StackStorm /
st2
| Conditions | 12 |
| Total Lines | 88 |
| Lines | 0 |
| Ratio | 0 % |
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Small methods make your code easier to understand, in particular if combined with a good name. Besides, if your method is small, finding a good name is usually much easier.
For example, if you find yourself adding comments to a method's body, this is usually a good sign to extract the commented part to a new method, and use the comment as a starting point when coming up with a good name for this new method.
Commonly applied refactorings include:
If many parameters/temporary variables are present:
Complex classes like ActionAliasFormatParser.get_extracted_param_value() often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
| 1 | # Licensed to the StackStorm, Inc ('StackStorm') under one or more |
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| 34 | def get_extracted_param_value(self): |
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| 35 | """ |
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| 36 | Match command against the format string and extract paramters from the command string. |
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| 37 | |||
| 38 | :rtype: ``dict`` |
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| 39 | """ |
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| 40 | result = {} |
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| 41 | |||
| 42 | param_stream = self._param_stream |
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| 43 | |||
| 44 | # As there's a lot of questions about using regular expressions, |
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| 45 | # I'll try to be thorough when documenting this code. |
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| 46 | |||
| 47 | # I'll split the whole convoluted regex into snippets to make it |
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| 48 | # a bit more readable (hopefully). |
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| 49 | snippets = dict() |
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| 50 | |||
| 51 | # Formats for keys and values: key is a non-spaced string, |
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| 52 | # value is anything in quotes or curly braces, or a single word. |
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| 53 | snippets['key'] = r'\s*(\S+?)\s*' |
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| 54 | snippets['value'] = r'""|\'\'|"(.+?)"|\'(.+?)\'|({.+?})|(\S+)' |
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| 55 | |||
| 56 | # Extended value: also matches unquoted text (caution). |
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| 57 | snippets['ext_value'] = r'""|\'\'|"(.+?)"|\'(.+?)\'|({.+?})|(.+?)' |
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| 58 | |||
| 59 | # Key-value pair: |
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| 60 | snippets['pairs'] = r'(?:^|\s+){key}=({value})'.format(**snippets) |
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| 61 | |||
| 62 | # End of string: multiple space-separated key-value pairs: |
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| 63 | snippets['ending'] = r'.*?(({pairs}\s*)*)$'.format(**snippets) |
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| 64 | |||
| 65 | # Default value in optional parameters: |
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| 66 | snippets['default'] = r'\s*=\s*(?:{ext_value})\s*'.format(**snippets) |
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| 67 | |||
| 68 | # Optional parameter (has a default value): |
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| 69 | snippets['optional'] = '{{' + snippets['key'] + snippets['default'] + '}}' |
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| 70 | |||
| 71 | # Required parameter (no default value): |
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| 72 | snippets['required'] = '{{' + snippets['key'] + '}}' |
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| 73 | |||
| 74 | # 1. Matching the arbitrary key-value pairs at the end of the command |
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| 75 | # to support extra parameters (not specified in the format string), |
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| 76 | # and cutting them from the command string afterwards. |
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| 77 | ending_pairs = re.match(snippets['ending'], param_stream, re.DOTALL) |
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| 78 | has_ending_pairs = ending_pairs and ending_pairs.group(1) |
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| 79 | if has_ending_pairs: |
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| 80 | kv_pairs = re.findall(snippets['pairs'], ending_pairs.group(1), re.DOTALL) |
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| 81 | param_stream = param_stream.replace(ending_pairs.group(1), '') |
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| 82 | param_stream = " %s " % (param_stream) |
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| 83 | |||
| 84 | # 2. Matching optional parameters (with default values). |
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| 85 | optional = re.findall(snippets['optional'], self._format, re.DOTALL) |
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| 86 | |||
| 87 | # Transforming our format string into a regular expression, |
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| 88 | # substituting {{ ... }} with regex named groups, so that param_stream |
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| 89 | # matched against this expression yields a dict of params with values. |
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| 90 | param_match = r'\1["\']?(?P<\2>(?:(?<=\').+?(?=\')|(?<=").+?(?=")|{.+?}|.+?))["\']?' |
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| 91 | reg = re.sub(r'(\s*)' + snippets['optional'], r'(?:' + param_match + r')?', self._format) |
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| 92 | reg = re.sub(r'(\s*)' + snippets['required'], param_match, reg) |
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| 93 | reg = '^\s*' + reg + r'\s*$' |
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| 94 | |||
| 95 | # 3. Matching the command against our regex to get the param values |
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| 96 | matched_stream = re.match(reg, param_stream, re.DOTALL) |
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| 97 | |||
| 98 | if not matched_stream: |
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| 99 | # If no match is found we throw since this indicates provided user string (command) |
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| 100 | # didn't match the provided format string |
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| 101 | raise ParseException('Command "%s" doesn\'t match format string "%s"' % |
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| 102 | (self._param_stream, self._format)) |
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| 103 | |||
| 104 | # Compiling results from the steps 1-3. |
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| 105 | if matched_stream: |
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| 106 | result = matched_stream.groupdict() |
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| 107 | |||
| 108 | for param in optional: |
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| 109 | matched_value = result[param[0]] if matched_stream else None |
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| 110 | matched_result = matched_value or ''.join(param[1:]) |
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| 111 | if matched_result is not None: |
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| 112 | result[param[0]] = matched_result |
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| 113 | |||
| 114 | if has_ending_pairs: |
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| 115 | for pair in kv_pairs: |
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| 116 | result[pair[0]] = ''.join(pair[2:]) |
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| 117 | |||
| 118 | if self._format and not (self._param_stream.strip() or any(result.values())): |
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| 119 | raise ParseException('No value supplied and no default value found.') |
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| 120 | |||
| 121 | return result |
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| 122 | |||
| 145 |
Escape sequences in Python are generally interpreted according to rules similar to standard C. Only if strings are prefixed with
rorRare they interpreted as regular expressions.The escape sequence that was used indicates that you might have intended to write a regular expression.
Learn more about the available escape sequences. in the Python documentation.