[游戏开发] java 抽象语法树（AST）系列二：变量定义

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[游戏开发]java 抽象语法树（AST）系列二：变量定义

第一讲：抽象语法树基本知识

一、字面量

字面量并不是定义，而是一个字面表达式，比如a=1，1就是一个字面

使用treeMaker.Literal进行定义

//com.sun.tools.javac.code.TypeTag 定义了各种基本的类型
treeMaker.Literal(typeTag, o);

二、int

使用JCVariableDecl进行变量的定义，注意modifier。

注意：基本类型即使也对了，编译的时候也会编译成int a = true这种形式，所以最好使用包装类型

JCTree.JCVariableDecl intI1 = treeMaker.VarDef(
        treeMaker.Modifiers(Flags.PARAMETER),
        names.fromString("intI1"),
        treeMaker.Ident(names.fromString("Integer")),
        treeMaker.Literal(i)
);
// 注意：实际生成了 int intI2 = true;
JCTree.JCVariableDecl intI2 = treeMaker.VarDef(
        treeMaker.Modifiers(Flags.PARAMETER),
        names.fromString("intI2"),
        treeMaker.TypeIdent(TypeTag.INT),
        treeMaker.Literal(TypeTag.INT, i)
);

三、short

//  注意：实际生成了 short short1 = true;
        JCTree.JCVariableDecl short1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("short1"),
                treeMaker.TypeIdent(TypeTag.SHORT),
                treeMaker.Literal(TypeTag.SHORT, 500)
        );
        JCTree.JCVariableDecl short2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("short2"),
                treeMaker.Ident(names.fromString("Short")),
                treeMaker.Literal(500)
        );

四、byte

//  注意：实际生成 byte byte1 = true;
        JCTree.JCVariableDecl byte1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("byte1"),
                treeMaker.TypeIdent(TypeTag.BYTE),
                treeMaker.Literal(TypeTag.BYTE, 1)
        );
        JCTree.JCVariableDecl byte2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("byte2"),
                treeMaker.Ident(names.fromString("Byte")),
                treeMaker.Literal(1)
        );

五、boolean

// boolean bo = true;
        JCTree.JCVariableDecl boolean1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("boolean1"),
                treeMaker.TypeIdent(TypeTag.BOOLEAN),
                treeMaker.Literal(true)
        );
        JCTree.JCVariableDecl boolean2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("boolean2"),
                treeMaker.Ident(names.fromString("Boolean")),
                treeMaker.Literal(false)
        );

六、char

JCTree.JCVariableDecl char1 = treeMaker.VarDef(
        treeMaker.Modifiers(Flags.PARAMETER),
        names.fromString("char1"),
        treeMaker.TypeIdent(TypeTag.CHAR),
        // 这里是不能使用'a'，否则会报错
        treeMaker.Literal(TypeTag.CHAR, 97)
);
JCTree.JCVariableDecl char2 = treeMaker.VarDef(
        treeMaker.Modifiers(Flags.PARAMETER),
        names.fromString("char2"),
        treeMaker.Ident(names.fromString("Character")),
        treeMaker.Literal(TypeTag.CHAR, 97)
);

七、long

JCTree.JCVariableDecl long1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("long1"),
                treeMaker.TypeIdent(TypeTag.LONG),
                treeMaker.Literal(12312L)
        );
        JCTree.JCVariableDecl long2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("long2"),
                treeMaker.Ident(names.fromString("Long")),
                treeMaker.Literal(12324L)
        );

八、double

JCTree.JCVariableDecl double1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("double1"),
                treeMaker.TypeIdent(TypeTag.DOUBLE),
                treeMaker.Literal(4.567D)
        );
        JCTree.JCVariableDecl double2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("double2"),
                treeMaker.Ident(names.fromString("Double")),
                treeMaker.Literal(4.567D)
        );

九、float

JCTree.JCVariableDecl float1 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("float1"),
                treeMaker.TypeIdent(TypeTag.FLOAT),
                treeMaker.Literal(4.567F)
        );
        JCTree.JCVariableDecl float2 = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("float2"),
                treeMaker.Ident(names.fromString("Float")),
                treeMaker.Literal(4.567F)
        );

十、object

// 需要先进行import
        JCTree.JCIdent jcIdent = treeMaker.Ident(names.fromString("com.leisure.lombok.thrift"));
        Name className = names.fromString("Test");
        JCTree.JCFieldAccess jcFieldAccess = treeMaker.Select(jcIdent, className);
        JCTree.JCImport anImport = treeMaker.Import(jcFieldAccess, false);
        jcCompilationUnit.defs = jcCompilationUnit.defs.append(anImport);
        JCTree.JCNewClass newClass = treeMaker.NewClass(null, null, treeMaker.Ident(names.fromString("Test")), List.nil(), null);
        JCTree.JCVariableDecl object = treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER),
                names.fromString("object"),
                treeMaker.Ident(names.fromString("Test")),
                newClass
        );