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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2004 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import com.google.common.base.Preconditions;
import com.google.debugging.sourcemap.Util;
import com.google.javascript.rhino.JSDocInfo.Visibility;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import com.google.javascript.rhino.TokenStream;
import java.util.HashMap;
import java.util.Map;
/**
* CodeGenerator generates codes from a parse tree, sending it to the specified
* CodeConsumer.
*
*/
class CodeGenerator {
private static final String LT_ESCAPED = "\\x3c";
private static final String GT_ESCAPED = "\\x3e";
// A memoizer for formatting strings as JS strings.
private final Map escapedJsStrings = new HashMap<>();
private final CodeConsumer cc;
private final OutputCharsetEncoder outputCharsetEncoder;
private final boolean preferSingleQuotes;
private final boolean preserveTypeAnnotations;
private final boolean trustedStrings;
private final boolean quoteKeywordProperties;
private CodeGenerator(CodeConsumer consumer) {
cc = consumer;
outputCharsetEncoder = null;
preferSingleQuotes = false;
trustedStrings = true;
preserveTypeAnnotations = false;
quoteKeywordProperties = false;
}
static CodeGenerator forCostEstimation(CodeConsumer consumer) {
return new CodeGenerator(consumer);
}
CodeGenerator(
CodeConsumer consumer,
CompilerOptions options) {
cc = consumer;
this.outputCharsetEncoder = new OutputCharsetEncoder(options.getOutputCharset());
this.preferSingleQuotes = options.preferSingleQuotes;
this.trustedStrings = options.trustedStrings;
this.preserveTypeAnnotations = options.preserveTypeAnnotations;
this.quoteKeywordProperties = options.quoteKeywordProperties;
}
/**
* Insert a ECMASCRIPT 5 strict annotation.
*/
public void tagAsStrict() {
add("'use strict';");
}
void add(String str) {
cc.add(str);
}
private void addIdentifier(String identifier) {
cc.addIdentifier(identifierEscape(identifier));
}
void add(Node n) {
add(n, Context.OTHER);
}
void add(Node n, Context context) {
if (!cc.continueProcessing()) {
return;
}
if (preserveTypeAnnotations && n.getJSDocInfo() != null) {
String jsdocAsString = JSDocInfoPrinter.print(n.getJSDocInfo());
// Don't print an empty jsdoc
if (!jsdocAsString.equals("/** */ ")) {
add(jsdocAsString);
}
}
int type = n.getType();
String opstr = NodeUtil.opToStr(type);
int childCount = n.getChildCount();
Node first = n.getFirstChild();
Node last = n.getLastChild();
// Handle all binary operators
if (opstr != null && first != last) {
Preconditions.checkState(
childCount == 2,
"Bad binary operator \"%s\": expected 2 arguments but got %s",
opstr, childCount);
int p = NodeUtil.precedence(type);
// For right-hand-side of operations, only pass context if it's
// the IN_FOR_INIT_CLAUSE one.
Context rhsContext = getContextForNoInOperator(context);
boolean needsParens = (context == Context.START_OF_EXPR) && first.isObjectPattern();
if (n.isAssign() && needsParens) {
add("(");
}
if (NodeUtil.isAssignmentOp(n) && NodeUtil.isAssignmentOp(last)) {
// Assignments are the only right-associative binary operators
addExpr(first, p, context);
cc.addOp(opstr, true);
addExpr(last, p, rhsContext);
} else {
unrollBinaryOperator(n, type, opstr, context, rhsContext, p, p + 1);
}
if (n.isAssign() && needsParens) {
add(")");
}
return;
}
cc.startSourceMapping(n);
switch (type) {
case Token.TRY:
{
Preconditions.checkState(
first.getNext().isBlock() && !first.getNext().hasMoreThanOneChild());
Preconditions.checkState(childCount >= 2 && childCount <= 3);
add("try");
add(first, Context.PRESERVE_BLOCK);
// second child contains the catch block, or nothing if there
// isn't a catch block
Node catchblock = first.getNext().getFirstChild();
if (catchblock != null) {
add(catchblock);
}
if (childCount == 3) {
cc.maybeInsertSpace();
add("finally");
add(last, Context.PRESERVE_BLOCK);
}
break;
}
case Token.CATCH:
Preconditions.checkState(childCount == 2);
cc.maybeInsertSpace();
add("catch");
cc.maybeInsertSpace();
add("(");
add(first);
add(")");
add(last, Context.PRESERVE_BLOCK);
break;
case Token.THROW:
Preconditions.checkState(childCount == 1);
add("throw");
cc.maybeInsertSpace();
add(first);
// Must have a ';' after a throw statement, otherwise safari can't
// parse this.
cc.endStatement(true);
break;
case Token.RETURN:
add("return");
if (childCount == 1) {
cc.maybeInsertSpace();
add(first);
} else {
Preconditions.checkState(childCount == 0);
}
cc.endStatement();
break;
case Token.VAR:
if (first != null) {
add("var ");
addList(first, false, getContextForNoInOperator(context), ",");
}
break;
case Token.CONST:
add("const ");
addList(first, false, getContextForNoInOperator(context), ",");
break;
case Token.LET:
add("let ");
addList(first, false, getContextForNoInOperator(context), ",");
break;
case Token.LABEL_NAME:
Preconditions.checkState(!n.getString().isEmpty());
addIdentifier(n.getString());
break;
case Token.DESTRUCTURING_LHS:
add(first);
if (first != last) {
Preconditions.checkState(childCount == 2);
cc.addOp("=", true);
add(last);
}
break;
case Token.NAME:
addIdentifier(n.getString());
maybeAddOptional(n);
maybeAddTypeDecl(n);
if (first != null && !first.isEmpty()) {
Preconditions.checkState(childCount == 1);
cc.addOp("=", true);
if (first.isComma()) {
addExpr(first, NodeUtil.precedence(Token.ASSIGN), Context.OTHER);
} else {
// Add expression, consider nearby code at lowest level of
// precedence.
addExpr(first, 0, getContextForNoInOperator(context));
}
}
break;
case Token.ARRAYLIT:
add("[");
addArrayList(first);
add("]");
break;
case Token.ARRAY_PATTERN:
add("[");
addArrayList(first);
add("]");
maybeAddTypeDecl(n);
break;
case Token.PARAM_LIST:
add("(");
addList(first);
add(")");
break;
case Token.DEFAULT_VALUE:
add(first);
maybeAddTypeDecl(n);
cc.addOp("=", true);
add(first.getNext());
break;
case Token.COMMA:
Preconditions.checkState(childCount == 2);
unrollBinaryOperator(
n, Token.COMMA, ",", context, getContextForNoInOperator(context), 0, 0);
break;
case Token.NUMBER:
Preconditions.checkState(childCount == 0);
cc.addNumber(n.getDouble());
break;
case Token.TYPEOF:
case Token.VOID:
case Token.NOT:
case Token.BITNOT:
case Token.POS:
{
// All of these unary operators are right-associative
Preconditions.checkState(childCount == 1);
cc.addOp(NodeUtil.opToStrNoFail(type), false);
addExpr(first, NodeUtil.precedence(type), Context.OTHER);
break;
}
case Token.NEG:
{
Preconditions.checkState(childCount == 1);
// It's important to our sanity checker that the code
// we print produces the same AST as the code we parse back.
// NEG is a weird case because Rhino parses "- -2" as "2".
if (n.getFirstChild().isNumber()) {
cc.addNumber(-n.getFirstChild().getDouble());
} else {
cc.addOp(NodeUtil.opToStrNoFail(type), false);
addExpr(first, NodeUtil.precedence(type), Context.OTHER);
}
break;
}
case Token.HOOK:
{
Preconditions.checkState(childCount == 3);
int p = NodeUtil.precedence(type);
Context rhsContext = getContextForNoInOperator(context);
addExpr(first, p + 1, context);
cc.addOp("?", true);
addExpr(first.getNext(), 1, rhsContext);
cc.addOp(":", true);
addExpr(last, 1, rhsContext);
break;
}
case Token.REGEXP:
if (!first.isString() || !last.isString()) {
throw new Error("Expected children to be strings");
}
String regexp = regexpEscape(first.getString(), outputCharsetEncoder);
// I only use one .add because whitespace matters
if (childCount == 2) {
add(regexp + last.getString());
} else {
Preconditions.checkState(childCount == 1);
add(regexp);
}
break;
case Token.FUNCTION: {
if (n.getClass() != Node.class) {
throw new Error("Unexpected Node subclass.");
}
Preconditions.checkState(childCount == 3);
if (n.isArrowFunction()) {
addArrowFunction(n, first, last, context);
} else {
addFunction(n, first, last, context);
}
break;
}
case Token.REST:
add("...");
add(first);
maybeAddTypeDecl(n);
break;
case Token.SPREAD:
add("...");
add(n.getFirstChild());
break;
case Token.EXPORT:
add("export");
if (n.getBooleanProp(Node.EXPORT_DEFAULT)) {
add("default");
}
if (n.getBooleanProp(Node.EXPORT_ALL_FROM)) {
add("*");
Preconditions.checkState(first != null && first.isEmpty());
} else {
add(first);
}
if (childCount == 2) {
add("from");
add(last);
}
processEnd(first, context);
break;
case Token.IMPORT:
add("import");
Node second = first.getNext();
if (!first.isEmpty()) {
add(first);
if (!second.isEmpty()) {
cc.listSeparator();
}
}
if (!second.isEmpty()) {
add(second);
}
if (!first.isEmpty() || !second.isEmpty()) {
add("from");
}
add(last);
cc.endStatement();
break;
case Token.EXPORT_SPECS:
case Token.IMPORT_SPECS:
add("{");
for (Node c = first; c != null; c = c.getNext()) {
if (c != first) {
cc.listSeparator();
}
add(c);
}
add("}");
break;
case Token.EXPORT_SPEC:
case Token.IMPORT_SPEC:
add(first);
if (first != last) {
add("as");
add(last);
}
break;
case Token.IMPORT_STAR:
add("*");
add("as");
add(n.getString());
break;
// CLASS -> NAME,EXPR|EMPTY,BLOCK
case Token.CLASS:
{
Preconditions.checkState(childCount == 3);
boolean classNeedsParens = (context == Context.START_OF_EXPR);
if (classNeedsParens) {
add("(");
}
Node name = first;
Node superClass = first.getNext();
Node members = last;
add("class");
if (!name.isEmpty()) {
add(name);
}
maybeAddGenericTypes(first);
if (!superClass.isEmpty()) {
add("extends");
add(superClass);
}
Node interfaces = (Node) n.getProp(Node.IMPLEMENTS);
if (interfaces != null) {
add("implements");
Node child = interfaces.getFirstChild();
add(child);
while ((child = child.getNext()) != null) {
add(",");
cc.maybeInsertSpace();
add(child);
}
}
add(members);
cc.endClass(context == Context.STATEMENT);
if (classNeedsParens) {
add(")");
}
}
break;
case Token.CLASS_MEMBERS:
case Token.INTERFACE_MEMBERS:
case Token.NAMESPACE_ELEMENTS:
cc.beginBlock();
for (Node c = first; c != null; c = c.getNext()) {
add(c);
processEnd(c, context);
cc.endLine();
}
cc.endBlock(false);
break;
case Token.ENUM_MEMBERS:
cc.beginBlock();
for (Node c = first; c != null; c = c.getNext()) {
add(c);
if (c.getNext() != null) {
add(",");
}
cc.endLine();
}
cc.endBlock(false);
break;
case Token.GETTER_DEF:
case Token.SETTER_DEF:
case Token.MEMBER_FUNCTION_DEF:
case Token.MEMBER_VARIABLE_DEF:
{
n.getParent().toStringTree();
Preconditions.checkState(
n.getParent().isObjectLit()
|| n.getParent().isClassMembers()
|| n.getParent().isInterfaceMembers()
|| n.getParent().isRecordType()
|| n.getParent().isIndexSignature());
maybeAddAccessibilityModifier(n);
if (n.isStaticMember()) {
add("static ");
}
if (!n.isMemberVariableDef() && n.getFirstChild().isGeneratorFunction()) {
Preconditions.checkState(type == Token.MEMBER_FUNCTION_DEF);
add("*");
}
switch (type) {
case Token.GETTER_DEF:
// Get methods have no parameters.
Preconditions.checkState(!first.getSecondChild().hasChildren());
add("get ");
break;
case Token.SETTER_DEF:
// Set methods have one parameter.
Preconditions.checkState(first.getSecondChild().hasOneChild());
add("set ");
break;
case Token.MEMBER_FUNCTION_DEF:
case Token.MEMBER_VARIABLE_DEF:
// nothing to do.
break;
}
// The name is on the GET or SET node.
String name = n.getString();
if (n.isMemberVariableDef()) {
add(n.getString());
maybeAddOptional(n);
maybeAddTypeDecl(n);
} else {
Preconditions.checkState(childCount == 1);
Preconditions.checkState(first.isFunction());
// The function referenced by the definition should always be unnamed.
Preconditions.checkState(first.getFirstChild().getString().isEmpty());
Node fn = first;
Node parameters = fn.getSecondChild();
Node body = fn.getLastChild();
// Add the property name.
if (!n.isQuotedString()
&& TokenStream.isJSIdentifier(name)
&&
// do not encode literally any non-literal characters that were
// Unicode escaped.
NodeUtil.isLatin(name)) {
add(name);
maybeAddGenericTypes(fn.getFirstChild());
} else {
// Determine if the string is a simple number.
double d = getSimpleNumber(name);
if (!Double.isNaN(d)) {
cc.addNumber(d);
} else {
addJsString(n);
}
}
maybeAddOptional(fn);
add(parameters);
maybeAddTypeDecl(fn);
add(body, Context.PRESERVE_BLOCK);
}
break;
}
case Token.SCRIPT:
case Token.BLOCK:
{
if (n.getClass() != Node.class) {
throw new Error("Unexpected Node subclass.");
}
boolean preserveBlock = context == Context.PRESERVE_BLOCK;
if (preserveBlock) {
cc.beginBlock();
}
boolean preferLineBreaks =
type == Token.SCRIPT
|| (type == Token.BLOCK
&& !preserveBlock
&& n.getParent() != null
&& n.getParent().isScript());
for (Node c = first; c != null; c = c.getNext()) {
add(c, Context.STATEMENT);
// VAR doesn't include ';' since it gets used in expressions
if (NodeUtil.isNameDeclaration(c)) {
cc.endStatement();
}
if (c.isFunction() || c.isClass()) {
cc.maybeLineBreak();
}
// Prefer to break lines in between top-level statements
// because top-level statements are more homogeneous.
if (preferLineBreaks) {
cc.notePreferredLineBreak();
}
}
if (preserveBlock) {
cc.endBlock(cc.breakAfterBlockFor(n, context == Context.STATEMENT));
}
break;
}
case Token.FOR:
if (childCount == 4) {
add("for");
cc.maybeInsertSpace();
add("(");
if (NodeUtil.isNameDeclaration(first)) {
add(first, Context.IN_FOR_INIT_CLAUSE);
} else {
addExpr(first, 0, Context.IN_FOR_INIT_CLAUSE);
}
add(";");
add(first.getNext());
add(";");
add(first.getNext().getNext());
add(")");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
} else {
Preconditions.checkState(childCount == 3);
add("for");
cc.maybeInsertSpace();
add("(");
add(first);
add("in");
add(first.getNext());
add(")");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
}
break;
case Token.FOR_OF:
// A "for-of" inside an array comprehension only has two children.
Preconditions.checkState(childCount == 3);
add("for");
cc.maybeInsertSpace();
add("(");
add(first);
add("of");
add(first.getNext());
add(")");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
break;
case Token.DO:
Preconditions.checkState(childCount == 2);
add("do");
addNonEmptyStatement(first, Context.OTHER, false);
cc.maybeInsertSpace();
add("while");
cc.maybeInsertSpace();
add("(");
add(last);
add(")");
cc.endStatement();
break;
case Token.WHILE:
Preconditions.checkState(childCount == 2);
add("while");
cc.maybeInsertSpace();
add("(");
add(first);
add(")");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
break;
case Token.EMPTY:
Preconditions.checkState(childCount == 0);
break;
case Token.GETPROP:
{
Preconditions.checkState(
childCount == 2, "Bad GETPROP: expected 2 children, but got %s", childCount);
Preconditions.checkState(last.isString(), "Bad GETPROP: RHS should be STRING");
boolean needsParens = (first.isNumber());
if (needsParens) {
add("(");
}
addExpr(first, NodeUtil.precedence(type), context);
if (needsParens) {
add(")");
}
if (quoteKeywordProperties && TokenStream.isKeyword(last.getString())) {
add("[");
add(last);
add("]");
} else {
add(".");
addIdentifier(last.getString());
}
break;
}
case Token.GETELEM:
Preconditions.checkState(
childCount == 2,
"Bad GETELEM node: Expected 2 children but got %s. For node: %s", childCount, n);
addExpr(first, NodeUtil.precedence(type), context);
add("[");
add(first.getNext());
add("]");
break;
case Token.WITH:
Preconditions.checkState(childCount == 2);
add("with(");
add(first);
add(")");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
break;
case Token.INC:
case Token.DEC:
{
Preconditions.checkState(childCount == 1);
String o = type == Token.INC ? "++" : "--";
boolean postProp = n.getBooleanProp(Node.INCRDECR_PROP);
if (postProp) {
addExpr(first, NodeUtil.precedence(type), context);
cc.addOp(o, false);
} else {
cc.addOp(o, false);
add(first);
}
break;
}
case Token.CALL:
// We have two special cases here:
// 1) If the left hand side of the call is a direct reference to eval,
// then it must have a DIRECT_EVAL annotation. If it does not, then
// that means it was originally an indirect call to eval, and that
// indirectness must be preserved.
// 2) If the left hand side of the call is a property reference,
// then the call must not a FREE_CALL annotation. If it does, then
// that means it was originally an call without an explicit this and
// that must be preserved.
if (isIndirectEval(first) || n.getBooleanProp(Node.FREE_CALL) && NodeUtil.isGet(first)) {
add("(0,");
addExpr(first, NodeUtil.precedence(Token.COMMA), Context.OTHER);
add(")");
} else {
addExpr(first, NodeUtil.precedence(type), context);
}
Node args = first.getNext();
add("(");
addList(args);
add(")");
break;
case Token.IF:
boolean hasElse = childCount == 3;
boolean ambiguousElseClause = context == Context.BEFORE_DANGLING_ELSE && !hasElse;
if (ambiguousElseClause) {
cc.beginBlock();
}
add("if");
cc.maybeInsertSpace();
add("(");
add(first);
add(")");
// An "if" node inside an array comprehension only has one child.
if (childCount == 1) {
break;
}
if (hasElse) {
addNonEmptyStatement(first.getNext(), Context.BEFORE_DANGLING_ELSE, false);
cc.maybeInsertSpace();
add("else");
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), false);
} else {
addNonEmptyStatement(first.getNext(), Context.OTHER, false);
Preconditions.checkState(childCount == 2);
}
if (ambiguousElseClause) {
cc.endBlock();
}
break;
case Token.NULL:
Preconditions.checkState(childCount == 0);
cc.addConstant("null");
break;
case Token.THIS:
Preconditions.checkState(childCount == 0);
add("this");
break;
case Token.SUPER:
Preconditions.checkState(childCount == 0);
add("super");
break;
case Token.NEW_TARGET:
Preconditions.checkState(childCount == 0);
add("new.target");
break;
case Token.YIELD:
add("yield");
if (n.isYieldFor()) {
Preconditions.checkNotNull(first);
add("*");
}
if (first != null) {
cc.maybeInsertSpace();
addExpr(first, NodeUtil.precedence(type), Context.OTHER);
}
break;
case Token.FALSE:
Preconditions.checkState(childCount == 0);
cc.addConstant("false");
break;
case Token.TRUE:
Preconditions.checkState(childCount == 0);
cc.addConstant("true");
break;
case Token.CONTINUE:
Preconditions.checkState(childCount <= 1);
add("continue");
if (childCount == 1) {
if (!first.isLabelName()) {
throw new Error("Unexpected token type. Should be LABEL_NAME.");
}
add(" ");
add(first);
}
cc.endStatement();
break;
case Token.DEBUGGER:
Preconditions.checkState(childCount == 0);
add("debugger");
cc.endStatement();
break;
case Token.BREAK:
Preconditions.checkState(childCount <= 1);
add("break");
if (childCount == 1) {
if (!first.isLabelName()) {
throw new Error("Unexpected token type. Should be LABEL_NAME.");
}
add(" ");
add(first);
}
cc.endStatement();
break;
case Token.EXPR_RESULT:
Preconditions.checkState(childCount == 1);
add(first, Context.START_OF_EXPR);
cc.endStatement();
break;
case Token.NEW:
add("new ");
int precedence = NodeUtil.precedence(type);
// If the first child contains a CALL, then claim higher precedence
// to force parentheses. Otherwise, when parsed, NEW will bind to the
// first viable parentheses (don't traverse into functions).
if (NodeUtil.containsType(first, Token.CALL, NodeUtil.MATCH_NOT_FUNCTION)) {
precedence = NodeUtil.precedence(first.getType()) + 1;
}
addExpr(first, precedence, Context.OTHER);
// '()' is optional when no arguments are present
Node next = first.getNext();
if (next != null) {
add("(");
addList(next);
add(")");
}
break;
case Token.STRING_KEY:
addStringKey(n);
break;
case Token.STRING:
Preconditions.checkState(childCount == 0, "A string may not have children");
addJsString(n);
break;
case Token.DELPROP:
Preconditions.checkState(childCount == 1);
add("delete ");
add(first);
break;
case Token.OBJECTLIT:
{
boolean needsParens = (context == Context.START_OF_EXPR);
if (needsParens) {
add("(");
}
add("{");
for (Node c = first; c != null; c = c.getNext()) {
if (c != first) {
cc.listSeparator();
}
Preconditions.checkState(
c.isComputedProp()
|| c.isGetterDef()
|| c.isSetterDef()
|| c.isStringKey()
|| c.isMemberFunctionDef());
add(c);
}
add("}");
if (needsParens) {
add(")");
}
break;
}
case Token.COMPUTED_PROP:
maybeAddAccessibilityModifier(n);
if (n.getBooleanProp(Node.STATIC_MEMBER)) {
add("static ");
}
if (n.getBooleanProp(Node.COMPUTED_PROP_GETTER)) {
add("get ");
} else if (n.getBooleanProp(Node.COMPUTED_PROP_SETTER)) {
add("set ");
} else if (last.getBooleanProp(Node.GENERATOR_FN)) {
add("*");
}
add("[");
add(first);
add("]");
// TODO(martinprobst): There's currently no syntax for properties in object literals that
// have type declarations on them (a la `{foo: number: 12}`). This comes up for, e.g.,
// function parameters with default values. Support when figured out.
maybeAddTypeDecl(n);
if (n.getBooleanProp(Node.COMPUTED_PROP_METHOD)
|| n.getBooleanProp(Node.COMPUTED_PROP_GETTER)
|| n.getBooleanProp(Node.COMPUTED_PROP_SETTER)) {
Node function = first.getNext();
Node params = function.getSecondChild();
Node body = function.getLastChild();
add(params);
add(body, Context.PRESERVE_BLOCK);
} else {
// This is a field or object literal property.
boolean isInClass = n.getParent().getType() == Token.CLASS_MEMBERS;
Node initializer = first.getNext();
if (initializer != null) {
// Object literal value.
Preconditions.checkState(
!isInClass, "initializers should only exist in object literals, not classes");
cc.addOp(":", false);
add(initializer);
} else {
// Computed properties must either have an initializer or be computed member-variable
// properties that exist for their type declaration.
Preconditions.checkState(n.getBooleanProp(Node.COMPUTED_PROP_VARIABLE), n);
}
}
break;
case Token.OBJECT_PATTERN:
addObjectPattern(n);
maybeAddTypeDecl(n);
break;
case Token.SWITCH:
add("switch(");
add(first);
add(")");
cc.beginBlock();
addAllSiblings(first.getNext());
cc.endBlock(context == Context.STATEMENT);
break;
case Token.CASE:
Preconditions.checkState(childCount == 2);
add("case ");
add(first);
addCaseBody(last);
break;
case Token.DEFAULT_CASE:
Preconditions.checkState(childCount == 1);
add("default");
addCaseBody(first);
break;
case Token.LABEL:
Preconditions.checkState(childCount == 2);
if (!first.isLabelName()) {
throw new Error("Unexpected token type. Should be LABEL_NAME.");
}
add(first);
add(":");
if (!last.isBlock()) {
cc.maybeInsertSpace();
}
addNonEmptyStatement(last, getContextForNonEmptyExpression(context), true);
break;
case Token.CAST:
add("(");
add(first);
add(")");
break;
case Token.TAGGED_TEMPLATELIT:
add(first, Context.START_OF_EXPR);
add(first.getNext());
break;
case Token.TEMPLATELIT:
add("`");
for (Node c = first; c != null; c = c.getNext()) {
if (c.isString()) {
add(c.getString());
} else {
// Can't use add() since isWordChar('$') == true and cc would add
// an extra space.
cc.append("${");
add(c.getFirstChild(), Context.START_OF_EXPR);
add("}");
}
}
add("`");
break;
// Type Declaration ASTs.
case Token.STRING_TYPE:
add("string");
break;
case Token.BOOLEAN_TYPE:
add("boolean");
break;
case Token.NUMBER_TYPE:
add("number");
break;
case Token.ANY_TYPE:
add("any");
break;
case Token.VOID_TYPE:
add("void");
break;
case Token.NAMED_TYPE:
// Children are a chain of getprop nodes.
add(first);
break;
case Token.ARRAY_TYPE:
addExpr(first, NodeUtil.precedence(Token.ARRAY_TYPE), context);
add("[]");
break;
case Token.FUNCTION_TYPE:
Node returnType = first;
add("(");
addList(first.getNext());
add(")");
cc.addOp("=>", true);
add(returnType);
break;
case Token.UNION_TYPE:
addList(first, "|");
break;
case Token.RECORD_TYPE:
add("{");
addList(first, false, Context.OTHER, ",");
add("}");
break;
case Token.PARAMETERIZED_TYPE:
// First child is the type that's parameterized, later children are the arguments.
add(first);
add("<");
addList(first.getNext());
add(">");
break;
// CLASS -> NAME,EXPR|EMPTY,BLOCK
case Token.GENERIC_TYPE_LIST:
add("<");
addList(first, false, Context.STATEMENT, ",");
add(">");
break;
case Token.GENERIC_TYPE:
addIdentifier(n.getString());
if (n.hasChildren()) {
add("extends");
cc.maybeInsertSpace();
add(n.getFirstChild());
}
break;
case Token.INTERFACE:
{
Preconditions.checkState(childCount == 3);
Node name = first;
Node superTypes = first.getNext();
Node members = last;
add("interface");
add(name);
maybeAddGenericTypes(name);
if (!superTypes.isEmpty()) {
add("extends");
Node superType = superTypes.getFirstChild();
add(superType);
while ((superType = superType.getNext()) != null) {
add(",");
cc.maybeInsertSpace();
add(superType);
}
}
add(members);
}
break;
case Token.ENUM:
{
Preconditions.checkState(childCount == 2);
Node name = first;
Node members = last;
add("enum");
add(name);
add(members);
break;
}
case Token.NAMESPACE: {
Preconditions.checkState(childCount == 2);
Node name = first;
Node elements = last;
add("namespace");
add(name);
add(elements);
break;
}
case Token.TYPE_ALIAS:
add("type");
add(n.getString());
cc.addOp("=", true);
add(last);
cc.endStatement(true);
break;
case Token.DECLARE:
add("declare");
add(first);
processEnd(n, context);
break;
case Token.INDEX_SIGNATURE:
add("[");
add(first);
add("]");
maybeAddTypeDecl(n);
cc.endStatement(true);
break;
case Token.CALL_SIGNATURE:
if (n.getBooleanProp(Node.CONSTRUCT_SIGNATURE)) {
add("new ");
}
maybeAddGenericTypes(n);
add(first);
maybeAddTypeDecl(n);
cc.endStatement(true);
break;
default:
throw new RuntimeException("Unknown type " + Token.name(type) + "\n" + n.toStringTree());
}
cc.endSourceMapping(n);
}
private boolean arrowFunctionNeedsParens(Node parent, Context context) {
if (parent == null) {
return false;
}
switch (parent.getType()) {
case Token.EXPR_RESULT:
case Token.COMMA:
// Arrow function bodies bind more tightly than commas, and need no parens in that case.
return false;
default:
return (context == Context.START_OF_EXPR);
}
}
private void addArrowFunction(Node n, Node first, Node last, Context context) {
Preconditions.checkState(first.getString().isEmpty());
boolean funcNeedsParens = arrowFunctionNeedsParens(n.getParent(), context);
if (funcNeedsParens) {
add("(");
}
maybeAddGenericTypes(first);
add(first.getNext()); // param list
maybeAddTypeDecl(n);
cc.addOp("=>", true);
if (last.isBlock()) {
add(last, Context.PRESERVE_BLOCK);
} else {
// This is a hack. Arrow functions have no token type, but
// blockless arrow function bodies have lower precedence than anything other than commas.
addExpr(last, NodeUtil.precedence(Token.COMMA) + 1, Context.PRESERVE_BLOCK);
}
cc.endFunction(context == Context.STATEMENT);
if (funcNeedsParens) {
add(")");
}
}
private void addFunction(Node n, Node first, Node last, Context context) {
boolean funcNeedsParens = (context == Context.START_OF_EXPR);
if (funcNeedsParens) {
add("(");
}
add("function");
if (n.isGeneratorFunction()) {
add("*");
if (!first.getString().isEmpty()) {
cc.maybeInsertSpace();
}
}
add(first);
maybeAddGenericTypes(first);
add(first.getNext()); // param list
maybeAddTypeDecl(n);
add(last, Context.PRESERVE_BLOCK);
cc.endFunction(context == Context.STATEMENT);
if (funcNeedsParens) {
add(")");
}
}
private void maybeAddAccessibilityModifier(Node n) {
Visibility access = (Visibility) n.getProp(Node.ACCESS_MODIFIER);
if (access != null) {
add(access.toString().toLowerCase() + " ");
}
}
private void maybeAddTypeDecl(Node n) {
if (n.getDeclaredTypeExpression() != null) {
add(":");
cc.maybeInsertSpace();
add(n.getDeclaredTypeExpression());
}
}
private void maybeAddGenericTypes(Node n) {
Node generics = (Node) n.getProp(Node.GENERIC_TYPE_LIST);
if (generics != null) {
add(generics);
}
}
private void maybeAddOptional(Node n) {
if (n.getBooleanProp(Node.OPT_ES6_TYPED)) {
add("?");
}
}
/**
* We could use addList recursively here, but sometimes we produce
* very deeply nested operators and run out of stack space, so we
* just unroll the recursion when possible.
*
* We assume nodes are left-recursive.
*/
private void unrollBinaryOperator(
Node n, int op, String opStr, Context context,
Context rhsContext, int leftPrecedence, int rightPrecedence) {
Node firstNonOperator = n.getFirstChild();
while (firstNonOperator.getType() == op) {
firstNonOperator = firstNonOperator.getFirstChild();
}
addExpr(firstNonOperator, leftPrecedence, context);
Node current = firstNonOperator;
do {
current = current.getParent();
cc.addOp(opStr, true);
addExpr(current.getSecondChild(), rightPrecedence, rhsContext);
} while (current != n);
}
static boolean isSimpleNumber(String s) {
int len = s.length();
if (len == 0) {
return false;
}
for (int index = 0; index < len; index++) {
char c = s.charAt(index);
if (c < '0' || c > '9') {
return false;
}
}
return len == 1 || s.charAt(0) != '0';
}
static double getSimpleNumber(String s) {
if (isSimpleNumber(s)) {
try {
long l = Long.parseLong(s);
if (l < NodeUtil.MAX_POSITIVE_INTEGER_NUMBER) {
return l;
}
} catch (NumberFormatException e) {
// The number was too long to parse. Fall through to NaN.
}
}
return Double.NaN;
}
/**
* @return Whether the name is an indirect eval.
*/
private static boolean isIndirectEval(Node n) {
return n.isName() && "eval".equals(n.getString()) &&
!n.getBooleanProp(Node.DIRECT_EVAL);
}
/**
* Adds a block or expression, substituting a VOID with an empty statement.
* This is used for "for (...);" and "if (...);" type statements.
*
* @param n The node to print.
* @param context The context to determine how the node should be printed.
*/
private void addNonEmptyStatement(
Node n, Context context, boolean allowNonBlockChild) {
Node nodeToProcess = n;
if (!allowNonBlockChild && !n.isBlock()) {
throw new Error("Missing BLOCK child.");
}
// Strip unneeded blocks, that is blocks with <2 children unless
// the CodePrinter specifically wants to keep them.
if (n.isBlock()) {
int count = getNonEmptyChildCount(n, 2);
if (count == 0) {
if (cc.shouldPreserveExtraBlocks()) {
cc.beginBlock();
cc.endBlock(cc.breakAfterBlockFor(n, context == Context.STATEMENT));
} else {
cc.endStatement(true);
}
return;
}
if (count == 1) {
// Hack around a couple of browser bugs:
// Safari needs a block around function declarations.
// IE6/7 needs a block around DOs.
Node firstAndOnlyChild = getFirstNonEmptyChild(n);
boolean alwaysWrapInBlock = cc.shouldPreserveExtraBlocks();
if (alwaysWrapInBlock || isBlockDeclOrDo(firstAndOnlyChild)) {
cc.beginBlock();
add(firstAndOnlyChild, Context.STATEMENT);
cc.maybeLineBreak();
cc.endBlock(cc.breakAfterBlockFor(n, context == Context.STATEMENT));
return;
} else {
// Continue with the only child.
nodeToProcess = firstAndOnlyChild;
}
}
if (count > 1) {
context = Context.PRESERVE_BLOCK;
}
}
if (nodeToProcess.isEmpty()) {
cc.endStatement(true);
} else {
add(nodeToProcess, context);
// VAR doesn't include ';' since it gets used in expressions - so any
// VAR in a statement context needs a call to endStatement() here.
if (nodeToProcess.isVar()) {
cc.endStatement();
}
}
}
/**
* @return Whether the Node is a DO or a declaration that is only allowed
* in restricted contexts.
*/
private static boolean isBlockDeclOrDo(Node n) {
if (n.isLabel()) {
Node labeledStatement = n.getLastChild();
if (!labeledStatement.isBlock()) {
return isBlockDeclOrDo(labeledStatement);
} else {
// For labels with block children, we need to ensure that a
// labeled FUNCTION or DO isn't generated when extraneous BLOCKs
// are skipped.
if (getNonEmptyChildCount(n, 2) == 1) {
return isBlockDeclOrDo(getFirstNonEmptyChild(n));
} else {
// Either a empty statement or an block with more than one child,
// way it isn't a FUNCTION or DO.
return false;
}
}
} else {
switch (n.getType()){
case Token.LET:
case Token.CONST:
case Token.FUNCTION:
case Token.CLASS:
case Token.DO:
return true;
default:
return false;
}
}
}
private void addExpr(Node n, int minPrecedence, Context context) {
if ((NodeUtil.precedence(n.getType()) < minPrecedence) ||
((context == Context.IN_FOR_INIT_CLAUSE) && n.isIn())){
add("(");
add(n, Context.OTHER);
add(")");
} else {
add(n, context);
}
}
void addList(Node firstInList) {
addList(firstInList, true, Context.OTHER, ",");
}
void addList(Node firstInList, String separator) {
addList(firstInList, true, Context.OTHER, separator);
}
void addList(Node firstInList, boolean isArrayOrFunctionArgument,
Context lhsContext, String separator) {
for (Node n = firstInList; n != null; n = n.getNext()) {
boolean isFirst = n == firstInList;
if (isFirst) {
addExpr(n, isArrayOrFunctionArgument ? 1 : 0, lhsContext);
} else {
cc.addOp(separator, true);
addExpr(n, isArrayOrFunctionArgument ? 1 : 0,
getContextForNoInOperator(lhsContext));
}
}
}
void addStringKey(Node n) {
String key = n.getString();
// Object literal property names don't have to be quoted if they
// are not JavaScript keywords
if (!n.isQuotedString()
&& !(quoteKeywordProperties && TokenStream.isKeyword(key))
&& TokenStream.isJSIdentifier(key)
// do not encode literally any non-literal characters that
// were Unicode escaped.
&& NodeUtil.isLatin(key)) {
add(key);
} else {
// Determine if the string is a simple number.
double d = getSimpleNumber(key);
if (!Double.isNaN(d)) {
cc.addNumber(d);
} else {
addJsString(n);
}
}
if (n.hasChildren()) {
add(":");
addExpr(n.getFirstChild(), 1, Context.OTHER);
}
}
void addObjectPattern(Node n) {
add("{");
for (Node child = n.getFirstChild(); child != null; child = child.getNext()) {
if (child != n.getFirstChild()) {
add(",");
}
add(child);
}
add("}");
}
/**
* This function adds a comma-separated list as is specified by an ARRAYLIT
* node with the associated skipIndexes array. This is a space optimization
* since we avoid creating a whole Node object for each empty array literal
* slot.
* @param firstInList The first in the node list (chained through the next
* property).
*/
void addArrayList(Node firstInList) {
boolean lastWasEmpty = false;
for (Node n = firstInList; n != null; n = n.getNext()) {
if (n != firstInList) {
cc.listSeparator();
}
addExpr(n, 1, Context.OTHER);
lastWasEmpty = n.isEmpty();
}
if (lastWasEmpty) {
cc.listSeparator();
}
}
void addCaseBody(Node caseBody) {
cc.beginCaseBody();
add(caseBody);
cc.endCaseBody();
}
void addAllSiblings(Node n) {
for (Node c = n; c != null; c = c.getNext()) {
add(c);
}
}
/** Outputs a JS string, using the optimal (single/double) quote character */
private void addJsString(Node n) {
String s = n.getString();
boolean useSlashV = n.getBooleanProp(Node.SLASH_V);
if (useSlashV) {
add(jsString(n.getString(), useSlashV));
} else {
String cached = escapedJsStrings.get(s);
if (cached == null) {
cached = jsString(n.getString(), useSlashV);
escapedJsStrings.put(s, cached);
}
add(cached);
}
}
private String jsString(String s, boolean useSlashV) {
int singleq = 0, doubleq = 0;
// could count the quotes and pick the optimal quote character
for (int i = 0; i < s.length(); i++) {
switch (s.charAt(i)) {
case '"': doubleq++; break;
case '\'': singleq++; break;
}
}
String doublequote, singlequote;
char quote;
if (preferSingleQuotes ?
(singleq <= doubleq) : (singleq < doubleq)) {
// more double quotes so enclose in single quotes.
quote = '\'';
doublequote = "\"";
singlequote = "\\\'";
} else {
// more single quotes so escape the doubles
quote = '\"';
doublequote = "\\\"";
singlequote = "\'";
}
return strEscape(s, quote, doublequote, singlequote, "\\\\",
outputCharsetEncoder, useSlashV, false);
}
/** Escapes regular expression */
String regexpEscape(String s, OutputCharsetEncoder outputCharsetEncoder) {
return strEscape(s, '/', "\"", "'", "\\", outputCharsetEncoder, false, true);
}
/* If the user doesn't want to specify an output charset encoder, assume
they want Latin/ASCII characters only.
*/
String regexpEscape(String s) {
return regexpEscape(s, null);
}
/** Helper to escape JavaScript string as well as regular expression */
private String strEscape(
String s,
char quote,
String doublequoteEscape,
String singlequoteEscape,
String backslashEscape,
OutputCharsetEncoder outputCharsetEncoder,
boolean useSlashV,
boolean isRegexp) {
StringBuilder sb = new StringBuilder(s.length() + 2);
sb.append(quote);
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
switch (c) {
case '\0': sb.append("\\x00"); break;
case '\u000B':
if (useSlashV) {
sb.append("\\v");
} else {
sb.append("\\x0B");
}
break;
// From the SingleEscapeCharacter grammar production.
case '\b': sb.append("\\b"); break;
case '\f': sb.append("\\f"); break;
case '\n': sb.append("\\n"); break;
case '\r': sb.append("\\r"); break;
case '\t': sb.append("\\t"); break;
case '\\': sb.append(backslashEscape); break;
case '\"': sb.append(doublequoteEscape); break;
case '\'': sb.append(singlequoteEscape); break;
// From LineTerminators (ES5 Section 7.3, Table 3)
case '\u2028': sb.append("\\u2028"); break;
case '\u2029': sb.append("\\u2029"); break;
case '=':
// '=' is a syntactically signficant regexp character.
if (trustedStrings || isRegexp) {
sb.append(c);
} else {
sb.append("\\x3d");
}
break;
case '&':
if (trustedStrings || isRegexp) {
sb.append(c);
} else {
sb.append("\\x26");
}
break;
case '>':
if (!trustedStrings && !isRegexp) {
sb.append(GT_ESCAPED);
break;
}
// Break --> into --\> or ]]> into ]]\>
//
// This is just to prevent developers from shooting themselves in the
// foot, and does not provide the level of security that you get
// with trustedString == false.
if (i >= 2 &&
((s.charAt(i - 1) == '-' && s.charAt(i - 2) == '-') ||
(s.charAt(i - 1) == ']' && s.charAt(i - 2) == ']'))) {
sb.append(GT_ESCAPED);
} else {
sb.append(c);
}
break;
case '<':
if (!trustedStrings && !isRegexp) {
sb.append(LT_ESCAPED);
break;
}
// Break 0x1f && c < 0x7f) {
// If we're given an outputCharsetEncoder, then check if the character can be
// represented in this character set. If no charsetEncoder provided - pass straight
// Latin characters through, and escape the rest. Doing the explicit character check is
// measurably faster than using the CharsetEncoder.
sb.append(c);
} else {
// Other characters can be misinterpreted by some JS parsers,
// or perhaps mangled by proxies along the way,
// so we play it safe and Unicode escape them.
Util.appendHexJavaScriptRepresentation(sb, c);
}
}
}
sb.append(quote);
return sb.toString();
}
static String identifierEscape(String s) {
// First check if escaping is needed at all -- in most cases it isn't.
if (NodeUtil.isLatin(s)) {
return s;
}
// Now going through the string to escape non-Latin characters if needed.
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
// Identifiers should always go to Latin1/ ASCII characters because
// different browser's rules for valid identifier characters are
// crazy.
if (c > 0x1F && c < 0x7F) {
sb.append(c);
} else {
Util.appendHexJavaScriptRepresentation(sb, c);
}
}
return sb.toString();
}
/**
* @param maxCount The maximum number of children to look for.
* @return The number of children of this node that are non empty up to
* maxCount.
*/
private static int getNonEmptyChildCount(Node n, int maxCount) {
int i = 0;
Node c = n.getFirstChild();
for (; c != null && i < maxCount; c = c.getNext()) {
if (c.isBlock()) {
i += getNonEmptyChildCount(c, maxCount - i);
} else if (!c.isEmpty()) {
i++;
}
}
return i;
}
/** Gets the first non-empty child of the given node. */
private static Node getFirstNonEmptyChild(Node n) {
for (Node c = n.getFirstChild(); c != null; c = c.getNext()) {
if (c.isBlock()) {
Node result = getFirstNonEmptyChild(c);
if (result != null) {
return result;
}
} else if (!c.isEmpty()) {
return c;
}
}
return null;
}
// Information on the current context. Used for disambiguating special cases.
// For example, a "{" could indicate the start of an object literal or a
// block, depending on the current context.
enum Context {
STATEMENT,
BEFORE_DANGLING_ELSE, // a hack to resolve the else-clause ambiguity
START_OF_EXPR,
PRESERVE_BLOCK,
// Are we inside the init clause of a for loop? If so, the containing
// expression can't contain an in operator. Pass this context flag down
// until we reach expressions which no longer have the limitation.
IN_FOR_INIT_CLAUSE,
OTHER
}
private static Context getContextForNonEmptyExpression(Context currentContext) {
return currentContext == Context.BEFORE_DANGLING_ELSE ?
Context.BEFORE_DANGLING_ELSE : Context.OTHER;
}
/**
* If we're in a IN_FOR_INIT_CLAUSE, we can't permit in operators in the
* expression. Pass on the IN_FOR_INIT_CLAUSE flag through subexpressions.
*/
private static Context getContextForNoInOperator(Context context) {
return (context == Context.IN_FOR_INIT_CLAUSE
? Context.IN_FOR_INIT_CLAUSE : Context.OTHER);
}
private void processEnd(Node n, Context context) {
switch (n.getType()) {
case Token.CLASS:
case Token.INTERFACE:
case Token.ENUM:
case Token.NAMESPACE:
cc.endClass(context == Context.STATEMENT);
break;
case Token.FUNCTION:
if (n.getLastChild().isEmpty()) {
cc.endStatement(true);
} else {
cc.endFunction(context == Context.STATEMENT);
}
break;
case Token.DECLARE:
if (n.getParent().getType() != Token.NAMESPACE_ELEMENTS) {
processEnd(n.getFirstChild(), context);
}
break;
case Token.EXPORT:
if (n.getParent().getType() != Token.NAMESPACE_ELEMENTS
&& n.getFirstChild().getType() != Token.DECLARE) {
processEnd(n.getFirstChild(), context);
}
break;
case Token.COMPUTED_PROP:
if (n.hasOneChild()) {
cc.endStatement(true);
}
break;
case Token.MEMBER_FUNCTION_DEF:
case Token.GETTER_DEF:
case Token.SETTER_DEF:
if (n.getFirstChild().getLastChild().isEmpty()) {
cc.endStatement(true);
}
break;
case Token.MEMBER_VARIABLE_DEF:
cc.endStatement(true);
break;
default:
if (context == Context.STATEMENT) {
cc.endStatement();
}
}
}
}
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