Improve VariableMap.forBytes performance

------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=190344384
google · Mar 27, 2018 · eaa0edf · eaa0edf
1 parent 01013ef
commit eaa0edf
Showing 1 changed file with 35 additions and 21 deletions.
diff --git a/src/com/google/javascript/jscomp/VariableMap.java b/src/com/google/javascript/jscomp/VariableMap.java
@@ -21,7 +21,6 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableBiMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedMap;
@@ -122,23 +121,30 @@ public byte[] toBytes() {
     return baos.toByteArray();
   }
 
-  @GwtIncompatible("com.google.common.base.Splitter.onPattern()")
-  private static final Splitter LINE_SPLITTER
-      = Splitter.onPattern("\\r?\\n").omitEmptyStrings();
-
   /**
    * Deserializes the variable map from a byte array returned by
    * {@link #toBytes()}.
    */
   @GwtIncompatible("com.google.common.base.Splitter.onPattern()")
   public static VariableMap fromBytes(byte[] bytes) throws ParseException {
-    Iterable<String> lines = LINE_SPLITTER.split(
+    String string = new String(bytes, UTF_8);
-        new String(bytes, UTF_8));
-
     ImmutableMap.Builder<String, String> map = ImmutableMap.builder();
-
+    int startOfLine = 0;
-    for (String line : lines) {
+    while (startOfLine < string.length()) {
-      int pos = findIndexOfChar(line, SEPARATOR);
+      int newLine = string.indexOf('\n', startOfLine);
+      if (newLine == -1) {
+        newLine = string.length();
+      }
+      int endOfLine = newLine;
+      if (string.charAt(newLine - 1) == '\r') {
+        newLine--;
+      }
+      String line = string.substring(startOfLine, newLine);
+      startOfLine = endOfLine + 1; // update index for next iteration
+      if (line.isEmpty()) {
+        continue;
+      }
+      int pos = findIndexOfUnescapedChar(line, SEPARATOR);
       if (pos <= 0) {
         throw new ParseException("Bad line: " + line, 0);
       }
@@ -155,23 +161,31 @@ private static String escape(String value) {
         .replace("\n", "\\n");
   }
 
-  private static int findIndexOfChar(String value, char stopChar) {
+  private static int findIndexOfUnescapedChar(String value, char stopChar) {
     int len = value.length();
-    for (int i = 0; i < len; i++) {
+    for (int i = 0; i < len; ) {
-      char c = value.charAt(i);
+      int stopCharIndex = value.indexOf(stopChar, i);
-      if (c == '\\' && ++i < len) {
+      if (stopCharIndex == -1) {
-        c = value.charAt(i);
+        return -1;
-      } else if (c == stopChar){
+      }
-        return i;
+      if (value.charAt(stopCharIndex - 1) != '\\') {
+        // it isn't escaped, return
+        return stopCharIndex;
       }
+      i = stopCharIndex + 1;
     }
     return -1;
   }
 
-  private static String unescape(CharSequence value) {
+  private static String unescape(String value) {
-    StringBuilder sb = new StringBuilder();
+    int slashIndex = value.indexOf('\\');
+    if (slashIndex == -1) {
+      return value;
+    }
+    StringBuilder sb = new StringBuilder(value.length() - 1);
+    sb.append(value, 0, slashIndex);
     int len = value.length();
-    for (int i = 0; i < len; i++) {
+    for (int i = slashIndex; i < len; i++) {
       char c = value.charAt(i);
       if (c == '\\' && ++i < len) {
         c = value.charAt(i);