framework/web/UrlManager.php
protected function buildRules($ruleDeclarations)
    {
        $builtRules = $this->getBuiltRulesFromCache($ruleDeclarations);
        if ($builtRules !== false) {
            return $builtRules;
        }

        $builtRules = [];
        $verbs = 'GET|HEAD|POST|PUT|PATCH|DELETE|OPTIONS';
        foreach ($ruleDeclarations as $key => $rule) {
            if (is_string($rule)) {
                $rule = ['route' => $rule];
                if (preg_match("/^((?:($verbs),)*($verbs))\\s+(.*)$/", $key, $matches)) {
                    $rule['verb'] = explode(',', $matches[1]);
                    // rules that are not applicable for GET requests should not be used to create URLs
                    if (!in_array('GET', $rule['verb'], true)) {
                        $rule['mode'] = UrlRule::PARSING_ONLY;
                    }
                    $key = $matches[4];
                }
                $rule['pattern'] = $key;
            }
            if (is_array($rule)) {
                $rule = Yii::createObject(array_merge($this->ruleConfig, $rule));
            }
            if (!$rule instanceof UrlRuleInterface) {
                throw new InvalidConfigException('URL rule class must implement UrlRuleInterface.');
            }
            $builtRules[] = $rule;
        }

        $this->setBuiltRulesCache($ruleDeclarations, $builtRules);

        return $builtRules;
    }
protected function buildRules($ruleDeclarations)
    {
        $builtRules = $this->getBuiltRulesFromCache($ruleDeclarations);
        if ($builtRules !== false) {
            return $builtRules;
        }

        $builtRules = [];
        $verbs = 'GET|HEAD|POST|PUT|PATCH|DELETE|OPTIONS';
        foreach ($ruleDeclarations as $key => $rule) {
            if (is_string($rule)) {
                $rule = ['route' => $rule];
                if (preg_match("/^((?:($verbs),)*($verbs))\\s+(.*)$/", $key, $matches)) {
                    $rule['verb'] = explode(',', $matches[1]);
                    // rules that are not applicable for GET requests should not be used to create URLs
                    if (!in_array('GET', $rule['verb'], true)) {
                        $rule['mode'] = UrlRule::PARSING_ONLY;
                    }
                    $key = $matches[4];
                }
                $rule['pattern'] = $key;
            }
            if (is_array($rule)) {
                $rule = Yii::createObject(array_merge($this->ruleConfig, $rule));
            }
            if (!$rule instanceof UrlRuleInterface) {
                throw new InvalidConfigException('URL rule class must implement UrlRuleInterface.');
            }
            $builtRules[] = $rule;
        }

        $this->setBuiltRulesCache($ruleDeclarations, $builtRules);

        return $builtRules;
    }
Builds URL rule objects from the given rule declarations.

@param array $ruleDeclarations the rule declarations. Each array element represents a single rule declaration.
Please refer to [[rules]] for the acceptable rule formats.
@return UrlRuleInterface[] the rule objects built from the given rule declarations
@throws InvalidConfigException if a rule declaration is invalid