import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * When we eliminate dead code, we must preserve var declarations as they are scoped to the whole
 * function. This method gathers var nodes from code passed to it, removing their initializers.
 *
 * @param deadCodeRoot the root node of eliminated dead code
 * @param statements a list that will be receiving the var nodes from the dead code, with their
 * initializers removed.
 */
static void extractVarNodesFromDeadCode(final Node deadCodeRoot, final List<Statement> statements) {
    deadCodeRoot.accept(new SimpleNodeVisitor() {
        @Override
        public boolean enterVarNode(final VarNode varNode) {
            statements.add(varNode.setInit(null));
            return false;
        }

        @Override
        public boolean enterFunctionNode(final FunctionNode functionNode) {
            // Don't descend into nested functions
            return false;
        }
    });
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
private static List<FunctionNode> directChildren(final FunctionNode functionNode) {
    final List<FunctionNode> dc = new ArrayList<>();
    functionNode.accept(new SimpleNodeVisitor() {
        @Override
        public boolean enterFunctionNode(final FunctionNode child) {
            if (child == functionNode) {
                return true;
            }
            if (lc.getParentFunction(child) == functionNode) {
                dc.add(child);
            }
            return false;
        }
    });
    return dc;
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
private boolean hasApplies(final FunctionNode functionNode) {
    try {
        functionNode.accept(new SimpleNodeVisitor() {
            @Override
            public boolean enterFunctionNode(final FunctionNode fn) {
                return fn == functionNode;
            }

            @Override
            public boolean enterCallNode(final CallNode callNode) {
                if (isApply(callNode)) {
                    throw HAS_APPLIES;
                }
                return true;
            }
        });
    } catch (final AppliesFoundException e) {
        return true;
    }

    log.fine("There are no applies in ", DebugLogger.quote(functionNode.getName()), " - nothing to do.");
    return false; // no applies
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * Define symbols for all variable declarations at the top of the function scope. This way we can get around
 * problems like
 *
 * while (true) {
 *   break;
 *   if (true) {
 *     var s;
 *   }
 * }
 *
 * to an arbitrary nesting depth.
 *
 * see NASHORN-73
 *
 * @param functionNode the FunctionNode we are entering
 * @param body the body of the FunctionNode we are entering
 */
private void acceptDeclarations(final FunctionNode functionNode, final Block body) {
    // This visitor will assign symbol to all declared variables.
    body.accept(new SimpleNodeVisitor() {
        @Override
        protected boolean enterDefault(final Node node) {
            // Don't bother visiting expressions; var is a statement, it can't be inside an expression.
            // This will also prevent visiting nested functions (as FunctionNode is an expression).
            return !(node instanceof Expression);
        }

        @Override
        public Node leaveVarNode(final VarNode varNode) {
            final IdentNode ident  = varNode.getName();
            final boolean blockScoped = varNode.isBlockScoped();
            if (blockScoped && lc.inUnprotectedSwitchContext()) {
                throwUnprotectedSwitchError(varNode);
            }
            final Block block = blockScoped ? lc.getCurrentBlock() : body;
            final Symbol symbol = defineSymbol(block, ident.getName(), ident, varNode.getSymbolFlags());
            if (varNode.isFunctionDeclaration()) {
                symbol.setIsFunctionDeclaration();
            }
            return varNode.setName(ident.setSymbol(symbol));
        }
    });
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
@SuppressWarnings("unchecked")
private static <T extends Node> T ensureUniqueNamesIn(final T node) {
    return (T)node.accept(new SimpleNodeVisitor() {
        @Override
        public Node leaveFunctionNode(final FunctionNode functionNode) {
            final String name = functionNode.getName();
            return functionNode.setName(lc, lc.getCurrentFunction().uniqueName(name));
        }

        @Override
        public Node leaveDefault(final Node labelledNode) {
            return labelledNode.ensureUniqueLabels(lc);
        }
    });
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
@Override
FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
    // It's not necessary to guard the marking of symbols as locals with this "if" condition for
    // correctness, it's just an optimization -- runtime type calculation is not used when the compilation
    // is not an on-demand optimistic compilation, so we can skip locals marking then.
    if (compiler.useOptimisticTypes() && compiler.isOnDemandCompilation()) {
        fn.getBody().accept(new SimpleNodeVisitor() {
            @Override
            public boolean enterFunctionNode(final FunctionNode functionNode) {
                // OTOH, we must not declare symbols from nested functions to be locals. As we're doing on-demand
                // compilation, and we're skipping parsing the function bodies for nested functions, this
                // basically only means their parameters. It'd be enough to mistakenly declare to be a local a
                // symbol in the outer function named the same as one of the parameters, though.
                return false;
            };
            @Override
            public boolean enterBlock(final Block block) {
                for (final Symbol symbol: block.getSymbols()) {
                    if (!symbol.isScope()) {
                        compiler.declareLocalSymbol(symbol.getName());
                    }
                }
                return true;
            };
        });
    }
    return fn;
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * Check if a property value contains a particular program point
 * @param value value
 * @param pp    program point
 * @return true if it's there.
 */
private static boolean propertyValueContains(final Expression value, final int pp) {
    return new Supplier<Boolean>() {
        boolean contains;

        @Override
        public Boolean get() {
            value.accept(new SimpleNodeVisitor() {
                @Override
                public boolean enterFunctionNode(final FunctionNode functionNode) {
                    return false;
                }

                @Override
                public boolean enterDefault(final Node node) {
                    if (contains) {
                        return false;
                    }
                    if (node instanceof Optimistic && ((Optimistic)node).getProgramPoint() == pp) {
                        contains = true;
                        return false;
                    }
                    return true;
                }
            });

            return contains;
        }
    }.get();
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * Was this expression or any of its subexpressions deoptimized in the current recompilation chain of rest-of methods?
 * @param rootExpr the expression being tested
 * @return true if the expression or any of its subexpressions was deoptimized in the current recompilation chain.
 */
private boolean isDeoptimizedExpression(final Expression rootExpr) {
    if(!isRestOf()) {
        return false;
    }
    return new Supplier<Boolean>() {
        boolean contains;
        @Override
        public Boolean get() {
            rootExpr.accept(new SimpleNodeVisitor() {
                @Override
                public boolean enterFunctionNode(final FunctionNode functionNode) {
                    return false;
                }
                @Override
                public boolean enterDefault(final Node node) {
                    if(!contains && node instanceof Optimistic) {
                        final int pp = ((Optimistic)node).getProgramPoint();
                        contains = isValid(pp) && isContinuationEntryPoint(pp);
                    }
                    return !contains;
                }
            });
            return contains;
        }
    }.get();
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * Check if a property value contains a particular program point
 * @param value value
 * @param pp    program point
 * @return true if it's there.
 */
private static boolean propertyValueContains(final Expression value, final int pp) {
    return new Supplier<Boolean>() {
        boolean contains;

        @Override
        public Boolean get() {
            value.accept(new SimpleNodeVisitor() {
                @Override
                public boolean enterFunctionNode(final FunctionNode functionNode) {
                    return false;
                }

                @Override
                public boolean enterObjectNode(final ObjectNode objectNode) {
                    return false;
                }

                @Override
                public boolean enterDefault(final Node node) {
                    if (contains) {
                        return false;
                    }
                    if (node instanceof Optimistic && ((Optimistic)node).getProgramPoint() == pp) {
                        contains = true;
                        return false;
                    }
                    return true;
                }
            });

            return contains;
        }
    }.get();
}
 

import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; //导入依赖的package包/类
/**
 * Define symbols for all variable declarations at the top of the function
 * scope. This way we can get around problems like
 *
 * while (true) { break; if (true) { var s; } }
 *
 * to an arbitrary nesting depth.
 *
 * see NASHORN-73
 *
 * @param functionNode the FunctionNode we are entering
 * @param body the body of the FunctionNode we are entering
 */
private void acceptDeclarations(final FunctionNode functionNode, final Block body) {
    // This visitor will assign symbol to all declared variables.
    body.accept(new SimpleNodeVisitor() {
        @Override
        protected boolean enterDefault(final Node node) {
            // Don't bother visiting expressions; var is a statement, it can't be inside an expression.
            // This will also prevent visiting nested functions (as FunctionNode is an expression).
            return !(node instanceof Expression);
        }

        @Override
        public Node leaveVarNode(final VarNode varNode) {
            final IdentNode ident = varNode.getName();
            final boolean blockScoped = varNode.isBlockScoped();
            if (blockScoped && lc.inUnprotectedSwitchContext()) {
                throw new ParserException("UnprotectedSwitchError");
            }
            final Block block = blockScoped ? lc.getCurrentBlock() : body;
            final Symbol symbol = defineSymbol(block, ident.getName(), ident, varNode.getSymbolFlags());
            if (varNode.isFunctionDeclaration()) {
                symbol.setIsFunctionDeclaration();
            }
            return varNode.setName(ident.setSymbol(symbol));
        }
    });
}