import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
/**
 * IfStatement :
 *      if ( Expression ) Statement else Statement
 *      if ( Expression ) Statement
 *
 * See 12.5
 *
 * Parse an IF statement.
 */
private void ifStatement() {
    // Capture IF token.
    final int  ifLine  = line;
    final long ifToken = token;
     // IF tested in caller.
    next();

    expect(LPAREN);
    final Expression test = expression();
    expect(RPAREN);
    final Block pass = getStatement();

    Block fail = null;
    if (type == ELSE) {
        next();
        fail = getStatement();
    }

    appendStatement(new IfNode(ifLine, ifToken, fail != null ? fail.getFinish() : pass.getFinish(), test, pass, fail));
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
@Override
public boolean enterIfNode(final IfNode ifNode) {
    enterDefault(ifNode);

    type("IfStatement");
    comma();

    property("test");
    ifNode.getTest().accept(this);
    comma();

    property("consequent");
    ifNode.getPass().accept(this);
    final Node elsePart = ifNode.getFail();
    comma();

    property("alternate");
    if (elsePart != null) {
        elsePart.accept(this);
    } else {
        nullValue();
    }

    return leave();
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
@Override
public boolean enterIfNode(final IfNode ifNode) {
    ifNode.toString(sb, printTypes);
    ifNode.getPass().accept(this);

    final Block fail = ifNode.getFail();

    if (fail != null) {
        sb.append(" else ");
        fail.accept(this);
    }
    if(ifNode.getLocalVariableConversion() != null) {
        assert fail == null;
        sb.append(" else ");
        printLocalVariableConversion(ifNode);
        sb.append(";");
    }
    return false;
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
@Override
public Node leaveIfNode(final IfNode ifNode) {
    final Node test = ifNode.getTest();
    if (test instanceof LiteralNode.PrimitiveLiteralNode) {
        final boolean isTrue = ((LiteralNode.PrimitiveLiteralNode<?>)test).isTrue();
        final Block executed = isTrue ? ifNode.getPass() : ifNode.getFail();
        final Block dropped  = isTrue ? ifNode.getFail() : ifNode.getPass();
        final List<Statement> statements = new ArrayList<>();

        if (executed != null) {
            statements.addAll(executed.getStatements()); // Get statements form executed branch
        }
        if (dropped != null) {
            extractVarNodes(dropped, statements); // Get var-nodes from non-executed branch
        }
        if (statements.isEmpty()) {
            return new EmptyNode(ifNode);
        }
        return BlockStatement.createReplacement(ifNode, ifNode.getFinish(), statements);
    }
    return ifNode;
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
@Override
public Node leaveIfNode(final IfNode ifNode) {
    final Node test = ifNode.getTest();
    if (test instanceof LiteralNode.PrimitiveLiteralNode) {
        final boolean isTrue = ((LiteralNode.PrimitiveLiteralNode<?>)test).isTrue();
        final Block executed = isTrue ? ifNode.getPass() : ifNode.getFail();
        final Block dropped  = isTrue ? ifNode.getFail() : ifNode.getPass();
        final List<Statement> statements = new ArrayList<>();

        if (executed != null) {
            statements.addAll(executed.getStatements()); // Get statements form executed branch
        }
        if (dropped != null) {
            extractVarNodesFromDeadCode(dropped, statements); // Get var-nodes from non-executed branch
        }
        if (statements.isEmpty()) {
            return new EmptyNode(ifNode);
        }
        return BlockStatement.createReplacement(ifNode, ifNode.getFinish(), statements);
    }
    return ifNode;
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
private static IfNode makeIfStateEquals(final int lineNumber, final long token, final int finish,
        final int value, final Block pass, final Statement fail) {
    return new IfNode(lineNumber, token, finish,
            new BinaryNode(Token.recast(token, TokenType.EQ_STRICT),
                    GetSplitState.INSTANCE, intLiteral(value)),
            pass,
            fail == null ? null : new Block(NO_TOKEN, NO_FINISH, fail));
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
@Override
public boolean enterIfNode(final IfNode ifNode) {
    curStat = new IfTreeImpl(ifNode,
            translateExpr(ifNode.getTest()),
            translateBlock(ifNode.getPass()),
            translateBlock(ifNode.getFail()));
    return false;
}
 

import jdk.nashorn.internal.ir.IfNode; //导入依赖的package包/类
IfTreeImpl(final IfNode node, final ExpressionTree cond,
        final StatementTree thenStat, final StatementTree elseStat) {
    super(node);
    this.cond = cond;
    this.thenStat = thenStat;
    this.elseStat = elseStat;
}