私は lex/yacc を初めて使用し、lex/yacc を使用して SQL パーサーを作成しています。ただし、特定の JOIN クエリ (以下にリスト) では、私のパーサーは意図的に「nested_join_statement」ルールではなく「select_statement」ルールにアクセスしています。
このクエリの正しい出力を取得しています: SELECT * FROM sample1 JOIN sample2 ON sample1.C1 = sample2.C4;
(これは「join_statement ルール」に進み、simple_join ルールを満たします)
しかし、私がこのクエリを試しているとき: SELECT * FROM (SELECT * FROM (SELECT * FROM sample1)T8)AS temp1 JOIN (SELECT * FROM (SELECT * FROM sample2)T9)as temp2 ON temp1.C1 = temp2.C4;
(これは理想的には「nested_join_statement」に送られるべきですが、代わりに「select statement」ルール内の「SELECT selection FROM LPAREN select_statement2 RPAREN VAR」ルールに送られ、次のエラー メッセージが表示されます: ERROR:syntax error, unexpected AS, VARを期待）
select_statement よりも nested_join_statement を優先していますが、それでもこのエラーが発生します。理由がわかりません。
lex の VAR は [A-Za-z][A-Za-z0-9_#-]* として定義されます
どんな助けでも大歓迎です。私は必死です。
manipulation_statement: NEWLINE
| join_statement SEMICOLON
| nested_join_statement SEMICOLON
| select_statement SEMICOLON { flag=0;q=0;}
| join_statement SEMICOLON NEWLINE
| nested_join_statement SEMICOLON NEWLINE
| select_statement SEMICOLON NEWLINE { flag=0;q=0;}
;
nested_join_statement: two_nest_select_join { for(x=0;x<q;x++) strcpy(sj[x], ""); i=0;j=0;vardot=0;q=0;flag=0;nest=0;}
;
join_statement:
simple_join { for(x=0;x<q;x++) strcpy(sj[x], ""); i=0;j=0;vardot=0;q=0;flag=0;}
| simple_join_nest_select { for(x=0;x<q;x++) strcpy(sj[x], ""); i=0;j=0;vardot=0;q=0;flag=0;}
;
simple_join: SELECT selection FROM VAR JOIN VAR ON VAR DOTS VAR EQUAL VAR DOTS VAR { printf("inside simple join\n");
if(strcmp($4,$8) == 0) join_table($4,$6,sj,q,$10,$14,"","");
else join_table($4,$6,sj,q,$14,$10,"",""); p=q;}
;
simple_join_nest_select: SELECT selection FROM VAR JOIN LPAREN select_statement RPAREN AS VAR ON VAR DOTS VAR EQUAL VAR DOTS VAR {
if (strcmp($4,$12) == 0) join_table($4,"_temp_",sj,q,$14,$18,"","");
else join_table($4,"_temp_",sj,q,$18,$14,"",""); p=q;}
;
two_nest_select_join: SELECT selection FROM LPAREN select_statement RPAREN AS VAR JOIN LPAREN select_statement RPAREN AS VAR ON VAR DOTS VAR EQUAL VAR DOTS VAR {
join_table("temp1","temp2",sj,q,$18,$22,"",""); }
;
select_statement: SELECT selection FROM VAR WHERE where_clause { select_table($4,s,i,whr_var,whr_val);
for(x=0;x<i;x++) strcpy(s[x],"");i=0; strcpy(whr_var,""); strcpy(whr_val,"");j=0;}
| SELECT selection FROM VAR { select_table($4,s,i,whr_var,whr_val);
for(x=0;x<i;x++) strcpy(s[x],"");i=0;j=0;}
| SELECT selection FROM LPAREN select_statement2 RPAREN VAR { printf("inner tab: %s\n", inner_tab); printf("dep:%d\n", dep+1);
for(x=0; x<i;x++) printf("%s\n", col_array[x]);
for(y=0; y<j;y++) printf("%d\n", col_count[y]);
strcpy(inner_tab,""); nest =1; dep=0;
for(x=0; x<i;x++) strcpy(col_array[x], "");
for(y=0; y<j;y++) col_count[x] =0;
i=0;j=0;k=0;m=0;}
;
select_statement2: SELECT selection2 FROM VAR { dep++; inner_tab=malloc(strlen($4)); strcpy(inner_tab,$4); }
| select_list
;
select_list: SELECT selection2 FROM LPAREN select_statement2 RPAREN VAR { dep++; }
;
selection2: ASTERISK { col_array[i] = $1; i++; m++; col_count[j] = m; j++; printf("in level:%d value of k:%d\n",j,m); k=0; m=0;}
| comma_list2 { col_count[j] = m; j++; printf("in level:%d value of k:%d\n",j,m); k=0; m=0; }
;
comma_list2: VAR { col_array[i] = $1; i++; m++;}
| comma_list2 COMMA VAR { col_array[i] = $3; i++; m++;
k=m;}
;
selection: ASTERISK { if(q != 0 || nest == 1) { for(x=0;x<j;x++) col_count[x]=0; i=0; j=0;flag=1;}
s[i] = $1; col_array[i] = $1; i++; col_count[j] = i; j++;
if(q == 0) {sj[q] = $1; q++;} printf("in level t:%d value of k:%d\n",j,i); printf("sj2:%s\n",sj[0]);}
| comma_list { if (flag ==1 ) {col_count[j] = i; j++; printf("in level 2:%d value of k:%d\n",j,i); k=0; m=0; printf("temp:");
for(x=0;x<i;x++) printf("%s ",s[x]); } else {col_count[j] = i; j++;} }
;
comma_list:
VAR { if(q != 0 || nest == 1) { for(x=0;x<j;x++) col_count[x]=0; i=0; j=0;flag=1;}
s[i] = $1; col_array[i] = $1; i++; if(q==0) {sj[q] = $1; q++; }}
| VAR DOTS VAR { strcpy(temp,""); strcat(temp,$1); strcat(temp,$2); strcat(temp,$3);
sj[q] = temp; q++;
printf("temps:"); for(x=0;x<q;x++) printf("%s\n",sj[x]);}
| comma_list COMMA vardot {if (flag == 1) { s[i] = $3; col_array[i] = $3, i++;} else {sj[q] = $3; q++; vardot++;s[i] = $3; col_array[i] = $3, i++;}
}
;