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每個語法節點Tree都有Type屬性，部分的語法節點有Symbol屬性，如下：

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與Symbol類型與Type類型之間的關系如下：

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下面是Symbol與Type之間的關系：

（1）MethodSymbol("finalize").type = MethodType("()void").tsym=

ClassSymbol("Method").type=ClassType("Method").tsym=ClassSymbol("Method")

（2）TypeVar("M").tsym=TypeSymbol("M").type=TypeVar("M").tsym

（3）PackageSymbol("java").type = PackageType("java").tsym=PackageSymbol("java")

（4）VarSymbol("length").type=Type("int").tsym=ClassSymbol("int").type=Type("int").tsym=ClassSymbol("int")

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下面是Node與Type之間的關系：

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class Outer{class Inner{} }public class Test01 extends Outer.Inner{public Test01(Outer o){o.super();} }

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Outer.Inner是一個樹節點，如果這個節點中的type有值，則直接返回即可，不用再進行標注?！　?/span>

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關于Node、Symbol與Type舉一個例子，如下：

import java.io.FileInputStream; import java.io.InputStream;public class TestScope<T1 extends InputStream,T2>{ public void test(){TestScope<FileInputStream,?> x = null;} }

截圖如下：?

JCTypeApply的Node結點中沒有Symbol屬性，但是每個Node中都有Type屬性，其值如上圖藍色部分。

ClassSymbol的Symbol結點中，由于每個Symbol中都有TypeSymbol類型的屬性，這個屬性值為com.test18.TestScope<T1,T2>

ClassType的Type結點中，由于每個Type中都有Symbol屬性，這個屬性的值為com.test18.TestScope?

1、Symbol

對于Symbol來說：

Symbol中既有Symbol類型屬性也有Type類型的屬性，如下：

/** The type of this symbol.*/public Type type;/** The owner of this symbol.*/public Symbol owner;/** The completer of this symbol.*/public Completer completer;/** A cache for the type erasure of this symbol.*/public Type erasure_field;　　

所以每個Symbol類型都有type屬性。

而標注Symbol類型的是Kinds枚舉類型，代碼如下：

/** Internal symbol kinds, which distinguish between elements of* different subclasses of Symbol. Symbol kinds are organized so they can be or'ed to sets.*/ public class Kinds {private Kinds() {} // uninstantiable/** The empty set of kinds.*/public final static int NIL = 0;/** The kind of package symbols.*/public final static int PCK = 1 << 0;/** The kind of type symbols (classes, interfaces and type variables).*/public final static int TYP = 1 << 1;/** The kind of variable symbols.*/public final static int VAR = 1 << 2;/** The kind of values (variables or non-variable expressions), includes VAR.*/public final static int VAL = (1 << 3) | VAR;/** The kind of methods.*/public final static int MTH = 1 << 4;/** The error kind, which includes all other kinds.*/public final static int ERR = (1 << 5) - 1;/** The set of all kinds.*/public final static int AllKinds = ERR;/** Kinds for erroneous symbols that complement the above*/public static final int ERRONEOUS = 1 << 6;public static final int AMBIGUOUS = ERRONEOUS+1; // ambiguous referencepublic static final int HIDDEN = ERRONEOUS+2; // hidden method or fieldpublic static final int STATICERR = ERRONEOUS+3; // nonstatic member from static contextpublic static final int ABSENT_VAR = ERRONEOUS+4; // missing variablepublic static final int WRONG_MTHS = ERRONEOUS+5; // methods with wrong argumentspublic static final int WRONG_MTH = ERRONEOUS+6; // one method with wrong argumentspublic static final int ABSENT_MTH = ERRONEOUS+7; // missing methodpublic static final int ABSENT_TYP = ERRONEOUS+8; // missing typepublic enum KindName implements Formattable {ANNOTATION("kindname.annotation"),CONSTRUCTOR("kindname.constructor"),INTERFACE("kindname.interface"),ENUM("kindname.enum"),STATIC("kindname.static"),TYPEVAR("kindname.type.variable"),BOUND("kindname.type.variable.bound"),VAR("kindname.variable"),VAL("kindname.value"),METHOD("kindname.method"),CLASS("kindname.class"),STATIC_INIT("kindname.static.init"),INSTANCE_INIT("kindname.instance.init"),PACKAGE("kindname.package");private String name;KindName(String name) {this.name = name;}public String toString() {return name;}public String getKind() {return "Kindname";}public String toString(Locale locale, Messages messages) {String s = toString();return messages.getLocalizedString(locale, "compiler.misc." + s);}}/** A KindName representing a given symbol kind*/public static KindName kindName(int kind) {switch (kind) {case PCK: return KindName.PACKAGE;case TYP: return KindName.CLASS;case VAR: return KindName.VAR;case VAL: return KindName.VAL;case MTH: return KindName.METHOD;default : throw new AssertionError("Unexpected kind: "+kind);}}/** A KindName representing a given symbol*/public static KindName kindName(Symbol sym) {switch (sym.getKind()) {case PACKAGE:return KindName.PACKAGE;case ENUM:return KindName.ENUM;case ANNOTATION_TYPE:case CLASS:return KindName.CLASS;case INTERFACE:return KindName.INTERFACE;case TYPE_PARAMETER:return KindName.TYPEVAR;case ENUM_CONSTANT:case FIELD:case PARAMETER:case LOCAL_VARIABLE:case EXCEPTION_PARAMETER:case RESOURCE_VARIABLE:return KindName.VAR;case CONSTRUCTOR:return KindName.CONSTRUCTOR;case METHOD:return KindName.METHOD;case STATIC_INIT:return KindName.STATIC_INIT;case INSTANCE_INIT:return KindName.INSTANCE_INIT;default:if (sym.kind == VAL)// I don't think this can happen but it can't harm// playing it safe --ahereturn KindName.VAL;elsethrow new AssertionError("Unexpected kind: "+sym.getKind());}}/** A set of KindName(s) representing a set of symbol's kinds.*/public static EnumSet<KindName> kindNames(int kind) {EnumSet<KindName> kinds = EnumSet.noneOf(KindName.class);if ((kind & VAL) != 0)kinds.add(((kind & VAL) == VAR) ? KindName.VAR : KindName.VAL);if ((kind & MTH) != 0) kinds.add(KindName.METHOD);if ((kind & TYP) != 0) kinds.add(KindName.CLASS);if ((kind & PCK) != 0) kinds.add(KindName.PACKAGE);return kinds;}/** A KindName representing the kind of a given class/interface type.*/public static KindName typeKindName(Type t) {if (t.tag == TYPEVAR ||t.tag == CLASS && (t.tsym.flags() & COMPOUND) != 0)return KindName.BOUND;else if (t.tag == PACKAGE)return KindName.PACKAGE;else if ((t.tsym.flags_field & ANNOTATION) != 0)return KindName.ANNOTATION;else if ((t.tsym.flags_field & INTERFACE) != 0)return KindName.INTERFACE;elsereturn KindName.CLASS;}/** A KindName representing the kind of a a missing symbol, given an* error kind.* */public static KindName absentKind(int kind) {switch (kind) {case ABSENT_VAR:return KindName.VAR;case WRONG_MTHS: case WRONG_MTH: case ABSENT_MTH:return KindName.METHOD;case ABSENT_TYP:return KindName.CLASS;default:throw new AssertionError("Unexpected kind: "+kind);}} }

Symbol可以通過訪問模式來訪問各個結點，定義如下：

（1）Symbol.Visitor<R, P>

符號類中定義的訪問者模式接口如下：

/*** A visitor for symbols. A visitor is used to implement operations* (or relations) on symbols. Most common operations on types are* binary relations and this interface is designed for binary* relations, that is, operations on the form* Symbol × P → R.* <!-- In plain text: Type x P -> R -->** @param <R> the return type of the operation implemented by this* visitor; use Void if no return type is needed.* @param <P> the type of the second argument (the first being the* symbol itself) of the operation implemented by this visitor; use* Void if a second argument is not needed.*/public interface Visitor<R,P> {R visitClassSymbol(ClassSymbol s, P arg);R visitMethodSymbol(MethodSymbol s, P arg);R visitPackageSymbol(PackageSymbol s, P arg);R visitOperatorSymbol(OperatorSymbol s, P arg);R visitVarSymbol(VarSymbol s, P arg);R visitTypeSymbol(TypeSymbol s, P arg);R visitSymbol(Symbol s, P arg);}　　

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（2）Types中的DefaultSymbolVisitor<R,S>

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/*** A default visitor for symbols. All visitor methods except* visitSymbol are implemented by delegating to visitSymbol. Concrete* subclasses must provide an implementation of visitSymbol and can* override other methods as needed.** @param <R> the return type of the operation implemented by this* visitor; use Void if no return type is needed.* @param <S> the type of the second argument (the first being the* symbol itself) of the operation implemented by this visitor; use* Void if a second argument is not needed.*/public static abstract class DefaultSymbolVisitor<R,S> implements Symbol.Visitor<R,S> {final public R visit(Symbol s, S arg) { return s.accept(this, arg); }public R visitClassSymbol(ClassSymbol s, S arg) { return visitSymbol(s, arg); }public R visitMethodSymbol(MethodSymbol s, S arg) { return visitSymbol(s, arg); }public R visitOperatorSymbol(OperatorSymbol s, S arg) { return visitSymbol(s, arg); }public R visitPackageSymbol(PackageSymbol s, S arg) { return visitSymbol(s, arg); }public R visitTypeSymbol(TypeSymbol s, S arg) { return visitSymbol(s, arg); }public R visitVarSymbol(VarSymbol s, S arg) { return visitSymbol(s, arg); }}

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2、Type

對于每個Type類型來說，只限定有TypeSymbol類型的屬性，也就是包、類和類型變量對應的符號。

// The defining class / interface / package / type variable public TypeSymbol typeSymbol; // 只有ClassSymbol與PackageSymbol繼承了TypeSymbol　　

標注每個Type類型的為TypeTags，代碼如下：

/** An interface for type tag values, which distinguish between different sorts of types.*/ public class TypeTags {private TypeTags() {} // uninstantiable/** The tag of the basic type `byte'.*/public static final int BYTE = 1;/** The tag of the basic type `char'.*/public static final int CHAR = BYTE+1;/** The tag of the basic type `short'.*/public static final int SHORT = CHAR+1;/** The tag of the basic type `int'.*/public static final int INT = SHORT+1;/** The tag of the basic type `long'.*/public static final int LONG = INT+1;/** The tag of the basic type `float'.*/public static final int FLOAT = LONG+1;/** The tag of the basic type `double'.*/public static final int DOUBLE = FLOAT+1;/** The tag of the basic type `boolean'.*/public static final int BOOLEAN = DOUBLE+1;/** The tag of the type `void'.*/public static final int VOID = BOOLEAN+1;/** The tag of all class and interface types.*/public static final int CLASS = VOID+1;/** The tag of all array types.*/public static final int ARRAY = CLASS+1;/** The tag of all (monomorphic 單一同態的) method types.*/public static final int METHOD = ARRAY+1;/** The tag of all package "types".*/public static final int PACKAGE = METHOD+1;/** The tag of all (source-level) type variables.*/public static final int TYPEVAR = PACKAGE+1;/** The tag of all type arguments.*/public static final int WILDCARD = TYPEVAR+1;/** The tag of all polymorphic (method-) types.*/public static final int FORALL = WILDCARD+1;/** The tag of the bottom type <null>.*/public static final int BOT = FORALL+1;/** The tag of a missing type.*/public static final int NONE = BOT+1;/** The tag of the error type.*/public static final int ERROR = NONE+1;/** The tag of an unknown type*/public static final int UNKNOWN = ERROR+1;/** The tag of all instantiatable type variables.*/public static final int UNDETVAR = UNKNOWN+1;/** The number of type tags.*/public static final int TypeTagCount = UNDETVAR+1;/** The maximum tag of a basic type.*/public static final int lastBaseTag = BOOLEAN;/** The minimum tag of a partial type*/public static final int firstPartialTag = ERROR; }

Javac為Type結果定義了訪問者接口，如下：

（1）Type.Visitor<R, S>

類型Type中定義的訪問者模式：

/*** A visitor for types. A visitor is used to implement operations* (or relations) on types. Most common operations on types are* binary relations and this interface is designed for binary* relations, that is, operations on the form* Type × S → R.* <!-- In plain text: Type x S -> R -->** @param <R> the return type of the operation implemented by this* visitor; use Void if no return type is needed.* @param <S> the type of the second argument (the first being the* type itself) of the operation implemented by this visitor; use* Void if a second argument is not needed.*/public interface Visitor<R,S> {R visitClassType(ClassType t, S s);R visitWildcardType(WildcardType t, S s);R visitArrayType(ArrayType t, S s);R visitMethodType(MethodType t, S s);R visitPackageType(PackageType t, S s);R visitTypeVar(TypeVar t, S s);R visitCapturedType(CapturedType t, S s);R visitForAll(ForAll t, S s);R visitUndeterminedVar(UndeterminedVar t, S s);R visitErrorType(ErrorType t, S s);R visitType(Type t, S s);}

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（2）Types中的DefaultTypeVisitor<R,S>，SimpleTypeVisitor<R,S>

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/*** A default visitor for types. All visitor methods except* visitType are implemented by delegating to visitType. Concrete* subclasses must provide an implementation of visitType and can* override other methods as needed.** @param <R> the return type of the operation implemented by this* visitor; use Void if no return type is needed.* @param <S> the type of the second argument (the first being the* type itself) of the operation implemented by this visitor; use* Void if a second argument is not needed.*/public static abstract class DefaultTypeVisitor<R,S> implements Type.Visitor<R,S> {final public R visit(Type t, S s) { return t.accept(this, s); }public R visitClassType(ClassType t, S s) { return visitType(t, s); }public R visitWildcardType(WildcardType t, S s) { return visitType(t, s); }public R visitArrayType(ArrayType t, S s) { return visitType(t, s); }public R visitMethodType(MethodType t, S s) { return visitType(t, s); }public R visitPackageType(PackageType t, S s) { return visitType(t, s); }public R visitTypeVar(TypeVar t, S s) { return visitType(t, s); }public R visitCapturedType(CapturedType t, S s) { return visitType(t, s); }public R visitForAll(ForAll t, S s) { return visitType(t, s); }public R visitUndeterminedVar(UndeterminedVar t, S s) { return visitType(t, s); }public R visitErrorType(ErrorType t, S s) { return visitType(t, s); }}

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/*** A <em>simple</em> visitor for types. This visitor is simple as* captured wildcards, for-all types (generic methods), and* undetermined（未確定的） type variables (part of inference) are hidden.* Captured wildcards are hidden by treating them as type* variables and the rest are hidden by visiting their qtypes.** @param <R> the return type of the operation implemented by this* visitor; use Void if no return type is needed.* @param <S> the type of the second argument (the first being the* type itself) of the operation implemented by this visitor; use* Void if a second argument is not needed.*/public static abstract class SimpleTypeVisitor<R,S> extends DefaultTypeVisitor<R,S> {@Overridepublic R visitCapturedType(CapturedType t, S s) {return visitTypeVar(t, s);}@Overridepublic R visitForAll(ForAll t, S s) {return visit(t.qtype, s);}@Overridepublic R visitUndeterminedVar(UndeterminedVar t, S s) {return visit(t.qtype, s);}}

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轉載于:https://www.cnblogs.com/extjs4/p/6897234.html

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