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Implement a ruleChecker to flow applied
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,89 @@ | ||
| package rules | ||
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| import ( | ||
| "regexp" | ||
| "fmt" | ||
| "errors" | ||
| ) | ||
|
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| // rules package defines a rule checker system. | ||
| // It checks the rule for a key and a value. The value is returned by a get function. | ||
| // | ||
| // a rule is a string formatted with following syntax and meaning: | ||
| // - '<key>:<value>' or '<key>=<value>' - True if key has value equal to <value>. '<key>:<value>' is kept for compatibility but is obsolete. | ||
| // - '<key>!=<value>' - True if key has a value NOT equal to <value> | ||
| // - '<key>=/<regexp>/' - True if key has value respecting <regexp>. | ||
| // - '<key>!=/<regexp>/' - True if key has a value NOT respecting <regexp> | ||
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| // RuleChecker is the core Object to manage a rule check. | ||
| type RuleChecker struct { | ||
| ruleRE *regexp.Regexp | ||
| ruleToCheck []string | ||
| key, op, value string | ||
| } | ||
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| // NewRuleChecker returns a RuleChecker object | ||
| func NewRuleChecker() (ret *RuleChecker) { | ||
| ret = new(RuleChecker) | ||
| ret.ruleRE, _ = regexp.Compile(`^(.*?)(:|!?=/?)(.*)(/?)$`) | ||
| return | ||
| } | ||
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| // Validate check if the rule string is valid and can be used to check. | ||
| // This function must be called before Check() | ||
| func (r *RuleChecker)Validate(rule string) (key, op, value string, err error) { | ||
| if r == nil { | ||
| err = errors.New("Invalid RuleChecker object") | ||
| return | ||
| } | ||
| r.ruleToCheck = r.ruleRE.FindStringSubmatch(rule) | ||
| if r.ruleToCheck == nil { | ||
| err = fmt.Errorf("rule '%s' is invalid. Format supported is '<key>[!]=<value>', <key>[!]=/<regExp>/", rule) | ||
| return | ||
| } | ||
| r.key = r.ruleToCheck[1] | ||
| r.op = r.ruleToCheck[2] | ||
| r.value = r.ruleToCheck[3] | ||
| return r.key, r.op, r.value, nil | ||
| } | ||
|
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| // Check check if the key respect the value/regexp and returns true if confirmed. | ||
| // | ||
| // The string value is given by the call to the `get` function | ||
| func (r *RuleChecker)Check(get func(string)(string, bool)) (matched bool, err error) { | ||
| if r == nil { | ||
| return false, errors.New("Invalid RuleChecker object") | ||
| } | ||
|
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| value, found := get(r.key) | ||
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| switch r.op { | ||
| case "=", ":": | ||
| if r.value == "*" && found { | ||
| return true, nil | ||
| } | ||
| return r.value == value, nil | ||
| case "!=": | ||
| if r.value == "*" && !found { | ||
| return true, nil | ||
| } | ||
| return r.value != value, nil | ||
| case "=/": | ||
| if r.ruleToCheck[4] != "/" { | ||
| return false, fmt.Errorf("Invalid regexp rule. Missing leading '/'") | ||
| } | ||
| matched, err = regexp.MatchString(r.value, value) | ||
| return | ||
| case "!=/": | ||
| if r.ruleToCheck[4] != "/" { | ||
| return false, fmt.Errorf("Invalid regexp rule. Missing leading '/'") | ||
| } | ||
| matched, err = regexp.MatchString(r.value, value) | ||
| if err != nil { | ||
| return | ||
| } | ||
| return !matched, nil | ||
| } | ||
|
|
||
| return | ||
| } |