Method parseContextExpr

src/sys/expressionparser.cxx:452–502

This will return a pointer to a FieldContext.

// This will return a pointer to a FieldContext.
FieldGeneratorPtr ExpressionParser::parseContextExpr(LexInfo& lex) const {
  lex.nextToken(); // eat '['

  FieldContext::variable_list variables;

  while (lex.curtok != ']') {
    if (lex.curtok == 0) {
      throw ParseException("Expecting ']' in context expression");
    }

    // Definition, ident = expression
    // First comes the identifier symbol
    if (lex.curtok != -2) {
      throw ParseException(
          "Expecting an identifier in context expression, but got curtok={:d} ({:c})",
          static_cast<int>(lex.curtok), lex.curtok);
    }
    string symbol = lex.curident;
    lex.nextToken();

    // Now should be '='
    if (lex.curtok != '=') {
      throw ParseException(
          "Expecting '=' after '{:s}' in context expression, but got curtok={:d} ({:c})",
          symbol, static_cast<int>(lex.curtok), lex.curtok);
    }
    lex.nextToken();

    // Should be expression
    FieldGeneratorPtr value = parseExpression(lex);

    variables.push_back(std::make_pair(symbol, value));

    if (lex.curtok == ',') {
      lex.nextToken(); // Skip comma
    }
  }
  lex.nextToken(); // eat ']'

  // Should now be '('
  if (lex.curtok != '(') {
    throw ParseException(
        "Expecting '(' after ] context expression,  but got curtok={:d} ({:c})",
        static_cast<int>(lex.curtok), static_cast<char>(lex.curtok));
  }

  // Get the next expression to evaluate, put into FieldContext
  // Note: Ensure that only the first expression in parentheses is parsed
  //       by calling parseParenExpr rather than parseExpression
  return std::make_shared<FieldContext>(variables, parseParenExpr(lex));
}

FieldGeneratorPtr ExpressionParser::parsePrimary(LexInfo& lex) const {
  switch (lex.curtok) {