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package com.sun.tools.javac.code;

import java.util.HashMap;
import java.util.Map;

import com.sun.tools.javac.code.Kinds.Kind;
import com.sun.tools.javac.code.Scope.WriteableScope;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.code.Symbol.Completer;
import com.sun.tools.javac.code.Symbol.CompletionFailure;
import com.sun.tools.javac.util.Context;

When a CompletionFailure is thrown when user code is running, it shouldn't be thrown out to the client code, but rather skipped, and then rethrown later if javac itself will complete the Symbol. On all places where javac invokes client code (e.g. TaskListeners, annotation Processors), the userCodeHandler should be set using setHandler, and the original handler should be restored when the control returns back to javac. Implementations of API methods should use Symbol.apiComplete() instead of Symbol.complete, as the apiComplete method will invoke handleAPICompletionFailure, which will catch the CompletionFailure and will either rethrow it or skip it, depending on the context.
/** When a CompletionFailure is thrown when user code is running, it shouldn't be * thrown out to the client code, but rather skipped, and then rethrown later if javac * itself will complete the Symbol. * * On all places where javac invokes client code (e.g. TaskListeners, annotation * Processors), the {@code userCodeHandler} should be set using * {@link DeferredCompletionFailureHandler#setHandler}, and the original handler * should be restored when the control returns back to javac. * * Implementations of API methods should use {@link Symbol#apiComplete()} instead of * {@link Symbol#complete}, as the {@code apiComplete} method will invoke * {@link DeferredCompletionFailureHandler#handleAPICompletionFailure }, which will * catch the CompletionFailure and will either rethrow it or skip it, depending on * the context. */
public class DeferredCompletionFailureHandler { protected static final Context.Key<DeferredCompletionFailureHandler> deferredCompletionFailureHandlerKey = new Context.Key<>(); public static DeferredCompletionFailureHandler instance(Context context) { DeferredCompletionFailureHandler instance = context.get(deferredCompletionFailureHandlerKey); if (instance == null) instance = new DeferredCompletionFailureHandler(context); return instance; } public final Handler userCodeHandler = new Handler() { private final Map<ClassSymbol, FlipSymbolDescription> class2Flip = new HashMap<>(); public void install() { class2Flip.values().forEach(f -> f.flip()); } public void handleAPICompletionFailure(CompletionFailure cf) { //ignore } public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter) { class2Flip.put(sym, new FlipSymbolDescription(sym, new DeferredCompleter(origCompleter) { @Override public void complete(Symbol sym) throws CompletionFailure { class2Flip.remove(sym); super.complete(sym); } })); } public void classSymbolRemoved(ClassSymbol sym) { class2Flip.remove(sym); } public void uninstall() { class2Flip.values().forEach(f -> f.flip()); } }; public final Handler speculativeCodeHandler = new Handler() { private final Map<ClassSymbol, FlipSymbolDescription> class2Flip = new HashMap<>(); public void install() { } public void handleAPICompletionFailure(CompletionFailure cf) { throw cf; } public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter) { class2Flip.put(sym, new FlipSymbolDescription(sym, new DeferredCompleter(origCompleter))); } public void classSymbolRemoved(ClassSymbol sym) { class2Flip.remove(sym); } public void uninstall() { class2Flip.values().forEach(f -> f.flip()); class2Flip.clear(); } }; public final Handler javacCodeHandler = new Handler() { public void install() { } public void handleAPICompletionFailure(CompletionFailure cf) { throw cf; } public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter) {} public void classSymbolRemoved(ClassSymbol sym) {} public void uninstall() { } }; private Handler handler = javacCodeHandler; protected DeferredCompletionFailureHandler(Context context) { context.put(deferredCompletionFailureHandlerKey, this); } public Handler setHandler(Handler h) { if (h == handler) return handler; handler.uninstall(); Handler prev = handler; handler = h; handler.install(); return prev; } public void handleAPICompletionFailure(CompletionFailure cf) { handler.handleAPICompletionFailure(cf); } public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter) { handler.classSymbolCompleteFailed(sym, origCompleter); } public void classSymbolRemoved(ClassSymbol sym) { handler.classSymbolRemoved(sym); } public boolean isDeferredCompleter(Completer c) { return c instanceof DeferredCompleter; } public interface Handler { public void install(); public void handleAPICompletionFailure(CompletionFailure cf); public void classSymbolCompleteFailed(ClassSymbol sym, Completer origCompleter); public void classSymbolRemoved(ClassSymbol sym); public void uninstall(); } private class DeferredCompleter implements Completer { private final Completer origCompleter; public DeferredCompleter(Completer origCompleter) { this.origCompleter = origCompleter; } @Override public void complete(Symbol sym) throws CompletionFailure { origCompleter.complete(sym); } } private static class FlipSymbolDescription { public final ClassSymbol sym; public Type type; public Kind kind; public WriteableScope members; public Completer completer; public FlipSymbolDescription(ClassSymbol sym, Completer completer) { this.sym = sym; this.type = sym.type; this.kind = sym.kind; this.members = null; this.completer = completer; } public void flip() { Type prevType = sym.type; sym.type = type; this.type = prevType; Kind prevKind = sym.kind; sym.kind = kind; this.kind = prevKind; Completer prevCompleter = sym.completer; sym.completer = completer; this.completer = prevCompleter; WriteableScope prevMembers = sym.members_field; sym.members_field = members; this.members = prevMembers; } } }