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nqlgrammar.py
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nqlgrammar.py
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import pyparsing as pp
import nqlast as nql
def _grammar():
# "tokens"
integer_ = pp.Word(pp.nums).setName('integer').setParseAction(lambda t: int(t[0]))
reserved_words = {'while', 'proc', 'global', 'if', 'return', 'else', 'elsif', 'switch',
'case', 'break', 'default', 'true', 'false'}
identifier_ = pp.Word(pp.alphas, pp.alphanums + '_') \
.addCondition((lambda t: t[0] not in reserved_words), \
message='reserved word').setName('identifier')
if_ = pp.Keyword('if')
else_ = pp.Keyword('else')
elsif_ = pp.Keyword('elsif')
while_ = pp.Keyword('while')
proc_ = pp.Keyword('proc')
global_ = pp.Keyword('global')
return_ = pp.Keyword('return')
switch_ = pp.Keyword('switch')
case_ = pp.Keyword('case')
default_ = pp.Keyword('default')
break_ = pp.Keyword('break')
true_ = pp.Keyword('true')
false_ = pp.Keyword('false')
lt_ = pp.Literal('<') + ~pp.Literal('=')
gt_ = pp.Literal('>') + ~pp.Literal('=')
le_ = pp.Literal('<=')
ge_ = pp.Literal('>=')
eq_ = pp.Literal('==')
ne_ = pp.Literal('!=')
not_ = pp.Literal('!') + ~pp.Literal('=')
and_ = pp.Literal('&&')
or_ = pp.Literal('||')
times_ = pp.Literal('*')
div_ = pp.Literal('/')
monus_ = pp.Literal('-')
equal_ = pp.Literal('=') + ~pp.Literal('=')
plus_ = pp.Literal('+')
semi_ = pp.Literal(';')
colon_ = pp.Suppress(':')
lpar_ = pp.Suppress('(')
rpar_ = pp.Suppress(')')
lbra_ = pp.Suppress('{')
rbra_ = pp.Suppress('}')
expr = pp.Forward()
# expression grammar
def a(action):
def wrapper(s,l,t):
# print(t)
return action(pp.lineno(l,s), t)
return wrapper
pri_int = integer_().setParseAction(a(lambda l,t: nql.Lit(lineno=l, value=int(t[0]))))
pri_reg = identifier_().setParseAction(a(lambda l,t: nql.Reg(lineno=l, name=t[0])))
pri_true = true_().setParseAction(lambda t: nql.TrueConst())
pri_false = false_().setParseAction(lambda t: nql.FalseConst())
pri_paren = (lpar_ + expr + rpar_)
pri_expr = pri_int | pri_true | pri_false | pri_reg | pri_paren
def callop(op, line, *children):
if isinstance(op, type):
return op(lineno=line, children=list(children))
else:
return op(line, *children)
def binop_level(prev, assoc, name, op_list):
def dobinop(line,lhs,op,rhs):
return callop(op, line, lhs, rhs)
def associate(s,l,t):
t = list(t)
line = pp.lineno(l, s)
while len(t) > 1:
if assoc == 'none':
if len(t) != 3:
raise pp.ParseException(s, l, name+' is not associative')
t[0:3] = [dobinop(line, *t[0:3])]
elif assoc == 'left':
t[0:3] = [dobinop(line, *t[0:3])]
elif assoc == 'right':
t[-4:-1] = [dobinop(line, *t[-4:-1])]
else:
assert not "unhandled associativity"
return t[0]
return (prev + pp.ZeroOrMore(op_list + prev)).setParseAction(associate).setName(name)
def prefix_level(prev, name, op_list):
def associate(s, l, t):
t = list(t)
while len(t) > 1:
t[-3:-1] = [callop(t[-2], pp.lineno(l, s), t[-1])]
return t[0]
return (pp.ZeroOrMore(op_list) + prev).setParseAction(associate).setName(name)
mul_multiply = times_().setParseAction(lambda t: nql.Mul)
mul_div = div_().setParseAction(lambda t: nql.Div)
mul_expr = binop_level(pri_expr, 'left', 'multiplicative expression', mul_multiply ^ mul_div)
add_add = plus_().setParseAction(lambda t: nql.Add)
add_monus = monus_().setParseAction(lambda t: nql.Monus)
add_expr = binop_level(mul_expr, 'left', 'additive expression', add_add ^ add_monus)
rel_less = lt_().setParseAction(lambda t: nql.Less)
rel_greater = gt_().setParseAction(lambda t: nql.Greater)
rel_lessequal = le_().setParseAction(lambda t: nql.LessEqual)
rel_greaterequal = ge_().setParseAction(lambda t: nql.GreaterEqual)
rel_equal = eq_().setParseAction(lambda t: nql.Equal)
rel_notequal = ne_().setParseAction(lambda t: nql.NotEqual)
rel_expr = binop_level(add_expr, 'none', 'relational expression', rel_less ^ rel_greater ^ rel_lessequal ^ rel_greaterequal ^ rel_equal ^ rel_notequal)
and_and = and_().setParseAction(lambda t: nql.And)
and_expr = binop_level(rel_expr, 'left', 'and', and_and)
or_or = or_().setParseAction(lambda t: nql.Or)
or_expr = binop_level(and_expr, 'left', 'or', or_or)
not_not = not_().setParseAction(lambda t: nql.Not)
not_expr = prefix_level(or_expr, 'not expression', not_not)
expr << not_expr
# statement grammar
stmt = pp.Forward()
block = (lbra_ + pp.ZeroOrMore(stmt) + rbra_).setParseAction(a(lambda l,t: nql.Block(lineno=l, children=list(t))))
st_whileloop = (while_ - lpar_ - expr - rpar_ - block).setParseAction(a(lambda l,t: nql.WhileLoop(lineno=l, children=[t[1],t[2]])))
else_chain = pp.Forward()
else_none = pp.Empty().setParseAction(lambda t: nql.Block())
else_else = (else_ - block).setParseAction(lambda t: t[1])
else_elsif = (elsif_ - lpar_ - expr - rpar_ - block - else_chain).setParseAction(a(lambda l,t: nql.IfThen(lineno=l, children=[t[1],t[2],t[3]])))
else_chain << (else_else ^ else_elsif ^ else_none)
st_if = (if_ - lpar_ - expr - rpar_ - block - else_chain).setParseAction(a(lambda l,t: nql.IfThen(lineno=l, children=[t[1], t[2], t[3]])))
st_assignment = (identifier_ + equal_ + expr + semi_).setParseAction(a(lambda l,t: nql.Assign(lineno=l, children=[nql.Reg(lineno=l, name=t[0]), t[2]])))
arglist = (lpar_ + pp.Optional(pp.delimitedList(identifier_)) + rpar_).setParseAction(lambda t: [list(t)])
st_proccall = (identifier_ + arglist + semi_).setParseAction(a(lambda l,t: nql.Call(lineno=l, func=t[0], children=[nql.Reg(lineno=l, name=arg) for arg in t[1]])))
st_return = (return_ + semi_).setParseAction(a(lambda l,t: nql.Return(lineno=l)))
st_break = (break_ + semi_).setParseAction(a(lambda l,t: nql.Break(lineno=l)))
case_arm = (case_ - integer_ - colon_ - pp.ZeroOrMore(stmt)).setParseAction(a(lambda l,t: nql.SwitchArm(lineno=l, case=t[1], children=list(t)[2:])))
def_arm = (default_ - colon_ - pp.ZeroOrMore(stmt)).setParseAction(a(lambda l,t: nql.SwitchArm(lineno=l, case=None, children=list(t)[1:])))
st_switch = (switch_ - lpar_ - expr - rpar_ - lbra_ - pp.ZeroOrMore(case_arm | def_arm) - rbra_) \
.setParseAction(a(lambda l,t: nql.Switch(lineno=l, children=list(t)[1:])))
stmt << (st_whileloop | st_if | st_switch | st_assignment | st_return | st_break | st_proccall | block)
# top level
procdef = (proc_ - identifier_ - arglist - block).setParseAction(a(lambda l,t: nql.ProcDef(lineno=l, name=t[1], parameters=t[2], children=[t[3]])))
globaldef = (global_ - identifier_ - semi_).setParseAction(a(lambda l,t: nql.GlobalReg(lineno=l, name=t[1])))
decl = procdef | globaldef
program = pp.ZeroOrMore(decl).setParseAction(a(lambda l,t: nql.Program(lineno=l, children=list(t))))
program.ignore(pp.cStyleComment)
program.enablePackrat()
return program
grammar = _grammar()