Hello,
I found that when writing a pre-processor, new tokens could be insert before the look-ahead token.
For example, using a syntax like C pre-processor (or Verilog pre-processor)
#define a b
#define B A
a B
will generate a result as "A b".
It could be solved by pushing the look-ahead token back to the look-ahead stack in my parser.
#restore the look-ahead token
if self.lookahead != None:
self.lookaheadstack.append(self.lookahead)
self.lookahead = None
#insert more token to parse
self.lookaheadstack.extend(macro)
And since a macro won't need the look-ahead token, the changing of next token won't disturb the parsing process.
To support this feature, the look-ahead token and the look-ahead stack need be visible in other function in the parser and I simply add "self." to each "lookahead" and "lookaheadstack" in function "parse", file "yacc.py".
It can successfully pass all of the given tests with command-line "pytest ./tests/".
========================== 11 passed in 0.08 seconds ===========================
By the way, I found that SLY is pretty cool. I had a dream to write a compiler when I was having my "compilers' principles" class and it really helps.
Hello, I found that when writing a pre-processor, new tokens could be insert before the look-ahead token. For example, using a syntax like C pre-processor (or Verilog pre-processor)
will generate a result as "A b". It could be solved by pushing the look-ahead token back to the look-ahead stack in my parser.
And since a macro won't need the look-ahead token, the changing of next token won't disturb the parsing process. To support this feature, the look-ahead token and the look-ahead stack need be visible in other function in the parser and I simply add "self." to each "lookahead" and "lookaheadstack" in function "parse", file "yacc.py".
It can successfully pass all of the given tests with command-line "pytest ./tests/".
========================== 11 passed in 0.08 seconds ===========================By the way, I found that SLY is pretty cool. I had a dream to write a compiler when I was having my "compilers' principles" class and it really helps.