cliff@.UCalgary.CA (Cliff Marcellus) (11/26/89)
Hello Fellow MIPSers, Has anyone else out there had opportunity to write a compiler using the MIPS version of YACC(1)??? I for one, would just like to say "bravo!" to the person(s) at MIPS responsible for generating this version! It performs better (ie. faster and has better error recovey) and has a wonderful debug mode (kicking out not only, "shift" and "reduce" conditions, but the productions in use also!) Well now the (not so) down side... does anyone know what a configuration in a state of the form : expression : expression PLUSOP $$56 error means? (I don't know what "$$56" is supposed to do for me, and it's not in the documentation -- at least I can't find it.) Many Thanks! Cliff -- Cliff Marcellus UUCP : {any backbone}!calgary!ssg-vax-a!cliff Dept of Physics and Astronomy DOMAIN : cliff@ssg-vax-a.phys.UCalgary.CA The University of Calgary SPAN : CANCAL::CLIFF OPINIONS WITHIN ARE MY OWN AND DO NOT REFLECT THOSE OF THE UNIVERSITY OF CALGARY
lai@mips.COM (David Lai) (11/30/89)
In article <2168@cs-spool.calgary.UUCP> cliff@.UCalgary.CA (Cliff Marcellus) writes: > > Well now the (not so) down side... does anyone know what a configuration > in a state of the form : > > expression : expression PLUSOP $$56 error > > means? (I don't know what "$$56" is supposed to do for me, and it's > not in the documentation -- at least I can't find it.) >-- >Cliff Marcellus UUCP : {any backbone}!calgary!ssg-vax-a!cliff >Dept of Physics and Astronomy DOMAIN : cliff@ssg-vax-a.phys.UCalgary.CA >The University of Calgary SPAN : CANCAL::CLIFF The $$56 is a generated reduction resulting from an action embedded in the reduction rule, ie: expression: expression PLUSOP { a=12; b=13; $$=100; } error { $$ = $3; } ; would be translated to two reductions: expression: expression PLUSOP $$1 error { $$=$3; } ; $$1: { a=12; b=13; $$=100; } ; The value of $$1 in the first rule's action ($3) is the value assigned to $$ in the second rule's action. -- "What is a DJ if he can't scratch?" - Uncle Jamms Army David Lai (lai@mips.com || {ames,prls,pyramid,decwrl}!mips!lai)