feat: support the priority between 'AND' and 'OR'

README.md

@@ -19,7 +19,7 @@ This project is inspired by sqlite, has a similar architecture with sqlite (but
 There are two version of `tinydb`:
 
 - `main.c` - In this program, I parse the SQL statements by spliting strings, thus the SQL statements are incomplete. And it does **NOT** support `where` keyword.
-- `main2.c` - In this, I implement an tiny SQL Parser based on Flex & Bison, thus the SQL statements in this program are mostly like sqlite or MySQL. And it supports `where` conditions.
+- `main2.c` - In this program, I implement an tiny SQL Parser based on Flex & Bison, thus the SQL statements in this program are mostly like sqlite or MySQL. And it supports `where` conditions.
 
 For both of them, they have the same format of database file.
 
@@ -99,7 +99,9 @@ Please note that there is a `';'` after each SQL statement.
 And the `conditions` support operators: `=, !=, >=, >, <=, <, AND, OR`, e.g.
 
 ```sql
-SELECT * FROM table WHERE id < 10 OR (id > 100 AND username = 'sinkinben');
+SELECT * FROM table WHERE id < 10 OR id > 100 AND username = 'sinkinben';
+SELECT * FROM table WHERE id = 1 AND username='1' OR id >= 10 AND id < 20;
+SELECT * FROM table WHERE id = 1 AND username='1' OR id >= 10 AND username < '20';
 ```
 
 The keywords `AND, OR` can be `and, or`.

docs/flex-and-bison.md

@@ -9,10 +9,10 @@ Before you read this article, you should know the basis prerequisites knowledge:
 Generally speaking, a compiler has 3 parts:
 
 - Front-end: Lexer/Scanner, Parser, Semantic Analyzer
-  - Front-end will produce IR (Internal Result)
+  - Front-end will produce IR (Internal Result).
 - Middle-end: Optimizer
 - Back-end: Code Generator
-  - Back-end will generate the binary code related to specific machine
+  - Back-end will generate the binary code related to specific machines.
 
 The tools "Flex & Bison" can help us to build the front-end of a compiler. In this article, we will introduce the basic usages of Flex and Bison via implementing a calculator.
 
@@ -162,7 +162,7 @@ From this example, we can know that `flex` can help us to generate the code of a
 
 ### Tokenizer
 
-Let's see some advaned usages. Now, we will tokenizer a expression in C language.
+Let's see some advaned usages, we will tokenize an expression in this section.
 
 ```c
 %{
@@ -235,7 +235,7 @@ number = 1000, type = 258
 
 ## Bison
 
-Suppose we have got all the `<token, type>` pairs, and we want to convert them into an AST, that what Bison can help us do.
+Suppose we have got all the `<token, type>` pairs, and we want to convert them into an AST, that's what Bison can help us do.
 
 ```cpp
 1 * 2 + 3 * 4 + 5
@@ -253,7 +253,7 @@ Suppose we have got all the `<token, type>` pairs, and we want to convert them i
 
 ### BNF
 
-Backus-Naur Form (BNF), is called "BNF 范式" in some Chinese textbooks. Our BNF example here is very simple (and naivce):
+Backus-Naur Form (BNF), is called "BNF 范式" in some Chinese textbooks. Our BNF example here is very simple (and naive):
 
 ```
 <exp>    ::= <factor>
@@ -268,7 +268,7 @@ In BNF,  `::=` can be read as "is a", and `|` can be read as "or". For example,
 
 ### Let's Build a Calculator
 
-> The source code of this part can be found in `sqlparser/calcdemo` of the github repo [tinydb](https://github.com/sinkinben/tinydb.git).
+> The source code of this part can be found in `sql-parser/calcdemo` of the github repo [tinydb](https://github.com/sinkinben/tinydb.git).
 
 In this part, we will show the basic usages of Bison via building a calculator (support `+, -, *, /` ) example.
 
@@ -333,7 +333,7 @@ term: NUMBER { $$ = $1; }
 %%
 ```
 
-And we make a simple modification on the flex source file above:
+And we make some simple modifications on the flex source file above:
 
 ```c
 // file: calc.l

sql-parser/sqlparser.y

@@ -63,8 +63,9 @@ void yyerror(const char *msg) { fprintf(stderr, "[tinydb] SQL Parser: %s\n", msg
 %type <update_node> updateitem
 %type <update_node> updateitemlist
 
-%type <intval> cmp_op logic_op
+%type <intval> cmp_op
 %type <condition_tree> conditionitem
+%type <condition_tree> conditionfactor
 %type <condition_tree> conditions
 
 
@@ -189,17 +190,14 @@ selectitemlist:
     }
 ;
 
-logic_op:
-    AND         { $$ = OP_AND; }
-|   OR          { $$ = OP_OR; }
-
 cmp_op:
     LESS        { $$ = OP_LESS; }
 |   LESS_EQUAL  { $$ = OP_LESS_EQUAL; }
 |   GREAT       { $$ = OP_GREAT; }
 |   GREAT_EQUAL { $$ = OP_GREAT_EQUAL; }
 |   EQUAL       { $$ = OP_EQUAL; }
 |   NOT_EQUAL   { $$ = OP_NOT_EQUAL; }
+;
 
 conditionitem:
     columnitem cmp_op NUMBER
@@ -212,18 +210,29 @@ conditionitem:
     }
 ;
 
-conditions:
+conditionfactor:
     conditionitem
     {
         $$ = $1;
     }
+|   conditionfactor AND conditionitem
+    {
+        $$ = alloc_condition((uint64_t)($1), OP_AND, (uint64_t)($3), false, COLUMN_DUMMY);
+    }
+;
+
+conditions:
+    conditionfactor
+    {
+        $$ = $1;
+    }
 |   '(' conditions ')'
     {
         $$ = $2;
     }
-|   conditions logic_op conditions
+|   conditions OR conditionfactor
     {
-        $$ = alloc_condition((uint64_t)($1), $2, (uint64_t)($3), false, COLUMN_DUMMY);
+        $$ = alloc_condition((uint64_t)($1), OP_OR, (uint64_t)($3), false, COLUMN_DUMMY);
     }
 ;