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parser.py
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80 lines (77 loc) · 2.29 KB
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from constants import *
def escaped(c):
if c == 'n':
return '\n'
elif c == 't':
return '\t'
elif c == '0':
return '\0'
return c
def _parse(s, i, enddelim):
l = []
while i < len(s) and s[i] not in enddelim:
while i < len(s) and s[i] in " \t\n":
i += 1
if i >= len(s):
break
if s[i] == "(":
parsed, i = _parse(s, i + 1, ")")
l.append((PARSED_CALL, parsed))
i += 1
elif s[i] == "{":
parsed, i = _parse(s, i + 1, "}")
l.append((PARSED_CALL, ((PARSED_IDENT, "cons"),) + parsed))
i += 1
elif s[i] == "#": # Comment
i += 1
while i < len(s) and s[i] != "\n":
i += 1
elif s[i] == "[": # List
parsed, i = _parse(s, i + 1, "]")
i += 1
u = (PARSED_IDENT, "[]")
for x in reversed(parsed):
u = (PARSED_CALL, ((PARSED_IDENT, "cons"), x, u))
l.append(u)
elif s[i] == "'": # Char
i += 1
if s[i] == "\\":
i += 1
c = escaped(s[i])
else:
c = s[i]
l.append((PARSED_CHAR, c))
i += 2
elif s[i] == '"': # String
i += 1
u = []
while s[i] != '"':
if s[i] == "\\":
c = escaped(s[i + 1])
i += 2
else:
c = s[i]
i += 1
u.append((TYPE_CHAR, c))
i += 1
z = (TYPE_NIL,)
for x in reversed(u):
z = (TYPE_CONS, (x, z))
l.append((PARSED_CONSTANT, z))
else:
a = ""
while i < len(s) and s[i] not in " \t\n" and s[i] not in enddelim:
a += s[i]
i += 1
if a != "":
try:
u = (PARSED_INT, int(a))
except:
if a in ["let", "let*", "letrec", "letrec*", "if"]:
u = (PARSED_KEYWORD, a)
else:
u = (PARSED_IDENT, a)
l.append(u)
return tuple(l), i
def parse(s):
return _parse(s, 0, "\0")[0]