Expressions in left hand side of indexed program counter relative expressions not resolved

[craigthomas]

Describe the bug
When an expression shows up in the left hand side of an indexed program counter relative expression, it is not resolved correctly.

To Reproduce

1. Create a file called test.asm and add the following contents to it:

                ORG     $3F00
TEMP            EQU     $0001
START           STX     1+TEMP,PCR
                END     START

2. Assemble the file with the following command:

python3 assembler.py test.asm --print

3. The following output will appear:

-- Assembled Statements --
$3F00                         ORG $3F00                          ;       
$3F00                  TEMP   EQU $0001                          ;   
$3F00 AF8C00          START   STX 1+TEMP,PCR                     ;                     
$3F02                         END START                          ; 

Expected behavior
Correct output should be:

-- Assembled Statements --
$3F00                         ORG $3F00                          ;             
$3F00                  TEMP   EQU $0001                          ;               
$3F00 AF8D0002        START   STX 1+TEMP,PCR                     ;                      
$3F04                         END START                          ;

Desktop (please complete the following information):

• OS: Ubuntu 20.04
• Python Version: 3.8.10

Additional Context
Currently the output of AF8C00 is exhibiting the problem as described in issue #51 . The correct output of AF8D as the instruction and addressing mode should be fixed by that issue first. Then the issue of the expression resolution can be fixed.

[craigthomas]

Closed by PR #54