module Tins::StringNamedPlaceholders

A module that provides methods for working with named placeholders in strings.

This module adds functionality to extract named placeholders from strings and assign values to them, making it easier to work with template-style strings that contain named substitution points.

@example Extracting named placeholders from a string

"Hello %{name}, you have %{count} messages".named_placeholders
# => [:name, :count]

@example Assigning values to named placeholders

template = "Welcome %{user}, your balance is %{amount}"
template.named_placeholders_assign(user: "Alice", amount: "$100")
# => {:user=>"Alice", :amount=>"$100"}

Public Instance Methods

named_placeholders ()

Source

# File lib/tins/string_named_placeholders.rb, line 26
def named_placeholders
  scan(/%\{([^}]+)\}/).inject([], &:concat).uniq.map(&:to_sym)
end

Returns an array of symbols representing the named placeholders found in the string.

This method scans the string for patterns matching named placeholders in the format %{name} and extracts the placeholder names, returning them as symbols in an array.

@return [Array<Symbol>] An array of unique symbol representations of the named placeholders found in the string.

named_placeholders_assign (hash, default: nil)

Source

# File lib/tins/string_named_placeholders.rb, line 45
def named_placeholders_assign(hash, default: nil)
  hash = hash.transform_keys(&:to_sym)
  named_placeholders.each_with_object({}) do |placeholder, h|
    h[placeholder] = hash[placeholder] ||
      (default.is_a?(Proc) ? default.(placeholder) : default)
  end
end

Assign values to named placeholders from a hash, using a default value for unspecified placeholders.

This method takes a hash of placeholder values and assigns them to the named placeholders found in the string. If a placeholder is not present in the input hash, the provided default value is used instead. The default can be a static value or a proc that receives the placeholder symbol as an argument.

@param hash [Hash] A hash mapping placeholder names to their corresponding values. @param default [Object, Proc] The default value to use for placeholders not present in the hash.

If a proc is provided, it will be called with the placeholder symbol.

@return [Hash] A new hash containing the assigned values for each named placeholder.

named_placeholders_interpolate (hash, default: nil)

Source

# File lib/tins/string_named_placeholders.rb, line 65
def named_placeholders_interpolate(hash, default: nil)
  values = named_placeholders_assign(hash, default:)
  self % values
end

Interpolate named placeholders in the string with values from a hash.

This method takes a hash of placeholder values and substitutes the named placeholders found in the string with their corresponding values. Placeholders that are not present in the input hash will be replaced with the provided default value.

@param hash [Hash] A hash mapping placeholder names to their corresponding values @param default [Object, Proc] The default value to use for placeholders not present in the hash

If a proc is provided, it will be called with the placeholder symbol

@return [String] A new string with named placeholders replaced by their values