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    1   /**
    2    * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
    3    */
    4   package net.sourceforge.pmd.rules.design;
    5
    6   import net.sourceforge.pmd.AbstractRule;
    7   import net.sourceforge.pmd.ast.ASTName;
    8   import net.sourceforge.pmd.ast.ASTWhileStatement;
    9   import net.sourceforge.pmd.ast.SimpleNode;
    10
    11  import java.util.ArrayList;
    12  import java.util.List;
    13
    14  public class PositionalIteratorRule extends AbstractRule {
    15
    16      public Object visit(ASTWhileStatement node, Object data) {
    17          if (hasNameAsChild((SimpleNode) node.jjtGetChild(0))) {
    18              String exprName = getName((SimpleNode) node.jjtGetChild(0));
    19              if (exprName.indexOf(".hasNext") != -1 && node.jjtGetNumChildren() > 1) {
    20
    21                  SimpleNode loopBody = (SimpleNode) node.jjtGetChild(1);
    22                  List<String> names = new ArrayList<String>();
    23                  collectNames(getVariableName(exprName), names, loopBody);
    24                  int nextCount = 0;
    25                  for (String name: names) {
    26                      if (name.indexOf(".next") != -1) {
    27                          nextCount++;
    28                      }
    29                  }
    30
    31                  if (nextCount > 1) {
    32                      addViolation(data, node);
    33                  }
    34
    35              }
    36          }
    37          return null;
    38      }
    39
    40      private String getVariableName(String exprName) {
    41          return exprName.substring(0, exprName.indexOf('.'));
    42      }
    43
    44      private void collectNames(String target, List<String> names, SimpleNode node) {
    45          for (int i = 0; i < node.jjtGetNumChildren(); i++) {
    46              SimpleNode child = (SimpleNode) node.jjtGetChild(i);
    47              if (child.jjtGetNumChildren() > 0) {
    48                  collectNames(target, names, child);
    49              } else {
    50                  if (child instanceof ASTName && isQualifiedName(child) && target.equals(getVariableName(child.getImage()))) {
    51                      names.add(child.getImage());
    52                  }
    53              }
    54          }
    55      }
    56
    57      private boolean hasNameAsChild(SimpleNode node) {
    58          while (node.jjtGetNumChildren() > 0) {
    59              if (node.jjtGetChild(0) instanceof ASTName) {
    60                  return true;
    61              }
    62              return hasNameAsChild((SimpleNode) node.jjtGetChild(0));
    63          }
    64          return false;
    65      }
    66
    67      private String getName(SimpleNode node) {
    68          while (node.jjtGetNumChildren() > 0) {
    69              if (node.jjtGetChild(0) instanceof ASTName) {
    70                  return ((ASTName) node.jjtGetChild(0)).getImage();
    71              }
    72              return getName((SimpleNode) node.jjtGetChild(0));
    73          }
    74          throw new IllegalArgumentException("Check with hasNameAsChild() first!");
    75      }
    76  }