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Make fewer calls to out.write() when serializing strings. On one Android test, this improved serialization time of some documents by 83%.

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TWEETS                              
   run          vm htmlSafe   ms linear runtime                    % 
Before app_process     true 68.7 ============================== 100% 
 After app_process     true 35.9 ===============                 52% 


                                  READER_LONG                         
   run          vm htmlSafe    ms linear runtime                    % 
Before app_process     true 439.0 ============================== 100%
 After app_process     true  74.5 =====                           17%
This commit is contained in:
Jesse Wilson 2012-04-12 13:24:37 +00:00
parent c890e31bba
commit a991e54157
1 changed files with 55 additions and 62 deletions
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117
gson/src/main/java/com/google/gson/stream/JsonWriter.java
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@ -122,6 +122,38 @@ import java.util.List;
*/
public class JsonWriter implements Closeable {
/*
* From RFC 4627, "All Unicode characters may be placed within the
* quotation marks except for the characters that must be escaped:
* quotation mark, reverse solidus, and the control characters
* (U+0000 through U+001F)."
*
* We also escape '\u2028' and '\u2029', which JavaScript interprets as
* newline characters. This prevents eval() from failing with a syntax
* error. http://code.google.com/p/google-gson/issues/detail?id=341
*/
private static final String[] REPLACEMENT_CHARS;
private static final String[] HTML_SAFE_REPLACEMENT_CHARS;
static {
REPLACEMENT_CHARS = new String[128];
for (int i = 0; i <= 0x1f; i++) {
REPLACEMENT_CHARS[i] = String.format("\\u%04x", (int) i);
}
REPLACEMENT_CHARS['"'] = "\\\"";
REPLACEMENT_CHARS['\\'] = "\\\\";
REPLACEMENT_CHARS['\t'] = "\\t";
REPLACEMENT_CHARS['\b'] = "\\b";
REPLACEMENT_CHARS['\n'] = "\\n";
REPLACEMENT_CHARS['\r'] = "\\r";
REPLACEMENT_CHARS['\f'] = "\\f";
HTML_SAFE_REPLACEMENT_CHARS = REPLACEMENT_CHARS.clone();
HTML_SAFE_REPLACEMENT_CHARS['<'] = "\\u003c";
HTML_SAFE_REPLACEMENT_CHARS['>'] = "\\u003e";
HTML_SAFE_REPLACEMENT_CHARS['&'] = "\\u0026";
HTML_SAFE_REPLACEMENT_CHARS['='] = "\\u003d";
HTML_SAFE_REPLACEMENT_CHARS['\''] = "\\u0027";
}
/** The output data, containing at most one top-level array or object. */
private final Writer out;
@ -482,72 +514,33 @@ public class JsonWriter implements Closeable {
}
private void string(String value) throws IOException {
String[] replacements = htmlSafe ? HTML_SAFE_REPLACEMENT_CHARS : REPLACEMENT_CHARS;
out.write("\"");
for (int i = 0, length = value.length(); i < length; i++) {
int last = 0;
int length = value.length();
for (int i = 0; i < length; i++) {
char c = value.charAt(i);
/*
* From RFC 4627, "All Unicode characters may be placed within the
* quotation marks except for the characters that must be escaped:
* quotation mark, reverse solidus, and the control characters
* (U+0000 through U+001F)."
*
* We also escape '\u2028' and '\u2029', which JavaScript interprets as
* newline characters. This prevents eval() from failing with a syntax
* error. http://code.google.com/p/google-gson/issues/detail?id=341
*/
switch (c) {
case '"':
case '\\':
out.write('\\');
out.write(c);
break;
case '\t':
out.write("\\t");
break;
case '\b':
out.write("\\b");
break;
case '\n':
out.write("\\n");
break;
case '\r':
out.write("\\r");
break;
case '\f':
out.write("\\f");
break;
case '<':
case '>':
case '&':
case '=':
case '\'':
if (htmlSafe) {
out.write(String.format("\\u%04x", (int) c));
} else {
out.write(c);
String replacement;
if (c < 128) {
replacement = replacements[c];
if (replacement == null) {
continue;
}
break;
case '\u2028':
case '\u2029':
out.write(String.format("\\u%04x", (int) c));
break;
default:
if (c <= 0x1F) {
out.write(String.format("\\u%04x", (int) c));
} else {
out.write(c);
}
break;
} else if (c == '\u2028') {
replacement = "\\u2028";
} else if (c == '\u2029') {
replacement = "\\u2029";
} else {
continue;
}
if (last < i) {
out.write(value, last, i - last);
}
out.write(replacement);
last = i + 1;
}
if (last < length) {
out.write(value, last, length - last);
}
out.write("\"");
}