gitlab-org--gitlab-foss/lib/gitlab/ci/pipeline/expression/lexer.rb

73 lines
1.8 KiB
Ruby

# 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::ParenthesisOpen,
Expression::Lexeme::ParenthesisClose,
Expression::Lexeme::Variable,
Expression::Lexeme::String,
Expression::Lexeme::Pattern,
Expression::Lexeme::Null,
Expression::Lexeme::Equals,
Expression::Lexeme::Matches,
Expression::Lexeme::NotEquals,
Expression::Lexeme::NotMatches,
Expression::Lexeme::And,
Expression::Lexeme::Or
].freeze
def self.lexemes
LEXEMES
end
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 = self.class.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