Matching math expression with regular expression?

by

Use a pushdown automaton for matching paranthesis http://en.wikipedia.org/wiki/Pushdown_automaton (or just a stack 😉 )

Details for the stack solution:

while (chr available)
    if chr == '(' then
      push '('
    else
      if chr == ')' then
        if stack.elements == 0 then
          print('too many or misplaced )')
          exit
        else
          pop //from stack
end while
if (stack.elements != 0)
  print('too many or misplaced(')

Even simple: just keep a counter instead of stack.

More Related Contents:

  1. Parsing scientific notation sensibly?
  2. Jmeter extracting fields/parsing JSON response
  3. Regular Expression Vs. String Parsing
  4. What is a Context Free Grammar?
  5. When is it best to use Regular Expressions over basic string splitting / substring’ing?
  6. Regular expression [ 1 ( 0 1* 0)* 1 ]* DFA
  7. subdomain htaccess rediect with query string
  8. How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
  9. What to do Regular expression pattern doesn’t match anywhere in string?
  10. Regex to pick characters outside of pair of quotes
  11. Match whitespace but not newlines
  12. Find ‘word’ not followed by a certain character
  13. Regex to split a CSV
  14. How can I match nested brackets using regex?
  15. How do I grep for all non-ASCII characters?
  16. How to match Cyrillic characters with a regular expression
  17. Random string that matches a regexp [duplicate]
  18. Negative matching using grep (match lines that do not contain foo)
  19. Remove all special characters from a string in R?
  20. Regular expression for validating names and surnames?
  21. Regular Expression: Numeric range [duplicate]
  22. Matching all words except one
  23. HTML5 Form Input Pattern Currency Format
  24. How to pattern match using regular expression in Scala?
  25. Javascript regex to validate IPv4 and IPv6 address, no hostnames
  26. What’s wrong with my lookahead regex in GNU sed?
  27. Splitting String in VBA using RegEx
  28. Regular expression to remove one parameter from query string
  29. Difference between regular expression modifiers (or flags) ‘m’ and ‘s’?
  30. Swift 3 – How do I extract captured groups in regular expressions?

Leave a Comment