Manages complex text expressions currently used in a number of actions including PutScreen and SetField.
Contains Three classes: TextExp, LitExp and VarExp
TextExp Class
A text expression is identified by matching single or double quotes and can include a backslash (\) to enable inclusion of a quote without terminating the text string parsing.
Field/variable values can be included without concatenation using the common Mustache/Handlebars syntax of double curly-braces ({{varname}}).
The Constructor takes the whole text expression as a parameter and compiles it into a list of LitExp and VarExp objects, each of which is either a simple text string or a field name reference. The Exec method then evaluates the list and returns a whole string, concatenating variables from the active dictionary.
public string Exec(HostScreen oScreen, Dictionary<string, object> connectInfo)
Using a simple StringBuilder concatenation runs through the list of expressions to create the return string.
LitExp Class
A very simple class that contains a simple text value that is returned with the GetText method
virtual public string GetText(HostScreen oScreen, Dictionary<string, object> connectInfo)
VarExp Class
Another simple class that inherits from LitExp so that the TextExp class can just maintain a list of TextExp objects and call the GetText in each one. Instead of holding a simple text value to return, the VarExp class contains a Field/variable name--it overrides GetText and returns the value found in the connectInfo dictionary. If the Field name is not found it returns an empty string.
