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include defs
# PARSE - parse Ratfor source program
subroutine parse
include COMMON_BLOCKS
character lexstr(MAXTOK)
integer lab, labval(MAXSTACK), lextyp(MAXSTACK), sp, token, i, t
integer lex
logical push_stack
sp = 1
lextyp(1) = EOF
for (token = lex(lexstr); token != EOF; token = lex(lexstr)) {
push_stack = .false.
switch (token) {
case LEXIF:
call ifcode (lab)
push_stack = .true.
case LEXIFERR:
call iferrc (lab, 1)
push_stack = .true.
case LEXIFNOERR:
call iferrc (lab, 0)
push_stack = .true.
case LEXDO:
call docode (lab)
push_stack = .true.
case LEXWHILE:
call whilec (lab)
push_stack = .true.
case LEXFOR:
call forcod (lab)
push_stack = .true.
case LEXREPEAT:
call repcod (lab)
push_stack = .true.
case LEXSWITCH:
call swcode (lab)
push_stack = .true.
case LEXCASE, LEXDEFAULT:
for (i=sp; i > 0; i=i-1) # find for most recent switch
if (lextyp(i) == LEXSWITCH)
break
if (i == 0)
call synerr ("illegal case or default.")
else
call cascod (labval (i), token)
case LEXDIGITS:
call labelc (lexstr)
push_stack = .true.
case LEXELSE:
t = lextyp(sp)
if (t == LEXIF | t == LEXIFERR | t == LEXIFNOERR)
call elseif (labval(sp))
else
call synerr ("Illegal else.")
t = lex (lexstr) # check for "else if"
call pbstr (lexstr)
if (t == LEXIF | t == LEXIFERR | t == LEXIFNOERR) {
call indent (-1) # cancel out indent +1
token = LEXIFELSE # prevent -indent at end
}
push_stack = .true.
case LEXTHEN:
if (lextyp(sp) == LEXIFERR | lextyp(sp) == LEXIFNOERR) {
call thenco (lextyp(sp), labval(sp))
lab = labval(sp)
token = lextyp(sp)
sp = sp - 1 # cancel out subsequent push
} else
call synerr ("Illegal 'then' clause in iferr statement.")
push_stack = .true.
case LEXLITERAL:
call litral
case LEXERRCHK:
call errchk
case LEXBEGIN:
call beginc
case LEXEND:
call endcod (lexstr)
if (sp != 1) {
call synerr ("Missing right brace or 'begin'.")
sp = 1
}
default:
if (token == LBRACE)
push_stack = .true.
else if (token == LEXDECL)
call declco (lexstr)
}
if (push_stack) {
if (body == NO) {
call synerr ("Missing 'begin' keyword.")
call beginc
}
sp = sp + 1 # beginning of statement
if (sp > MAXSTACK)
call baderr ("Stack overflow in parser.")
lextyp(sp) = token # stack type and value
labval(sp) = lab
} else if (token != LEXCASE & token != LEXDEFAULT) {
if (token == RBRACE)
token = LEXRBRACE
switch (token) {
case LEXOTHER:
call otherc (lexstr)
case LEXBREAK, LEXNEXT:
call brknxt (sp, lextyp, labval, token)
case LEXRETURN:
call retcod
case LEXGOTO:
call gocode
case LEXSTRING:
if (body == NO)
call strdcl
else
call otherc (lexstr)
case LEXRBRACE:
if (lextyp(sp) == LBRACE)
sp = sp - 1
else if (lextyp(sp) == LEXSWITCH) {
call swend (labval(sp))
sp = sp - 1
} else
call synerr ("Illegal right brace.")
}
token = lex (lexstr) # peek at next token
call pbstr (lexstr)
call unstak (sp, lextyp, labval, token)
}
}
if (sp != 1)
call synerr ("unexpected EOF.")
end
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