Class: SportDb::Tokens

Inherits:
Object
  • Object
show all
Defined in:
lib/sportdb/parser/lexer_buffer.rb

Overview

token iter/find better name

e.g. TokenBuffer/Scanner or such ??

Instance Method Summary collapse

Constructor Details

#initialize(tokens) ⇒ Tokens

Returns a new instance of Tokens.



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 19

def initialize( tokens )
    @tokens = tokens
    @pos = 0
end

Instance Method Details

#collect(&blk) ⇒ Object 



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 84

def collect( &blk )
    tokens = []
    loop do
      break if eos?
      tokens <<  if block_given?
                    blk.call( self.next )
                 else
                    self.next
                 end
    end
    tokens
end

#cur ⇒ Object

return token type (e.g. :TEXT, :NUM, etc.)



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 51

def cur()           peek(0); end

#eos? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sportdb/parser/lexer_buffer.rb', line 25

def eos?() @pos >= @tokens.size; end

#include?(*types) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sportdb/parser/lexer_buffer.rb', line 28

def include?( *types )
    pos = @pos
    ## puts "  starting include? #{types.inspect} @ #{pos}"
    while pos < @tokens.size do
        return true   if types.include?( @tokens[pos][0] )
        pos +=1
    end
    false
end

#match?(*pattern) ⇒ Boolean

pattern e.g. [:TEXT, [:VS,:SCORE], :TEXT]

Returns:

  • (Boolean) 


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# File 'lib/sportdb/parser/lexer_buffer.rb', line 39

def match?( *pattern )
    ## puts "  starting match? #{pattern.inspect} @ #{@pos}"
    pattern.each_with_index do |types,offset|
        ## if single symbol wrap in array
        types = types.is_a?(Array) ? types : [types]
        return false  unless types.include?( peek(offset) )
    end
    true
end

#next ⇒ Object

note - returns complete token



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 73

def next
   # if @pos >= @tokens.size
   #     raise ArgumentError, "end of array - #{@pos} >= #{@tokens.size}"
   # end
   #   throw (standard) end of iteration here why? why not?

    t = @tokens[@pos]
    @pos += 1
    t
end

#peek(offset = 1) ⇒ Object 



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 63

def peek(offset=1)
    ## return nil if eos
    if @pos+offset >= @tokens.size
        nil
    else
       @tokens[@pos+offset][0]
    end
end

#pos ⇒ Object 



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 24

def pos()  @pos; end

#text(offset = 0) ⇒ Object

return content (assumed to be text)



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# File 'lib/sportdb/parser/lexer_buffer.rb', line 53

def text(offset=0)
    ## raise error - why? why not?
    ##   return nil?
    if peek( offset ) != :text
        raise ArgumentError, "text(#{offset}) - token not a text type"
    end
    @tokens[@pos+offset][1]
end