sql parser: add a demo to show usage of sql parser

sql-parser/demo.c

@@ -0,0 +1,52 @@
+/**
+ * @file demo.c
+ * @author sinkinben@outlook.com
+ * @brief A demo to show the usage of `yyparse()`
+ * @date 2022-01-28
+ *
+ * @copyright Copyright (c) 2022
+ *
+ *
+ * SELECT:
+ *   select * from tblname;
+ *   select c1, c2, c3, c4 from tblname;
+ *   select * from tblid where a != 'ss3' and b > 10 and c <= 9 and d == 'aa';
+ *   select c1, c2, c3,c4 from tblid where a != 'ss3' and b > 10 and c <= 9 and d == 'aa' or e >= 16;
+ * CREATE:
+ *   create table tbl1 (c1 int(10), c2 char(16), c3 int(32));
+ *   create table mytable (id int(16), msg1 varchar(32), msg2 varchar(64));
+ * TODO:
+ *   1) Free the resource, when the SQL parsing processes are finished,
+ *      e.g. schema_list, select_list, and condition_tree.
+ *   2) The priority between 'AND' and 'OR' is ignored, since I forget how to fix shift/reduce confilcts :-(.
+ *      Run: bison -d -v sqlparser.y, in the 'sqlparser.output', we can see the shift/reduce conflicts
+ *      For example:
+ *      + A AND B OR C => A AND (B OR C), which should be (A AND B) OR C
+ *      + A AND B OR C AND D => A AND (B OR (C AND D)), which should be (A AND B) OR (C AND D)
+ *      + This is a deadly disadvantage for this dummy sql parser.
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include "sqlparser.tab.h"
+
+typedef struct yy_buffer_state * YY_BUFFER_STATE;
+extern YY_BUFFER_STATE yy_scan_string(const char *);
+extern void yy_delete_buffer(YY_BUFFER_STATE);
+extern int yyparse();
+
+int main(int argc, char *argv[])
+{
+    size_t len;
+    char *ptr = NULL;
+    while (1)
+    {
+        printf("tinydb > ");
+        getline(&ptr, &len, stdin);
+        ptr[len - 2] = '\0';
+
+        YY_BUFFER_STATE buffer = yy_scan_string(ptr);
+        /* 0 - Success, 1 - Fail */
+        yyparse();
+        yy_delete_buffer(buffer);
+    }
+}

sql-parser/makefile

@@ -2,8 +2,11 @@ CC=clang -std=gnu17 -Wall -Wno-pointer-to-int-cast
 build:
 	flex sqlex.l
 	bison -d sqlparser.y
-	# use 'gcc -fl' if you build on Linux
-	$(CC) sqlparser.tab.c lex.yy.c -ll
 
 clean:
-	rm a.out lex.yy.c *.tab.c *.tab.h
+	rm a.out lex.yy.c *.tab.c *.tab.h
+
+demo: build
+	# use 'gcc -fl' if you build on Linux
+	$(CC) sqlparser.tab.c lex.yy.c demo.c -ll
+	./a.out

sql-parser/sqlparser.y

@@ -18,7 +18,6 @@ int yywrap() { return 1; }
 
 void yyerror(const char *msg) { fprintf(stderr, "error: %s\n", msg); }
 
-int main(int argc, char *argv[]) { yyparse(); }
 
 %}
 
@@ -44,7 +43,6 @@ int main(int argc, char *argv[]) { yyparse(); }
 // token's value
 %token<strval> STRING IDNAME INT CHAR
 %token<intval> NUMBER
-%token<intval> AND OR
 
 // BNF's value
 %type <schema_node> createitem
@@ -144,13 +142,13 @@ cmp_op:
 conditionitem:
     columnitem cmp_op NUMBER
     {
-        $$ = alloc_condition(&($1->schema), $2, $3, true);
+        $$ = alloc_condition((uint64_t)(&($1->schema)), $2, $3, true);
         printf("[conditionitem NUMBER]");
         print_tree($$, 0);
     }
 |   columnitem cmp_op STRING
     {
-        $$ = alloc_condition(&($1->schema), $2, $3, true);
+        $$ = alloc_condition((uint64_t)(&($1->schema)), $2, (uint64_t)($3), true);
         printf("[conditionitem STRING]");
         print_tree($$, 0);
     }
@@ -174,7 +172,7 @@ conditions:
         printf("[logic %d] right: ", $2);
         print_tree($3, 0);
 
-        $$ = alloc_condition($1, $2, $3, false);
+        $$ = alloc_condition((uint64_t)($1), $2, (uint64_t)($3), false);
     }
 ;