Clite(抽象語法).ppt

clite語法類型的非概要信息和意義 (2014025704-116),Program:Declarations 和一個Compound; Declaration:個體Declaration序列； Declaration:個體變量，其類型和大小； Type:int,bool,float,char集合的部分； Statement:子類Compound,Skip,Assignment,Conditional和Loop; Compound:個體Statement序列，以他們出現(xiàn)的順序執(zhí)行。每一個出現(xiàn)在抽象語法樹的相同層次。 Skip:跳轉語句 Assignment:將表達式賦給變量的語句,conditional:一個表達式(test)和兩個語句（thenbranch和elsebranch),其中一個被執(zhí)行則另一個則跳過。在if-then語句，elsebranch作為一個Skip語句的實例。 Lood:一個表達式（test)和一個只要測試結果是ture就不斷重復的語句（循環(huán)體）。 Expression:子類Variable,Value,Binary,和Unary; Binary:一個Operater和兩個Expression; Unary:一個Operator和兩個Expression; Operator: 數(shù)學運算符：plus,minus,times,divide,Value:有子類IntValue,FloatValue,BoolValue和CharValue intValue:整數(shù)值 FloatValue:浮點數(shù)值，描述從計算機近似值到一非整數(shù)值。 BoolValue:Boolean值，也就是說不是ture就是false; Char Value:單個字符值；,Clite程序抽象語法樹： 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/*仔細看一下其實也不難-取決你態(tài)度*/,A.1 Clite 詞匯和具體句法 /*所有引用變量必須聲明*/ 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 /*所有聲明變量必須唯一*/ 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