Clite(抽象语法).ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,clite语法类型的非概要信息和意义,(2014025704-116),P,rogram: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;,C,ompound: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:&,|,|,=,+,-,和/,表现：,boolean运算符：and,or,not;,关系运算符：less than,less or equal,equal,not equal,greater than,greater,or equal;,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=&|,RelationalOp=|!=|=,ArithmeticOp=+|-|*|/,Unary=!|-,Variable=String id,ArrayRef=String id;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 Statement-if(Expression)Statement else Statement,WhileStatement-while(Expression)Statement,Expression-Conjunction|Conjunction,Conjunction-Equality&Equality,Equality-RelationEquOp Relation,EquOp-=|!=,Relation-AdditionRelOp Addition,RelOp-|=,Addition-Term AddOp Term,AddOp-+|-,Term-Factor MulOp Factor,MuiOp-*|/|%,Factor-UnaryOpPrimary,UnaryOp-|!,Primary-Identifier Expression|Literal|(Expression),|Type(Expression),Identifier-Letter Letter|Digit,Boolean-true|false,Float-Integer.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=&|,RelationalOp=|!=|=,ArithmeticOp=+|-|*|/,Unary=!|-,Variable=String id,ArrayRef=String id;Expression index,Value=IntValue|BoolValue|FloatValue|CharValue,IniValue=Integer intValue,FloatValue=Float floatvalue,BoolValue=Boolean boolvalue,CharValue=Character charvalue,