[pclasses-devel] StringTool

[stephan b. <st...@s1...>]

Okay, i needed some string util code for the App layer, and wanted to 
move some out of ps11n, so i finally went ahead and ported the string 
util code into Util/StringTool.

It is namespace P::StringTool, encapsulating several commonly-useful 
string operations. Some of these will be especially useful for P, e.g. 
translateEntities(). i didn't call it Util::String, because that would 
mislead people to think it's only for the Unicode::String class. The 
name StringUtil has the same problem. Okay, maybe StringTool does as 
well :/. i'm open to suggestions for new names.

Consider the problem of encoding URLs. e.g:
"http://foo/?foo=bar bar bar"
==>
"http://foo/?foo=bar%20bar%20bar"

With translateEntities() encoding and decoding are trivial and generic:

map<string,string> map;
map[" "] = "%20";
map["..."] = "..."; // usw...

encode:
string u = "http://foo/?foo=bar bar bar";
StringTool::translateEntities( u, map );
// ^^^ modifies u in-place

decode:
StringTool::translateEntities( u, map, true );
// ^^^ 'true' == do reverse mapping

All of s11n's serializers use this simple approach to do their, e.g. XML 
entity translation/escaping. By serving the translation maps through 
Phoenix, we ensure a) they are not populated until they're actually 
used and b) if they're called post-main() they get repopulated with the 
translations.


Another useful func is expandDollarRefs():

map["HOME"] = getenv("HOME");

string foo = expandDollarRefs( "${HOME}/.myconfig", map );
or:
foo = "${HOME}/.myconfig";
expandDollarRefsInline( foo, map ); // edits foo in-place


Then, of course, there's the well-overused lexical casting:

string s = StringTool::to(myobj); // tostring
MyType m = StringTool::from("value"); // fromstring


There's a small demo under test/StringToolTest.cpp:

tringToolTest.cpp:18 : StringTool tests...
StringToolTest.cpp:29 : string: [this $bar is a ${foo} input ${bar}. 
$UNMAPPED_VAR, \ \ \\ ${} $ \$  escaped \${foo}.]
expanded: [this BARBAR is a FOOFOO input BARBAR. $UNMAPPED_VAR, \ \ \\ 
${} $ $  escaped ${foo}.]
StringToolTest.cpp:33 : escaped string: [this \$bar is a \${foo} input 
\${bar}. \$UNMAPPED_VAR, \ \ \\ \${} \$ \\$  escaped \\${foo}.]
pre-escaped, expanded: [this $bar is a ${foo} input ${bar}. 
$UNMAPPED_VAR, \ \ \\ ${} $ \$  escaped \${foo}.]
StringToolTest.cpp:46 : reference string=[this is a '<"test string">'. 
$GOODGRIEF!]
StringToolTest.cpp:48 : 7 translated: [this is a &apos;&lt;&quot;test 
string&quot;&gt;&apos;. excellent!]
StringToolTest.cpp:50 : 7 reverse translated: [this is a '<"test 
string">'. $GOODGRIEF!]



-- 
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"...pleasure is a grace and is not obedient to the commands
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