feat(frontend): 添加SysY.g4语法和词法描述

src/antlr4/SysY.g4

@@ -1,68 +1,172 @@
-// 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。
+// SysY 子集语法
+grammar SysY;
 
-// 后续需要自行添加
+//----词法规则（优先级从高到低）----//
+//keywords
+Void    : 'void';
+Int     : 'int';
+Float   : 'float';
+Const   : 'const';
+If      : 'if';
+Else    : 'else';
+While   : 'while';
+Break   : 'break';
+Continue: 'continue';
+Return  : 'return';
 
-grammar SysY;
+//Two-character operator (long preferred)
+LeOp    : '<=';
+GeOp    : '>=';
+EqOp    : '==';
+NeOp    : '!=';
+AndOp   : '&&';
+OrOp    : '||';
 
-/*===-------------------------------------------===*/
-/* Lexer rules                                     */
-/*===-------------------------------------------===*/
+//single character operators
+AddOp   : '+';
+SubOp   : '-';
+MulOp   : '*';
+DivOp   : '/';
+QuoOp   : '%';
+NotOp   : '!';
+LOp     : '<';
+GOp     : '>';
+Assign  : '=';
 
-INT: 'int';
-RETURN: 'return';
+//Separator
+Semi    : ';';
+Comma   : ',';
+L_PAREN : '(';
+R_PAREN : ')';
+L_BRACK : '[';
+R_BRACK : ']';
+L_BRACE : '{';
+R_BRACE : '}';
 
-ASSIGN: '=';
-ADD: '+';
+//const numeric classes
+//Number... change
+// float first
+// 16进制float first
+HEX_FLOAT
+    : '0' [xX](
+        // 形式1: 0x1.921fb6p+1  (有小数点和指数)
+          HEX_DIGIT* '.' HEX_DIGIT+ [pP] [+-]? DECIMAL_DIGIT+
+        | // 形式2: 0x1p+1  (没有小数点，只有指数)
+          HEX_DIGIT+ [pP] [+-]? DECIMAL_DIGIT+
+        | // 形式3: 0x.AP-3  (小数点开头)
+          '.' HEX_DIGIT+ [pP] [+-]? DECIMAL_DIGIT+
+    )
+    ;
+fragment HEX_DIGIT: [0-9a-fA-F];
+fragment DECIMAL_DIGIT: [0-9];
 
-LPAREN: '(';
-RPAREN: ')';
-LBRACE: '{';
-RBRACE: '}';
-SEMICOLON: ';';
+// 10进制float
+DEC_FLOAT
+    : [0-9]+ '.' [0-9]* EXP? //1.2/1./1.2e10/...
+    | '.' [0-9]+ EXP?  //.1/.1e2
+    | [0-9]+ EXP  //1e2/1e-2
+    ;
+fragment EXP: [eE] [+-]? [0-9]+;
 
-ID: [a-zA-Z_][a-zA-Z_0-9]*;
-ILITERAL: [0-9]+;
+HEX_INT: '0' [xX] [0-9a-fA-F]+; //16进制
+OCTAL_INT: '0' [0-7]*; //8进制
+DECIMAL_INT: [1-9][0-9]*; //10进制
+ZERO: '0'; //单独0
 
-WS: [ \t\r\n] -> skip;
-LINECOMMENT: '//' ~[\r\n]* -> skip;
-BLOCKCOMMENT: '/*' .*? '*/' -> skip;
+// TODO: 后续完善IR后，移除Number兼容规则
+Number
+    : HEX_FLOAT
+    | DEC_FLOAT
+    | HEX_INT
+    | OCTAL_INT
+    | DECIMAL_INT
+    | ZERO
+    ;
+  
+// 标识符（放最后）
+Ident
+    : [a-zA-Z_][a-zA-Z_0-9]*
+    ;
 
-/*===-------------------------------------------===*/
-/* Syntax rules                                    */
-/*===-------------------------------------------===*/
+// 注释和空白
+WS
+    : [ \t\r\n]+ -> skip
+    ;
+
+COMMENT
+    : '//' ~[\r\n]* -> skip
+    ;
+
+BLOCK_COMMENT
+    : '/*' .*? '*/' -> skip
+    ;
 
+//----语法规则----//
 compUnit
-    : funcDef EOF
+    : (funcDef|decl|program) EOF
+    ;
+
+program
+    : (decl|funcDef)+
     ;
 
 decl
-    : btype varDef SEMICOLON
+    : varDecl
+    | constDecl
+    ;
+
+constDecl
+    : Const bType constDef (Comma constDef)* Semi
+    ;
+
+bType
+    : Int
+    | Float
     ;
 
-btype
-    : INT
+constDef
+    : Ident (L_BRACK constExp R_BRACK)* Assign constInitVal
+    ;
+
+constInitVal
+    : constExp
+    | L_BRACE (constInitVal (Comma constInitVal)*)? R_BRACE
+    ;
+
+varDecl
+    : bType varDef (Comma varDef)* Semi
+    | Int Ident (Assign exp)? Semi
     ;
 
 varDef
-    : lValue (ASSIGN initValue)?
+    : Ident (L_BRACK constExp R_BRACK)* (Assign initVal)?
     ;
 
-initValue
+initVal
     : exp
+    | L_BRACE (initVal (Comma initVal)*)? R_BRACE
     ;
 
 funcDef
-    : funcType ID LPAREN RPAREN blockStmt
+    : funcType Ident L_PAREN (funcFParams)? R_PAREN block
     ;
 
 funcType
-    : INT
+    : Void
+    | Int
+    | Float
+    ;
+
+funcFParams
+    : funcFParam (Comma funcFParam)*
+    ;
+
+funcFParam
+    : bType Ident (L_BRACK R_BRACK (L_BRACK exp R_BRACK)*)?
     ;
 
-blockStmt
-    : LBRACE blockItem* RBRACE
+block
+    : L_BRACE (blockItem)* R_BRACE
     ;
 
 blockItem
@@ -71,28 +175,92 @@ blockItem
     ;
 
 stmt
-    : returnStmt
+    : lVal Assign exp Semi
+    | (exp)? Semi
+    | block
+    | If L_PAREN cond R_PAREN stmt (Else stmt)?
+    | While L_PAREN cond R_PAREN stmt
+    | Break Semi
+    | Continue Semi
+    | returnStmt
     ;
 
 returnStmt
-    : RETURN exp SEMICOLON
+    : Return (exp)? Semi
     ;
 
 exp
-    : LPAREN exp RPAREN          # parenExp
-    | var                        # varExp
-    | number                     # numberExp
-    | exp ADD exp                # additiveExp
+    : addExp
+    ;
+
+cond
+    : lOrExp
+    ;
+
+lVal
+    : Ident (L_BRACK exp R_BRACK)*
+    ;
+
+primary
+    : L_PAREN exp R_PAREN
+    | lVal
+    | Number              // 让旧代码能用
+    | HEX_FLOAT
+    | DEC_FLOAT
+    | HEX_INT
+    | OCTAL_INT
+    | DECIMAL_INT
+    | ZERO
+    | Ident
+    ;
+
+unaryExp
+    : primary
+    | Ident L_PAREN (funcRParams)? R_PAREN
+    | unaryOp unaryExp
     ;
 
-var
-    : ID
+unaryOp
+    : AddOp
+    | SubOp
+    | NotOp
     ;
 
-lValue
-    : ID
+funcRParams
+    : exp (Comma exp)*
     ;
 
-number
-    : ILITERAL
+mulExp
+    : unaryExp
+    | mulExp (MulOp|DivOp|QuoOp) unaryExp
     ;
+
+addExp
+    : mulExp
+    | addExp (AddOp|SubOp) mulExp
+    | primary (AddOp primary)*
+    ;
+
+relExp
+    : addExp
+    | relExp (LOp|GOp|LeOp|GeOp) addExp
+    ;
+
+eqExp
+    : relExp
+    | eqExp (EqOp|NeOp) relExp
+    ;
+
+lAndExp
+    : eqExp
+    | lAndExp AndOp eqExp
+    ;
+
+lOrExp
+    : lAndExp
+    | lOrExp OrOp lAndExp
+    ;
+
+constExp
+    : addExp
+    ;