Parser

Source Code

parser.rs

FIXME

• Some of the identifier used in an assembly program are declared only after in the program (e.g. A = label\nlabel:). My program crash because it tries to read in the Hashtable containing the identifiers but finds nothing.
  • Maybe I should iterate twice : one for the directive (equivalent of preprocessor in C) and one for the actual instructions > Even this solution is not ideal because to assign a value to each label identifier we need to know the actual address in the program …
  • I finally addressed this problem by letting the identifier string in the bit_stream and making a function replace_identifier that is called at the end of the parsing function
• Instruction of the type A = D are making my program to crash because the parser is expecting a Token::Operation after D. The tricky part is that in order to detect this case we must read the token after D. Making the program to have unexpected behavior after that because the first token after D is already consumed.
  • A fix may be to reinsert the token we read at the beginning of our iterable but I doubt it is easily possible.
  • A cleaner approach might be to stop reading token after the sequence Register Assignement Register and let our main loop consume the remaining token. Of course we will need to match for Token::Operation in our main pattern matching structure. And we will need to partially accumulate the bitstream …

  • see iter.peek() (aka ‘lookahead’) even better: multipeek()