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263 lines
8.1 KiB
Python
263 lines
8.1 KiB
Python
# SPDX-License-Identifier: AGPL-3.0-or-later
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"""A plugin for converting measured values from one unit to another unit (a
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unit converter).
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The plugin looks up the symbols (given in the query term) in a list of
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converters, each converter is one item in the list (compare
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:py:obj:`ADDITIONAL_UNITS`). If the symbols are ambiguous, the matching units
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of measurement are evaluated. The weighting in the evaluation results from the
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sorting of the :py:obj:`list of unit converters<symbol_to_si>`.
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Enable in ``settings.yml``:
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.. code:: yaml
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enabled_plugins:
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..
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- 'Unit converter plugin'
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"""
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import re
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import babel.numbers
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from flask_babel import gettext, get_locale
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from searx import data
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name = "Unit converter plugin"
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description = gettext("Convert between units")
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default_on = True
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plugin_id = "unit_converter"
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preference_section = "general"
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CONVERT_KEYWORDS = ["in", "to", "as"]
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# inspired from https://stackoverflow.com/a/42475086
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RE_MEASURE = r'''
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(?P<sign>[-+]?) # +/- or nothing for positive
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(\s*) # separator: white space or nothing
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(?P<number>[\d\.,]*) # number: 1,000.00 (en) or 1.000,00 (de)
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(?P<E>[eE][-+]?\d+)? # scientific notation: e(+/-)2 (*10^2)
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(\s*) # separator: white space or nothing
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(?P<unit>\S+) # unit of measure
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'''
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ADDITIONAL_UNITS = [
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{
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"si_name": "Q11579",
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"symbol": "°C",
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"to_si": lambda val: val + 273.15,
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"from_si": lambda val: val - 273.15,
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},
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{
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"si_name": "Q11579",
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"symbol": "°F",
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"to_si": lambda val: (val + 459.67) * 5 / 9,
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"from_si": lambda val: (val * 9 / 5) - 459.67,
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},
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]
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"""Additional items to convert from a measure unit to a SI unit (vice versa).
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.. code:: python
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{
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"si_name": "Q11579", # Wikidata item ID of the SI unit (Kelvin)
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"symbol": "°C", # symbol of the measure unit
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"to_si": lambda val: val + 273.15, # convert measure value (val) to SI unit
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"from_si": lambda val: val - 273.15, # convert SI value (val) measure unit
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},
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{
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"si_name": "Q11573",
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"symbol": "mi",
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"to_si": 1609.344, # convert measure value (val) to SI unit
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"from_si": 1 / 1609.344 # convert SI value (val) measure unit
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},
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The values of ``to_si`` and ``from_si`` can be of :py:obj:`float` (a multiplier)
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or a callable_ (val in / converted value returned).
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.. _callable: https://docs.python.org/3/glossary.html#term-callable
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"""
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ALIAS_SYMBOLS = {
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'°C': ('C',),
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'°F': ('F',),
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'mi': ('L',),
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}
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"""Alias symbols for known unit of measure symbols / by example::
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'°C': ('C', ...), # list of alias symbols for °C (Q69362731)
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'°F': ('F', ...), # list of alias symbols for °F (Q99490479)
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'mi': ('L',), # list of alias symbols for mi (Q253276)
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"""
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SYMBOL_TO_SI = []
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def symbol_to_si():
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"""Generates a list of tuples, each tuple is a measure unit and the fields
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in the tuple are:
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0. Symbol of the measure unit (e.g. 'mi' for measure unit 'miles' Q253276)
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1. SI name of the measure unit (e.g. Q11573 for SI unit 'metre')
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2. Factor to get SI value from measure unit (e.g. 1mi is equal to SI 1m
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multiplied by 1609.344)
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3. Factor to get measure value from from SI value (e.g. SI 100m is equal to
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100mi divided by 1609.344)
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The returned list is sorted, the first items are created from
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``WIKIDATA_UNITS``, the second group of items is build from
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:py:obj:`ADDITIONAL_UNITS` and items created from :py:obj:`ALIAS_SYMBOLS`.
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If you search this list for a symbol, then a match with a symbol from
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Wikidata has the highest weighting (first hit in the list), followed by the
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symbols from the :py:obj:`ADDITIONAL_UNITS` and the lowest weighting is
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given to the symbols resulting from the aliases :py:obj:`ALIAS_SYMBOLS`.
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"""
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global SYMBOL_TO_SI # pylint: disable=global-statement
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if SYMBOL_TO_SI:
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return SYMBOL_TO_SI
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# filter out units which can't be normalized to a SI unit and filter out
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# units without a symbol / arcsecond does not have a symbol
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# https://www.wikidata.org/wiki/Q829073
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for item in data.WIKIDATA_UNITS.values():
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if item['to_si_factor'] and item['symbol']:
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SYMBOL_TO_SI.append(
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(
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item['symbol'],
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item['si_name'],
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1 / item['to_si_factor'], # from_si
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item['to_si_factor'], # to_si
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item['symbol'],
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)
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)
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for item in ADDITIONAL_UNITS:
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SYMBOL_TO_SI.append(
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(
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item['symbol'],
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item['si_name'],
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item['from_si'],
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item['to_si'],
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item['symbol'],
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)
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)
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alias_items = []
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for item in SYMBOL_TO_SI:
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for alias in ALIAS_SYMBOLS.get(item[0], ()):
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alias_items.append(
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(
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alias,
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item[1],
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item[2], # from_si
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item[3], # to_si
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item[0], # origin unit
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)
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)
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SYMBOL_TO_SI = SYMBOL_TO_SI + alias_items
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return SYMBOL_TO_SI
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def _parse_text_and_convert(search, from_query, to_query):
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# pylint: disable=too-many-branches, too-many-locals
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if not (from_query and to_query):
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return
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measured = re.match(RE_MEASURE, from_query, re.VERBOSE)
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if not (measured and measured.group('number'), measured.group('unit')):
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return
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# Symbols are not unique, if there are several hits for the from-unit, then
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# the correct one must be determined by comparing it with the to-unit
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# https://github.com/searxng/searxng/pull/3378#issuecomment-2080974863
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# first: collecting possible units
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source_list, target_list = [], []
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for symbol, si_name, from_si, to_si, orig_symbol in symbol_to_si():
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if symbol == measured.group('unit'):
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source_list.append((si_name, to_si))
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if symbol == to_query:
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target_list.append((si_name, from_si, orig_symbol))
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if not (source_list and target_list):
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return
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source_to_si = target_from_si = target_symbol = None
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# second: find the right unit by comparing list of from-units with list of to-units
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for source in source_list:
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for target in target_list:
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if source[0] == target[0]: # compare si_name
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source_to_si = source[1]
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target_from_si = target[1]
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target_symbol = target[2]
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if not (source_to_si and target_from_si):
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return
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_locale = get_locale() or 'en_US'
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value = measured.group('sign') + measured.group('number') + (measured.group('E') or '')
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value = babel.numbers.parse_decimal(value, locale=_locale)
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# convert value to SI unit
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if isinstance(source_to_si, (float, int)):
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value = float(value) * source_to_si
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else:
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value = source_to_si(float(value))
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# convert value from SI unit to target unit
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if isinstance(target_from_si, (float, int)):
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value = float(value) * target_from_si
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else:
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value = target_from_si(float(value))
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if measured.group('E'):
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# when incoming notation is scientific, outgoing notation is scientific
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result = babel.numbers.format_scientific(value, locale=_locale)
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else:
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result = babel.numbers.format_decimal(value, locale=_locale, format='#,##0.##########;-#')
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search.result_container.answers['conversion'] = {'answer': f'{result} {target_symbol}'}
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def post_search(_request, search):
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# only convert between units on the first page
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if search.search_query.pageno > 1:
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return True
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query = search.search_query.query
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query_parts = query.split(" ")
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if len(query_parts) < 3:
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return True
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for query_part in query_parts:
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for keyword in CONVERT_KEYWORDS:
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if query_part == keyword:
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from_query, to_query = query.split(keyword, 1)
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_parse_text_and_convert(search, from_query.strip(), to_query.strip())
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return True
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return True
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