591. Tag Validator Hard

1/**
2 * [591] Tag Validator
3 *
4 * Given a string representing a code snippet, implement a tag validator to parse the code and return whether it is valid.
5 * A code snippet is valid if all the following rules hold:
6 * <ol>
7 * 	The code must be wrapped in a valid closed tag. Otherwise, the code is invalid.
8 * 	A closed tag (not necessarily valid) has exactly the following format : <TAG_NAME>TAG_CONTENT</TAG_NAME>. Among them, <TAG_NAME> is the start tag, and </TAG_NAME> is the end tag. The TAG_NAME in start and end tags should be the same. A closed tag is valid if and only if the TAG_NAME and TAG_CONTENT are valid.
9 * 	A valid TAG_NAME only contain upper-case letters, and has length in range [1,9]. Otherwise, the TAG_NAME is invalid.
10 * 	A valid TAG_CONTENT may contain other valid closed tags, cdata and any characters (see note1) EXCEPT unmatched <, unmatched start and end tag, and unmatched or closed tags with invalid TAG_NAME. Otherwise, the TAG_CONTENT is invalid.
11 * 	A start tag is unmatched if no end tag exists with the same TAG_NAME, and vice versa. However, you also need to consider the issue of unbalanced when tags are nested.
12 * 	A < is unmatched if you cannot find a subsequent >. And when you find a < or </, all the subsequent characters until the next > should be parsed as TAG_NAME (not necessarily valid).
13 * 	The cdata has the following format : <![CDATA[CDATA_CONTENT]]>. The range of CDATA_CONTENT is defined as the characters between <![CDATA[ and the first subsequent ]]>.
14 * 	CDATA_CONTENT may contain any characters. The function of cdata is to forbid the validator to parse CDATA_CONTENT, so even it has some characters that can be parsed as tag (no matter valid or invalid), you should treat it as regular characters.
15 * </ol>
16 *  
17 * Example 1:
18 * 
19 * Input: code = "<DIV>This is the first line <![CDATA[<div>]]></DIV>"
20 * Output: true
21 * Explanation: 
22 * The code is wrapped in a closed tag : <DIV> and </DIV>. 
23 * The TAG_NAME is valid, the TAG_CONTENT consists of some characters and cdata. 
24 * Although CDATA_CONTENT has an unmatched start tag with invalid TAG_NAME, it should be considered as plain text, not parsed as a tag.
25 * So TAG_CONTENT is valid, and then the code is valid. Thus return true.
26 * 
27 * Example 2:
28 * 
29 * Input: code = "<DIV>>>  ![cdata[]] <![CDATA[<div>]>]]>]]>>]</DIV>"
30 * Output: true
31 * Explanation:
32 * We first separate the code into : start_tag|tag_content|end_tag.
33 * start_tag -> "<DIV>"
34 * end_tag -> "</DIV>"
35 * tag_content could also be separated into : text1|cdata|text2.
36 * text1 -> ">>  ![cdata[]] "
37 * cdata -> "<![CDATA[<div>]>]]>", where the CDATA_CONTENT is "<div>]>"
38 * text2 -> "]]>>]"
39 * The reason why start_tag is NOT "<DIV>>>" is because of the rule 6.
40 * The reason why cdata is NOT "<![CDATA[<div>]>]]>]]>" is because of the rule 7.
41 * 
42 * Example 3:
43 * 
44 * Input: code = "<A>  <B> </A>   </B>"
45 * Output: false
46 * Explanation: Unbalanced. If "<A>" is closed, then "<B>" must be unmatched, and vice versa.
47 * 
48 *  
49 * Constraints:
50 * 
51 * 	1 <= code.length <= 500
52 * 	code consists of English letters, digits, '<', '>', '/', '!', '[', ']', '.', and ' '.
53 * 
54 */
55pub struct Solution {}
56
57// problem: https://leetcode.com/problems/tag-validator/
58// discuss: https://leetcode.com/problems/tag-validator/discuss/?currentPage=1&orderBy=most_votes&query=
59
60// submission codes start here
61
62impl Solution {
63    pub fn is_valid(code: String) -> bool {
64        false
65    }
66}
67
68// submission codes end
69
70#[cfg(test)]
71mod tests {
72    use super::*;
73
74    #[test]
75    fn test_591() {
76    }
77}
78