Package com.singularsys.jep.configurableparser.matchers

Class BracketedSequenceGrammarMatcher

java.lang.Object
com.singularsys.jep.configurableparser.matchers.BracketedSequenceGrammarMatcher
All Implemented Interfaces:
GrammarMatcher, Serializable
public class BracketedSequenceGrammarMatcher extends Object implements GrammarMatcher
A GrammarMatcher which matches lists of items with the syntax or a simple list [1,2,3,4]. This differs from the ListGrammarMatcher in that the comma operator is treated like a normal operator and parsed using the ShuntingYard. So 1,2,3,4 is parsed as a single subexpression rather than as four subexpressions.

To set up first a new sequence operator must be created. This should be a binary operator with right associativity. It should have a precedence level lower than all other operators. This operator should be passed to the constructor of the FunctionSequenceGrammarMatcher and possibly also the BracketedSequenceGrammarMatcher. 

 OperatorTable2 ot = new StandardOperatorTable2();
 Operator seqOp = new Operator(",", null, Operator.BINARY+Operator.RIGHT);
 ot.appendOperator(new OperatorKey() {}, seqOp, optab.getAssign()); // lower precedence than assignment
 
 ConfigurableParser cp = new ConfigurableParser();
 cp.addHashComments();
 cp.addSlashComments();
 cp.addSingleQuoteStrings();
 cp.addDoubleQuoteStrings();
 cp.addWhiteSpace();
 cp.addExponentNumbers();
 cp.addSymbols("(",")","[","]"); // "," not include in symbols
 cp.setImplicitMultiplicationSymbols("(","["); 
 cp.addOperatorTokenMatcher();
 cp.addIdentifiers();
 cp.addSemiColonTerminator();
 cp.addWhiteSpaceCommentFilter();
 cp.addBracketMatcher("(",")"); 
 
 // Add the function matcher
 cp.addGrammarMatcher(new FunctionSequenceGrammarMatcher(
                cp.getSymbolToken("("),
                cp.getSymbolToken(")"),
                seqOp));
 // Add the bracket matcher
 cp.addGrammarMatcher(new BracketedSequenceGrammarMatcher(
                cp.getSymbolToken("["),
                cp.getSymbolToken("]"),
                seqOp
                )); 
 cp.addArrayAccessMatcher("[","]");
 Jep jep = new Jep(ot,cp);
See Also:

  • Constructor Details

    • BracketedSequenceGrammarMatcher

      public BracketedSequenceGrammarMatcher(Token open, Token close, Operator seqOp)
      Constructor. The operator for the list is found in the init() method
      Parameters:
      open - token representing an opening bracket
      close - token representing a closing bracket
      seqOp - operator representing the sequence

  • Method Details

    • init

      public void init(Jep jep)
      Description copied from interface: GrammarMatcher
      Delayed initialisation, this method is called whenever components of the jep instance are changed.
      Specified by:
      init in interface GrammarMatcher
      Parameters:
      jep - the current jep instance.

    • match

      public Node match(Lookahead2Iterator<Token> it, GrammarParser parser) throws ParseException
      Description copied from interface: GrammarMatcher
      Test whether the input matches this pattern.
      Specified by:
      match in interface GrammarMatcher
      Parameters:
      it - An iterator inspecting the input
      parser - the parser to use when evaluating sub expressions
      Returns:
      if matched returns a node representing the content, return null is does not match
      Throws:
      ParseException - if there is a syntactical error in the input.