Compiler Construction
Explain how a parse-tree representation of a program may be converted into a
stack-based intermediate language giving sketches of code to translate expressions,
assignments and the if-then-else command; you should also explain how
occurrences of a variable in an expression or assignment are translated.
The program may be assumed to conform to the following syntax:
E -> n | x | E + E | f(E,E)
D -> let f(x,x) = {Dseq; Cseq; E} | let x = E
C -> x := E; | if E then C else C
Cseq -> C | C Cseq
Dseq -> D | D Dseq
with start symbol Dseq. Here n corresponds to integer constants, x corresponds to
identifiers used as variable names and f corresponds to identifiers used as function
names (you may assume these are disjoint). The function declaration construct
has the effect of defining a function which, when called, makes declarations,
performs commands and then returns the result of its expression; note that therefore
functions may be defined within functions, but the above restriction on identifiers
means that they cannot be returned as results. [20 marks]