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First working LISP parser

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This commit is contained in:
David Schmenk 2024-06-27 14:41:06 -07:00
parent b8d300f9f9
commit 0baad05c04
1 changed files with 77 additions and 52 deletions
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129
src/toolsrc/drawl.pla
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@ -23,7 +23,8 @@ struc t_sym
char[0] name
end
predef print(s_expr)#0
predef parse_expr(evalptr, depth)#2
predef print(s_expr)
def new_cons
var consptr
@ -86,6 +87,24 @@ def parse_sym(evalptr)#2 // return evalptr, symptr
return evalptr, new_sym(symptr, evalptr - symptr)
end
def parse_elem(evalptr, depth)#2 // return evalptr, exprptr
var elemptr
if ^evalptr == '('
evalptr++
evalptr, elemptr = parse_expr(evalptr, depth + 1)
elsif (^evalptr == '-' and is_num(^(evalptr+1))) or is_num(^evalptr)
evalptr, elemptr = parse_num(evalptr)
elsif is_alphasym(^evalptr)
evalptr, elemptr = parse_sym(evalptr)
else
putc('\\')
putc(^evalptr)
evalptr++
fin
return evalptr, elemptr
end
def parse_expr(evalptr, depth)#2 // return evalptr, exprptr
var exprptr, consptr, elemptr
@ -112,27 +131,33 @@ def parse_expr(evalptr, depth)#2 // return evalptr, exprptr
is ' '
evalptr++
break
is '('
evalptr++
evalptr, elemptr = parse_expr(evalptr, depth + 1)
break
is ')'
putln
return evalptr, exprptr
otherwise
return evalptr + 1, exprptr
is '('
evalptr++
if depth == 0
puts("Invalid S-Expression\n")
^evalptr = 0
depth++
else
evalptr, elemptr = parse_expr(evalptr, depth + 1)
fin
break
is '.'
evalptr++
evalptr, elemptr = parse_expr(evalptr, 0)
//
// Add expression to CDR
//
if not (consptr and consptr=>car)
puts("Invalid . operator\n")
return evalptr, NULL
fin
if (^evalptr == '-' and is_num(^(evalptr+1))) or is_num(^evalptr)
evalptr, elemptr = parse_num(evalptr)
elsif is_alphasym(^evalptr)
evalptr, elemptr = parse_sym(evalptr)
else
putc('\\')
putc(^evalptr)
evalptr++
consptr=>cdr = elemptr
return evalptr, exprptr
otherwise
evalptr, elemptr = parse_elem(evalptr, depth)
if depth == 0
return evalptr, elemptr
fin
wend
if elemptr
@ -140,15 +165,13 @@ def parse_expr(evalptr, depth)#2 // return evalptr, exprptr
// Add element to S-expression
//
if not consptr
consptr = elemptr
consptr = new_cons
exprptr = consptr
else
if consptr=>car
consptr=>cdr = new_cons
consptr = consptr=>cdr
fin
consptr=>car = elemptr
consptr=>cdr = new_cons
consptr = consptr=>cdr
fin
consptr=>car = elemptr
fin
loop
return evalptr, exprptr
@ -173,37 +196,39 @@ end
def print_elem(s_expr)#0
byte t
when s_expr->type & TYPE_MASK
is CONS_TYPE
print(s_expr)
break
is NUM_TYPE
puti(s_expr=>val)
break
is SYM_TYPE
t = s_expr->type
s_expr->type = t & SYM_LEN
puts(s_expr + type)
s_expr->type = t
break;
is NULL
puts("NIL")
wend
if not s_expr
puts("NIL")
else
when s_expr->type & TYPE_MASK
is CONS_TYPE
print(s_expr)
break
is NUM_TYPE
puti(s_expr=>val)
break
is SYM_TYPE
t = s_expr->type
s_expr->type = t & SYM_LEN
puts(s_expr + type)
s_expr->type = t
break;
wend
fin
end
def print(s_expr)#0
putc('(')
while s_expr
if s_expr->type == CONS_TYPE
print_elem(s_expr=>car)
s_expr = s_expr=>cdr
else
print_elem(s_expr)
s_expr = NULL
fin
loop
putc(')')
def print(s_expr)
if not s_expr; return FALSE; fin
if s_expr->type == CONS_TYPE
putc('(')
print_elem(s_expr=>car)
putc('.')
print_elem(s_expr=>cdr)
putc(')')
else
print_elem(s_expr)
fin
return TRUE
end
while print(eval(read)); loop
while print(eval(read)); putln; loop
done