diff --git a/src/antlr4/SysY.g4 b/src/antlr4/SysY.g4
index 4c5d788..262f07a 100644
--- a/src/antlr4/SysY.g4
+++ b/src/antlr4/SysY.g4
@@ -47,48 +47,44 @@ MUL: '*';
 DIV: '/';
 MOD: '%';
 NOT: '!';
-SUB: '-';
-MUL: '*';
-DIV: '/';
-MOD: '%';
-EQ: '==';
-NEQ: '!=';
-LT: '<';
-GT: '>';
-LE: '<=';
-GE: '>=';
-NOT: '!';
-AND: '&&';
-OR: '||';
 
 LPAREN: '(';
 RPAREN: ')';
 LBRACK: '[';
 RBRACK: ']';
-LBRACK: '[';
-RBRACK: ']';
 LBRACE: '{';
 RBRACE: '}';
 COMMA: ',';
-COMMA: ',';
 SEMICOLON: ';';
 
 ID: [a-zA-Z_][a-zA-Z_0-9]*;
 
-ILITERAL
-    : '0' | [1-9][0-9]* // Decimal
-    | '0' [0-7]+        // Octal
-    | ('0x' | '0X') [0-9a-fA-F]+ // Hex
+HEX_FLOAT_LITERAL
+    : ('0x' | '0X') HEX_DIGIT* '.' HEX_DIGIT+ BINARY_EXPONENT
+    | ('0x' | '0X') HEX_DIGIT+ '.' HEX_DIGIT* BINARY_EXPONENT
+    | ('0x' | '0X') HEX_DIGIT+ BINARY_EXPONENT
+    ;
+
+DEC_FLOAT_LITERAL
+    : DEC_DIGIT+ '.' DEC_DIGIT* DEC_EXPONENT?
+    | '.' DEC_DIGIT+ DEC_EXPONENT?
+    | DEC_DIGIT+ DEC_EXPONENT
+    ;
+
+HEX_INT_LITERAL
+    : ('0x' | '0X') HEX_DIGIT+
+    ;
+
+OCT_INT_LITERAL
+    : '0' OCT_DIGIT+
     ;
 
-FLITERAL
-    : ([0-9]* '.' [0-9]+ | [0-9]+ '.') ([eE] [+-]? [0-9]+)?
-    | [0-9]+ [eE] [+-]? [0-9]+
-    | ('0x'|'0X') ([0-9a-fA-F]* '.' [0-9a-fA-F]+ | [0-9a-fA-F]+ '.') ([pP] [+-]? [0-9]+)?
-    | ('0x'|'0X') [0-9a-fA-F]+ [pP] [+-]? [0-9]+
+DEC_INT_LITERAL
+    : '0'
+    | [1-9] DEC_DIGIT*
     ;
 
-WS: [ \t\r\n]+ -> skip;
+WS: [ \t\r\n] -> skip;
 LINECOMMENT: '//' ~[\r\n]* -> skip;
 BLOCKCOMMENT: '/*' .*? '*/' -> skip;
 
@@ -130,16 +126,7 @@ bType
     ;
 
 constDef
-    : ID (LBRACK constExp RBRACK)* ASSIGN constInitVal
-    ;
-
-constInitVal
-    : constExp
-    | LBRACE (constInitVal (COMMA constInitVal)*)? RBRACE
-    ;
-
-varDecl
-    : btype varDef (COMMA varDef)* SEMICOLON
+    : ID constIndex* ASSIGN constInitVal
     ;
 
 varDef
@@ -157,11 +144,11 @@ constInitVal
 
 initVal
     : exp
-    | LBRACE (initValue (COMMA initValue)*)? RBRACE
+    | LBRACE (initVal (COMMA initVal)*)? RBRACE
     ;
 
 funcDef
-    : funcType ID LPAREN funcFParams? RPAREN blockStmt
+    : funcType ID LPAREN funcFParams? RPAREN block
     ;
 
 funcType
@@ -175,7 +162,7 @@ funcFParams
     ;
 
 funcFParam
-    : btype ID (LBRACK RBRACK (LBRACK exp RBRACK)*)?
+    : bType ID (LBRACK RBRACK (LBRACK exp RBRACK)*)?
     ;
 
 block
@@ -188,53 +175,107 @@ blockItem
     ;
 
 stmt
-    : lValue ASSIGN exp SEMICOLON            # assignStmt
-    | exp? SEMICOLON                         # exprStmt
-    | blockStmt                              # blockStmtStmt
-    | IF LPAREN cond RPAREN stmt (ELSE stmt)? # ifStmt
-    | WHILE LPAREN cond RPAREN stmt          # whileStmt
-    | BREAK SEMICOLON                        # breakStmt
-    | CONTINUE SEMICOLON                     # continueStmt
-    | RETURN exp? SEMICOLON                  # returnStmt
+    : lVal ASSIGN exp SEMICOLON
+    | exp? SEMICOLON
+    | block
+    | IF LPAREN cond RPAREN stmt (ELSE stmt)?
+    | WHILE LPAREN cond RPAREN stmt
+    | BREAK SEMICOLON
+    | CONTINUE SEMICOLON
+    | RETURN exp? SEMICOLON
     ;
 
 exp
-    : LPAREN exp RPAREN                      # parenExp
-    | lValue                                 # lvalExp
-    | number                                 # numberExp
-    | ID LPAREN funcRParams? RPAREN          # callExp
-    | unaryOp exp                            # unaryExp
-    | exp (MUL | DIV | MOD) exp              # mulExp
-    | exp (ADD | SUB) exp                    # addExp
-    | exp (LT | GT | LE | GE) exp            # relExp
-    | exp (EQ | NEQ) exp                     # eqExp
-    | exp AND exp                            # lAndExp
-    | exp OR exp                             # lOrExp
+    : addExp
     ;
 
 cond
-    : exp
+    : lOrExp
     ;
 
-lValue
+lVal
     : ID (LBRACK exp RBRACK)*
     ;
 
+primaryExp
+    : LPAREN exp RPAREN
+    | lVal
+    | number
+    ;
+
 number
-    : ILITERAL                               # intConst
-    | FLITERAL                               # floatConst
+    : intConst
+    | floatConst
+    ;
+
+intConst
+    : DEC_INT_LITERAL
+    | OCT_INT_LITERAL
+    | HEX_INT_LITERAL
     ;
 
-unaryOp
+floatConst
+    : DEC_FLOAT_LITERAL
+    | HEX_FLOAT_LITERAL
+    ;
+
+unaryExp
+    : primaryExp
+    | ID LPAREN funcRParams? RPAREN
+    | addUnaryOp unaryExp
+    ;
+
+addUnaryOp
     : ADD
     | SUB
-    | NOT
     ;
 
 funcRParams
     : exp (COMMA exp)*
     ;
 
+mulExp
+    : unaryExp
+    | mulExp MUL unaryExp
+    | mulExp DIV unaryExp
+    | mulExp MOD unaryExp
+    ;
+
+addExp
+    : mulExp
+    | addExp ADD mulExp
+    | addExp SUB mulExp
+    ;
+
+relExp
+    : addExp
+    | relExp LT addExp
+    | relExp GT addExp
+    | relExp LE addExp
+    | relExp GE addExp
+    ;
+
+eqExp
+    : relExp
+    | eqExp EQ relExp
+    | eqExp NE relExp
+    ;
+
+lAndExp
+    : condUnaryExp
+    | lAndExp AND condUnaryExp
+    ;
+
+lOrExp
+    : lAndExp
+    | lOrExp OR lAndExp
+    ;
+
+condUnaryExp
+    : eqExp
+    | NOT condUnaryExp
+    ;
+
 constExp
-    : exp
+    : addExp
     ;