rankings) == 1
+
+
+def test_name_with_qualifier():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])],
+                   [(2, TokenType.QUALIFIER, [(55, 'hotel')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1),
+                                                  qualifier=TokenRange(1, 2))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert not search.countries.values
+    assert not search.housenumbers.values
+    assert search.qualifiers.values == [('this', 'that')]
+    assert len(search.lookups) == 1
+    assert len(search.rankings) == 1
+
+
+def test_name_with_housenumber_search():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])],
+                   [(2, TokenType.HOUSENUMBER, [(66, '66')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1),
+                                                  housenumber=TokenRange(1, 2))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert not search.countries.values
+    assert search.housenumbers.values == ['66']
+    assert len(search.lookups) == 1
+    assert len(search.rankings) == 1
+
+
+def test_name_and_address():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])],
+                   [(2, TokenType.PARTIAL, [(2, 'b')]),
+                    (2, TokenType.WORD, [(101, 'b')])],
+                   [(3, TokenType.PARTIAL, [(3, 'c')]),
+                    (3, TokenType.WORD, [(102, 'c')])]
+                  )
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1),
+                                                  address=[TokenRange(1, 2),
+                                                           TokenRange(2, 3)])))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert not search.countries.values
+    assert not search.housenumbers.values
+    assert len(search.lookups) == 2
+    assert len(search.rankings) == 3
+
+
+def test_name_and_complex_address():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])],
+                   [(2, TokenType.PARTIAL, [(2, 'b')]),
+                    (3, TokenType.WORD, [(101, 'bc')])],
+                   [(3, TokenType.PARTIAL, [(3, 'c')])],
+                   [(4, TokenType.PARTIAL, [(4, 'd')]),
+                    (4, TokenType.WORD, [(103, 'd')])]
+                  )
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1),
+                                                  address=[TokenRange(1, 2),
+                                                           TokenRange(2, 4)])))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert not search.countries.values
+    assert not search.housenumbers.values
+    assert len(search.lookups) == 2
+    assert len(search.rankings) == 2
+
+
+def test_name_only_near_search():
+    q = make_query([(1, TokenType.CATEGORY, [(88, 'g')])],
+                   [(2, TokenType.PARTIAL, [(1, 'a')]),
+                    (2, TokenType.WORD, [(100, 'a')])])
+    builder = SearchBuilder(q, SearchDetails())
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(1, 2),
+                                                  category=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.NearSearch)
+    assert isinstance(search.search, dbs.PlaceSearch)
+
+
+def test_name_only_search_with_category():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs({'categories': [('foo', 'bar')]}))
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.NearSearch)
+    assert isinstance(search.search, dbs.PlaceSearch)
+
+
+def test_name_only_search_with_countries():
+    q = make_query([(1, TokenType.PARTIAL, [(1, 'a')]),
+                    (1, TokenType.WORD, [(100, 'a')])])
+    builder = SearchBuilder(q, SearchDetails.from_kwargs({'countries': 'de,en'}))
+
+    searches = list(builder.build(TokenAssignment(name=TokenRange(0, 1))))
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert not search.postcodes.values
+    assert set(search.countries.values) == {'de', 'en'}
+    assert not search.housenumbers.values
+
+
+def make_counted_searches(name_part, name_full, address_part, address_full):
+    q = QueryStruct([Phrase(PhraseType.NONE, '')])
+    for i in range(2):
+        q.add_node(BreakType.WORD, PhraseType.NONE)
+    q.add_node(BreakType.END, PhraseType.NONE)
+
+    q.add_token(TokenRange(0, 1), TokenType.PARTIAL,
+                MyToken(0.5, 1, name_part, 'name_part', True))
+    q.add_token(TokenRange(0, 1), TokenType.WORD,
+                MyToken(0, 101, name_full, 'name_full', True))
+    q.add_token(TokenRange(1, 2), TokenType.PARTIAL,
+                MyToken(0.5, 2, address_part, 'address_part', True))
+    q.add_token(TokenRange(1, 2), TokenType.WORD,
+                MyToken(0, 102, address_full, 'address_full', True))
+
+    builder = SearchBuilder(q, SearchDetails())
+
+    return list(builder.build(TokenAssignment(name=TokenRange(0, 1),
+                                              address=[TokenRange(1, 2)])))
+
+
+def test_infrequent_partials_in_name():
+    searches = make_counted_searches(1, 1, 1, 1)
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert len(search.lookups) == 2
+    assert len(search.rankings) == 2
+
+    assert set((l.column, l.lookup_type) for l in search.lookups) == \
+            {('name_vector', 'lookup_all'), ('nameaddress_vector', 'restrict')}
+
+
+def test_frequent_partials_in_name_but_not_in_address():
+    searches = make_counted_searches(10000, 1, 1, 1)
+
+    assert len(searches) == 1
+    search = searches[0]
+
+    assert isinstance(search, dbs.PlaceSearch)
+    assert len(search.lookups) == 2
+    assert len(search.rankings) == 2
+
+    assert set((l.column, l.lookup_type) for l in search.lookups) == \
+            {('nameaddress_vector', 'lookup_all'), ('name_vector', 'restrict')}
+
+
+def test_frequent_partials_in_name_and_address():
+    searches = make_counted_searches(10000, 1, 10000, 1)
+
+    assert len(searches) == 2
+
+    assert all(isinstance(s, dbs.PlaceSearch) for s in searches)
+    searches.sort(key=lambda s: s.penalty)
+
+    assert set((l.column, l.lookup_type) for l in searches[0].lookups) == \
+            {('name_vector', 'lookup_any'), ('nameaddress_vector', 'restrict')}
+    assert set((l.column, l.lookup_type) for l in searches[1].lookups) == \
+            {('nameaddress_vector', 'lookup_all'), ('name_vector', 'lookup_all')}

test/python/api/search/test_token_assignment.py

@@ -29,7 +29,7 @@ def make_query(*args):
 
         start = len(q.nodes) - 1
         for end, ttype in tlist:
-            q.add_token(TokenRange(start, end), ttype, [dummy])
+            q.add_token(TokenRange(start, end), ttype, dummy)
 
     q.add_node(BreakType.END, PhraseType.NONE)