近日天氣寒冷，學習的熱情都快被這氣溫給打壓下去，早晨起不來，晚上又想早點躺在被窩里面，這樣下去，感覺整個人如同咸魚一般。無決心者，然小事可擾之，坐立不安，思前想后，時不待也，欲成事之，必靜之以練其心智，久而久之，不成難矣！
//booleanmodel.h
#ifndef BOOLEANMODEL_H
#define BOOLEANMODEL_H
#include "node.h"
#include <QAbstractItemModel>
class Node;
class BooleanModel:public QAbstractItemModel
{
public:
BooleanModel(QObject *parent=0);
~BooleanModel();
void setRootNode(Node *node);
QModelIndex index(int row,int column,const QModelIndex &parent)const;
QModelIndex parent(const QModelIndex &child)const;
int rowCount(const QModelIndex &parent) const;
int columnCount(const QModelIndex &parent) const;
QVariant data(const QModelIndex &index,int role) const;
QVariant headerData(int section,Qt::Orientation orientation,int role) const;
private:
Node *nodeFromIndex(const QModelIndex &index)const;
Node *rootNode;
};
#endif // BOOLEANMODEL_H
//booleanparser.h
#ifndef BOOLEAMPARSER_H
#define BOOLEAMPARSER_H
#include "node.h"
class BooleanParser
{
public:
Node *parse(const QString &expr);
private:
Node *parseOrExpression();
Node *parseAndExpression();
Node *parseNotExpression();
Node *parseAtom();
Node *parseIdentifier();
void addChild(Node *parent,Node *child);
void addToken(Node *parent,const QString &str,Node::Type type);
bool matchToken(const QString &str) const;
QString in;
int pos;
};
#endif // BOOLEANPARSER_H
//booleanwindow.h
#ifndef BOOLEANWINDOW_H
#define BOOLEANWINDOW_H
#include <QWidget>
class QLabel;
class QLineEdit;
class QTreeView;
class BooleanModel;
class BooleanWindow:public QWidget
{
Q_OBJECT
public:
BooleanWindow();
private slots:
void booleanExpressionChanged(const QString &expr);
private:
QLabel *label;
QLineEdit *lineEdit;
BooleanModel *booleanModel;
QTreeView *treeView;
};
#endif // BOOLEANWINDOW_H
//node.h
#ifndef NODE_H
#define NODE_H
#include <QString>
#include <QList>
//node類為樹的節(jié)點
class Node
{
public:
enum Type{Root,OrExpression,AndExpression,NotExpression,Atom,Identifier,Operator,Punctuator};
Node(Type type,const QString &str="");
~Node();
Type type;//類型是否為操作符
QString str;//存數(shù)據(jù)
Node *parent;//指向父節(jié)點
QList<Node *> children;//保存node所有節(jié)點
};
#endif // NODE_H
//booleanmodel.cpp
#include "booleanmodel.h"
BooleanModel::BooleanModel(QObject *parent):QAbstractItemModel(parent)
{
rootNode=0;
}
BooleanModel::~BooleanModel()
{
delete rootNode;
}
void BooleanModel::setRootNode(Node *node)
{
beginResetModel();
delete rootNode;
rootNode=node;
endResetModel();
}
//返回第row行，第column列，父節(jié)點為parent的元素QModelIndex對象
QModelIndex BooleanModel::index(int row, int column, const QModelIndex &parent) const
{
if(!rootNode||row<0||column<0)
return QModelIndex();
Node *parentNode=nodeFromIndex(parent);
Node *childNode=parentNode->children.value(row);
if(!childNode)
return QModelIndex();
return createIndex(row,column,childNode);
}
int BooleanModel::rowCount(const QModelIndex &parent) const
{
if(parent.column()>0){
return 0;
}
Node *parentNode =nodeFromIndex(parent);
if(!parentNode)
return 0;
return parentNode->children.count();
}
int BooleanModel::columnCount(const QModelIndex &) const
{
return 2;
}
//返回子節(jié)點所屬的父節(jié)點的索引
QModelIndex BooleanModel::parent(const QModelIndex &child)const
{
Node *node=nodeFromIndex(child);
if(!node)
return QModelIndex();
Node *parentNode=node->parent;
if(!parentNode)
return QModelIndex();
Node *grandparentNode=parentNode->parent;
if(!grandparentNode)
return QModelIndex();
int row=grandparentNode->children.indexOf(parentNode);
return createIndex(row,0,parentNode);
}
//返回單元格的顯示值
QVariant BooleanModel::data(const QModelIndex &index, int role) const
{
if(role!=Qt::DisplayRole)
return QVariant();
Node *node=nodeFromIndex(index);
if(!node)
return QVariant();
if(index.column()==0){
switch (node->type){
case Node::Root:
return tr("Root");
case Node::OrExpression:
return tr("OR Expression");
case Node::AndExpression:
return tr("AND Expression");
case Node::NotExpression:
return tr("NOT Expression");
case Node::Atom:
return tr("Atom");
case Node::Identifier:
return tr("Identifier");
case Node::Operator:
return tr("Operator");
case Node::Punctuator:
return tr("Punctuator");
default:
return tr("Unknown");
}
}else if(index.column()==1){
return node->str;
}
return QVariant();
}
QVariant BooleanModel::headerData(int section, Qt::Orientation orientation, int role) const
{
if(orientation==Qt::Horizontal&&role==Qt::DisplayRole){
if(section==0){
return tr("Node");
}else if(section==1){
return tr("Value");
}
}
return QVariant();
}
Node *BooleanModel::nodeFromIndex(const QModelIndex &index) const
{
if(index.isValid()){
return static_cast<Node *>(index.internalPointer());
}else{
return rootNode;
}
}
//booleanparser.cpp
#include "booleanparser.h"
Node *BooleanParser::parse(const QString &expr)
{
in=expr;
in.replace(" ","");
pos=0;//當前字符的位置
//創(chuàng)建根節(jié)點
Node *node=new Node(Node::Root);
addChild(node,parseOrExpression());
return node;
}
//布爾表達式not and or優(yōu)先級從高到低
//遞歸下降算法
Node *BooleanParser::parseOrExpression()
{
Node *childNode=parseAndExpression();
if(matchToken("||")){
Node *node=new Node(Node::OrExpression);
addChild(node,childNode);
while(matchToken("||")){
addToken(node,"||",Node::Operator);
addChild(node,parseAndExpression());
}
return node;
}else{
return childNode;
}
}
Node *BooleanParser::parseAndExpression()
{
Node *childNode=parseNotExpression();
if(matchToken("&&")){
Node *node=new Node(Node::AndExpression);
addChild(node,childNode);
while(matchToken("&&")){
addToken(node,"&&",Node::Operator);
addChild(node,parseNotExpression());
}
return node;
}else{
return childNode;
}
}
Node *BooleanParser::parseNotExpression()
{
if(matchToken("!")){
Node *node=new Node(Node::NotExpression);
while(matchToken("!"))
addToken(node,"!",Node::Operator);
addChild(node,parseAtom());
return node;
}else{
return parseAtom();
}
}
Node *BooleanParser::parseAtom()
{
if(matchToken("(")){
Node *node=new Node(Node::Atom);
addToken(node,"(",Node::Punctuator);
addChild(node,parseOrExpression());
addToken(node,")",Node::Punctuator);
return node;
}else{
return parseIdentifier();
}
}
Node *BooleanParser::parseIdentifier()
{
int startPos=pos;
while(pos<in.length()&&in[pos].isLetterOrNumber())
++pos;
if(pos>startPos){
return new Node(Node::Identifier,in.mid(startPos,pos-startPos));
}else{
return 0;
}
}
void BooleanParser::addChild(Node *parent, Node *child)
{
if(child){
parent->children+=child;
parent->str+=child->str;
child->parent=parent;
}
}
void BooleanParser::addToken(Node *parent, const QString &str, Node::Type type)
{
if(in.mid(pos,str.length())==str){
addChild(parent,new Node(type,str));
pos+=str.length();
}
}
bool BooleanParser::matchToken(const QString &str) const
{
return in.mid(pos,str.length())==str;
}
//booleanwindow.cpp
#include <QtGui>
#include <QtWidgets>
#include "booleanmodel.h"
#include "booleanparser.h"
#include "booleanwindow.h"
BooleanWindow::BooleanWindow()
{
label=new QLabel(tr("Boolean expression"));
lineEdit =new QLineEdit;
booleanModel=new BooleanModel(this);
treeView=new QTreeView;
treeView->setModel(booleanModel);
connect(lineEdit,SIGNAL(textChanged(const QString &)),this,SLOT(booleanExpressionChanged(const QString &)));
QGridLayout *layout=new QGridLayout;
layout->addWidget(label,0,0);
layout->addWidget(lineEdit,0,1);
layout->addWidget(treeView,1,0,1,2);
setLayout(layout);
setWindowTitle(tr("Boolean Parser"));
}
void BooleanWindow::booleanExpressionChanged(const QString &expr)
{
BooleanParser parser;
Node *rootNode=parser.parse(expr);
booleanModel->setRootNode(rootNode);
}
//main.cpp
#include <QApplication>
#include "booleanwindow.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
BooleanWindow window;
window.show();
return a.exec();
}
//node.cpp
#include "node.h"
Node::Node(Type type,const QString &str)
{
this->type=type;
this->str=str;
parent=0;
}
Node::~Node()
{
qDeleteAll(children);//刪除所有元素，參數(shù)必為指針類型，調(diào)用后指針不會賦值為零
}
備注：QT錯誤undefined reference to vtable for **,解決辦法刪除debug下面的Makefile文件，我自己是將編譯后的文件全部刪除后，重新編譯就可以了，原因是添加Q_OBJECT宏之后，沒有經(jīng)過qt解析信號與槽相關部分，導致編譯器編譯出錯。
