feat: 实现控制流语句、表达式优先级及测试脚本

src/antlr4/SysY.g4

@@ -171,21 +171,74 @@ blockItem
     ;
 
 stmt
-    : returnStmt
+    : assignStmt
+    | returnStmt
+    | blockStmt
+    | ifStmt
+    | whileStmt
+    | breakStmt
+    | continueStmt
+    | expStmt
+    ;
+
+expStmt
+    : exp SEMICOLON
+    ;
+
+assignStmt
+    : lValue ASSIGN exp SEMICOLON
     ;
 
 returnStmt
     : RETURN (exp)? SEMICOLON
     ;
 
+ifStmt
+    : IF LPAREN exp RPAREN stmt (ELSE stmt)?
+    ;
+
+whileStmt
+    : WHILE LPAREN exp RPAREN stmt
+    ;
+
+breakStmt
+    : BREAK SEMICOLON
+    ;
+
+continueStmt
+    : CONTINUE SEMICOLON
+    ;
+
+// 表达式
+lValue
+    : ID (LBRACK exp RBRACK)*
+    ;
+
 exp
     : LPAREN exp RPAREN          # parenExp
     | lValue                     # lValueExp
     | number                     # numberExp
+    | ID LPAREN (funcRParams)? RPAREN # funcCallExp
+    | NOT exp                    # notExp
+    | ADD exp                    # unaryAddExp
+    | SUB exp                    # unarySubExp
+    | exp MUL exp                # mulExp
+    | exp DIV exp                # divExp
+    | exp MOD exp                # modExp
+    | exp ADD exp                # addExp
+    | exp SUB exp                # subExp
+    | exp LT exp                 # ltExp
+    | exp LE exp                 # leExp
+    | exp GT exp                 # gtExp
+    | exp GE exp                 # geExp
+    | exp EQ exp                 # eqExp
+    | exp NE exp                 # neExp
+    | exp AND exp                # andExp
+    | exp OR exp                 # orExp
     ;
 
-lValue
-    : ID (LBRACK exp RBRACK)*
+funcRParams
+    : exp (COMMA exp)*
     ;
 
 number