Class: MetaParse::Matcher

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

Overview

General class to match a simple pattern against a scanner. Subclasses implement compound matching.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(spec) ⇒ Matcher

Initialize Matcher with Matcher spec.



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# File 'lib/meta_parse.rb', line 190

def initialize(spec)
  @spec = spec
end

Instance Attribute Details

#spec ⇒ Object

Returns the value of attribute spec.



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# File 'lib/meta_parse.rb', line 152

def spec
  @spec
end

Class Method Details

.compile(spec) ⇒ Object

Compile a Matcher specification into a concrete Matcher or subclass.



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# File 'lib/meta_parse.rb', line 157

def self.compile(spec)
  case spec
  when Matcher
    spec
  when String, Regexp
    Matcher.new spec
  when Array
    case spec[0]
    when :or
        compiled_body = spec[1..-1].map { |x| self.compile x }
      AlternativeMatcher.new(compiled_body)
    when :and
        compiled_body = spec[1..-1].map { |x| self.compile x }
      SequentialMatcher.new(compiled_body)
    when :*, :+, :'?'
      compiled_body = self.compile(spec[1])
      case spec[0]
      when :'?'
        min = 0
        max = 1
      when :+
        min = 1
      end
      RepetitionMatcher.new(compiled_body, min, max, *spec[4..-1])
    end
  when Proc, Symbol
    FunctionMatcher.new spec
  end
end

Instance Method Details

#inspect ⇒ Object 



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# File 'lib/meta_parse.rb', line 198

def inspect
  "<match #{show}>"
end

#m(string) ⇒ Object

Syntactic sugar to create MetaScanner and match self against string.



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# File 'lib/meta_parse.rb', line 247

def m(string)
  match MetaScanner.new(string)
end

#m?(string) ⇒ Boolean

Syntactic sugar to create MetaScanner and match? self against string.

Returns:

  • (Boolean) 


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# File 'lib/meta_parse.rb', line 240

def m?(string)
  match? MetaScanner.new(string)
end

#match(scanner, context = nil) ⇒ Object

Like match? but clone self first if stateful.

Subclasses should not implement match, but should call it on peers.



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# File 'lib/meta_parse.rb', line 226

def match(scanner, context=nil)
  (stateful ? clone : self).match? scanner, context
end

#match?(scanner, context = nil) ⇒ Boolean

Try to match own pattern/combination against supplied scanner. Context is unused.

Subclasses should implement match? but not call it on peers.

Returns:

  • (Boolean) 


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

def match?(scanner, context=nil)
  case scanner
  when MetaScanner
    result = scanner.scan spec
    result
  else
    raise "match? requires scanner"
    # FIXME: Why doesn't the coercion below work?
  # when String
  #   match?(MetaParse::MetaScanner.new(scanner), context)
  #   (MetaScanner.new(scanner)).scan spec
  end
end

#show ⇒ Object 



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# File 'lib/meta_parse.rb', line 194

def show
    spec.inspect
end

#stateful ⇒ Object

Is this Matcher stateful? A class attribute which may be overriden by subclasses.



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# File 'lib/meta_parse.rb', line 233

def stateful
  false
end