模版引擎之简单实现

模版，大家肯定都比较熟悉的一个概念，刚学C#（Java）那会老师就告诉我们，类是对象的模版。今天写这个模版其实是我用于生成js代码的，当然不限于生成js,其实跟codesmith有着差不多的功能，只是没那么强大，下面我写一些思路

我这个模版目前用于生成Ext的Grid和添加，编辑 表单，所以主角的又（怎么会是又呢，呵呵）是数据库表，不过这些信息被我存到前一篇博客里提到的Model里去了（通过特性的方式）。

        出于方便，我还是把Model的代码贴一下： 

//------------------------------------------------------------------------------
// <auto-generated>
//     This code generated by the tool, do not propose to amend
//       Generation time:2012/7/16 18:01:54
// </auto-generated>
//------------------------------------------------------------------------------
using System;
using System.Data;
using System.Runtime.Serialization;
using XDbFramework;
using System.Xml.Serialization;
using System.Diagnostics;
using System.CodeDom.Compiler;

namespace ExinSoft.Host.Model
{
    [Serializable]
    [Table(TableName = "Agent" ,Descripton = "代理")]
      [GeneratedCodeAttribute("System.Xml", "2.0.50727.4927")]
    [DebuggerStepThroughAttribute()]
    [XmlRootAttribute(Namespace = "http://www.scexin.com/", IsNullable = true)]
    [DataContract(Namespace = "http://www.scexin.com/")]
    public partial class Model_Agent
    {
        
        [Column(KeyType = KeyTypeEnum.PrimaryKey,ColumnName="AgentID",DbType=SqlDbType.BigInt, Index=0,Description="编号")]
        [DataMember(Order = 0)]
        public  long? AgentID{get;set;}
    
        
        [Column(ColumnName="AgentLevelID",ForeignKeyTableName="AgentLevel",ForeignKeyFiledName="AgentLevelID", DbType=SqlDbType.Int, Index=1,Description="等级编号")]
        [DataMember(Order = 1)]
        public  int? AgentLevelID{get;set;}
    
        
        [Column(ColumnName="SuperiorAgentID",ForeignKeyTableName="Agent",ForeignKeyFiledName="AgentID", DbType=SqlDbType.BigInt, Index=2,Description="套餐编号")]
        [DataMember(Order = 2)]
        public  long? SuperiorAgentID{get;set;}
    
        
        [Column(ColumnName="CustomerID",ForeignKeyTableName="Customers",ForeignKeyFiledName="CustomerID", DbType=SqlDbType.BigInt, Index=3,Description="客户编号")]
        [DataMember(Order = 3)]
        public  long? CustomerID{get;set;}
    
        
        [Column(ColumnName="AddTime",DbType=SqlDbType.DateTime, Index=4,Description="操作时间")]
        [DataMember(Order = 4)]
        public  DateTime? AddTime{get;set;}
    
    }    
}

没错，这些信息被存放于储如“[Column(ColumnName="AgentLevelID",ForeignKeyTableName="AgentLevel",ForeignKeyFiledName="AgentLevelID", DbType=SqlDbType.Int, Index=1,Description="等级编号")]”这行特性标记中，稍作解释

ColumnName ：列名，ForeignKeyTableName：外键表名，ForeignKeyFiledName：外键表的主键列名，DbType：字段类型，Description：描述

 有了这些基本信息，便够了，现在我们就来解释上一篇讲到的数据库表数据的浏览功能，主角（模版）登场 ，分步实现

1.定义模块标签，现在模版功能还不是很强大，没有实现语法分析如if等，目前只是简单的实现了for和标签替换，上代码 

public const string ColumnEachTagName = "columnsEach"; //循环列
        public const string DateColumnTagName = "dateColumn";  //日期列
        public const string PkColumnTagName = "pkColumn";      //主键列
        public const string TextColumnTagName = "textColumn";  //文本列
        public const string BoolColumnTagName = "boolColumn";  //bool列
        public const string EveryColumnTagName = "everyColumn";//所有列
        public const string NumberColumnTagName = "numberColumn";//数字列
        public const string MoneyColumnTagName = "moneyColumn";  //money型列
        public const string ColumnNameTagName = "[columnName]";  //列名
        public const string UnlessLastTagName = "unlessLast";    //除非最后一个
        public const string TableTagName = "[table]";            //表名
        public const string FkColumnTagName = "fkColumn";        //外键列名
        public const string FkTableTagName = "[fkTable]";        //外键表名
        public const string ColumnDescriptionTagName = "[columnDescription]";  //列描述
        public const string PkColumnNameTagName = "[pkColumnName]";   //主键列名

  

通过上面代码，我们可以将标签划分为三类

1.占位符类，如[table],[pkColumnName]，[columnDescription]

2.语法类，如columnsEach，unlessLast

3.筛选类 如dateColumn,pkColumn,textColumn,boolColumn……

       2.写模版文件 

var [table]AddPostUrl = '/proc/[table]/?action=add';
var [table]UpdatePostUrl = '/proc/[table]/?action=update';
var [table]Form;
var [table]IdStr;
function initAdd[table]Form(containerid, idstr,rowObj) {
    if (!idstr)
        [table]IdStr = containerid;
    else
        [table]IdStr = idstr;
    [table]Form = new Ext.FormPanel({
        labelWidth: 100, // label settings here cascade unless overridden
        url: [table]AddPostUrl,
        frame: true,
        bodyStyle: 'padding:5px 5px 0',
        buttonAlign: 'left',
        defaults: {  350 },
        defaultType: 'textfield',
        renderTo: containerid,
        items: [
@columnsEach:        
@pkColumn:
            {
                xtype: 'hidden',
                name: '[columnName]',
                id: '[columnName]' + idstr,
                value: null == rowObj ? null : rowObj.get('[columnName]'),
                readOnly: true
            }@unlessLast:, @<unlessLast@<pkColumn
    @everyColumn:
            {
                xtype: 'textfield',
                fieldLabel: '[columnDescription]',
                name: '[columnName]',
                allowBlank: false,
                value: null == rowObj ? null : rowObj.get('[columnName]'),
                id: '[columnName]' + idstr
            }@unlessLast:, @<unlessLast@<everyColumn
    @dateColumn:
            {
                xtype: 'datefield',
                fieldLabel: '[columnDescription]',
                name: '[columnName]',
                allowBlank: false,
                value: null == rowObj || !Ext.isDate(rowObj.get('[columnName]')) ? null : rowObj.get('[columnName]').dateFormat('Y-m-d H:i:s'),format:'Y-m-d H:i:s',
                id: '[columnName]' + idstr
            }@unlessLast:, @<unlessLast@<dateColumn  
    @<columnsEach
            ],
            buttons: getAddOrEditButton('[table]')
    });

@columnsEach:
    @fkColumn:
    $('#[columnName]' + idstr).focus(function() {
        loadGrid('[fkTable]', this, $('#hidden[columnName]' + idstr)[0],'[columnName]');
    });@<fkColumn

@<columnsEach
            
            
if (Ext.getCmp(containerid + '_tab'))
    Ext.getCmp(containerid + '_tab').add([table]Form);

}

看到这个模块，也就清楚如果写了，一个标记，我们得让程序知道从哪里开始，又从哪里结束，所以我这里以@tagName:开始，@<tagName结束，所以我的TagIndex类里也依赖这一点

3.进行语法分析和替换动作

    这是很重要的一步了，要操作标签，首先我们得找到标签。很简单，一个IndexOf就足够了，但是我要稍微封装一下，如下： 

using System;

namespace TemplateEngine
{
    public class TagIndex
    {
        public bool FindThisTag { get { return Start >= 0; } }
        public int Start
        {
            get
            {
                return Source.IndexOf("@" + TagName, System.StringComparison.Ordinal);
            }
        }
        public int End
        {
            get
            {
                return Source.IndexOf("@<" + TagName, System.StringComparison.Ordinal); ;
            }
        }
        public string Source { get; set; }
        public string TagName { get; set; }
        public string Content
        {
            get
            {
                return Source.Substring(Start + string.Format("@{0}:", TagName).Length, End - Start - string.Format("@<{0}", TagName).Length);
            }
        }

        public string RealContent
        {
            get
            {
                return Source.Substring(Start, End - Start + string.Format("@<{0}", TagName).Length);
            }
        }


        public static TagIndex GetTag(string str, string tagName)
        {
            var startOfAt = str.IndexOf("@" + tagName, System.StringComparison.Ordinal);
            if (startOfAt < 0)
                return new TagIndex { TagName = tagName, Source = str };
            var endOfAt = str.IndexOf("@<" + tagName, System.StringComparison.Ordinal);
            if (endOfAt < 0) throw new FormatException(string.Format("模版缺少@<{0}这一结束标记", tagName));
            return new TagIndex { TagName = tagName, Source = str };
        }
    }
}

 标签找到之后，便是分析替换，像上面的[table]（占位符类）标签，我们当然直接替换就可以了，但是语法类的我们还得稍加分析才行，拿columnsEach举例吧，上伪代码

  var forTag = TagIndex.GetTag(str, "columnEach");
            while (forTag.FindThisTag)
            {
                var forStr = forTag.RealContent;
                string fields = string.Empty;

                MathTag mathTag = new MathTag(forStr);

                columns.ForEach(m =>
                {
                     //去替换里面的占位符类标签
                }

             }      

 再来看看unlessLast标签，定义这个标签的用意在于，最后一行就不输出标签里面的内容，使用场景如：给表格加入列时，最后一列我们不需要加逗号，见下图(当然不是只针对这种场景)

 

如上图，第一处有“,” 第二处则没有，要实现这一点，我们在模版文件里这样写

@everyColumn:
            {
                xtype: 'textfield',
                fieldLabel: '[columnDescription]',
                name: '[columnName]',
                allowBlank: false,
                value: null == rowObj ? null : rowObj.get('[columnName]'),
                id: '[columnName]' + idstr

                    }@unlessLast:, @<unlessLast@<everyColumn  

            

可能有人会说，这也太大材小用了吧，呵呵，希望你能提出意见，我现在只想到这种方式。下面把所有代码粘过来，有需要的可以改改.

using System.IO;
using System.Text;
using XDbFramework;

namespace TemplateEngine
{
    public class Generator
    {
        public const string ColumnEachTagName = "columnsEach"; //循环列
        public const string DateColumnTagName = "dateColumn";  //日期列
        public const string PkColumnTagName = "pkColumn";      //主键列
        public const string TextColumnTagName = "textColumn";  //文本列
        public const string BoolColumnTagName = "boolColumn";  //bool列
        public const string EveryColumnTagName = "everyColumn";//所有列
        public const string NumberColumnTagName = "numberColumn";//数字列
        public const string MoneyColumnTagName = "moneyColumn";  //money型列
        public const string ColumnNameTagName = "[columnName]";  //列名
        public const string UnlessLastTagName = "unlessLast";    //除非最后一个
        public const string TableTagName = "[table]";            //表名
        public const string FkColumnTagName = "fkColumn";        //外键列名
        public const string FkTableTagName = "[fkTable]";        //外键表名
        public const string ColumnDescriptionTagName = "[columnDescription]";  //列描述
        public const string PkColumnNameTagName = "[pkColumnName]";   //主键列名

        private readonly string _template;

        public Generator(string templatePath)
        {
            using (var reader = new StreamReader(templatePath, encoding: Encoding.UTF8))
            {
                _template = reader.ReadToEnd();
            }
        }

        public string Generate<T>() where T : class
        {
            var table = DalHelper.GetTableInfo(typeof(T));
            var columns = DalHelper.GetTypeColumns<T>();
            var str = _template.Replace(TableTagName, table.TableName);
            var pkColumn = columns.Find(m => m.KeyType == KeyTypeEnum.PrimaryKey);
            if (pkColumn != null)
                str = str.Replace(PkColumnNameTagName, pkColumn.ColumnName);

            var forTag = TagIndex.GetTag(str, ColumnEachTagName);
            while (forTag.FindThisTag)
            {
                var forStr = forTag.RealContent;
                string fields = string.Empty;

                MathTag mathTag = new MathTag(forStr);

                columns.ForEach(m =>
                {
                    string tmpStr = string.Empty;
                    TagIndex tag = mathTag.GetTagIndexByColumn(m);
                    if (tag != null)
                    {
                        tmpStr = tag.Content
                            .Replace(ColumnNameTagName, m.ColumnName)
                            .Replace(ColumnDescriptionTagName, m.Description)
                            .Replace(FkTableTagName, m.ForeignKeyTableName);
                    }
                    var unlessLastTag = TagIndex.GetTag(tmpStr, UnlessLastTagName);
                    if (unlessLastTag.FindThisTag)
                    {
                        if (m == columns[columns.Count - 1])
                        {
                            tmpStr = tmpStr.Replace(unlessLastTag.RealContent, string.Empty);
                        }
                        else
                        {
                            tmpStr = tmpStr.Replace(unlessLastTag.RealContent, unlessLastTag.Content);
                        }
                    }
                    fields += tmpStr;
                });

                str = str.Replace(forStr, fields);
                forTag = TagIndex.GetTag(str, ColumnEachTagName);
            }
            return str;
        }
    }
}

using System;
using XDbFramework;

namespace TemplateEngine
{
    public class MathTag
    {
        private string _sourceString;
        private TagIndex pkTag;
        private TagIndex fkTag;
        private TagIndex textTag;
        private TagIndex dateTag;
        private TagIndex numberTag;
        private TagIndex moneyTag;
        private TagIndex boolTag;
        private TagIndex everyTag;


        public MathTag(string sourceString)
        {
            _sourceString = sourceString;
            pkTag = TagIndex.GetTag(sourceString, Generator.PkColumnTagName);
            fkTag = TagIndex.GetTag(sourceString, Generator.FkColumnTagName);
            textTag = TagIndex.GetTag(sourceString, Generator.TextColumnTagName);
            dateTag = TagIndex.GetTag(sourceString, Generator.DateColumnTagName);
            numberTag = TagIndex.GetTag(sourceString, Generator.NumberColumnTagName);
            moneyTag = TagIndex.GetTag(sourceString, Generator.MoneyColumnTagName);
            boolTag = TagIndex.GetTag(sourceString, Generator.BoolColumnTagName);
            everyTag = TagIndex.GetTag(sourceString, Generator.EveryColumnTagName);
        }

        public TagIndex GetTagIndexByColumn(ColumnAttribute m)
        {
            if (m.KeyType == KeyTypeEnum.PrimaryKey && pkTag.FindThisTag)
            {
                return pkTag;
            }
            if ((m.CType == typeof(DateTime) || m.CType == typeof(DateTime?)) && dateTag.FindThisTag)
            {
                return dateTag;
            }
            if ((m.CType == typeof(bool) || m.CType == typeof(bool?)) && boolTag.FindThisTag)
            {
                return boolTag;
            }
            if ((m.CType == typeof(float) || m.CType == typeof(decimal) || m.CType == typeof(double) || m.CType == typeof(float?) || m.CType == typeof(decimal?) || m.CType == typeof(double?)) && moneyTag.FindThisTag)
            {
                return moneyTag;
            }
            if ((m.CType == typeof(int) || m.CType == typeof(int?) || m.CType == typeof(long) || m.CType == typeof(long?)) && numberTag.FindThisTag)
            {
                return numberTag;
            }
            if (m.CType == typeof(string) && textTag.FindThisTag)
            {
                return textTag;
            }
            if (m.KeyType == KeyTypeEnum.ForeignKey && fkTag.FindThisTag)
            {
                return fkTag;
            } if (everyTag.FindThisTag)
            {
                return everyTag;
            }
            return null;
        }
    }
}

 好,这里整个过程也就差不多结束了（不知道怎么替换？当然是Replace）