由于老师要求，最近在做oceanbase存储过程的实现，在oceanbase 0.4以前是不支持存储过程的。实现的主要步骤主要包括 1、语法解析 2、词法解析 3、具体执行语法树的步骤 现在先来说说语法解析吧，在这一块主要是使用的flex（ 词法分析器生成工具） 和bison(语

由于老师要求，最近在做oceanbase存储过程的实现，在oceanbase 0.4以前是不支持存储过程的。实现的主要步骤主要包括

1、语法解析

2、词法解析

3、具体执行语法树的步骤

现在先来说说语法解析吧，在这一块主要是使用的flex（ 词法分析器生成工具） 和bison(语法分析器生成器) 这两个是对用户输入的存储过程语句进行解析的

来具体说说该怎么实现对sql语句的分析吧

1、首先建立一个lex的文件

%option noyywrap nodefault yylineno case-insensitive

%{

#include "prosql.tab.hpp"
#include 
#include 
#include 
#include 
#include 
//YYSTYPE yylval;
int oldstate;
extern "C" int yylex();
//extern "C" int yyparse();
extern "C" void yyerror(const char *s, ...);
extern char globalInputText[10000];
extern int readInputForLexer( char *buffer, int *numBytesRead, int maxBytesToRead );
#undef YY_INPUT
#define YY_INPUT(b,r,s) readInputForLexer(b,&r,s)
%}

%x COMMENT

%%

CREATE	{ return CREATE; }
PROCEDURE	{ return PROCEDURE; }
SQL	{ return SQL; }

DECLARE	{ return DECLARE; }
SET	{ return SET; }
BEGIN	{ return BEGINT; }
END	{ return END; }

INT	{ return INT; }
VARCHAR	{ return VARCHAR; }
DATE	{ return DATE; }
TIME	{ return TIME; }
DOUBLE	{ return DOUBLE; }

IF	{ return IF; }
THEN	{ return THEN; }
ELSE	{ return ELSE; }
ENDIF	{ return ENDIF; }
FOR	{ return FOR; }
WHEN	{ return WHEN; }
WHILE	{ return WHILE; }


[0-9]+	{ yylval.strval = strdup(yytext);/*printf("number=%s\n",yylval.strval);*/ return INTNUM; }/*number*/

[0-9]+"."[0-9]* |
"."[0-9]+	|
[0-9]+E[-+]?[0-9]+	|
[0-9]+"."[0-9]*E[-+]?[0-9]+ |
"."[0-9]*E[-+]?[0-9]+	{ yylval.strval = strdup(yytext);/*printf("float=%s\n",yylval.strval);*/ return APPROXNUM; }/*double*/

TRUE	{ yylval.strval = "1";/*printf("bool=%s\n",yylval.strval);*/ return BOOL; }/*bool*/

FALSE	{ yylval.strval = "0";/*printf("bool=%s\n",yylval.strval);*/ return BOOL; }/*bool*/

'(\\.|''|[^'\n])*'	|
\"(\\.|\"\"|[^"\n])*\" {
	char *temp = strdup(yytext); 
	yylval.strval = strdup(yytext);

	//GetCorrectString(yylval.strval, temp);
	
	/*printf("string=%s\n",yylval.strval);*/
	return STRING;
	}/*string*/
'(\\.|[^'\n])*$	{ yyerror("Unterminated string %s", yytext); }
\"(\\.|[^"\n])*$	{ yyerror("Unterminated string %s", yytext); }


X'[0-9A-F]+' | 
0X[0-9A-F]+ 	{ yylval.strval = strdup(yytext); return STRING; }


0B[01]+ |
B'[01]+' { yylval.strval = strdup(yytext); return STRING; }


[-+&~|^/%*(),.;!] { return yytext[0]; }

"&&"	{ return ANDOP; }
"||"	{ return OR; }

"<"	{ yylval.subtok = 1; return COMPARISON; }
">"	{ yylval.subtok = 2; return COMPARISON; }
"!="	|
"<>"	{ yylval.subtok = 3; return COMPARISON; }
"="	{ yylval.subtok = 4; return COMPARISON; }
"<="	{ yylval.subtok = 5; return COMPARISON; }
">="	{ yylval.subtok = 6; return COMPARISON; }
"<=>"	{ yylval.subtok = 12; return COMPARISON; }

"<<"	{ yylval.subtok = 1; return SHIFT; }
">>"	{ yylval.subtok = 2; return SHIFT; }


[A-Za-z][A-Za-z0-9_]*	{ yylval.strval = strdup(yytext);
	 /*printf("name 1=%s\n",yylval.strval);*/
 return NAME; }
`[^`/\\.\n]+` { yylval.strval = strdup(yytext+1);
	 /*printf("name 2=%s\n",yylval.strval);*/
 yylval.strval[yyleng-2] = 0;
 return NAME; }

`[^`\n]*$ { yyerror("unterminated quoted name %s", yytext); }


@[0-9a-z_.$]+ |
@\"[^"\n]+\" |
@`[^`\n]+` |
@'[^'\n]+' { yylval.strval = strdup(yytext+1); return USERVAR; }

@\"[^"\n]*$ { yyerror("unterminated quoted user variable %s", yytext); }
@`[^`\n]*$ { yyerror("unterminated quoted user variable %s", yytext); }
@'[^'\n]*$ { yyerror("unterminated quoted user variable %s", yytext); }

":=" { return ASSIGN; }

#.*	;
"--"[ \t].*	;

"/*" { oldstate = YY_START; BEGIN COMMENT; }
"*/" { BEGIN oldstate; }
.|\n ;
<> { yyerror("unclosed comment"); }


[ \t\n] /* white space */
. { yyerror("mystery character '%c'", *yytext); }

%%

这一部分呢就是对 每个我们自定义的满足正则的识别 

接下来是对词的语法识别

%{
#include 
#include 
#include 
#include 
#include 
char * parsetreeroot=NULL;
extern "C" int yylex();
extern "C" int yyparse();
extern "C" void yyerror(const char *s, ...);
char globalInputText[10000];
int globalReadOffset;
int readInputForLexer( char *buffer, int *numBytesRead, int maxBytesToRead );
char * mystrcat(char *s1,char *s2)
{
	char *p1=(char *)malloc(strlen(s1)+strlen(s2)+1);
	strcpy(p1,s1);
	strcat(p1,s2);
	return p1;
}
%}
%locations
%union {
	int intval;	
	double floatval;	
	char *strval;
	int subtok;
}
%token  NAME
%token  STRING
%token  INTNUM
%token  BOOL
%token  APPROXNUM
%token  USERVAR

%type  stmt_root create_stmt para_list definition data_type pro_block pro_parameters declare_list set_list 
%type  assign_var pro_body pro_stmt_list sql_stmt expr



%right ASSIGN
%left OR
%left XOR
%left ANDOP

%left NOT '!'
%left BETWEEN
%left  COMPARISON /* = <> < > <= >= <=> */
%left '|'
%left '&'
%left  SHIFT /* << >> */
%left '+' '-'
%left '*' '/' '%' MOD
%left '^'

%token CREATE
%token PROCEDURE
%token PRONAME
%token DECLARE
%token SET
%token BEGINT
%token END
%token SQL

%token INT
%token VARCHAR
%token DATE
%token TIME
%token DOUBLE

%token IF
%token NOT
%token EXISTS
%token THEN
%token ELSE
%token ENDIF
%token FOR
%token WHEN
%token WHILE
%start stmt_root
%%

stmt_root: create_stmt pro_block { $$=mystrcat($1,$2); parsetreeroot=$$;}
;
create_stmt: CREATE PROCEDURE NAME '(' para_list ')' 
	{
	char *temp=mystrcat("create procedure ",$3);
	temp=mystrcat(temp,"(");
	temp=mystrcat(temp,$5);
	$$=mystrcat(temp,")(create)\n");
	}
;
/*
opt_if_not_exists:	 { $$ = 0; } 
 | IF NOT EXISTS { $$ = 1; } 
 ;
*/
para_list: definition { $$=$1; }
|definition ',' para_list 
	{	
	
	char *temp=mystrcat($1,",");
	$$=mystrcat(temp,$3); 
	}
;
definition: USERVAR data_type 
	{	
	
	char *temp=mystrcat($1," ");
	$$=mystrcat(temp,$2);
	
	}
;

data_type:
 DATE 	{$$="date"; }
 | TIME	{$$="time"; }
 | VARCHAR '(' INTNUM ')' 	{$$="varchar"; }
 | INT 	{$$="int"; }
 | DOUBLE 	{$$="double"; }	
 ;

pro_block: BEGINT pro_parameters pro_body END 
	{ 
	char *temp=mystrcat("begin\n",$2);
	temp=mystrcat(temp,"");
	temp=mystrcat(temp,$3);
	$$=mystrcat(temp,"end");
	//printf("pro_body %s\n",$3);
	}
;

pro_parameters: declare_list ';' { $$=mystrcat($1,";(declare)\n");}
|pro_parameters declare_list ';' 
	{ 
	char *temp=mystrcat($1,$2);
	$$=mystrcat(temp,";(declare)\n");
	}
|pro_parameters set_list ';' 
	{
	 	char *temp=mystrcat($1,$2);
	$$=mystrcat(temp,";(set)\n");
	}
;

declare_list:
|DECLARE definition 
	{
	$$=mystrcat("declare ",$2);
	}
|declare_list ',' definition 
	{ 
	char *temp=mystrcat($1,",");
	$$=mystrcat(temp,$3); 
	}
;

set_list:
|SET assign_var 
	{
	$$=mystrcat("set ",$2); 
	}
| set_list ',' assign_var 
	{	
	char *temp=mystrcat($1,",");
	$$=mystrcat(temp,$3); 
	}
;

assign_var : USERVAR COMPARISON expr
	{ 	
	char *temp=mystrcat($1,"=");
	$$=mystrcat(temp,$3); 
	}
;

expr: NAME { $$=$1;}
 | STRING { $$=$1;}
 | INTNUM { $$=$1;}
 | APPROXNUM 	 { $$=$1;}	
 | BOOL { $$=$1;}
 ;

pro_body : pro_stmt_list { $$=$1; }
;
pro_stmt_list: sql_stmt {$$=$1; }
|pro_stmt_list sql_stmt 
	{
	$$=mystrcat($1,$2);
	}
;
sql_stmt: 
|SQL NAME ';' { $$=mystrcat($2,";(sql)\n");}
;
%%
/*
int main(int argc, char* argv[])
{
	yyparse();
}*/
int readInputForLexer( char *buffer, int *numBytesRead, int maxBytesToRead ) {
	int numBytesToRead = maxBytesToRead;
	int bytesRemaining = strlen(globalInputText)-globalReadOffset;
	int i;
	if ( numBytesToRead > bytesRemaining ) { numBytesToRead = bytesRemaining; }
	for ( i = 0; i < numBytesToRead; i++ ) {
	buffer[i] = globalInputText[globalReadOffset+i];
	}
	*numBytesRead = numBytesToRead;
	globalReadOffset += numBytesToRead;
	return 0;
}
void yyerror(const char *s, ...)
{
 fprintf(stderr, "error: %s\n", s);
}
void zzerror(const char *s, ...)
{
	extern int yylineno;

	va_list ap;
	va_start(ap, s);

	fprintf(stderr, "%d: error: ", yylineno);
	vfprintf(stderr, s, ap);
	fprintf(stderr, "\n");
}

int yywrap(void)
{
 return 1;
}
char* getsql()
{	
	return parsetreeroot;
}

这部分就是对上一个识别出来的词 进行顺序上的确定，构成一个完整的语法

这些需要在linux环境下进行调试

bison -d 文件名

flex 文件名