public Expression visit()

in src/main/java/net/hydromatic/linq4j/expressions/OptimizeVisitor.java [80:153]
59 lines of code
23 McCabe index (conditional complexity)

  public Expression visit(
      TernaryExpression ternary,
      Expression expression0,
      Expression expression1,
      Expression expression2) {
    switch (ternary.getNodeType()) {
    case Conditional:
      Boolean always = always(expression0);
      if (always != null) {
        // true ? y : z  ===  y
        // false ? y : z  === z
        return always
            ? expression1
            : expression2;
      }
      if (expression1.equals(expression2)) {
        // a ? b : b   ===   b
        return expression1;
      }
      // !a ? b : c == a ? c : b
      if (expression0 instanceof UnaryExpression) {
        UnaryExpression una = (UnaryExpression) expression0;
        if (una.getNodeType() == ExpressionType.Not) {
          return Expressions.makeTernary(ternary.getNodeType(),
              una.expression, expression2, expression1);
        }
      }

      // a ? true : b  === a || b
      // a ? false : b === !a && b
      always = always(expression1);
      if (always != null && isKnownNotNull(expression2)) {
        return (always
                 ? Expressions.orElse(expression0, expression2)
                 : Expressions.andAlso(Expressions.not(expression0),
            expression2)).accept(this);
      }

      // a ? b : true  === !a || b
      // a ? b : false === a && b
      always = always(expression2);
      if (always != null && isKnownNotNull(expression1)) {
        return (always
                 ? Expressions.orElse(Expressions.not(expression0),
                    expression1)
                 : Expressions.andAlso(expression0, expression1)).accept(this);
      }

      if (expression0 instanceof BinaryExpression
          && (expression0.getNodeType() == ExpressionType.Equal
              || expression0.getNodeType() == ExpressionType.NotEqual)) {
        BinaryExpression cmp = (BinaryExpression) expression0;
        Expression expr = null;
        if (eq(cmp.expression0, expression2)
            && eq(cmp.expression1, expression1)) {
          // a == b ? b : a === a (hint: if a==b, then a == b ? a : a)
          // a != b ? b : a === b (hint: if a==b, then a != b ? b : b)
          expr = expression0.getNodeType() == ExpressionType.Equal
              ? expression2 : expression1;
        }
        if (eq(cmp.expression0, expression1)
            && eq(cmp.expression1, expression2)) {
          // a == b ? a : b === b (hint: if a==b, then a == b ? b : b)
          // a != b ? a : b === a (hint: if a==b, then a == b ? a : a)
          expr = expression0.getNodeType() == ExpressionType.Equal
              ? expression2 : expression1;
        }
        if (expr != null) {
          return expr;
        }
      }
    }
    return super.visit(ternary, expression0, expression1, expression2);
  }