Helper class to create ICU rules from a configuration file.
"""
import io
-import yaml
import logging
-from collections import defaultdict
import itertools
+from pathlib import Path
+import re
+import yaml
from icu import Transliterator
from nominatim.errors import UsageError
+import nominatim.tokenizer.icu_variants as variants
LOG = logging.getLogger()
+def _flatten_yaml_list(content):
+ if not content:
+ return []
+
+ if not isinstance(content, list):
+ raise UsageError("List expected in ICU yaml configuration.")
+
+ output = []
+ for ele in content:
+ if isinstance(ele, list):
+ output.extend(_flatten_yaml_list(ele))
+ else:
+ output.append(ele)
+
+ return output
+
+
+class VariantRule:
+ """ Saves a single variant expansion.
+
+ An expansion consists of the normalized replacement term and
+ a dicitonary of properties that describe when the expansion applies.
+ """
+
+ def __init__(self, replacement, properties):
+ self.replacement = replacement
+ self.properties = properties or {}
+
class ICURuleLoader:
""" Compiler for ICU rules from a tokenizer configuration file.
def __init__(self, configfile):
self.configfile = configfile
+ self.variants = set()
if configfile.suffix == '.yaml':
self._load_from_yaml()
def get_search_rules(self):
""" Return the ICU rules to be used during search.
- The rules combine normalization, compound decomposition (including
- abbreviated compounds) and transliteration.
+ The rules combine normalization and transliteration.
"""
# First apply the normalization rules.
rules = io.StringIO()
rules.write(self.normalization_rules)
- # For all compound suffixes: add them in their full and any abbreviated form.
- suffixes = set()
- for suffix in self.compound_suffixes:
- suffixes.add(suffix)
- suffixes.update(self.abbreviations.get(suffix, []))
-
- for suffix in sorted(suffixes, key=lambda x:len(x), reverse=True):
- rules.write("'{0} ' > ' {0} ';".format(suffix))
-
- # Finally add transliteration.
+ # Then add transliteration.
rules.write(self.transliteration_rules)
return rules.getvalue()
The result is a list of pairs: the first item is the sequence to
replace, the second is a list of replacements.
"""
- synonyms = defaultdict(set)
+ return self.variants
- for full, abbr in self.abbreviations.items():
- key = ' ' + full + ' '
- # Entries in the abbreviation list always apply to full words:
- synonyms[key].update((' ' + a + ' ' for a in abbr))
- # Replacements are optional, so add a noop
- synonyms[key].add(key)
+ def _yaml_include_representer(self, loader, node):
+ value = loader.construct_scalar(node)
- # Entries in the compound list expand to themselves and to
- # abbreviations.
- for suffix in self.compound_suffixes:
- keyset = synonyms[suffix + ' ']
- keyset.add(' ' + suffix + ' ')
- keyset.update((' ' + a + ' ' for a in self.abbreviations.get(suffix, [])))
- # The terms the entries are shortended to, need to be decompunded as well.
- for abbr in self.abbreviations.get(suffix, []):
- synonyms[abbr + ' '].add(' ' + abbr + ' ')
-
- # sort the resulting list by descending length (longer matches are prefered).
- sorted_keys = sorted(synonyms.keys(), key=lambda x: len(x), reverse=True)
+ if Path(value).is_absolute():
+ content = Path(value).read_text()
+ else:
+ content = (self.configfile.parent / value).read_text()
- return [(k, list(synonyms[k])) for k in sorted_keys]
+ return yaml.safe_load(content)
def _load_from_yaml(self):
- rules = yaml.load(self.configfile.read_text())
+ yaml.add_constructor('!include', self._yaml_include_representer,
+ Loader=yaml.SafeLoader)
+ rules = yaml.safe_load(self.configfile.read_text())
self.normalization_rules = self._cfg_to_icu_rules(rules, 'normalization')
self.transliteration_rules = self._cfg_to_icu_rules(rules, 'transliteration')
- self._parse_compound_suffix_list(self._get_section(rules, 'compound_suffixes'))
- self._parse_abbreviation_list(self._get_section(rules, 'abbreviations'))
+ self._parse_variant_list(self._get_section(rules, 'variants'))
def _get_section(self, rules, section):
"""
content = self._get_section(rules, section)
- if isinstance(content, str):
- return (self.configfile.parent / content).read_text().replace('\n', ' ')
+ if content is None:
+ return ''
+
+ return ';'.join(_flatten_yaml_list(content)) + ';'
- return ';'.join(content) + ';'
+ def _parse_variant_list(self, rules):
+ self.variants.clear()
- def _parse_compound_suffix_list(self, rules):
if not rules:
- self.compound_suffixes = set()
return
- norm = Transliterator.createFromRules("rule_loader_normalization",
- self.normalization_rules)
+ rules = _flatten_yaml_list(rules)
- # Make sure all suffixes are in their normalised form.
- self.compound_suffixes = set((norm.transliterate(s) for s in rules))
+ vmaker = _VariantMaker(self.normalization_rules)
+ properties = []
+ for section in rules:
+ # Create the property field and deduplicate against existing
+ # instances.
+ props = variants.ICUVariantProperties.from_rules(section)
+ for existing in properties:
+ if existing == props:
+ props = existing
+ break
+ else:
+ properties.append(props)
- def _parse_abbreviation_list(self, rules):
- self.abbreviations = defaultdict(list)
+ for rule in (section.get('words') or []):
+ self.variants.update(vmaker.compute(rule, props))
- if not rules:
- return
- norm = Transliterator.createFromRules("rule_loader_normalization",
- self.normalization_rules)
+class _VariantMaker:
+ """ Generater for all necessary ICUVariants from a single variant rule.
- for rule in rules:
- parts = rule.split('=>')
- if len(parts) != 2:
- LOG.fatal("Syntax error in abbreviation section, line: %s", rule)
- raise UsageError("Syntax error in tokenizer configuration file.")
+ All text in rules is normalized to make sure the variants match later.
+ """
- # Make sure all terms match the normalised version.
- fullterms = (norm.transliterate(t.strip()) for t in parts[0].split(','))
- abbrterms = (norm.transliterate(t.strip()) for t in parts[1].split(','))
+ def __init__(self, norm_rules):
+ self.norm = Transliterator.createFromRules("rule_loader_normalization",
+ norm_rules)
- for full, abbr in itertools.product(fullterms, abbrterms):
- self.abbreviations[full].append(abbr)
+
+ def compute(self, rule, props):
+ """ Generator for all ICUVariant tuples from a single variant rule.
+ """
+ parts = re.split(r'(\|)?([=-])>', rule)
+ if len(parts) != 4:
+ raise UsageError("Syntax error in variant rule: " + rule)
+
+ decompose = parts[1] is None
+ src_terms = [self._parse_variant_word(t) for t in parts[0].split(',')]
+ repl_terms = (self.norm.transliterate(t.strip()) for t in parts[3].split(','))
+
+ # If the source should be kept, add a 1:1 replacement
+ if parts[2] == '-':
+ for src in src_terms:
+ if src:
+ for froms, tos in _create_variants(*src, src[0], decompose):
+ yield variants.ICUVariant(froms, tos, props)
+
+ for src, repl in itertools.product(src_terms, repl_terms):
+ if src and repl:
+ for froms, tos in _create_variants(*src, repl, decompose):
+ yield variants.ICUVariant(froms, tos, props)
+
+
+ def _parse_variant_word(self, name):
+ name = name.strip()
+ match = re.fullmatch(r'([~^]?)([^~$^]*)([~$]?)', name)
+ if match is None or (match.group(1) == '~' and match.group(3) == '~'):
+ raise UsageError("Invalid variant word descriptor '{}'".format(name))
+ norm_name = self.norm.transliterate(match.group(2))
+ if not norm_name:
+ return None
+
+ return norm_name, match.group(1), match.group(3)
+
+
+_FLAG_MATCH = {'^': '^ ',
+ '$': ' ^',
+ '': ' '}
+
+
+def _create_variants(src, preflag, postflag, repl, decompose):
+ if preflag == '~':
+ postfix = _FLAG_MATCH[postflag]
+ # suffix decomposition
+ src = src + postfix
+ repl = repl + postfix
+
+ yield src, repl
+ yield ' ' + src, ' ' + repl
+
+ if decompose:
+ yield src, ' ' + repl
+ yield ' ' + src, repl
+ elif postflag == '~':
+ # prefix decomposition
+ prefix = _FLAG_MATCH[preflag]
+ src = prefix + src
+ repl = prefix + repl
+
+ yield src, repl
+ yield src + ' ', repl + ' '
+
+ if decompose:
+ yield src, repl + ' '
+ yield src + ' ', repl
+ else:
+ prefix = _FLAG_MATCH[preflag]
+ postfix = _FLAG_MATCH[postflag]
+
+ yield prefix + src + postfix, prefix + repl + postfix
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