Class: PatchYAML::QueryParser

Inherits:
Object
  • Object
show all
Defined in:
lib/patchyaml/query_parser.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query) ⇒ QueryParser

Returns a new instance of QueryParser.



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# File 'lib/patchyaml/query_parser.rb', line 7

def initialize(query)
  @path = []
  @pos = 0
  @start = 0
  @query = query.each_char.to_a
  @current_path = nil
end

Class Method Details

.parse(query) ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 5

def self.parse(query) = new(query).parse

Instance Method Details

#advance ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 16

def advance = @query[@pos].tap { @pos += 1 }

#digit?(value = nil) ⇒ Boolean

Returns:



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# File 'lib/patchyaml/query_parser.rb', line 22

def digit?(value = nil)
  value = peek if value.nil?
  !value.nil? && value >= "0" && value <= "9"
end

#eof? ⇒ Boolean

Returns:



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# File 'lib/patchyaml/query_parser.rb', line 17

def eof? = @pos >= @query.length

#mark ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 19

def mark = @start = @pos

#matches?(char) ⇒ Boolean

Returns:



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# File 'lib/patchyaml/query_parser.rb', line 18

def matches?(char) = peek == char

#non_separator? ⇒ Boolean

Returns:



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# File 'lib/patchyaml/query_parser.rb', line 27

def non_separator?
  peek != "[" && peek != "."
end

#parse ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 41

def parse
  until eof?
    next parse_index if digit?

    case peek
    when "["
      parse_expression_path
    when "."
      push_path
    else
      parse_simple_path
    end
  end

  @path
end

#parse_expression_path ⇒ Object

Raises:



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# File 'lib/patchyaml/query_parser.rb', line 65

def parse_expression_path
  raise ArgumentError, "Expected '[', found #{peek} at index #{@pos}" unless peek == "["

  advance # Consume [
  mark
  advance until peek == "]" || eof?

  raise ArgumentError, "Unterminated expression path at index #{@pos}" unless peek == "]"

  v = value
  advance # Consume ]

  unless v.include? "="
    raise ArgumentError, "Invalid expression path at index #{@start}: Expected expression to be in the format " \
                         "key=value"
  end

  key, value = v.split("=", 2).map(&:strip)

  value = case
  when digit?(value[0])
    value.to_i
  when ['"', "'"].include?(value[0])
    parse_quoted(value)
  when "true"
    true
  when "false"
    false
  else
    value
  end

  @current_path = { kind: :expression, key:, value: }
  push_path
end

#parse_index ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 58

def parse_index
  mark
  advance while digit?
  @current_path = { kind: :index, value: value.to_i }
  push_path
end

#parse_quoted(value) ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 108

def parse_quoted(value)
  quote = value[0]
  escaping = false
  v = []
  chars = value[1...].each_char.to_a

  until chars.empty?
    ch = chars.shift

    if ch == "\\"
      escaping = true
      next
    end

    if escaping
      escaping = false

      case ch
      when quote
        v << quote
      else
        v << "\\"
        v << ch
      end
      next
    end

    break if ch == quote

    v << ch
  end

  unless chars.empty?
    raise ArgumentError, "Invalid expression #{value}: Stray #{chars.shift} after closing #{quote}"
  end

  v.join
end

#parse_simple_path ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 101

def parse_simple_path
  mark
  advance until !non_separator? || eof?
  @current_path = { kind: :simple, value: value }
  push_path
end

#peek ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 15

def peek = @query[@pos]

#push_path ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 31

def push_path
  if @current_path
    @path << @current_path
    @current_path = nil
  end

  advance if peek == "."
  mark
end

#value ⇒ Object 



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# File 'lib/patchyaml/query_parser.rb', line 20

def value = @query[@start...@pos].join