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require "strscan"
module Lrama
class Lexer
class Token
class UserCode < Token
def references
@references ||= _references
end
private
def _references
scanner = StringScanner.new(s_value)
references = []
while !scanner.eos? do
case
when reference = scan_reference(scanner)
references << reference
when scanner.scan(/\/\*/)
scanner.scan_until(/\*\//)
else
scanner.getch
end
end
references
end
def scan_reference(scanner)
start = scanner.pos
case
# $ references
# It need to wrap an identifier with brackets to use ".-" for identifiers
when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?\$/) # $$, $<long>$
tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
return Lrama::Grammar::Reference.new(type: :dollar, name: "$", ex_tag: tag, first_column: start, last_column: scanner.pos)
when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?(\d+)/) # $1, $2, $<long>1
tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
return Lrama::Grammar::Reference.new(type: :dollar, index: Integer(scanner[2]), ex_tag: tag, first_column: start, last_column: scanner.pos)
when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?([a-zA-Z_][a-zA-Z0-9_]*)/) # $foo, $expr, $<long>program (named reference without brackets)
tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
return Lrama::Grammar::Reference.new(type: :dollar, name: scanner[2], ex_tag: tag, first_column: start, last_column: scanner.pos)
when scanner.scan(/\$(<[a-zA-Z0-9_]+>)?\[([a-zA-Z_.][-a-zA-Z0-9_.]*)\]/) # $[expr.right], $[expr-right], $<long>[expr.right] (named reference with brackets)
tag = scanner[1] ? Lrama::Lexer::Token::Tag.new(s_value: scanner[1]) : nil
return Lrama::Grammar::Reference.new(type: :dollar, name: scanner[2], ex_tag: tag, first_column: start, last_column: scanner.pos)
# @ references
# It need to wrap an identifier with brackets to use ".-" for identifiers
when scanner.scan(/@\$/) # @$
return Lrama::Grammar::Reference.new(type: :at, name: "$", first_column: start, last_column: scanner.pos)
when scanner.scan(/@(\d+)/) # @1
return Lrama::Grammar::Reference.new(type: :at, index: Integer(scanner[1]), first_column: start, last_column: scanner.pos)
when scanner.scan(/@([a-zA-Z][a-zA-Z0-9_]*)/) # @foo, @expr (named reference without brackets)
return Lrama::Grammar::Reference.new(type: :at, name: scanner[1], first_column: start, last_column: scanner.pos)
when scanner.scan(/@\[([a-zA-Z_.][-a-zA-Z0-9_.]*)\]/) # @[expr.right], @[expr-right] (named reference with brackets)
return Lrama::Grammar::Reference.new(type: :at, name: scanner[1], first_column: start, last_column: scanner.pos)
end
end
end
end
end
end
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