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Posted to dev@velocity.apache.org by bu...@apache.org on 2004/11/11 12:58:01 UTC
DO NOT REPLY [Bug 32179] New: -
Workaround the lack of equality in CharSequence.
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http://issues.apache.org/bugzilla/show_bug.cgi?id=32179
Workaround the lack of equality in CharSequence.
Summary: Workaround the lack of equality in CharSequence.
Product: Velocity
Version: 1.4
Platform: All
URL: http://java.sun.com/j2se/1.4.2/docs/api/java/lang/CharSe
quence.html
OS/Version: All
Status: NEW
Severity: Enhancement
Priority: Other
Component: Source
AssignedTo: velocity-dev@jakarta.apache.org
ReportedBy: artem@bizlink.ru
CharSequence is a nice addition to the Java API,
helping to encapsulate implementation details
and allowing programmers to use StringBuffer,
mutable strings (such as
http://mg4j.dsi.unimi.it/docs/it/unimi/dsi/mg4j/util/MutableString.html )
or even their custom classes directly
instead of costly process of converting everything into a String.
One of the remaining drawbacks of the CharSequence
is the lack of support for the Object#equals method.
Fortunately, in Velocity it can be easily fixed
in the ASTEQNode and ASTNENode classes.
Example of the fix is provided in the following patches.
--- org/apache/velocity/runtime/parser/node/original/ASTEQNode.java Wed Apr
14 09:26:42 2004
+++ org/apache/velocity/runtime/parser/node/ASTEQNode.java Thu Nov 11 14:21:
03 2004
@@ -101,6 +101,20 @@
}
else
{
+
+ /*
+ * Comparison of CharSequence objects.
+ */
+ if (left instanceof CharSequence && right instanceof CharSequence)
+ {
+ final CharSequence a = (CharSequence) left;
+ final CharSequence b = (CharSequence) right;
+ final int aLen = a.length(); final int bLen = b.length();
+ if( aLen != bLen ) return false;
+ int n = aLen; while( 0 != n-- ) if( a.charAt( n ) != b.charAt( n )
) return false;
+ return true;
+ }
+
rsvc.error("Error in evaluation of == expression."
+ " Both arguments must be of the same Class."
+ " Currently left = " + left.getClass() + ", right =
"
--- org/apache/velocity/runtime/parser/node/original/ASTNENode.java Wed Apr
14 09:26:42 2004
+++ org/apache/velocity/runtime/parser/node/ASTNENode.java Thu Nov 11 14:22:
04 2004
@@ -74,6 +74,20 @@
}
else
{
+
+ /*
+ * Comparison of CharSequence objects.
+ */
+ if (left instanceof CharSequence && right instanceof CharSequence)
+ {
+ final CharSequence a = (CharSequence) left;
+ final CharSequence b = (CharSequence) right;
+ final int aLen = a.length(); final int bLen = b.length();
+ if( aLen != bLen ) return true;
+ int n = aLen; while( 0 != n-- ) if( a.charAt( n ) != b.charAt( n )
) return true;
+ return false;
+ }
+
rsvc.error("Error in evaluation of != expression."
+ " Both arguments must be of the same Class."
+ " Currently left = " + left.getClass() + ", right =
"
The additional check should not have any performance impact,
since it is performed where the 'Both arguments must be of the same Class'
error was.
I really hope Velocity will incorporate at least that minimal
support for CharSequence, making Java environment
to be a lot friendlier to some of us.
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