atitit..sql update语法的词法分析，与语法ast构建
1. 要使用sql udpate语法的dsl ，需要写个解释器。。 1
1. 要使用sql udpate语法的dsl ，需要写个解释器。。
主要应用在orm框架上，使得update 跟个insert的语法统一
注意的要点：：
单引号的转义实现
单引号内的逗号，等号的实现。
作者:: 老哇的爪子 Attilax 艾龙， EMAIL:1466519819@qq.com
转载请注明来源： http://blog.csdn.net/attilax
2. 词法分析的实现
2.1. 扫描器的实现 SqlUpExpTokener
s = "fld1=1,fld2='at''t,lax',fld3='val3'";
public List getTokenList(String s) {
// DslPaserContext context = new DslPaserContext();
Context4sqlUpExp context = new Context4sqlUpExp();
context.setState(new iniState());
int n = 0;
while (!(context.state instanceof FinishState)) {
// System.out.println(n);
// ����
context.request(s);
n++;
if (n > 200)
break;
}
for (Token tk : context.tokenList) {
// if(tk.value.trim().length()>0)
System.out.println(tk.value + "===");
}
return (List) context.tokenList;
}
2.2. 等号操作符的转态 EqxState
public class EqxState implements State {
@Override
public void handle(String sampleParameter, Context context) {
Context4sqlUpExp ctt = (Context4sqlUpExp) context;
char curchar = ctt.curchar;
if (ctt.lastKeystate instanceof CommaState || ctt.lastKeystate instanceof CommaState || ctt.lastKeystate instanceof com.attilax.dsm.state.iniState) {
Token tk = new Token();
tk.value = ctt.curToken.value.trim();
ctt.tokenList.add(tk);
ctt.tokenList.add(new Token() {
{
this.value = "=";
}
});
ctt.curToken = new Token();
ctt.lastKeystate=new EqxState();
} else
ctt.curToken.value += curchar;
ctt.curcharIndex++;
}
2.3. 单引号的转态 SingleQuoeState
public class SingleQuoeState implements State {
/* (non-Javadoc)
* @see com.attilax.designpatter.statepatter.State#handle(java.lang.String)
*/
@Override
public void handle(String sampleParameter) {
// TODO Auto-generated method stub
}
/* (non-Javadoc)
* @see com.attilax.designpatter.statepatter.State#handle(java.lang.String, com.attilax.designpatter.statepatter.Context)
*/
@Override
public void handle(String sampleParameter, Context context) {
Context4sqlUpExp ctt = (Context4sqlUpExp) context;
char curchar=ctt.curchar;
ctt. SingleQuoeCount++;
// ctt.curToken.value+=curchar;
//sec queot
if( nextAlsoSq(ctt) && ctt. SingleQuoeCount%2==0 )
{
ctt.curToken.value=ctt.curToken.value+new StringBuffer().append(curchar).toString();
ctt.curcharIndex++;
return;
}
else if( preAlsoSq(ctt) && ctt. SingleQuoeCount%2==1 )
{
ctt.curToken.value=ctt.curToken.value+new StringBuffer().append(curchar).toString();
ctt.curcharIndex++;
return;
}
else if(ctt.lastKeystate instanceof EqxState)
{
ctt.curToken=new Token();
ctt.lastKeystate=new SingleQuoetStartState();
}
else if (ctt.lastKeystate instanceof SingleQuoetStartState )//first queot
{
Token tk=new Token();
tk.value=ctt.curToken.value;
ctt.tokenList.add(tk);
// ctt.tokenList.add(new Token(){{ this.value="," ; }});
ctt.curToken=new Token();
ctt.lastKeystate=new SingleQuoeEndState();
}
ctt.curcharIndex++;
}
/**
@author attilax 老哇的爪子
@since p2g m_n_5
*/
private boolean preAlsoSq(Context4sqlUpExp ctt) {
if( ctt.charArr[ctt.curcharIndex-1]=='\'')
return true;
else
return false;
}
/**
@author attilax 老哇的爪子
* @param ctt
@since p2g m_c_s
*/
private boolean nextAlsoSq(Context4sqlUpExp ctt) {
try {
if( ctt.charArr[ctt.curcharIndex+1]=='\'')
return true;
else
return false;
} catch (ArrayIndexOutOfBoundsException e) {
return false;
}
}
}
2.4. 逗号操作的转态 CommaState
public void handle(String sampleParameter, Context context) {
Context4sqlUpExp ctt = (Context4sqlUpExp) context;
char curchar = ctt.curchar;
if(ctt.lastKeystate instanceof EqxState )
{
//
Token tk=new Token();
tk.value=ctt.curToken.value.trim();
ctt.tokenList.add(tk);
ctt.tokenList.add(new Token() {
{
this.value = ",";
}
});
ctt.curToken = new Token();
ctt.lastKeystate = new CommaState();
}
else if( ctt.lastKeystate instanceof SingleQuoeEndState)
{
ctt.tokenList.add(new Token() {
{
this.value = ",";
}
});
ctt.curToken = new Token();
ctt.lastKeystate = new CommaState();
ctt. SingleQuoeCount=0;
}
else
{
ctt.curToken.value+=curchar;
}
// ctt.curToken.value+=curchar;
ctt.curcharIndex++;
}
3. 构建语法树ast
这里使用map作为Ast的存储格式。。最终序列化为json
public class AstBuilder {
public Context ctx = new Context();
// ����ı��ʽ
public AbstractExpression expression;
public Map astRoot = new HashMap();
private String expStr;
@SuppressWarnings("all")
public static void main(String[] args) throws CantFindRitBrack {
String expStr2 = " method1( param1;\r\n method2(param2);";
expStr2 = "fld1=1,fld2='at''t,lax',fld3='val3'";
AstBuilder clt = new AstBuilder(expStr2);
clt.tkr = new SqlUpExpTokener();
Object rzt = clt.build();// AST
System.out.println(JSONObject.fromObject(clt.astRoot).toString(10));
//System.out.println(JsonUtil4jackjson.buildNormalBinder().toJson(rzt));
}
// ���캯������,������
public AstBuilder(String expStr) throws CantFindRitBrack {
this.expStr = expStr;
}
Tokener tkr;
List<Token> tokenList;
private Object build() throws CantFindRitBrack {
tokenList = tkr.getTokenList(this.expStr);
// ����һ����ջ������������Ⱥ�˳��
// Stack<AbstractExpression> stack = ctx.stack;
// ����
for (int i = 0; i < tokenList.size(); i++) {
Token tk = tokenList.get(i);
if (tk.value.equals(",") ) {
Token key = tokenList.get(i - 3);
this.astRoot.put(key.value, tokenList.get(i - 1).value);
}
if( i==tokenList.size()-1 )
{
this.astRoot.put(tokenList.get(i - 2).value, tokenList.get(i).value);
}
}
return this.astRoot;
// ���������׳���
// this.expression = stack.pop();
}
4. 最终输出ast结构
{
"fld1": "1",
"fld3": "val3",
"fld2": "at''t,lax"
}