Top level parsing process

Top level parsing process

 

fb.bas:fbCompile() is called from the fbc frontend for every input file. Parsing (and compiling) of the file begins here.

fb.bas:fbCompile()

• Open the input .bas
  
• Start the emitter (ir) (Open the output .asm)
  
• fbMainBegin() (Build the AST for the implicit main() or static constructor for module-level code)
  
• fbPreIncludes()
  
  • fbIncludeFile() for every preinclude (found on the fbc command line)
    
• cProgram()
  
• fbMainEnd() (Close the implicit main())
  
• Finish emitting (ir) (Finish generating the .asm and close it)
  
• Close the input .bas
  
  

fb.bas:fbIncludeFile()

• Include file search
  
• lexPush() (Push a new lexer context to parse this #include file without disturbing the lexer's state in the parent file)
  
• Open the include file
  
• cProgram()
  
• Close the include file
  
• lexPop() (Restore the lexer state to the parent file)
  
  

parser-toplevel.bas:cProgram() is the root of the FB grammar, and parses a file. Here's a short & quick run down of what is done:

• cLine() repeatedly until EOF
  
  • cLabel()
    
  • cStatement()
    
    • Declarations
      
      • UDT declarations, typedefs
        
      • Variables (DIM, VAR, ...)
        
      • Procedure declarations (DECLARE)
        
      • Procedure bodies (SUB, FUNCTION, ...)
        

• Compounds statements (IF/ELSE, DO/LOOP, EXIT/CONTINUE DO, ...)
  
• Procedure calls
  
• Function result assignments
  
• Quirk statements (special QB rtlib/gfxlib statements)
  
• ASM blocks
  
• Assignments
  
• Procedure pointer calls