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Added support for negative variables in the tokenizer and ptoken object.

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glm94
2020-04-26 18:17:40 -05:00
parent 350021a42b
commit dcf8a50f34
3 changed files with 20 additions and 8 deletions
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tokenizer.py
+18 -6
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@@ -9,6 +9,7 @@ def get_tokens_from_expression_string(expression_string):
tmp = ""
parsing_number = False
symbols_dic = {} # Dictionary to keep track of the no. of times each variable appears.
variable_is_negative = False
for i in range(0, len(expression_string)):
c = expression_string[i]
@@ -26,8 +27,7 @@ def get_tokens_from_expression_string(expression_string):
continue
elif c == '-' and not parsing_number:
if expression_string[i + 1] == '.' or expression_string[i + 1].isdigit():
print(tokens[-1].value)
if expression_string[i + 1] == '.' or expression_string[i + 1].isdigit():
if token.TokenType.get_operator(tokens[-1].value) != token.TokenType.unknown:#tokens[-1].type == token.TokenType
#print(tokens[-1].value)
#tokens.append(token.Token('+', token.TokenType.add))
@@ -40,6 +40,10 @@ def get_tokens_from_expression_string(expression_string):
tokens.append(token.Token(c, token.TokenType.get_operator(c)))
parsing_number = False
tmp = ""
elif expression_string[i + 1].isalpha():
#Must be a variable.
if tokens[-1].type == token.TokenType.exp_start:
variable_is_negative = True
else:
tokens.append(token.Token(c, token.TokenType.get_operator(c)))
parsing_number = False
@@ -71,7 +75,7 @@ def get_tokens_from_expression_string(expression_string):
if len(tokens) > 1:
lookBehind = tokens[-1]
if lookBehind.type == token.TokenType.exp_end:
tokens.append(token.Token("^", token.TokenType.power))
tokens.append(token.Token("^", token.TokenType.power))
if (i + 1) < len(expression_string):
lookAHead = expression_string[i + 1]
@@ -88,7 +92,8 @@ def get_tokens_from_expression_string(expression_string):
symbols_dic[c] += 1
else:
symbols_dic[c] = 1
tokens.append(token.Token(c + str(symbols_dic[c]), token.TokenType.variable))
tokens.append(token.Token(c + str(symbols_dic[c]), token.TokenType.variable, variable_is_negative))
variable_is_negative = False
parsing_number = False
tmp = ""
@@ -104,7 +109,10 @@ def replace_variables(tokens, new_constants):
newTokenList = []
for t in tokens:
if t.type == token.TokenType.variable:
newTokenList.append(token.Token(new_constants.pop(0), token.TokenType.constant))
if not t.is_negative_variable:
newTokenList.append(token.Token(new_constants.pop(0), token.TokenType.constant))
else:
newTokenList.append(token.Token(new_constants.pop(0) * -1, token.TokenType.constant))
else:
newTokenList.append(token.Token(t.value, t.type))
@@ -112,7 +120,11 @@ def replace_variables(tokens, new_constants):
def print_token_list(tokens):
for tk in tokens:
print("%s " %(tk.value), end = "")#, token.TokenType.get_token_type_name(tk.type)), end = "")
if tk.type == token.TokenType.variable:
if tk.is_negative_variable:
print("-%s " %(tk.value), end = "")
else:
print("%s " %(tk.value), end = "")
print()
def stringify_token_list(tokens):