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 <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <malloc.h>
//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; }
<COMMENT>"*/" { BEGIN oldstate; }
<COMMENT>.|\n ;
<COMMENT><<EOF>> { 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 <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>
#include <malloc.h>
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 <strval> NAME
%token <strval> STRING
%token <strval> INTNUM
%token <strval> BOOL
%token <strval> APPROXNUM
%token <strval> USERVAR
%type <strval> stmt_root create_stmt para_list definition data_type pro_block pro_parameters declare_list set_list
%type <strval> assign_var pro_body pro_stmt_list sql_stmt expr
%right ASSIGN
%left OR
%left XOR
%left ANDOP
%left NOT '!'
%left BETWEEN
%left <subtok> COMPARISON /* = <> < > <= >= <=> */
%left '|'
%left '&'
%left <subtok> 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