Added EBNF choice handling
This commit is contained in:
152
tests/test_ebnf.py
Normal file
152
tests/test_ebnf.py
Normal file
@@ -0,0 +1,152 @@
|
||||
import pytest
|
||||
from sly import Lexer, Parser
|
||||
|
||||
class CalcLexer(Lexer):
|
||||
# Set of token names. This is always required
|
||||
tokens = { ID, NUMBER, PLUS, MINUS, TIMES, DIVIDE, ASSIGN, COMMA }
|
||||
literals = { '(', ')' }
|
||||
|
||||
# String containing ignored characters between tokens
|
||||
ignore = ' \t'
|
||||
|
||||
# Regular expression rules for tokens
|
||||
ID = r'[a-zA-Z_][a-zA-Z0-9_]*'
|
||||
PLUS = r'\+'
|
||||
MINUS = r'-'
|
||||
TIMES = r'\*'
|
||||
DIVIDE = r'/'
|
||||
ASSIGN = r'='
|
||||
COMMA = r','
|
||||
|
||||
@_(r'\d+')
|
||||
def NUMBER(self, t):
|
||||
t.value = int(t.value)
|
||||
return t
|
||||
|
||||
# Ignored text
|
||||
ignore_comment = r'\#.*'
|
||||
|
||||
@_(r'\n+')
|
||||
def newline(self, t):
|
||||
self.lineno += t.value.count('\n')
|
||||
|
||||
def error(self, t):
|
||||
self.errors.append(t.value[0])
|
||||
self.index += 1
|
||||
|
||||
def __init__(self):
|
||||
self.errors = []
|
||||
|
||||
|
||||
class CalcParser(Parser):
|
||||
tokens = CalcLexer.tokens
|
||||
|
||||
def __init__(self):
|
||||
self.names = { }
|
||||
self.errors = [ ]
|
||||
|
||||
@_('ID ASSIGN expr')
|
||||
def statement(self, p):
|
||||
self.names[p.ID] = p.expr
|
||||
|
||||
@_('ID "(" [ arglist ] ")"')
|
||||
def statement(self, p):
|
||||
return (p.ID, p.arglist)
|
||||
|
||||
@_('expr { COMMA expr }')
|
||||
def arglist(self, p):
|
||||
return [p.expr0, *p.expr1]
|
||||
|
||||
@_('expr')
|
||||
def statement(self, p):
|
||||
return p.expr
|
||||
|
||||
@_('term { PLUS|MINUS term }')
|
||||
def expr(self, p):
|
||||
lval = p.term0
|
||||
for op, rval in p[1]:
|
||||
if op == '+':
|
||||
lval = lval + rval
|
||||
elif op == '-':
|
||||
lval = lval - rval
|
||||
return lval
|
||||
|
||||
@_('factor { TIMES|DIVIDE factor }')
|
||||
def term(self, p):
|
||||
lval = p.factor0
|
||||
for op, rval in p[1]:
|
||||
if op == '*':
|
||||
lval = lval * rval
|
||||
elif op == '/':
|
||||
lval = lval / rval
|
||||
return lval
|
||||
|
||||
@_('MINUS factor')
|
||||
def factor(self, p):
|
||||
return -p.factor
|
||||
|
||||
@_("'(' expr ')'")
|
||||
def factor(self, p):
|
||||
return p.expr
|
||||
|
||||
@_('NUMBER')
|
||||
def factor(self, p):
|
||||
return int(p.NUMBER)
|
||||
|
||||
@_('ID')
|
||||
def factor(self, p):
|
||||
try:
|
||||
return self.names[p.ID]
|
||||
except LookupError:
|
||||
print(f'Undefined name {p.ID!r}')
|
||||
return 0
|
||||
|
||||
def error(self, tok):
|
||||
self.errors.append(tok)
|
||||
|
||||
|
||||
# Test basic recognition of various tokens and literals
|
||||
def test_simple():
|
||||
lexer = CalcLexer()
|
||||
parser = CalcParser()
|
||||
|
||||
result = parser.parse(lexer.tokenize('a = 3 + 4 * (5 + 6)'))
|
||||
assert result == None
|
||||
assert parser.names['a'] == 47
|
||||
|
||||
result = parser.parse(lexer.tokenize('3 + 4 * (5 + 6)'))
|
||||
assert result == 47
|
||||
|
||||
def test_ebnf():
|
||||
lexer = CalcLexer()
|
||||
parser = CalcParser()
|
||||
result = parser.parse(lexer.tokenize('a()'))
|
||||
assert result == ('a', None)
|
||||
|
||||
result = parser.parse(lexer.tokenize('a(2+3)'))
|
||||
assert result == ('a', [5])
|
||||
|
||||
result = parser.parse(lexer.tokenize('a(2+3, 4+5)'))
|
||||
assert result == ('a', [5, 9])
|
||||
|
||||
def test_parse_error():
|
||||
lexer = CalcLexer()
|
||||
parser = CalcParser()
|
||||
|
||||
result = parser.parse(lexer.tokenize('a 123 4 + 5'))
|
||||
assert result == 9
|
||||
assert len(parser.errors) == 1
|
||||
assert parser.errors[0].type == 'NUMBER'
|
||||
assert parser.errors[0].value == 123
|
||||
|
||||
# TO DO: Add tests
|
||||
# - error productions
|
||||
# - embedded actions
|
||||
# - lineno tracking
|
||||
# - various error cases caught during parser construction
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
Reference in New Issue
Block a user