feat(grammar): 完善 SysY.g4 语法定义支持 Lab1 要求

- 扩展 SysY 语法定义以支持更多合法程序
- 完善词法和语法规则，增强解析能力
- 确保符合 SysY 语言规范

src/antlr4/SysY.g4

@@ -1,31 +1,61 @@
-// SysY 子集语法：支持形如
-// int main() { int a = 1; int b = 2; return a + b; }
-// 的最小返回表达式编译。
-
-// 后续需要自行添加
-
 grammar SysY;
 
 /*===-------------------------------------------===*/
 /* Lexer rules                                     */
 /*===-------------------------------------------===*/
 
+CONST: 'const';
 INT: 'int';
+FLOAT: 'float';
+VOID: 'void';
+IF: 'if';
+ELSE: 'else';
+WHILE: 'while';
+BREAK: 'break';
+CONTINUE: 'continue';
 RETURN: 'return';
 
 ASSIGN: '=';
 ADD: '+';
+SUB: '-';
+MUL: '*';
+DIV: '/';
+MOD: '%';
+EQ: '==';
+NEQ: '!=';
+LT: '<';
+GT: '>';
+LE: '<=';
+GE: '>=';
+NOT: '!';
+AND: '&&';
+OR: '||';
 
 LPAREN: '(';
 RPAREN: ')';
+LBRACK: '[';
+RBRACK: ']';
 LBRACE: '{';
 RBRACE: '}';
+COMMA: ',';
 SEMICOLON: ';';
 
 ID: [a-zA-Z_][a-zA-Z_0-9]*;
-ILITERAL: [0-9]+;
 
-WS: [ \t\r\n] -> skip;
+ILITERAL
+    : '0' | [1-9][0-9]* // Decimal
+    | '0' [0-7]+        // Octal
+    | ('0x' | '0X') [0-9a-fA-F]+ // Hex
+    ;
+
+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]+
+    ;
+
+WS: [ \t\r\n]+ -> skip;
 LINECOMMENT: '//' ~[\r\n]* -> skip;
 BLOCKCOMMENT: '/*' .*? '*/' -> skip;
 
@@ -34,31 +64,62 @@ BLOCKCOMMENT: '/*' .*? '*/' -> skip;
 /*===-------------------------------------------===*/
 
 compUnit
-    : funcDef EOF
+    : (decl | funcDef)+ EOF
     ;
 
 decl
-    : btype varDef SEMICOLON
+    : constDecl
+    | varDecl
+    ;
+
+constDecl
+    : CONST btype constDef (COMMA constDef)* SEMICOLON
     ;
 
 btype
     : INT
+    | FLOAT
+    ;
+
+constDef
+    : ID (LBRACK constExp RBRACK)* ASSIGN constInitVal
+    ;
+
+constInitVal
+    : constExp
+    | LBRACE (constInitVal (COMMA constInitVal)*)? RBRACE
+    ;
+
+varDecl
+    : btype varDef (COMMA varDef)* SEMICOLON
     ;
 
 varDef
-    : lValue (ASSIGN initValue)?
+    : ID (LBRACK constExp RBRACK)*
+    | ID (LBRACK constExp RBRACK)* ASSIGN initValue
     ;
 
 initValue
     : exp
+    | LBRACE (initValue (COMMA initValue)*)? RBRACE
     ;
 
 funcDef
-    : funcType ID LPAREN RPAREN blockStmt
+    : funcType ID LPAREN funcFParams? RPAREN blockStmt
     ;
 
 funcType
-    : INT
+    : VOID
+    | INT
+    | FLOAT
+    ;
+
+funcFParams
+    : funcFParam (COMMA funcFParam)*
+    ;
+
+funcFParam
+    : btype ID (LBRACK RBRACK (LBRACK exp RBRACK)*)?
     ;
 
 blockStmt
@@ -71,28 +132,53 @@ blockItem
     ;
 
 stmt
-    : returnStmt
-    ;
-
-returnStmt
-    : RETURN exp SEMICOLON
+    : 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
     ;
 
 exp
-    : LPAREN exp RPAREN          # parenExp
-    | var                        # varExp
-    | number                     # numberExp
-    | exp ADD exp                # additiveExp
+    : 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
     ;
 
-var
-    : ID
+cond
+    : exp
     ;
 
 lValue
-    : ID
+    : ID (LBRACK exp RBRACK)*
     ;
 
 number
-    : ILITERAL
+    : ILITERAL                               # intConst
+    | FLITERAL                               # floatConst
+    ;
+
+unaryOp
+    : ADD
+    | SUB
+    | NOT
+    ;
+
+funcRParams
+    : exp (COMMA exp)*
+    ;
+
+constExp
+    : exp
     ;