Class: AcceptLanguage::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/accept_language/parser.rb

Overview

Parses Accept-Language header fields into structured data, extracting language tags and their quality values (q-values). Validates input according to RFC 2616 specifications and handles edge cases like malformed inputs and implicit quality values.

Examples:

parser = Parser.new("da, en-GB;q=0.8, en;q=0.7")
parser.match(:en, :da) # => :da

See Also:

Constant Summary collapse

DEFAULT_QUALITY =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

"1"
SEPARATOR =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

","
SPACE =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

" "
SUFFIX =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

";q="
QVALUE_PATTERN =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

/\A(?:0(?:\.[0-9]{1,3})?|1(?:\.0{1,3})?|\.[0-9]{1,3})\z/
LANGTAG_PATTERN =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

/\A(?:\*|[a-zA-Z]{1,8}(?:-[a-zA-Z0-9]{1,8})*)\z/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(field) ⇒ Parser

Initializes a new Parser instance by importing and processing the given Accept-Language header field.

Parameters:

  • field (String) —

    The Accept-Language header field to parse.



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# File 'lib/accept_language/parser.rb', line 36

def initialize(field)
  @languages_range = import(field)
end

Instance Attribute Details

#languages_range ⇒ Hash<String, BigDecimal> (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Parsed language tags and their quality values.

Returns:

  • (Hash<String, BigDecimal>) —

    Parsed language tags and their quality values



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# File 'lib/accept_language/parser.rb', line 31

def languages_range
  @languages_range
end

Instance Method Details

#match(*available_langtags) ⇒ String, ...

Finds the best matching language from available options based on user preferences. Considers quality values and language tag specificity (e.g., “en-US” vs “en”).

Examples:

Match against specific language options

parser.match("en", "fr", "de") # => "en" if English is preferred

Match with region-specific tags

parser.match("en-US", "en-GB", "fr") # => "en-GB" if British English is preferred

Parameters:

  • available_langtags (Array<String, Symbol>) —

    Languages supported by your application

Returns:

  • (String, Symbol, nil) —

    Best matching language tag or nil if no match found



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# File 'lib/accept_language/parser.rb', line 50

def match(*available_langtags)
  Matcher.new(**languages_range).call(*available_langtags)
end