1+ //! For detecting the [restriction level](https://www.unicode.org/reports/tr39/#Restriction_Level_Detection)
2+ //! a string conforms to
3+
4+ use crate :: mixed_script:: AugmentedScriptSet ;
5+ use unicode_script:: { Script , ScriptExtension } ;
6+ use crate :: GeneralSecurityProfile ;
7+
8+ #[ derive( Copy , Clone , PartialEq , PartialOrd , Eq , Ord , Debug , Hash ) ]
9+ /// The [Restriction level](https://www.unicode.org/reports/tr39/#Restriction_Level_Detection)
10+ /// a string conforms to
11+ pub enum RestrictionLevel {
12+ /// https://www.unicode.org/reports/tr39/#ascii_only
13+ ASCIIOnly ,
14+ /// https://www.unicode.org/reports/tr39/#single_script
15+ SingleScript ,
16+ /// https://www.unicode.org/reports/tr39/#highly_restrictive
17+ HighlyRestrictive ,
18+ /// https://www.unicode.org/reports/tr39/#moderately_restrictive
19+ ModeratelyRestrictive ,
20+ /// https://www.unicode.org/reports/tr39/#minimally_restrictive
21+ MinimallyRestrictive ,
22+ /// https://www.unicode.org/reports/tr39/#unrestricted
23+ Unrestricted ,
24+ }
25+
26+ /// Utilities for determining which [restriction level](https://www.unicode.org/reports/tr39/#Restriction_Level_Detection)
27+ /// a string satisfies
28+ pub trait RestrictionLevelDetection : Sized {
29+ /// Detect the [restriction level](https://www.unicode.org/reports/tr39/#Restriction_Level_Detection)
30+ ///
31+ /// This will _not_ check identifier well-formedness, as different applications may have different notions of well-formedness
32+ fn detect_restriction_level ( self ) -> RestrictionLevel ;
33+
34+
35+ /// Check if a string satisfies the supplied [restriction level](https://www.unicode.org/reports/tr39/#Restriction_Level_Detection)
36+ ///
37+ /// This will _not_ check identifier well-formedness, as different applications may have different notions of well-formedness
38+ fn check_restriction_level ( self , level : RestrictionLevel ) -> bool {
39+ self . detect_restriction_level ( ) <= level
40+ }
41+ }
42+
43+ impl RestrictionLevelDetection for & ' _ str {
44+ fn detect_restriction_level ( self ) -> RestrictionLevel {
45+ let mut ascii_only = true ;
46+ let mut set = AugmentedScriptSet :: default ( ) ;
47+ let mut exclude_latin_set = AugmentedScriptSet :: default ( ) ;
48+ for ch in self . chars ( ) {
49+ if !GeneralSecurityProfile :: identifier_allowed ( ch) {
50+ return RestrictionLevel :: Unrestricted ;
51+ }
52+ if ch. is_ascii ( ) {
53+ ascii_only = false ;
54+ }
55+ let ch_set = ch. into ( ) ;
56+ set. intersect_with ( ch_set) ;
57+ if !ch_set. base . contains_script ( Script :: Latin ) {
58+ exclude_latin_set. intersect_with ( ch_set) ;
59+ }
60+ }
61+
62+ if ascii_only {
63+ return RestrictionLevel :: ASCIIOnly ;
64+ } else if !set. is_empty ( ) {
65+ return RestrictionLevel :: SingleScript ;
66+ } else if exclude_latin_set. kore || exclude_latin_set. hanb || exclude_latin_set. jpan {
67+ return RestrictionLevel :: HighlyRestrictive ;
68+ } else if let ScriptExtension :: Single ( script) = exclude_latin_set. base {
69+ if script. is_recommended ( ) && script != Script :: Cyrillic && script != Script :: Greek {
70+ return RestrictionLevel :: ModeratelyRestrictive ;
71+ }
72+ }
73+ return RestrictionLevel :: MinimallyRestrictive ;
74+ }
75+ }
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