Class: Addressable::Template

Inherits:
Object
  • Object
show all
Defined in:
lib/addressable/template.rb

Overview

This is an implementation of a URI template based on <a href=“tinyurl.com/uritemplatedraft03”>URI Template draft 03</a>.

Defined Under Namespace

Classes: InvalidTemplateOperatorError, InvalidTemplateValueError, MatchData, TemplateOperatorAbortedError

Constant Summary collapse

OPERATOR_EXPANSION = 
/\{-([a-zA-Z]+)\|([#{anything}]+)\|([#{anything}]+)\}/
VARIABLE_EXPANSION = 
/\{([#{anything}]+?)(?:=([#{anything}]+))?\}/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pattern) ⇒ Addressable::Template

Creates a new Addressable::Template object.

Parameters:

  • pattern (#to_str) —

    The URI Template pattern.



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# File 'lib/addressable/template.rb', line 129

def initialize(pattern)
  if !pattern.respond_to?(:to_str)
    raise TypeError, "Can't convert #{pattern.class} into String."
  end
  @pattern = pattern.to_str.freeze
end

Instance Attribute Details

#pattern ⇒ String (readonly)

Returns The Template object’s pattern.

Returns:

  • (String) —

    The Template object’s pattern.



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# File 'lib/addressable/template.rb', line 138

def pattern
  @pattern
end

Instance Method Details

#expand(mapping, processor = nil) ⇒ Addressable::URI

Expands a URI template into a full URI.

The object should respond to either the validate or transform messages or both. Both the validate and transform methods should take two parameters: name and value. The validate method should return true or false; true if the value of the variable is valid, false otherwise. An InvalidTemplateValueError exception will be raised if the value is invalid. The transform method should return the transformed variable value as a String. If a transform method is used, the value will not be percent encoded automatically. Unicode normalization will be performed both before and after sending the value to the transform method.

Examples:

class ExampleProcessor
  def self.validate(name, value)
    return !!(value =~ /^[\w ]+$/) if name == "query"
    return true
  end

  def self.transform(name, value)
    return value.gsub(/ /, "+") if name == "query"
    return value
  end
end

Addressable::Template.new(
  "http://example.com/search/{query}/"
).expand(
  {"query" => "an example search query"},
  ExampleProcessor
).to_str
#=> "http://example.com/search/an+example+search+query/"

Addressable::Template.new(
  "http://example.com/search/{-list|+|query}/"
).expand(
  {"query" => "an example search query".split(" ")}
).to_str
#=> "http://example.com/search/an+example+search+query/"

Addressable::Template.new(
  "http://example.com/search/{query}/"
).expand(
  {"query" => "bogus!"},
  ExampleProcessor
).to_str
#=> Addressable::Template::InvalidTemplateValueError

Parameters:

  • mapping (Hash) —

    The mapping that corresponds to the pattern.

  • processor (#validate, #transform) (defaults to: nil) —

    An optional processor object may be supplied.

Returns:



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# File 'lib/addressable/template.rb', line 456

def expand(mapping, processor=nil)
  result = self.pattern.dup
  transformed_mapping = transform_mapping(mapping, processor)
  result.gsub!(
    /#{OPERATOR_EXPANSION}|#{VARIABLE_EXPANSION}/
  ) do |capture|
    if capture =~ OPERATOR_EXPANSION
      operator, argument, variables, default_mapping =
        parse_template_expansion(capture, transformed_mapping)
      expand_method = "expand_#{operator}_operator"
      if ([expand_method, expand_method.to_sym] & private_methods).empty?
        raise InvalidTemplateOperatorError,
          "Invalid template operator: #{operator}"
      else
        send(expand_method.to_sym, argument, variables, default_mapping)
      end
    else
      varname, _, vardefault = capture.scan(/^\{(.+?)(=(.*))?\}$/)[0]
      transformed_mapping[varname] || vardefault
    end
  end
  return Addressable::URI.parse(result)
end

#extract(uri, processor = nil) ⇒ Hash, NilClass

Extracts a mapping from the URI using a URI Template pattern.

The object should respond to either the restore or match messages or both. The restore method should take two parameters: [String] name and [String] value. The restore method should reverse any transformations that have been performed on the value to ensure a valid URI. The match method should take a single parameter: [String] name. The match method should return a String containing a regular expression capture group for matching on that particular variable. The default value is “.*?”. The match method has no effect on multivariate operator expansions.

The Hash mapping that was extracted from the URI, or nil if the URI didn’t match the template.

Examples:

class ExampleProcessor
  def self.restore(name, value)
    return value.gsub(/\+/, " ") if name == "query"
    return value
  end

  def self.match(name)
    return ".*?" if name == "first"
    return ".*"
  end
end

uri = Addressable::URI.parse(
  "http://example.com/search/an+example+search+query/"
)
Addressable::Template.new(
  "http://example.com/search/{query}/"
).extract(uri, ExampleProcessor)
#=> {"query" => "an example search query"}

uri = Addressable::URI.parse("http://example.com/a/b/c/")
Addressable::Template.new(
  "http://example.com/{first}/{second}/"
).extract(uri, ExampleProcessor)
#=> {"first" => "a", "second" => "b/c"}

uri = Addressable::URI.parse("http://example.com/a/b/c/")
Addressable::Template.new(
  "http://example.com/{first}/{-list|/|second}/"
).extract(uri)
#=> {"first" => "a", "second" => ["b", "c"]}

Parameters:

  • uri (Addressable::URI, #to_str) —

    The URI to extract from.

  • processor (#restore, #match) (defaults to: nil) —

    A template processor object may optionally be supplied.

Returns:

  • (Hash, NilClass) 


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# File 'lib/addressable/template.rb', line 204

def extract(uri, processor=nil)
  match_data = self.match(uri, processor)
  return (match_data ? match_data.mapping : nil)
end

#inspect ⇒ String

Returns a String representation of the Template object’s state.

Returns:

  • (String) —

    The Template object’s state, as a String.



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# File 'lib/addressable/template.rb', line 144

def inspect
  sprintf("#<%s:%#0x PATTERN:%s>",
    self.class.to_s, self.object_id, self.pattern)
end

#match(uri, processor = nil) ⇒ Hash, NilClass

Extracts match data from the URI using a URI Template pattern.

The object should respond to either the restore or match messages or both. The restore method should take two parameters: [String] name and [String] value. The restore method should reverse any transformations that have been performed on the value to ensure a valid URI. The match method should take a single parameter: [String] name. The match method should return a String containing a regular expression capture group for matching on that particular variable. The default value is “.*?”. The match method has no effect on multivariate operator expansions.

The Hash mapping that was extracted from the URI, or nil if the URI didn’t match the template.

Examples:

class ExampleProcessor
  def self.restore(name, value)
    return value.gsub(/\+/, " ") if name == "query"
    return value
  end

  def self.match(name)
    return ".*?" if name == "first"
    return ".*"
  end
end

uri = Addressable::URI.parse(
  "http://example.com/search/an+example+search+query/"
)
match = Addressable::Template.new(
  "http://example.com/search/{query}/"
).match(uri, ExampleProcessor)
match.variables
#=> ["query"]
match.captures
#=> ["an example search query"]

uri = Addressable::URI.parse("http://example.com/a/b/c/")
match = Addressable::Template.new(
  "http://example.com/{first}/{second}/"
).match(uri, ExampleProcessor)
match.variables
#=> ["first", "second"]
match.captures
#=> ["a", "b/c"]

uri = Addressable::URI.parse("http://example.com/a/b/c/")
match = Addressable::Template.new(
  "http://example.com/{first}/{-list|/|second}/"
).match(uri)
match.variables
#=> ["first", "second"]
match.captures
#=> ["a", ["b", "c"]]

Parameters:

  • uri (Addressable::URI, #to_str) —

    The URI to extract from.

  • processor (#restore, #match) (defaults to: nil) —

    A template processor object may optionally be supplied.

Returns:

  • (Hash, NilClass) 


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# File 'lib/addressable/template.rb', line 273

def match(uri, processor=nil)
  uri = Addressable::URI.parse(uri)
  mapping = {}

  # First, we need to process the pattern, and extract the values.
  expansions, expansion_regexp =
    parse_template_pattern(pattern, processor)
  unparsed_values = uri.to_str.scan(expansion_regexp).flatten

  if uri.to_str == pattern
    return Addressable::Template::MatchData.new(uri, self, mapping)
  elsif expansions.size > 0 && expansions.size == unparsed_values.size
    expansions.each_with_index do |expansion, index|
      unparsed_value = unparsed_values[index]
      if expansion =~ OPERATOR_EXPANSION
        operator, argument, variables =
          parse_template_expansion(expansion)
        extract_method = "extract_#{operator}_operator"
        if ([extract_method, extract_method.to_sym] &
            private_methods).empty?
          raise InvalidTemplateOperatorError,
            "Invalid template operator: #{operator}"
        else
          begin
            send(
              extract_method.to_sym, unparsed_value, processor,
              argument, variables, mapping
            )
          rescue TemplateOperatorAbortedError
            return nil
          end
        end
      else
        name = expansion[VARIABLE_EXPANSION, 1]
        value = unparsed_value
        if processor != nil && processor.respond_to?(:restore)
          value = processor.restore(name, value)
        end
        if mapping[name] == nil || mapping[name] == value
          mapping[name] = value
        else
          return nil
        end
      end
    end
    return Addressable::Template::MatchData.new(uri, self, mapping)
  else
    return nil
  end
end

#partial_expand(mapping, processor = nil) ⇒ Addressable::Template

Expands a URI template into another URI template.

The object should respond to either the validate or transform messages or both. Both the validate and transform methods should take two parameters: name and value. The validate method should return true or false; true if the value of the variable is valid, false otherwise. An InvalidTemplateValueError exception will be raised if the value is invalid. The transform method should return the transformed variable value as a String. If a transform method is used, the value will not be percent encoded automatically. Unicode normalization will be performed both before and after sending the value to the transform method.

Examples:

Addressable::Template.new(
  "http://example.com/{one}/{two}/"
).partial_expand({"one" => "1"}).pattern
#=> "http://example.com/1/{two}/"

Addressable::Template.new(
  "http://example.com/search/{-list|+|query}/"
).partial_expand(
  {"query" => "an example search query".split(" ")}
).pattern
#=> "http://example.com/search/an+example+search+query/"

Addressable::Template.new(
  "http://example.com/{-join|&|one,two}/"
).partial_expand({"one" => "1"}).pattern
#=> "http://example.com/?one=1{-prefix|&two=|two}"

Addressable::Template.new(
  "http://example.com/{-join|&|one,two,three}/"
).partial_expand({"one" => "1", "three" => 3}).pattern
#=> "http://example.com/?one=1{-prefix|&two=|two}&three=3"

Parameters:

  • mapping (Hash) —

    The mapping that corresponds to the pattern.

  • processor (#validate, #transform) (defaults to: nil) —

    An optional processor object may be supplied.

Returns:



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# File 'lib/addressable/template.rb', line 367

def partial_expand(mapping, processor=nil)
  result = self.pattern.dup
  transformed_mapping = transform_mapping(mapping, processor)
  result.gsub!(
    /#{OPERATOR_EXPANSION}|#{VARIABLE_EXPANSION}/
  ) do |capture|
    if capture =~ OPERATOR_EXPANSION
      operator, argument, variables, default_mapping =
        parse_template_expansion(capture, transformed_mapping)
      expand_method = "expand_#{operator}_operator"
      if ([expand_method, expand_method.to_sym] & private_methods).empty?
        raise InvalidTemplateOperatorError,
          "Invalid template operator: #{operator}"
      else
        send(
          expand_method.to_sym, argument, variables,
          default_mapping, true
        )
      end
    else
      varname, _, vardefault = capture.scan(/^\{(.+?)(=(.*))?\}$/)[0]
      if transformed_mapping[varname]
        transformed_mapping[varname]
      elsif vardefault
        "{#{varname}=#{vardefault}}"
      else
        "{#{varname}}"
      end
    end
  end
  return Addressable::Template.new(result)
end

#variable_defaults ⇒ Hash

Returns a mapping of variables to their default values specified in the template. Variables without defaults are not returned.

Returns:

  • (Hash) —

    Mapping of template variables to their defaults



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# File 'lib/addressable/template.rb', line 497

def variable_defaults
  @variable_defaults ||=
    Hash[*ordered_variable_defaults.reject { |k, v| v.nil? }.flatten]
end

#variables ⇒ Array Also known as: keys

Returns an Array of variables used within the template pattern. The variables are listed in the Array in the order they appear within the pattern. Multiple occurrences of a variable within a pattern are not represented in this Array.

Returns:

  • (Array) —

    The variables present in the template’s pattern.



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# File 'lib/addressable/template.rb', line 487

def variables
  @variables ||= ordered_variable_defaults.map { |var, val| var }.uniq
end