Canonical distinct fields string

Sometimes we need to resolve CRM items to Outlook items where we don't have a foreign id on either side; so we need to resolve on distinct fields. An object will be deemed to match if the values of all the distinct fields on both sides match (note that, for Contacts, we need to do something more sophisticated than this, since a contact should probably be considered to be 'the same' if either the email address or the phone number match).

The canonical name of a field is all lower case, with words separated by underscores. The canonical value of a field is as follows:

1. for a string, the string surrounded by single quotes, with each embedded single quote prefixed by a backslash character, and each embedded backslash character preceded by an additional backslash character;
2. for an integer, the base 10 representation of the integer;
3. for a real number, the base 10 decimal representation of the number;
4. for a date, the ISO8601 UTC representation of the date, surrounded by single quotes.

For each module we deal with, there will be a list of distinct fields, as follows:

Calls

1. subject
2. start_time

Contacts

1. first_name
2. last_name
3. email1

Meetings

1. subject
2. start_time

Tasks

1. name
2. date_start