validator.rb

 # Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # The Universal Permissive License (UPL), Version 1.0
 #
 # Subject to the condition set forth below, permission is hereby granted to any
 # person obtaining a copy of this software, associated documentation and/or
 # data (collectively the "Software"), free of charge and under any and all
 # copyright rights in the Software, and any and all patent rights owned or
 # freely licensable by each licensor hereunder covering either (i) the
 # unmodified Software as contributed to or provided by such licensor, or (ii)
 # the Larger Works (as defined below), to deal in both
 #
 # (a) the Software, and
 #
 # (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 # one is included with the Software each a "Larger Work" to which the Software
 # is contributed by such licensors),
 #
 # without restriction, including without limitation the rights to copy, create
 # derivative works of, display, perform, and distribute the Software and make,
 # use, sell, offer for sale, import, export, have made, and have sold the
 # Software and the Larger Work(s), and to sublicense the foregoing rights on
 # either these or other terms.
 #
 # This license is subject to the following condition:
 #
 # The above copyright notice and either this complete permission notice or at a
 # minimum a reference to the UPL must be included in all copies or substantial
 # portions of the Software.
 #
 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.

module FunctionValidator
  ALLOWED_FUNCTIONS = %w[sin cos log sqrt]

  def self.validate(expr)
    expr = expr.to_s # Workaround until GR-38544 is fixed
    expr.split(/x|[-+*\/()^]/).each do |term|
      unless term.empty?
        is_number = (Float(term) rescue false)
        unless is_number
          unless ALLOWED_FUNCTIONS.include? term
            return "Unknown expression: #{term}"
          end
        end
      end
    end
    ""
  end
end

Polyglot.export :Validator, FunctionValidator