[geany/geany] 6781ab: python: optimize skipEverything()

[Jiří Techet]

Branch:      refs/heads/master
Author:      Jiří Techet <techet at gmail.com>
Committer:   Jiří Techet <techet at gmail.com>
Date:        Thu, 25 Jun 2015 20:10:32 UTC
Commit:      6781ab30c54efdb29d41e45bc20cc2eec0124f66
             https://github.com/geany/geany/commit/6781ab30c54efdb29d41e45bc20cc2eec0124f66

Log Message:
-----------
python: optimize skipEverything()

Most of the time there's no start of a string which means all the 10
strcmp()s are done for every character of the input. This is very expensive:
before this patch this function alone takes 55% of the parser time.
When comparing by character (and avoiding further comparison if the first
character doesn't match), this function takes only 11% of the parser time
so the performance of the parser nearly doubles.

In addition check for the "rb" prefix which is possible in Python 3.

Ported from universal-ctags.


Modified Paths:
--------------
    tagmanager/ctags/python.c

Modified: tagmanager/ctags/python.c
33 lines changed, 20 insertions(+), 13 deletions(-)
===================================================================
@@ -244,20 +244,27 @@ static const char *skipEverything (const char *cp)
 			match = 1;
 
 		/* these checks find unicode, binary (Python 3) and raw strings */
-		if (!match && (
-			!strncasecmp(cp, "u'", 2) || !strncasecmp(cp, "u\"", 2) ||
-			!strncasecmp(cp, "r'", 2) || !strncasecmp(cp, "r\"", 2) ||
-			!strncasecmp(cp, "b'", 2) || !strncasecmp(cp, "b\"", 2)))
+		if (!match)
 		{
-			match = 1;
-			cp += 1;
-		}
-		if (!match && (
-			!strncasecmp(cp, "ur'", 3) || !strncasecmp(cp, "ur\"", 3) ||
-			!strncasecmp(cp, "br'", 3) || !strncasecmp(cp, "br\"", 3)))
-		{
-			match = 1;
-			cp += 2;
+			boolean r_first = (*cp == 'r' || *cp == 'R');
+
+			/* "r" | "R" | "u" | "U" | "b" | "B" */
+			if (r_first || *cp == 'u' || *cp == 'U' ||  *cp == 'b' || *cp == 'B')
+			{
+				unsigned int i = 1;
+
+				/*  r_first -> "rb" | "rB" | "Rb" | "RB"
+				   !r_first -> "ur" | "UR" | "Ur" | "uR" | "br" | "Br" | "bR" | "BR" */
+				if (( r_first && (cp[i] == 'b' || cp[i] == 'B')) ||
+					(!r_first && (cp[i] == 'r' || cp[i] == 'R')))
+					i++;
+
+				if (cp[i] == '\'' || cp[i] == '"')
+				{
+					match = 1;
+					cp += i;
+				}
+			}
 		}
 		if (match)
 		{



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