def declarations(allocVar):
while SC.sym == CONST:
getSym()
if SC.sym == IDENT: ident = SC.val; getSym()
else: mark("constant name expected")
if SC.sym == EQ: getSym()
else: mark("= expected")
x = expression()
if type(x) == Const: newDecl(ident, x)
else: mark('expression not constant')
while SC.sym == TYPE:
getSym()
if SC.sym == IDENT: ident = SC.val; getSym()
else: mark("type name expected")
if SC.sym == EQ: getSym()
else: mark("= expected")
x = typ(); newDecl(ident, x) # x is of type ST.Type
start = len(topScope())
while SC.sym == VAR:
getSym(); typedIds()
var = allocVar(topScope(), start)
while SC.sym == PROCEDURE:
getSym()
if SC.sym == LPAREN:
getSym()
if SC.sym == IDENT: r = SC.val; getSym()
else: mark("identifier expected")
if SC.sym == COLON: getSym()
else: mark("':' expected")
tp = typ().val
if SC.sym == RPAREN: getSym()
else: mark(") expected")
else: r = None
if SC.sym == IDENT: ident = SC.val; getSym()
else: mark("procedure name expected")
newDecl(ident, Proc([], [])) # entered without parameters
sc = topScope(); openScope() # new scope for parameters and body
if r: newDecl(r, Var(tp))
if SC.sym == LPAREN: getSym()
else: mark("( expected")
if SC.sym == IDENT: typedIds()
fp = topScope()
if SC.sym == RPAREN: getSym()
else: mark(") expected")
d = len(fp)
if SC.sym == RARROW:
getSym()
if SC.sym == LPAREN: getSym()
else: mark('( expected')
typedIds()
if SC.sym == RPAREN: getSym()
else: mark(') expected')
sc[-1].par, sc[-1].res = fp[:d], fp[d:] # procedure parameters updated
para = CG.genProcStart(ident, fp[:d], fp[d:])
body(ident, para); closeScope() # scope for parameters and body closed
return var
def typedIds(kind):
if SC.sym == IDENT:
tid = [SC.val]
getSym()
else:
mark("identifier expected")
tid = []
while SC.sym == COMMA:
getSym()
if SC.sym == IDENT:
tid.append(SC.val)
getSym()
else:
mark('identifier expected')
if SC.sym == COLON:
getSym()
tp = typ().val
if tp != None:
for i in tid:
newDecl(i, kind(tp))
else:
mark("':' expected")
def typedIds():
if SC.sym == IDENT: tid = [SC.val]; getSym()
else: mark("identifier expected")
while SC.sym == COMMA:
getSym()
if SC.sym == IDENT: tid.append(SC.val); getSym()
else: mark('identifier expected')
if SC.sym == COLON: getSym()
else: mark("':' expected")
tp = typ().val
for i in tid: newDecl(i, Var(tp))
while SC.sym == COMMA:
getSym()
if SC.sym == IDENT: tid = [SC.val]; getSym()
else: mark("identifier expected")
while SC.sym == COMMA:
getSym()
if SC.sym == IDENT: tid.append(SC.val); getSym()
else: mark('identifier expected')
if SC.sym == COLON: getSym()
else: mark("':' expected")
tp = typ().val
for i in tid: newDecl(i, Var(tp))
def program():
newDecl('boolean', Type(CG.genBool(Bool)))
newDecl('integer', Type(CG.genInt(Int)))
newDecl('true', Const(Bool, 1))
newDecl('false', Const(Bool, 0))
newDecl('read', StdProc([], [Var(Int)]))
newDecl('write', StdProc([Var(Int)], []))
newDecl('writeln', StdProc([], []))
CG.genProgStart()
declarations(CG.genGlobalVars)
if SC.sym == PROGRAM: getSym()
else: mark("'program' expected")
ident = SC.val
if SC.sym == IDENT: getSym()
else: mark('program name expected')
openScope(); CG.genProgEntry(ident); x = body(ident, 0)
closeScope(); x = CG.genProgExit(x)
return x
def program():
newDecl('boolean', Type(CG.genBool(Bool)))
newDecl('integer', Type(CG.genInt(Int)))
newDecl('true', Const(Bool, 1))
newDecl('false', Const(Bool, 0))
newDecl('read', StdProc([Ref(Int)]))
newDecl('write', StdProc([Var(Int)]))
newDecl('writeln', StdProc([]))
CG.genProgStart()
if SC.sym == PROGRAM:
getSym()
else:
mark("'program' expected")
ident = SC.val
if SC.sym == IDENT:
getSym()
else:
mark('program name expected')
if SC.sym == SEMICOLON:
getSym()
else:
mark('; expected')
declarations(CG.genGlobalVars)
CG.genProgEntry(ident)
x = compoundStatement()
return CG.genProgExit(x)
def declarations(allocVar):
if SC.sym not in FIRSTDECL | FOLLOWDECL:
getSym()
mark("'begin' or declaration expected")
while SC.sym not in FIRSTDECL | STRONGSYMS | FOLLOWDECL:
getSym()
while SC.sym == CONST:
getSym()
if SC.sym == IDENT:
ident = SC.val
getSym()
if SC.sym == EQ:
getSym()
else:
mark("= expected")
x = expression()
if type(x) == Const:
newDecl(ident, x)
else:
mark('expression not constant')
else:
mark("constant name expected")
if SC.sym == SEMICOLON:
getSym()
else:
mark("; expected")
while SC.sym == TYPE:
getSym()
if SC.sym == IDENT:
ident = SC.val
getSym()
if SC.sym == EQ:
getSym()
else:
mark("= expected")
x = typ()
newDecl(ident, x) # x is of type ST.Type
if SC.sym == SEMICOLON:
getSym()
else:
mark("; expected")
else:
mark("type name expected")
start = len(topScope())
while SC.sym == VAR:
getSym()
typedIds(Var)
if SC.sym == SEMICOLON:
getSym()
else:
mark("; expected")
varsize = allocVar(topScope(), start)
while SC.sym == PROCEDURE:
getSym()
if SC.sym == IDENT:
getSym()
else:
mark("procedure name expected")
ident = SC.val
newDecl(ident, Proc([])) # entered without parameters
sc = topScope()
CG.genProcStart()
openScope() # new scope for parameters and body
if SC.sym == LPAREN:
getSym()
if SC.sym in {VAR, IDENT}:
if SC.sym == VAR:
getSym()
typedIds(Ref)
else:
typedIds(Var)
while SC.sym == SEMICOLON:
getSym()
if SC.sym == VAR:
getSym()
typedIds(Ref)
else:
typedIds(Var)
else:
mark("formal parameters expected")
fp = topScope()
sc[-1].par = fp[:] # procedure parameters updated
if SC.sym == RPAREN:
getSym()
else:
mark(") expected")
else:
fp = []
parsize = CG.genFormalParams(fp)
if SC.sym == SEMICOLON:
getSym()
else:
mark("; expected")
localsize = declarations(CG.genLocalVars)
CG.genProcEntry(ident, parsize, localsize)
x = compoundStatement()
CG.genProcExit(x, parsize, localsize)
closeScope() # scope for parameters and body closed
if SC.sym == SEMICOLON:
getSym()
else:
mark("; expected")
return varsize