remote-server/src/main/java/test/remote/server/service/impl/CalculatorImpl.java

   1 package test.remote.server.service.impl;
   2
   3 import java.util.ArrayList;
   4 import java.util.HashMap;
   5 import java.util.List;
   6 import java.util.Map;
   7
   8 import org.springframework.stereotype.Service;
   9
  10 import test.remote.server.domain.Op;
  11 import test.remote.server.domain.OpBinary;
  12 import test.remote.server.domain.OpConstant;
  13 import test.remote.server.domain.OpType;
  14 import test.remote.server.service.Calculator;
  15
  16 @Service
  17 public class CalculatorImpl implements Calculator {
  18
  19         private List<Long> stack = new ArrayList<Long>();
  20
  21         public CalculatorImpl() {
  22         }
  23
  24         @Override
  25         public void push(String atom) {
  26                 final Map<String,OpType> str2Type = new HashMap<String,OpType>();
  27                 for (OpType t: OpType.findAllOpTypes()) {
  28                         str2Type.put(t.getName(), t);
  29                 }
  30
  31                 if (atom == null) {
  32                         throw new NullPointerException();
  33                 }
  34                 if (atom.equals("+") || atom.equals("-") || atom.equals("*")) {
  35                         final int size = stack.size();
  36                         final OpBinary op = new OpBinary();
  37                         op.setType(str2Type.get(atom));
  38                         op.setLeft(Op.findOp(stack.get(size - 1)));
  39                         op.setRight(Op.findOp(stack.get(size - 2)));
  40                         op.persist();
  41                         stack.add(op.getId());
  42                 }
  43                 else {
  44                         Double v = Double.parseDouble(atom);
  45                         final OpConstant op = new OpConstant();
  46                         op.setType(str2Type.get("CONST"));
  47                         op.setValue(v);
  48                         op.persist();
  49                         stack.add(op.getId());
  50                 }
  51         }
  52
  53         @Override
  54         public Double eval() {
  55                 final Apply apply = new ApplyImpl();
  56                 for (Long id: stack) {
  57                         final Op op = Op.findOp(id);
  58                         op.visit(apply);
  59                 }
  60                 final OpConstant result = new OpConstant();
  61                 result.setValue(apply.pop());
  62                 return result.getValue();
  63         }
  64
  65         @Override
  66         public void clear() {
  67                 for (Long l: stack) {
  68                         Op.findOp(l).remove();
  69                 }
  70         }
  71
  72 }