Class: MODL::Tokeniser::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/modl/tokeniser/context.rb

Overview

A parsing context for a MODL String

Constant Summary collapse

WS = 
" \t\r\n"
INTEGER_REGEX = 
'^-?(?:0|[1-9]\d*)$'
FLOAT_REGEX = 
'^-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?$'
NON_STRING_TOKENS = 
'[]();"=`'

Instance Method Summary collapse

Constructor Details

#initialize(str) ⇒ Context

Returns a new instance of Context.



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# File 'lib/modl/tokeniser/context.rb', line 12

def initialize(str)
  @str = str
  @tokens = []
  @tok_start = 0
end

Instance Method Details

#escaped?(str, pos) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/modl/tokeniser/context.rb', line 108

def escaped?(str, pos)
  pos >= 0 && (str[pos] == '~' || str[pos] == '\\')
end

#next_token ⇒ Object 



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# File 'lib/modl/tokeniser/context.rb', line 24

def next_token
  while @tok_start < @str.length
    break unless WS.include?(@str[@tok_start])

    @tok_start += 1
  end

  return false if @tok_start >= @str.length

  case @str[@tok_start]
  when '('
    tok_type = :lparen
    tok_end = @tok_start + 1
  when ')'
    tok_type = :rparen
    tok_end = @tok_start + 1
  when '['
    tok_type = :lbracket
    tok_end = @tok_start + 1
  when ']'
    tok_type = :rbracket
    tok_end = @tok_start + 1
  when ';'
    tok_type = :struct_sep
    tok_end = @tok_start + 1
  when '='
    tok_type = :equals
    tok_end = @tok_start + 1
  when '"'
    tok_type = :quoted
    tok_end = scan_to_end_of_quoted(@str, @tok_start, '"')
  when '`'
    tok_type = :quoted
    tok_end = scan_to_end_of_quoted(@str, @tok_start, '`')
  else
    tok_type = :string
    tok_end = scan_to_end_of_string(@str, @tok_start)
  end

  tok_value = @str[@tok_start..(tok_end - 1)].strip

  if tok_value.match? INTEGER_REGEX
    number = tok_value.to_i
    @tokens.push Token.new(:integer, number, @tok_start, tok_end)
  elsif tok_value.match? FLOAT_REGEX
    number = tok_value.to_f
    @tokens.push Token.new(:float, number, @tok_start, tok_end)
  elsif tok_value == 'null'
    @tokens.push Token.new(:null, nil, @tok_start, tok_end)
  elsif tok_value == 'true'
    @tokens.push Token.new(true, true, @tok_start, tok_end)
  elsif tok_value == 'false'
    @tokens.push Token.new(false, false, @tok_start, tok_end)
  else
    @tokens.push Token.new(tok_type, tok_value, @tok_start, tok_end)
  end

  @tok_start = tok_end
  tok_end < @str.length
end

#parse ⇒ Object 



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# File 'lib/modl/tokeniser/context.rb', line 18

def parse
  while next_token
  end
  @tokens
end

#scan_to_end_of_quoted(str, start, quote_char) ⇒ Object 



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# File 'lib/modl/tokeniser/context.rb', line 85

def scan_to_end_of_quoted(str, start, quote_char)
  end_str = start + 1
  while end_str < str.length
    end_char = str[end_str]
    prev_char = str[end_str - 1]

    break if end_char == quote_char && prev_char != '\\' && prev_char != '~'

    end_str += 1
  end
  end_str + 1
end

#scan_to_end_of_string(str, start) ⇒ Object 



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# File 'lib/modl/tokeniser/context.rb', line 98

def scan_to_end_of_string(str, start)
  end_str = start + 1
  while end_str < str.length
    break if NON_STRING_TOKENS.include?(str[end_str]) && !escaped?(str, end_str - 1)

    end_str += 1
  end
  end_str
end