Re: [Quickfix-developers] Field name to number conversion

[George H. <ge...@so...>]

Mike,

After reading your message I felt like a neanderthal man watching the  
space shuttle take off (and with the same level of understanding).

I did not even realize it could be done this way.

So, many thanks for this very cool piece of code.

This was my approach:

Given a file of Field names that I am interested in:

    1 #
   2 #
   3 # @(#) $Id: system.tgs xxxx 2008-08-22 04:29:18Z svn $
   4 # @(#) Test Field Tags
   5 #
   6 ClOrdID                              #    11
   7 MsgType                              #    35
   8 OrderQty                             #    38
   9 OrdType                              #    40
  10 Price                                #    44
  11 Side                                 #    54
  12 Symbol                               #    55

I create a string-to-field number using XML reader against the Data  
Dictionary.
This means that the Data Dictionary must be used.

In the code I do:

In global.h
     //
     // Simple class to keep track of names and tags
     class Tags2Nums {
         public:
             std::string name;
             int number;
             std::string strNumber;
             int header;
             int trailer;
             int required;
     };

     std::string lmsgstr;
     //
     // The vector below is used to keep track on the name <-> number  
relationship
     vector<Tags2Nums> tagVector;

In Application.cpp

        for( unsigned int ui=0; ui < tagVector.size(); ui++ ) {
             if( !tagVector[ui].header ) {
                 //
                 // Get the text of the message
                 lmsgstr = message.getField(tagVector[ui].number);
                 std::cerr << "\t" << tagVector[ui].name << ":" <<
                     "[" << tagVector[ui].number << "] " << lmsgstr <<  
std::endl;
              } else {
		// Header tags are processed differently
                 printf("\tFound Header Tag\n");
              }
         }

Does this make sense or am I really on the wrong track here?

-George

On Aug 30, 2008, at 12:47 PM, Mike Gatny wrote:

> QuickFIX Documentation: http://www.quickfixengine.org/quickfix/doc/html/index.html
> QuickFIX Support: http://www.quickfixengine.org/services.html
>
> George,
>
> If I understand correctly, you need a lookup of field name (as string)
> -> field number (as int)?
>
> What about leveraging the code generator? I.e. create a stylesheet in
> the spec/ dir:
>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
> version="1.0">
>  <xsl:output method="text" encoding="UTF-8"/>
>
>  <xsl:template match="text()"/>
>
>  <xsl:template match="/">/* -*- C++ -*- */
>  <xsl:copy-of select="document('COPYRIGHT.xml')"/>
> #ifndef FIX_FIELDNAMESTONUMBERS_H
> #define FIX_FIELDNAMESTONUMBERS_H
>
> #include &lt;map&gt;
> #include &lt;string&gt;
>
> class FieldNamesToNumbers
> {
> private:
> 	std::map&lt;std::string,int&gt; fieldNamesToNumbers_;
>
> public:
>
> 	int get(const std::string &amp; fieldName)
> 	{
> 		return fieldNamesToNumbers_[fieldName];
> 	}
>
> 	FieldNamesToNumbers()
> 	{
> 		<xsl:apply-templates/>
> 	}
> };
>
> #endif
> </xsl:template>
> <xsl:template match="fields/field">
> 		fieldNamesToNumbers_["<xsl:value-of select="@name"/>"] =  
> <xsl:value-of
> select="@number"/>;
> </xsl:template>
> </xsl:stylesheet>
>
> Run this command (or better yet, add it to spec/generate_c++.sh):
> xsltproc -o ../src/C++/FieldNamesToNumbers.h FieldNamesToNumbers.xsl
> FIX44.xml
>
> And in your code:
>
> #include <quickfix/FieldNamesToNumbers.h>
> FieldNamesToNumbers conv;
> /* ... */
> message.getField(conv.get(field_name_1_from_config_file));
> message.getField(conv.get(field_name_2_from_config_file));
>
> Now you'll always be up-to-date with the lastest data dictionary.
> Simply re-run the generator if it changes.
>
> -- 
> Mike Gatny
> Connamara Systems, LLC
> http://www.connamara.com/
>
>
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