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# frozen_string_literal: true
module Gitlab
module Ci
module Pipeline
module Expression
class Lexer
include ::Gitlab::Utils::StrongMemoize
SyntaxError = Class.new(Expression::ExpressionError)
LEXEMES = [
Expression::Lexeme::Variable,
Expression::Lexeme::String,
Expression::Lexeme::Pattern,
Expression::Lexeme::Null,
Expression::Lexeme::Equals,
Expression::Lexeme::Matches
].freeze
MAX_TOKENS = 100
def initialize(statement, max_tokens: MAX_TOKENS)
@scanner = StringScanner.new(statement)
@max_tokens = max_tokens
end
def tokens
strong_memoize(:tokens) { tokenize }
end
def lexemes
tokens.map(&:to_lexeme)
end
private
def tokenize
tokens = []
@max_tokens.times do
@scanner.skip(/\s+/) # ignore whitespace
return tokens if @scanner.eos?
lexeme = LEXEMES.find do |type|
type.scan(@scanner).tap do |token|
tokens.push(token) if token.present?
end
end
unless lexeme.present?
raise Lexer::SyntaxError, _('Unknown lexeme found!')
end
end
raise Lexer::SyntaxError, _('Too many tokens!')
end
end
end
end
end
end
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