Re: Operator-precedence v.s. LL(1)

ejxue@ntu.ac.sg writes:


>Textbooks on compilers usually contain discussions about
>the relationships between the other types of grammars.


Very few textbooks distinguish between grammars and languages. After
reading many of the ``standard'' works one is left with the impression that
because a LALR(1)-based compiler generator is used then the ``language'' is
itself LALR(1). Though you can substitute your favourite parsing scheme for
LALR(1) as appropriate.


>I do not seem to come across a discussion regarding to
>the grammars accepted by operator-precedence and LL(1)
>(or recursive descent).


The dragon books (Green or Red) do not make this distinction. However, in
Tremblay and Sorenson there is a short$ comparison of parsing schemes. They
have a diagram which attempts to relate the various schemes together. I'll
try to reproduce their diagram here but you'd do better to refer to p410 of
``The Theory and Practice of Compiler Writing'' for better rendition.


                  Context-Free
                            |
                            +------------+
                            | |
              Unambiguous Operator
              Context-free Precedence
                            |
                        LR(k)
                            |
                            +------------------+
                            | |
                        LR(1) MSP
                            +-------+ |
                      LALR(1) | Extended Prec.
          +--------+ | |
          | SLR(1) +--------+ |
          | | | |
          | +---------------+| |
      LL(1) | Simple
                        LR(0) Precedence


>(1) What is the precise relationship between the two? (op prec and LL(1))


Hopefully their diagram puts them (and other schemes) into perspective.


--


Regards, Trevor.


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Trevor Jenkins
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      "We need bigger and better books", Jimmy Tingle (Damned in the USA)


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