Optimise WriteEscapedJavaScriptString
Skip attempting write when string is empty. FirstCharToEscape was introduced for the async version and gives a faster means to identify the first block before any escaping, so may as well use it here too. Conversely, WriteEscapedStringThroughBuffer was introduced to share code between the sync and async versions, but later optimisations meant it was no longer used by the async. Inline the code back again.
This commit is contained in:
Jon Hanna
committed by
James Newton-King
James Newton-King
parent
de82488549
commit
7a93892d03
@@ -30,6 +30,7 @@ using System.Threading;
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using System.Threading.Tasks;
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#endif
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using System.Collections.Generic;
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using System.Diagnostics;
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#if NET20
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using Newtonsoft.Json.Utilities.LinqBridge;
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#else
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@@ -149,137 +150,158 @@ namespace Newtonsoft.Json.Utilities
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writer.Write(delimiter);
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}
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if (s != null)
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if (!string.IsNullOrEmpty(s))
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{
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int lastWritePosition = 0;
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for (int i = 0; i < s.Length; i++)
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int lastWritePosition = FirstCharToEscape(s, charEscapeFlags, stringEscapeHandling);
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if (lastWritePosition == -1)
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{
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char c = s[i];
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if (c < charEscapeFlags.Length && !charEscapeFlags[c])
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{
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continue;
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}
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string escapedValue;
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switch (c)
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{
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case '\t':
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escapedValue = @"\t";
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break;
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case '\n':
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escapedValue = @"\n";
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break;
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case '\r':
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escapedValue = @"\r";
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break;
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case '\f':
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escapedValue = @"\f";
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break;
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case '\b':
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escapedValue = @"\b";
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break;
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case '\\':
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escapedValue = @"\\";
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break;
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case '\u0085': // Next Line
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escapedValue = @"\u0085";
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break;
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case '\u2028': // Line Separator
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escapedValue = @"\u2028";
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break;
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case '\u2029': // Paragraph Separator
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escapedValue = @"\u2029";
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break;
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default:
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if (c < charEscapeFlags.Length || stringEscapeHandling == StringEscapeHandling.EscapeNonAscii)
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{
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if (c == '\'' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
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{
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escapedValue = @"\'";
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}
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else if (c == '"' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
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{
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escapedValue = @"\""";
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}
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else
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{
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if (writeBuffer == null || writeBuffer.Length < UnicodeTextLength)
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{
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writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, UnicodeTextLength, writeBuffer);
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}
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StringUtils.ToCharAsUnicode(c, writeBuffer);
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// slightly hacky but it saves multiple conditions in if test
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escapedValue = EscapedUnicodeText;
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}
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}
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else
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{
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escapedValue = null;
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}
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break;
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}
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if (escapedValue == null)
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{
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continue;
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}
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bool isEscapedUnicodeText = string.Equals(escapedValue, EscapedUnicodeText);
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if (i > lastWritePosition)
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{
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int length = i - lastWritePosition + ((isEscapedUnicodeText) ? UnicodeTextLength : 0);
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int start = (isEscapedUnicodeText) ? UnicodeTextLength : 0;
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if (writeBuffer == null || writeBuffer.Length < length)
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{
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char[] newBuffer = BufferUtils.RentBuffer(bufferPool, length);
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// the unicode text is already in the buffer
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// copy it over when creating new buffer
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if (isEscapedUnicodeText)
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{
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Array.Copy(writeBuffer, newBuffer, UnicodeTextLength);
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}
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BufferUtils.ReturnBuffer(bufferPool, writeBuffer);
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writeBuffer = newBuffer;
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}
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s.CopyTo(lastWritePosition, writeBuffer, start, length - start);
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// write unchanged chars before writing escaped text
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writer.Write(writeBuffer, start, length - start);
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}
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lastWritePosition = i + 1;
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if (!isEscapedUnicodeText)
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{
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writer.Write(escapedValue);
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}
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else
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{
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writer.Write(writeBuffer, 0, UnicodeTextLength);
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}
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}
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if (lastWritePosition == 0)
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{
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// no escaped text, write entire string
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writer.Write(s);
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}
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else
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{
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int length = WriteEscapedStringThroughBuffer(s, lastWritePosition, bufferPool, ref writeBuffer);
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if (lastWritePosition != 0)
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{
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if (writeBuffer == null || writeBuffer.Length < lastWritePosition)
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{
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writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, lastWritePosition, writeBuffer);
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}
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// write remaining text
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writer.Write(writeBuffer, 0, length);
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// write unchanged chars at start of text.
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s.CopyTo(0, writeBuffer, 0, lastWritePosition);
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writer.Write(writeBuffer, 0, lastWritePosition);
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}
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int length;
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for (int i = lastWritePosition; i < s.Length; i++)
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{
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char c = s[i];
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if (c < charEscapeFlags.Length && !charEscapeFlags[c])
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{
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continue;
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}
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string escapedValue;
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switch (c)
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{
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case '\t':
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escapedValue = @"\t";
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break;
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case '\n':
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escapedValue = @"\n";
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break;
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case '\r':
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escapedValue = @"\r";
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break;
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case '\f':
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escapedValue = @"\f";
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break;
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case '\b':
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escapedValue = @"\b";
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break;
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case '\\':
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escapedValue = @"\\";
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break;
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case '\u0085': // Next Line
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escapedValue = @"\u0085";
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break;
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case '\u2028': // Line Separator
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escapedValue = @"\u2028";
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break;
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case '\u2029': // Paragraph Separator
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escapedValue = @"\u2029";
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break;
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default:
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if (c < charEscapeFlags.Length || stringEscapeHandling == StringEscapeHandling.EscapeNonAscii)
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{
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if (c == '\'' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
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{
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escapedValue = @"\'";
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}
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else if (c == '"' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
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{
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escapedValue = @"\""";
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}
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else
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{
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if (writeBuffer == null || writeBuffer.Length < UnicodeTextLength)
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{
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writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, UnicodeTextLength, writeBuffer);
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}
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StringUtils.ToCharAsUnicode(c, writeBuffer);
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// slightly hacky but it saves multiple conditions in if test
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escapedValue = EscapedUnicodeText;
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}
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}
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else
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{
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escapedValue = null;
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}
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break;
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}
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if (escapedValue == null)
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{
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continue;
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}
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bool isEscapedUnicodeText = string.Equals(escapedValue, EscapedUnicodeText);
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if (i > lastWritePosition)
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{
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length = i - lastWritePosition + ((isEscapedUnicodeText) ? UnicodeTextLength : 0);
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int start = (isEscapedUnicodeText) ? UnicodeTextLength : 0;
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if (writeBuffer == null || writeBuffer.Length < length)
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{
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char[] newBuffer = BufferUtils.RentBuffer(bufferPool, length);
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// the unicode text is already in the buffer
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// copy it over when creating new buffer
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if (isEscapedUnicodeText)
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{
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Array.Copy(writeBuffer, newBuffer, UnicodeTextLength);
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}
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BufferUtils.ReturnBuffer(bufferPool, writeBuffer);
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writeBuffer = newBuffer;
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}
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s.CopyTo(lastWritePosition, writeBuffer, start, length - start);
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// write unchanged chars before writing escaped text
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writer.Write(writeBuffer, start, length - start);
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}
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lastWritePosition = i + 1;
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if (!isEscapedUnicodeText)
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{
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writer.Write(escapedValue);
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}
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else
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{
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writer.Write(writeBuffer, 0, UnicodeTextLength);
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}
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}
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Debug.Assert(lastWritePosition != 0);
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length = s.Length - lastWritePosition;
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if (length > 0)
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{
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if (writeBuffer == null || writeBuffer.Length < length)
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{
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writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, length, writeBuffer);
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}
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s.CopyTo(lastWritePosition, writeBuffer, 0, length);
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// write remaining text
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writer.Write(writeBuffer, 0, length);
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}
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}
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}
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@@ -290,20 +312,6 @@ namespace Newtonsoft.Json.Utilities
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}
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}
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private static int WriteEscapedStringThroughBuffer(string s, int lastWritePosition, IArrayPool<char> bufferPool, ref char[] writeBuffer)
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{
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int length = s.Length - lastWritePosition;
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if (writeBuffer == null || writeBuffer.Length < length)
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{
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writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, length, writeBuffer);
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}
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s.CopyTo(lastWritePosition, writeBuffer, 0, length);
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return length;
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}
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public static string ToEscapedJavaScriptString(string value, char delimiter, bool appendDelimiters, StringEscapeHandling stringEscapeHandling)
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{
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bool[] charEscapeFlags = GetCharEscapeFlags(stringEscapeHandling, delimiter);
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