representation of keywords
I think you're confused about the nature of VHDL.  There isn't a 1-1 mapping between VHDL keywords and gates, rather, most of the keywords you listed are composed of many gates.  

The standard logic gates are: 


NOT
AND
OR
XOR
NAND
NOR
XNOR 


There are a few additional structures, such as flip-flops, but the number of basic representations is small.  Higher-level abstractions like while and if-else are composed of a large number of these gates, which are themselves composed of a number of transistors.  The transistors are the actual hardware, there is no basic electronics component for the symbols you've shown.  Everything above the transistors is an abstraction of hardware.

If you're familiar with the architecture of a program in software, what you're asking is very similar to the question "What's the assembly instruction for the class or Array.length keyword?"  There is none. Those keywords are compiled to a number of assembly instructions; there's not a 1-1 mapping.