/*
* Copyright 2011 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 static com.google.common.base.Strings.isNullOrEmpty;
import com.google.common.base.Preconditions;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
/**
* Just to fold known methods when they are called with constants.
*
*/
class PeepholeReplaceKnownMethods extends AbstractPeepholeOptimization {
private final boolean late;
private final boolean useTypes;
/**
* @param late When late is true, this mean we are currently running after
* most of the other optimizations. In this case we avoid changes that make
* the code larger (but otherwise easier to analyze - such as using string
* splitting).
*/
PeepholeReplaceKnownMethods(boolean late, boolean useTypes) {
this.late = late;
this.useTypes = useTypes;
}
@Override
Node optimizeSubtree(Node subtree) {
if (subtree.isCall()){
return tryFoldKnownMethods(subtree);
}
return subtree;
}
private Node tryFoldKnownMethods(Node subtree) {
// For now we only support string methods .join(),
// .indexOf(), .substring() and .substr()
// and numeric methods parseInt() and parseFloat().
subtree = tryFoldArrayJoin(subtree);
if (subtree.isCall()) {
Node callTarget = subtree.getFirstChild();
if (callTarget == null) {
return subtree;
}
if (NodeUtil.isGet(callTarget)) {
subtree = tryFoldKnownStringMethods(subtree, callTarget);
} else if (callTarget.isName()) {
subtree = tryFoldKnownNumericMethods(subtree, callTarget);
}
}
return subtree;
}
/**
* Try to evaluate known String methods
* .indexOf(), .substr(), .substring()
*/
private Node tryFoldKnownStringMethods(Node subtree, Node callTarget) {
Preconditions.checkArgument(subtree.isCall());
// check if this is a call on a string method
// then dispatch to specific folding method.
Node stringNode = callTarget.getFirstChild();
Node functionName = callTarget.getLastChild();
if (!functionName.isString()) {
return subtree;
}
boolean isStringLiteral = stringNode.isString();
String functionNameString = functionName.getString();
Node firstArg = callTarget.getNext();
if (isStringLiteral) {
if (functionNameString.equals("split")) {
return tryFoldStringSplit(subtree, stringNode, firstArg);
} else if (firstArg == null) {
switch (functionNameString) {
case "toLowerCase":
return tryFoldStringToLowerCase(subtree, stringNode);
case "toUpperCase":
return tryFoldStringToUpperCase(subtree, stringNode);
}
} else {
if (NodeUtil.isImmutableValue(firstArg)) {
switch (functionNameString) {
case "indexOf":
case "lastIndexOf":
return tryFoldStringIndexOf(subtree, functionNameString, stringNode, firstArg);
case "substr":
return tryFoldStringSubstr(subtree, stringNode, firstArg);
case "substring":
case "slice":
return tryFoldStringSubstringOrSlice(subtree, stringNode, firstArg);
case "charAt":
return tryFoldStringCharAt(subtree, stringNode, firstArg);
case "charCodeAt":
return tryFoldStringCharCodeAt(subtree, stringNode, firstArg);
}
}
}
}
if (useTypes
&& firstArg != null
&& (isStringLiteral
|| (stringNode.getTypeI() != null
&& stringNode.getTypeI().isStringValueType()))) {
if (subtree.hasXChildren(3)) {
Double maybeStart = NodeUtil.getNumberValue(firstArg, useTypes);
if (maybeStart != null) {
int start = maybeStart.intValue();
Double maybeLengthOrEnd = NodeUtil.getNumberValue(firstArg.getNext(), useTypes);
if (maybeLengthOrEnd != null) {
switch (functionNameString) {
case "substr":
int length = maybeLengthOrEnd.intValue();
if (start >= 0 && length == 1) {
return replaceWithCharAt(subtree, callTarget, firstArg);
}
break;
case "substring":
case "slice":
int end = maybeLengthOrEnd.intValue();
if (end - start == 1) {
return replaceWithCharAt(subtree, callTarget, firstArg);
}
}
}
}
}
}
return subtree;
}
/**
* Try to evaluate known Numeric methods
* parseInt(), parseFloat()
*/
private Node tryFoldKnownNumericMethods(Node subtree, Node callTarget) {
Preconditions.checkArgument(subtree.isCall());
if (isASTNormalized()) {
// check if this is a call on a string method
// then dispatch to specific folding method.
String functionNameString = callTarget.getString();
Node firstArgument = callTarget.getNext();
if ((firstArgument != null) && (firstArgument.isString() || firstArgument.isNumber())
&& (functionNameString.equals("parseInt") || functionNameString.equals("parseFloat"))) {
subtree = tryFoldParseNumber(subtree, functionNameString, firstArgument);
}
}
return subtree;
}
/**
* @return The lowered string Node.
*/
private Node tryFoldStringToLowerCase(Node subtree, Node stringNode) {
// From Rhino, NativeString.java. See ECMA 15.5.4.11
String lowered = stringNode.getString().toLowerCase(Locale.ROOT);
Node replacement = IR.string(lowered);
subtree.replaceWith(replacement);
reportCodeChange();
return replacement;
}
/**
* @return The upped string Node.
*/
private Node tryFoldStringToUpperCase(Node subtree, Node stringNode) {
// From Rhino, NativeString.java. See ECMA 15.5.4.12
String upped = stringNode.getString().toUpperCase(Locale.ROOT);
Node replacement = IR.string(upped);
subtree.replaceWith(replacement);
reportCodeChange();
return replacement;
}
/**
* @param input string representation of a number
* @return string with leading and trailing zeros removed
*/
private static String normalizeNumericString(String input) {
if (isNullOrEmpty(input)) {
return input;
}
int startIndex = 0;
int endIndex = input.length() - 1;
// Remove leading zeros
while (startIndex < input.length() && input.charAt(startIndex) == '0' &&
input.charAt(startIndex) != '.') {
startIndex++;
}
// Remove trailing zeros only after the decimal
if (input.indexOf('.') >= 0) {
while (endIndex >= 0 && input.charAt(endIndex) == '0') {
endIndex--;
}
if (input.charAt(endIndex) == '.') {
endIndex--;
}
}
if (startIndex >= endIndex) {
return input;
}
return input.substring(startIndex, endIndex + 1);
}
/**
* Try to evaluate parseInt, parseFloat:
* parseInt("1") -> 1
* parseInt("1", 10) -> 1
* parseFloat("1.11") -> 1.11
*/
private Node tryFoldParseNumber(
Node n, String functionName, Node firstArg) {
Preconditions.checkArgument(n.isCall());
boolean isParseInt = functionName.equals("parseInt");
Node secondArg = firstArg.getNext();
// Second argument is only used as the radix for parseInt
int radix = 0;
if (secondArg != null) {
if (!isParseInt) {
return n;
}
// Third-argument and non-numeric second arg are problematic. Discard.
if (secondArg.getNext() != null || !secondArg.isNumber()) {
return n;
} else {
double tmpRadix = secondArg.getDouble();
if (tmpRadix != (int) tmpRadix) {
return n;
}
radix = (int) tmpRadix;
if (radix < 0 || radix == 1 || radix > 36) {
return n;
}
}
}
// stringVal must be a valid string.
String stringVal = null;
Double checkVal;
if (firstArg.isNumber()) {
checkVal = NodeUtil.getNumberValue(firstArg);
if (!(radix == 0 || radix == 10) && isParseInt) {
//Convert a numeric first argument to a different base
stringVal = String.valueOf(checkVal.intValue());
} else {
// If parseFloat is called with a numeric argument,
// replace it with just the number.
// If parseInt is called with a numeric first argument and the radix
// is 10 or omitted, just replace it with the number
Node numericNode;
if (isParseInt) {
numericNode = IR.number(checkVal.intValue());
} else {
numericNode = IR.number(checkVal);
}
n.replaceWith(numericNode);
reportCodeChange();
return numericNode;
}
} else {
stringVal = NodeUtil.getStringValue(firstArg);
if (stringVal == null) {
return n;
}
//Check that the string is in a format we can recognize
checkVal = NodeUtil.getStringNumberValue(stringVal);
if (checkVal == null) {
return n;
}
stringVal = NodeUtil.trimJsWhiteSpace(stringVal);
if (stringVal.isEmpty()) {
return n;
}
}
Node newNode;
if (stringVal.equals("0")) {
// Special case for parseInt("0") or parseFloat("0")
newNode = IR.number(0);
} else if (isParseInt) {
if (radix == 0 || radix == 16) {
if (stringVal.length() > 1 &&
stringVal.substring(0, 2).equalsIgnoreCase("0x")) {
radix = 16;
stringVal = stringVal.substring(2);
} else if (radix == 0) {
// if a radix is not specified or is 0 and the most
// significant digit is "0", the string will parse
// with a radix of 8 on some browsers, so leave
// this case alone. This check does not apply in
// script mode ECMA5 or greater
if (!isEcmaScript5OrGreater() &&
stringVal.substring(0, 1).equals("0")) {
return n;
}
radix = 10;
}
}
int newVal = 0;
try {
newVal = Integer.parseInt(stringVal, radix);
} catch (NumberFormatException e) {
return n;
}
newNode = IR.number(newVal);
} else {
String normalizedNewVal = "0";
try {
double newVal = Double.parseDouble(stringVal);
newNode = IR.number(newVal);
normalizedNewVal = normalizeNumericString(String.valueOf(newVal));
} catch (NumberFormatException e) {
return n;
}
// Make sure that the parsed number matches the original string
// This prevents rounding differences between the Java implementation
// and native script.
if (!normalizeNumericString(stringVal).equals(normalizedNewVal)) {
return n;
}
}
n.replaceWith(newNode);
reportCodeChange();
return newNode;
}
/**
* Try to evaluate String.indexOf/lastIndexOf:
* "abcdef".indexOf("bc") -> 1
* "abcdefbc".indexOf("bc", 3) -> 6
*/
private Node tryFoldStringIndexOf(
Node n, String functionName, Node lstringNode, Node firstArg) {
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(lstringNode.isString());
String lstring = NodeUtil.getStringValue(lstringNode);
boolean isIndexOf = functionName.equals("indexOf");
Node secondArg = firstArg.getNext();
String searchValue = NodeUtil.getStringValue(firstArg);
// searchValue must be a valid string.
if (searchValue == null) {
return n;
}
int fromIndex = isIndexOf ? 0 : lstring.length();
if (secondArg != null) {
// Third-argument and non-numeric second arg are problematic. Discard.
if (secondArg.getNext() != null || !secondArg.isNumber()) {
return n;
} else {
fromIndex = (int) secondArg.getDouble();
}
}
int indexVal = isIndexOf ? lstring.indexOf(searchValue, fromIndex)
: lstring.lastIndexOf(searchValue, fromIndex);
Node newNode = IR.number(indexVal);
n.replaceWith(newNode);
reportCodeChange();
return newNode;
}
/**
* Try to fold an array join: ['a', 'b', 'c'].join('') -> 'abc';
*/
private Node tryFoldArrayJoin(Node n) {
Node callTarget = n.getFirstChild();
if (callTarget == null || !callTarget.isGetProp()) {
return n;
}
Node right = callTarget.getNext();
if (right != null) {
if (right.getNext() != null || !NodeUtil.isImmutableValue(right)) {
return n;
}
}
Node arrayNode = callTarget.getFirstChild();
Node functionName = arrayNode.getNext();
if (!arrayNode.isArrayLit() ||
!functionName.getString().equals("join")) {
return n;
}
if (right != null && right.isString()
&& ",".equals(right.getString())) {
// "," is the default, it doesn't need to be explicit
n.removeChild(right);
reportCodeChange();
}
String joinString = (right == null) ? "," : NodeUtil.getStringValue(right);
List<Node> arrayFoldedChildren = new LinkedList<>();
StringBuilder sb = null;
int foldedSize = 0;
Node prev = null;
Node elem = arrayNode.getFirstChild();
// Merges adjacent String nodes.
while (elem != null) {
if (NodeUtil.isImmutableValue(elem) || elem.isEmpty()) {
if (sb == null) {
sb = new StringBuilder();
} else {
sb.append(joinString);
}
sb.append(NodeUtil.getArrayElementStringValue(elem));
} else {
if (sb != null) {
Preconditions.checkNotNull(prev);
// + 2 for the quotes.
foldedSize += sb.length() + 2;
arrayFoldedChildren.add(
IR.string(sb.toString()).useSourceInfoIfMissingFrom(prev));
sb = null;
}
foldedSize += InlineCostEstimator.getCost(elem);
arrayFoldedChildren.add(elem);
}
prev = elem;
elem = elem.getNext();
}
if (sb != null) {
Preconditions.checkNotNull(prev);
// + 2 for the quotes.
foldedSize += sb.length() + 2;
arrayFoldedChildren.add(
IR.string(sb.toString()).useSourceInfoIfMissingFrom(prev));
}
// one for each comma.
foldedSize += arrayFoldedChildren.size() - 1;
int originalSize = InlineCostEstimator.getCost(n);
switch (arrayFoldedChildren.size()) {
case 0:
Node emptyStringNode = IR.string("");
n.getParent().replaceChild(n, emptyStringNode);
reportCodeChange();
return emptyStringNode;
case 1:
Node foldedStringNode = arrayFoldedChildren.remove(0);
if (foldedSize > originalSize) {
return n;
}
arrayNode.detachChildren();
if (!foldedStringNode.isString()) {
// If the Node is not a string literal, ensure that
// it is coerced to a string.
Node replacement = IR.add(
IR.string("").srcref(n),
foldedStringNode);
foldedStringNode = replacement;
}
n.getParent().replaceChild(n, foldedStringNode);
reportCodeChange();
return foldedStringNode;
default:
// No folding could actually be performed.
if (arrayNode.hasXChildren(arrayFoldedChildren.size())) {
return n;
}
int kJoinOverhead = "[].join()".length();
foldedSize += kJoinOverhead;
foldedSize += (right != null) ? InlineCostEstimator.getCost(right) : 0;
if (foldedSize > originalSize) {
return n;
}
arrayNode.detachChildren();
for (Node node : arrayFoldedChildren) {
arrayNode.addChildToBack(node);
}
reportCodeChange();
break;
}
return n;
}
/**
* Try to fold .substr() calls on strings
*/
private Node tryFoldStringSubstr(Node n, Node stringNode, Node arg1) {
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(stringNode.isString());
Preconditions.checkArgument(arg1 != null);
int start;
int length;
String stringAsString = stringNode.getString();
Double maybeStart = NodeUtil.getNumberValue(arg1, useTypes);
if (maybeStart != null) {
start = maybeStart.intValue();
} else {
return n;
}
Node arg2 = arg1.getNext();
if (arg2 != null) {
Double maybeLength = NodeUtil.getNumberValue(arg2, useTypes);
if (maybeLength != null) {
length = maybeLength.intValue();
} else {
return n;
}
if (arg2.getNext() != null) {
// If we got more args than we expected, bail out.
return n;
}
} else {
// parameter 2 not passed
length = stringAsString.length() - start;
}
// Don't handle these cases. The specification actually does
// specify the behavior in some of these cases, but we haven't
// done a thorough investigation that it is correctly implemented
// in all browsers.
if ((start + length) > stringAsString.length() ||
(length < 0) ||
(start < 0)) {
return n;
}
String result = stringAsString.substring(start, start + length);
Node resultNode = IR.string(result);
Node parent = n.getParent();
parent.replaceChild(n, resultNode);
reportCodeChange();
return resultNode;
}
/**
* Try to fold .substring() or .slice() calls on strings
*/
private Node tryFoldStringSubstringOrSlice(Node n, Node stringNode, Node arg1) {
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(stringNode.isString());
Preconditions.checkArgument(arg1 != null);
int start;
int end;
String stringAsString = stringNode.getString();
Double maybeStart = NodeUtil.getNumberValue(arg1, useTypes);
if (maybeStart != null) {
start = maybeStart.intValue();
} else {
return n;
}
Node arg2 = arg1.getNext();
if (arg2 != null) {
Double maybeEnd = NodeUtil.getNumberValue(arg2, useTypes);
if (maybeEnd != null) {
end = maybeEnd.intValue();
} else {
return n;
}
if (arg2.getNext() != null) {
// If we got more args than we expected, bail out.
return n;
}
} else {
// parameter 2 not passed
end = stringAsString.length();
}
// Don't handle these cases. The specification actually does
// specify the behavior in some of these cases, but we haven't
// done a thorough investigation that it is correctly implemented
// in all browsers.
if ((end > stringAsString.length()) || (start > stringAsString.length())
|| (start < 0) || (end < 0)
|| (start > end)) {
return n;
}
String result = stringAsString.substring(start, end);
Node resultNode = IR.string(result);
Node parent = n.getParent();
parent.replaceChild(n, resultNode);
reportCodeChange();
return resultNode;
}
private Node replaceWithCharAt(Node n, Node callTarget, Node firstArg) {
// TODO(moz): Maybe correct the arity of the function type here.
callTarget.getLastChild().setString("charAt");
firstArg.getNext().detach();
reportCodeChange();
return n;
}
/**
* Try to fold .charAt() calls on strings
*/
private Node tryFoldStringCharAt(Node n, Node stringNode, Node arg1) {
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(stringNode.isString());
int index;
String stringAsString = stringNode.getString();
if (arg1 != null && arg1.isNumber()
&& arg1.getNext() == null) {
index = (int) arg1.getDouble();
} else {
return n;
}
if (index < 0 || stringAsString.length() <= index) {
// http://es5.github.com/#x15.5.4.4 says "" is returned when index is
// out of bounds but we bail.
return n;
}
Node resultNode = IR.string(
stringAsString.substring(index, index + 1));
Node parent = n.getParent();
parent.replaceChild(n, resultNode);
reportCodeChange();
return resultNode;
}
/**
* Try to fold .charCodeAt() calls on strings
*/
private Node tryFoldStringCharCodeAt(Node n, Node stringNode, Node arg1) {
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(stringNode.isString());
int index;
String stringAsString = stringNode.getString();
if (arg1 != null && arg1.isNumber()
&& arg1.getNext() == null) {
index = (int) arg1.getDouble();
} else {
return n;
}
if (index < 0 || stringAsString.length() <= index) {
// http://es5.github.com/#x15.5.4.5 says NaN is returned when index is
// out of bounds but we bail.
return n;
}
Node resultNode = IR.number(stringAsString.charAt(index));
Node parent = n.getParent();
parent.replaceChild(n, resultNode);
reportCodeChange();
return resultNode;
}
/**
* Support function for jsSplit, find the first occurrence of
* separator within stringValue starting at startIndex.
*/
private static int jsSplitMatch(String stringValue, int startIndex,
String separator) {
if (startIndex + separator.length() > stringValue.length()) {
return -1;
}
int matchIndex = stringValue.indexOf(separator, startIndex);
if (matchIndex < 0) {
return -1;
}
return matchIndex;
}
/**
* Implement the JS String.split method using a string separator.
*/
private String[] jsSplit(String stringValue, String separator, int limit) {
Preconditions.checkArgument(limit >= 0);
Preconditions.checkArgument(stringValue != null);
// For limits of 0, return an empty array
if (limit == 0) {
return new String[0];
}
// If a separator is not specified, return the entire string as
// the only element of an array.
if (separator == null) {
return new String[] {stringValue};
}
List<String> splitStrings = new ArrayList<>();
// If an empty string is specified for the separator, split apart each
// character of the string.
if (separator.isEmpty()) {
for (int i = 0; i < stringValue.length() && i < limit; i++) {
splitStrings.add(stringValue.substring(i, i + 1));
}
} else {
int startIndex = 0;
int matchIndex;
while ((matchIndex =
jsSplitMatch(stringValue, startIndex, separator)) >= 0 &&
splitStrings.size() < limit) {
splitStrings.add(stringValue.substring(startIndex, matchIndex));
startIndex = matchIndex + separator.length();
}
if (splitStrings.size() < limit) {
if (startIndex < stringValue.length()) {
splitStrings.add(stringValue.substring(startIndex));
} else {
splitStrings.add("");
}
}
}
return splitStrings.toArray(new String[0]);
}
/**
* Try to fold .split() calls on strings
*/
private Node tryFoldStringSplit(Node n, Node stringNode, Node arg1) {
if (late) {
return n;
}
Preconditions.checkArgument(n.isCall());
Preconditions.checkArgument(stringNode.isString());
String separator = null;
String stringValue = stringNode.getString();
// Maximum number of possible splits
int limit = stringValue.length() + 1;
if (arg1 != null) {
if (arg1.isString()) {
separator = arg1.getString();
} else if (!arg1.isNull()) {
return n;
}
Node arg2 = arg1.getNext();
if (arg2 != null) {
if (arg2.isNumber()) {
limit = Math.min((int) arg2.getDouble(), limit);
if (limit < 0) {
return n;
}
} else {
return n;
}
}
}
// Split the string and convert the returned array into JS nodes
String[] stringArray = jsSplit(stringValue, separator, limit);
Node arrayOfStrings = IR.arraylit();
for (String element : stringArray) {
arrayOfStrings.addChildToBack(IR.string(element).srcref(stringNode));
}
Node parent = n.getParent();
parent.replaceChild(n, arrayOfStrings);
reportCodeChange();
return arrayOfStrings;
}
}