Coverage for python/lsst/daf/butler/registry/queries/expressions.py : 23%

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1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
21from __future__ import annotations
23__all__ = () # all symbols intentionally private; for internal package use.
26from sqlalchemy.sql import not_, or_, and_, literal, FromClause
28from ...core.utils import NamedValueSet, NamedKeyDict
29from ...core import DimensionUniverse, Dimension, DimensionElement
30from .exprParser import TreeVisitor
31from ._structs import QueryColumns
34def categorizeIdentifier(universe: DimensionUniverse, name: str):
35 """Categorize an identifier in a parsed expression as either a `Dimension`
36 name (indicating the primary key for that dimension) or a non-primary-key
37 column in a `DimensionElement` table.
39 Parameters
40 ----------
41 universe : `DimensionUniverse`
42 All known dimensions.
43 name : `str`
44 Identifier to categorize.
46 Returns
47 -------
48 element : `DimensionElement`
49 The `DimensionElement` the identifier refers to.
50 column : `str` or `None`
51 The name of a column in the table for ``element``, or `None` if
52 ``element`` is a `Dimension` and the requested column is its primary
53 key.
55 Raises
56 ------
57 LookupError
58 Raised if the identifier refers to a nonexistent `DimensionElement`
59 or column.
60 RuntimeError
61 Raised if the expression refers to a primary key in an illegal way.
62 This exception includes a suggestion for how to rewrite the expression,
63 so at least its message should generally be propagated up to a context
64 where the error can be interpreted by a human.
65 """
66 table, sep, column = name.partition('.')
67 if column:
68 try:
69 element = universe[table]
70 except KeyError as err:
71 raise LookupError(f"No dimension element with name '{table}'.") from err
72 if isinstance(element, Dimension) and column == element.primaryKey.name:
73 # Allow e.g. "visit.id = x" instead of just "visit = x"; this
74 # can be clearer.
75 return element, None
76 elif column in element.graph.names:
77 # User said something like "patch.tract = x" or
78 # "tract.tract = x" instead of just "tract = x" or
79 # "tract.id = x", which is at least needlessly confusing and
80 # possibly not actually a column name, though we can guess
81 # what they were trying to do.
82 # Encourage them to clean that up and try again.
83 raise RuntimeError(
84 f"Invalid reference to '{table}.{column}' in expression; please use "
85 f"'{column}' or '{column}.{universe[column].primaryKey.name}' instead."
86 )
87 else:
88 if column not in element.RecordClass.__slots__:
89 raise LookupError(f"Column '{column} not found in table for {element}.")
90 return element, column
91 else:
92 try:
93 dimension = universe.dimensions[table]
94 except KeyError as err:
95 raise LookupError(f"No dimension with name '{table}.") from err
96 return dimension, None
99class InspectionVisitor(TreeVisitor):
100 """Implements TreeVisitor to identify dimension elements that need
101 to be included in a query, prior to actually constructing a SQLAlchemy
102 WHERE clause from it.
104 Parameters
105 ----------
106 universe : `DimensionUniverse`
107 All known dimensions.
108 """
110 def __init__(self, universe: DimensionUniverse):
111 self.universe = universe
112 self.keys = NamedValueSet()
113 self.metadata = NamedKeyDict()
115 def visitNumericLiteral(self, value, node):
116 # Docstring inherited from TreeVisitor.visitNumericLiteral
117 pass
119 def visitStringLiteral(self, value, node):
120 # Docstring inherited from TreeVisitor.visitStringLiteral
121 pass
123 def visitIdentifier(self, name, node):
124 # Docstring inherited from TreeVisitor.visitIdentifier
125 element, column = categorizeIdentifier(self.universe, name)
126 if column is not None:
127 self.metadata.setdefault(element, []).append(column)
128 else:
129 self.keys.add(element)
131 def visitUnaryOp(self, operator, operand, node):
132 # Docstring inherited from TreeVisitor.visitUnaryOp
133 pass
135 def visitBinaryOp(self, operator, lhs, rhs, node):
136 # Docstring inherited from TreeVisitor.visitBinaryOp
137 pass
139 def visitIsIn(self, lhs, values, not_in, node):
140 # Docstring inherited from TreeVisitor.visitIsIn
141 pass
143 def visitParens(self, expression, node):
144 # Docstring inherited from TreeVisitor.visitParens
145 pass
147 def visitRangeLiteral(self, start, stop, stride, node):
148 # Docstring inherited from TreeVisitor.visitRangeLiteral
149 pass
152class ClauseVisitor(TreeVisitor):
153 """Implements TreeVisitor to convert the tree into a SQLAlchemy WHERE
154 clause.
156 Parameters
157 ----------
158 universe : `DimensionUniverse`
159 All known dimensions.
160 columns: `QueryColumns`
161 Struct that organizes the special columns known to the query
162 under construction.
163 elements: `NamedKeyDict`
164 `DimensionElement` instances and their associated tables.
165 """
167 unaryOps = {"NOT": lambda x: not_(x), 167 ↛ exitline 167 didn't run the lambda on line 167
168 "+": lambda x: +x,
169 "-": lambda x: -x}
170 """Mapping or unary operator names to corresponding functions"""
172 binaryOps = {"OR": lambda x, y: or_(x, y), 172 ↛ exitline 172 didn't run the lambda on line 172
173 "AND": lambda x, y: and_(x, y),
174 "=": lambda x, y: x == y,
175 "!=": lambda x, y: x != y,
176 "<": lambda x, y: x < y,
177 "<=": lambda x, y: x <= y,
178 ">": lambda x, y: x > y,
179 ">=": lambda x, y: x >= y,
180 "+": lambda x, y: x + y,
181 "-": lambda x, y: x - y,
182 "*": lambda x, y: x * y,
183 "/": lambda x, y: x / y,
184 "%": lambda x, y: x % y}
185 """Mapping or binary operator names to corresponding functions"""
187 def __init__(self, universe: DimensionUniverse,
188 columns: QueryColumns, elements: NamedKeyDict[DimensionElement, FromClause]):
189 self.universe = universe
190 self.columns = columns
191 self.elements = elements
193 def visitNumericLiteral(self, value, node):
194 # Docstring inherited from TreeVisitor.visitNumericLiteral
195 # Convert string value into float or int
196 try:
197 value = int(value)
198 except ValueError:
199 value = float(value)
200 return literal(value)
202 def visitStringLiteral(self, value, node):
203 # Docstring inherited from TreeVisitor.visitStringLiteral
204 return literal(value)
206 def visitIdentifier(self, name, node):
207 # Docstring inherited from TreeVisitor.visitIdentifier
208 element, column = categorizeIdentifier(self.universe, name)
209 if column is not None:
210 return self.elements[element].columns[column]
211 else:
212 return self.columns.getKeyColumn(element)
214 def visitUnaryOp(self, operator, operand, node):
215 # Docstring inherited from TreeVisitor.visitUnaryOp
216 func = self.unaryOps.get(operator)
217 if func:
218 return func(operand)
219 else:
220 raise ValueError(f"Unexpected unary operator `{operator}' in `{node}'.")
222 def visitBinaryOp(self, operator, lhs, rhs, node):
223 # Docstring inherited from TreeVisitor.visitBinaryOp
224 func = self.binaryOps.get(operator)
225 if func:
226 return func(lhs, rhs)
227 else:
228 raise ValueError(f"Unexpected binary operator `{operator}' in `{node}'.")
230 def visitIsIn(self, lhs, values, not_in, node):
231 # Docstring inherited from TreeVisitor.visitIsIn
233 # `values` is a list of literals and ranges, range is represented
234 # by a tuple (start, stop, stride). We need to transform range into
235 # some SQL construct, simplest would be to generate a set of literals
236 # and add it to the same list but it could become too long. What we
237 # do here is to introduce some large limit on the total number of
238 # items in IN() and if range exceeds that limit then we do something
239 # like:
240 #
241 # X IN (1, 2, 3)
242 # OR
243 # (X BETWEEN START AND STOP AND MOD(X, STRIDE) = MOD(START, STRIDE))
244 #
245 # or for NOT IN case
246 #
247 # NOT (X IN (1, 2, 3)
248 # OR
249 # (X BETWEEN START AND STOP
250 # AND MOD(X, STRIDE) = MOD(START, STRIDE)))
252 max_in_items = 1000
254 # split the list into literals and ranges
255 literals, ranges = [], []
256 for item in values:
257 if isinstance(item, tuple):
258 ranges.append(item)
259 else:
260 literals.append(item)
262 clauses = []
263 for start, stop, stride in ranges:
264 count = (stop - start + 1) // stride
265 if len(literals) + count > max_in_items:
266 # X BETWEEN START AND STOP
267 # AND MOD(X, STRIDE) = MOD(START, STRIDE)
268 expr = lhs.between(start, stop)
269 if stride != 1:
270 expr = and_(expr, (lhs % stride) == (start % stride))
271 clauses.append(expr)
272 else:
273 # add all values to literal list, stop is inclusive
274 literals += [literal(value) for value in range(start, stop+1, stride)]
276 if literals:
277 # add IN() in front of BETWEENs
278 clauses.insert(0, lhs.in_(literals))
280 expr = or_(*clauses)
281 if not_in:
282 expr = not_(expr)
284 return expr
286 def visitParens(self, expression, node):
287 # Docstring inherited from TreeVisitor.visitParens
288 return expression.self_group()
290 def visitRangeLiteral(self, start, stop, stride, node):
291 # Docstring inherited from TreeVisitor.visitRangeLiteral
293 # Just return a triple and let parent clauses handle it,
294 # stride can be None which means the same as 1.
295 return (start, stop, stride or 1)