Class: List::Matcher

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

Defined Under Namespace

Classes: Alternate, CharClass, Leaf, Node, Sequence, Special, SpecialPattern

Constant Summary collapse

QRX =

to make a replacement of Regexp.quote that ignores characters that only need quoting inside character classes

Regexp.new "([" + ( (1..255).map(&:chr).select{ |c| Regexp.quote(c) != c } - %w(-) ).map{ |c| Regexp.quote c }.join + "])"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(atomic: true, backtracking: true, bound: false, strip: false, case_insensitive: false, multiline: false, normalize_whitespace: false, symbols: {}, name: false, vet: false) ⇒ Matcher

Returns a new instance of Matcher.



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# File 'lib/list_matcher.rb', line 21

def initialize(
      atomic:               true,
      backtracking:         true,
      bound:                false,
      strip:                false,
      case_insensitive:     false,
      multiline:            false,
      normalize_whitespace: false,
      symbols:              {},
      name:                 false,
      vet:                  false
    )
  @atomic               = atomic
  @backtracking         = backtracking
  @strip                = strip || normalize_whitespace
  @case_insensitive     = case_insensitive
  @multiline            = multiline
  @symbols              = deep_dup symbols
  @_bound               = bound
  @bound                = !!bound
  @normalize_whitespace = normalize_whitespace
  @vet                  = vet
  if name
    raise "" unless name.is_a?(String) || name.is_a?(Symbol)
    if Regexp.new "(?<#{name}>.*)"   # stir up any errors that might arise from using this name in a named capture
      @name = name
    end
  end
  if bound == :string
    @word_test   = /./
    @left_bound  = '\A'
    @right_bound = '\z'
  elsif bound == :line
    @word_test   = /./
    @left_bound  = '^'
    @right_bound = '$'
  elsif bound.is_a? Hash
    @word_test   = bound[:test]  || raise(SyntaxError.new('no boundary test provided'))
    @left_bound  = bound[:left]  || raise(SyntaxError.new('no left boundary expression provided'))
    @right_bound = bound[:right] || raise(SyntaxError.new('no right boundary expression provided'))
  elsif bound === true || bound == :word
    @word_test   = /\w/
    @left_bound  = '\b'
    @right_bound = '\b'
  elsif !( bound === false )
    raise "unfamiliar value for :bound option: #{bound.inspect}"
  end
  if normalize_whitespace
    @symbols[' '] = { pattern: '\s++' }
  end
  symbols.keys.each do |k|
    raise "symbols variable #{k} is neither a string, a symbol, nor a regex" unless k.is_a?(String) || k.is_a?(Symbol) || k.is_a?(Regexp)
  end
  if vet
    Special.new( self, @symbols, [] ).verify
  end
end

Instance Attribute Details

#atomic ⇒ Object (readonly)

Returns the value of attribute atomic.



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# File 'lib/list_matcher.rb', line 5

def atomic
  @atomic
end

#backtracking ⇒ Object (readonly)

Returns the value of attribute backtracking.



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# File 'lib/list_matcher.rb', line 5

def backtracking
  @backtracking
end

#bound ⇒ Object (readonly)

Returns the value of attribute bound.



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# File 'lib/list_matcher.rb', line 5

def bound
  @bound
end

#case_insensitive ⇒ Object (readonly)

Returns the value of attribute case_insensitive.



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# File 'lib/list_matcher.rb', line 5

def case_insensitive
  @case_insensitive
end

#left_bound ⇒ Object (readonly)

Returns the value of attribute left_bound.



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# File 'lib/list_matcher.rb', line 5

def left_bound
  @left_bound
end

#multiline ⇒ Object (readonly)

Returns the value of attribute multiline.



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# File 'lib/list_matcher.rb', line 5

def multiline
  @multiline
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/list_matcher.rb', line 5

def name
  @name
end

#normalize_whitespace ⇒ Object (readonly)

Returns the value of attribute normalize_whitespace.



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# File 'lib/list_matcher.rb', line 5

def normalize_whitespace
  @normalize_whitespace
end

#right_bound ⇒ Object (readonly)

Returns the value of attribute right_bound.



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# File 'lib/list_matcher.rb', line 5

def right_bound
  @right_bound
end

#strip ⇒ Object (readonly)

Returns the value of attribute strip.



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# File 'lib/list_matcher.rb', line 5

def strip
  @strip
end

#vet ⇒ Object (readonly)

Returns the value of attribute vet.



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# File 'lib/list_matcher.rb', line 5

def vet
  @vet
end

#word_test ⇒ Object (readonly)

Returns the value of attribute word_test.



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# File 'lib/list_matcher.rb', line 5

def word_test
  @word_test
end

Class Method Details

.pattern(list, opts = {}) ⇒ Object

convenience method for one-off regexen where there’s no point in keeping around a pattern generator



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# File 'lib/list_matcher.rb', line 9

def self.pattern(list, opts={})
  self.new(**opts).pattern list
end

.quote(s) ⇒ Object 



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# File 'lib/list_matcher.rb', line 203

def self.quote(s)
  s.gsub(QRX) { |c| Regexp.quote c }
end

.rx(list, opts = {}) ⇒ Object

like self.pattern, but returns a regex rather than a string



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# File 'lib/list_matcher.rb', line 14

def self.rx(list, opts={})
  self.new(**opts).rx list
end

Instance Method Details

#bud(opts = {}) ⇒ Object

returns a new pattern matcher differing from the original only in the options specified



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# File 'lib/list_matcher.rb', line 80

def bud(opts={})
  opts = {
    atomic:               @atomic,
    backtracking:         @backtracking,
    bound:                @_bound,
    strip:                @strip,
    case_insensitive:     @case_insensitive,
    multiline:            @multiline,
    normalize_whitespace: @normalize_whitespace,
    symbols:              @symbols,
    name:                 @name,
    vet:                  @vet && opts[:symbols]
  }.merge opts
  self.class.new(**opts)
end

#modifiers ⇒ Object 



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# File 'lib/list_matcher.rb', line 126

def modifiers
  ( @modifiers ||= if case_insensitive || multiline
    [ ( 'i' if case_insensitive ), ( 'm' if multiline ) ].compact.join
  else
    [nil]
  end )[0]
end

#pattern(list, opts = {}) ⇒ Object

converst list into a string representing a regex pattern suitable for inclusion in a larger regex



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# File 'lib/list_matcher.rb', line 97

def pattern( list, opts={} )
  return bud(opts).pattern list unless opts.empty?
  list = list.compact.map(&:to_s).select{ |s| s.length > 0 }
  list.map!(&:strip).select!{ |s| s.length > 0 } if strip
  list.map!{ |s| s.gsub /\s++/, ' ' } if normalize_whitespace
  return nil if list.empty?
  specializer = Special.new self, @symbols, list
  list = specializer.normalize

  root = tree list, specializer
  root.root = true
  root.flatten
  rx = root.convert
  if m = modifiers
    rx = "(?#{m}:#{rx})"
    grouped = true
  end
  if name
    rx = "(?<#{name}>#{rx})"
    grouped = true
  end
  return rx if grouped && backtracking
  if atomic && !root.atomic?
    wrap rx
  else
    rx
  end
end

#pfx ⇒ Object 



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# File 'lib/list_matcher.rb', line 139

def pfx
  @pfx ||= backtracking ? '(?:' : '(?>'
end

#qmark ⇒ Object 



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# File 'lib/list_matcher.rb', line 143

def qmark
  @qmark ||= backtracking ? '?' : '?+'
end

#quote(s) ⇒ Object 



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# File 'lib/list_matcher.rb', line 207

def quote(s)
  self.class.quote s
end

#rx(list, opts = {}) ⇒ Object

like pattern but it returns a regex instead of a string



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# File 'lib/list_matcher.rb', line 135

def rx(list, opts={})
  Regexp.new pattern(list, opts)
end

#tree(list, symbols) ⇒ Object 



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# File 'lib/list_matcher.rb', line 155

def tree(list, symbols)
  if list.size == 1
    leaves = list[0].chars.map do |c|
      symbols.symbols(c) || Leaf.new( self, c )
    end
    if leaves.length == 1
      leaves.first
    else
      Sequence.new self, *leaves
    end
  elsif list.all?{ |w| w.length == 1 }
    chars = list.select{ |w| !symbols.symbols(w) }
    if chars.size > 1
      list -= chars
      c = CharClass.new self, chars
    end
    a = Alternate.new self, symbols, list unless list.empty?
    a.children.unshift c if a && c
    a || c
  elsif c = best_prefix(list)   # found a fixed-width prefix pattern
    if optional = c[1].include?('')
      c[1].reject!{ |w| w == '' }
    end
    c1 = tree c[0], symbols
    c2 = tree c[1], symbols
    c2.optional = optional
    Sequence.new self, c1, c2
  elsif c = best_suffix(list)   # found a fixed-width suffix pattern
    if optional = c[0].include?('')
      c[0].reject!{ |w| w == '' }
    end
    c1 = tree c[0], symbols
    c1.optional = optional
    c2 = tree c[1], symbols
    Sequence.new self, c1, c2
  else
    grouped = list.group_by{ |w| w[0] }
    chars = grouped.select{ |_, w| w.size == 1 && w[0].size == 1 && !symbols.symbols(w[0]) }.map{ |v, _| v }
    if chars.size > 1
      list -= chars
      c = CharClass.new self, chars
    end
    a = Alternate.new self, symbols, list
    a.children.unshift c if c
    a
  end
end

#wrap(s) ⇒ Object 



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# File 'lib/list_matcher.rb', line 147

def wrap(s)
  pfx + s + ')'
end

#wrap_size ⇒ Object 



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# File 'lib/list_matcher.rb', line 151

def wrap_size
  @wrap_size ||= pfx.length + 1
end