Update required phrase generation

* This update decouples the creation of is_required_phrase rules from
  updating existing rules in a separate CLI. This makes it easier to
  control which rule are used as required phrases.

* This now skip to process more rules when adding required phrases to
  existing rules: any rule that cannot be matched approximately is
  skipped and only tiny rules, but also many other rules.

* This checks that no rule get a required phrase added that would
  break in the middle of a URL, email, or copyright. This is done by
  checking that no required phrase injection changes the set of
  ignorables of a rule and could break a URL making it no longer a
  proper URL. Same for emails or copyrights.

* This extends "skipping" the collection of required phrases to skip
  a rule from both required phrases collection for generationg new rules
  AND injection of new required phrases in rule text. This allow to
  handle exceptions more easily.

* The "is_required_phrase" rules creation now creates rules using
  improved content: the case and punctuation of the phrase text are
  preserved; the rule is created as "is_license_reference" which is
  going to be correct in the vast majority of the cases.

* When matched, the "is_required_phrase" rules are treated the same
  as continuous rules and can only be matched exactly.

* The "is_required_phrase" rules are now validated extensively to
  ensure that there is no conflict with other rule flags.

* The code to "trace" the source of a required_phase inject now uses
  the new standard "source" rule field, and the code related to handling
  this field has been simplified.

* Required phrases injection has not yet been tested as working.

Signed-off-by: Philippe Ombredanne <[email protected]>

setup.cfg

@@ -159,6 +159,7 @@ console_scripts =
     scancode-license-data = licensedcode.license_db:dump_scancode_license_data
     regen-package-docs = packagedcode.regen_package_docs:regen_package_docs
     add-required-phrases = licensedcode.required_phrases:add_required_phrases
+	gen-new-required-phrases-rules = licensedcode.required_phrases:gen_required_phrases_rules
 
 # These are configurations for ScanCode plugins as setuptools entry points.
 # Each plugin entry hast this form:

src/licensedcode/match.py

@@ -2129,12 +2129,14 @@ def filter_matches_missing_required_phrases(
     A required phrase must be matched exactly without gaps or unknown words.
 
     A rule with "is_continuous" set to True is the same as if its whole text
-    was defined as a keyphrase and is processed here too.
+    was defined as a required phrase and is processed here too.
+    Same for a rule with "is_required_phrase" set to True.
+
     """
-    # never discard a solo match, unless matched to "is_continuous" rule
+    # never discard a solo match, unless matched to "is_continuous" or "is_required_phrase" rule
     if len(matches) == 1:
         rule = matches[0]
-        if not rule.is_continuous:
+        if not (rule.is_continuous or rule.is_required_phrase):
             return matches, []
 
     kept = []
@@ -2149,7 +2151,7 @@ def filter_matches_missing_required_phrases(
         if trace:
             logger_debug('  CHECKING KEY PHRASES for:', match)
 
-        is_continuous = match.rule.is_continuous
+        is_continuous = match.rule.is_continuous or match.rule.is_required_phrase
         ikey_spans = match.rule.required_phrase_spans
 
         if not (ikey_spans or is_continuous):