Clite(抽象语法).ppt

clite语法类型的非概要信息和意义 (2014025704-116),Program:Declarations 和一个Compound; Declaration:个体Declaration序列； Declaration:个体变量，其类型和大小； Type:int,bool,float,char集合的部分； Statement:子类Compound,Skip,Assignment,Conditional和Loop; Compound:个体Statement序列，以他们出现的顺序执行。每一个出现在抽象语法树的相同层次。 Skip:跳转语句 Assignment:将表达式赋给变量的语句,conditional:一个表达式(test)和两个语句（thenbranch和elsebranch),其中一个被执行则另一个则跳过。在if-then语句，elsebranch作为一个Skip语句的实例。 Lood:一个表达式（test)和一个只要测试结果是ture就不断重复的语句（循环体）。 Expression:子类Variable,Value,Binary,和Unary; Binary:一个Operater和两个Expression; Unary:一个Operator和两个Expression; Operator: 数学运算符：plus,minus,times,divide,Value:有子类IntValue,FloatValue,BoolValue和CharValue intValue:整数值 FloatValue:浮点数值，描述从计算机近似值到一非整数值。 BoolValue:Boolean值，也就是说不是ture就是false; Char Value:单个字符值；,Clite程序抽象语法树： Program=Declarations decpart; Statements body; Declaration=Declaration* Declaration=VarableDecl | ArrayDecl VariableDecl=Variable v;Type t ArrayDecl=Variable v;Typt t;Integer size Type= int | bool | float | char Statements=Statemment* statement=Skip | Block |Assignment |Conditional |Loop Skip= Block=Statements Conditionnal=Expression test ;Statement thenbranch,elsebranch Loop=Expression test;Statement body Assignment=VariableRef target;Expression source Expression=VariableRef | Value | Binary |Unary,Variable Ref=Variable | ArrayRef Binary=Operator op;Expression term1,term2 Unary=UnaryOp op;Expression term Operator=BooleanOp | RelationnalOp | ArithmeticOp BooleanlOp= Expression index Value = IntValue | BoolValue | FloatValue | CharValue IniValue =Integer intValue FloatValue=Float floatvalue BoolValue =Boolean boolvalue CharValue = Character charvalue/*仔细看一下其实也不难-取决你态度*/,A.1 Clite 词汇和具体句法 /*所有引用变量必须声明*/ Program int main () Declarations Statements Declarations Declaration Declaration Type Identifier integer .Identifier integer; Type int | bool | float | char Statements-Statement Statement: | Block | Assignment | If Statement | WhileStatement Block -Statement Assignment -Identifier Expression =Expression; If Statementif (Expression) Statement else Statement WhileStatement while (Expression) Statement ExpressionConjunction |Conjunction Conjunction Equality& Equality EqualityRelationEquOp Relation ,EquOp-= | != RelationAdditionRelOp Addition RelOp | = Addition Term AddOp Term AddOp+ | - Term Factor MulOp Factor MuiOp* | / | % FactorUnaryOpPrimary UnaryOp - | ! PrimaryIdentifier Expression | Literal | (Expression ) | Type (Expression) Identifier Letter Letter | Digit Boolean-true | false FloatInteger .Integer Char ASCIIChar,A.2 Clite 的抽象句法 /*所有声明变量必须唯一*/ Program =Declarations decpart; Statements body; Declaration =Declaration* Declarations =VariableDecl | ArrayDecl VariableDecl = Variable V ; Type t ArrayDecl = Variable v;Type t;Integer size Type= int | bool | float | char Statements =Statement* Statement =Skip | Block | Assignment | Conditional | Loop Skip = Block=Statements Conditional=Experssion test;Statement thenbranch, elsebranch Loop=Expression test ;Statement body Assignment=VariableRef target ; Expression source Expression =VariableRef | Value |Binary | Unary VariableRef =Variable | ArrayRef,Binary=BinaryOp op;Expression term1,term2 Unary=UnaryOp op;Expression term1,term2 Operator=BooleanOp | RelationalOp | ArithmeticOp | UnaryOp BooleanlOp= Expression index