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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <ctype.h>
  4.  
  5. typedef enum { Error='e', First='F', Name='N', Text='T', Left='L', } Mode;
  6. typedef enum { Begin='B', End='E', } Type;
  7.  
  8. typedef struct Tag {
  9. 	char name;
  10. 	Type type;
  11. } Tag;
  12.  
  13. static inline int
  14. istarch(int ch) {
  15. 	return (isalnum(ch) || ch == ' ');
  16. }
  17.  
  18. static Tag*
  19. read_tag_name(Tag* tag, char** src) {
  20. 	Mode m = First;
  21. 	char* p = *src;
  22.  
  23. 	tag->name = 0;
  24.  
  25. 	for (; ; ++p) {
  26. 		char ch = *p;
  27. 		if (ch == '\0')
  28. 			goto error;
  29.  
  30. 		switch (m) {
  31. 			default: goto error; break;
  32. 			case First:
  33. 				if (isalpha(ch)) {
  34. 					tag->name = ch;
  35. 					tag->type = Begin;
  36. 					m = Name;
  37. 				} else if (ch == '/') {
  38. 					tag->type = End;
  39. 					m = Name;
  40. 				} else {
  41. 					goto error;
  42. 				}
  43. 				break;
  44. 			case Name:
  45. 				if (isalpha(ch)) {
  46. 					tag->name = ch;
  47. 				} else if (ch == '>') {
  48. 					if (!tag->name)
  49. 						goto error;
  50. 					goto success;
  51. 				}
  52. 				break;
  53. 		}
  54. 	}
  55. error:
  56. 	*src = p;
  57. 	return NULL;
  58. success:
  59. 	*src = p;
  60. 	return tag;
  61. }
  62.  
  63. static Tag*
  64. read_tag(Tag* btag, char** src) {
  65. 	Mode m = First;
  66. 	char* p = *src;
  67.  
  68. 	if (!btag)
  69. 		goto error;
  70.  
  71. 	for (; ; ++p) {
  72. 		char ch = *p;
  73. 		if (ch == '\0') {
  74. 			goto error;
  75. 		}
  76.  
  77. 		switch (m) {
  78. 			default: goto error; break;
  79. 			case First:
  80. 				if (istarch(ch)) m = Text;
  81. 				else if (ch == '<') m = Left;
  82. 				break;
  83. 			case Text:
  84. 				if (ch == '<') m = Left;
  85. 				break;
  86. 			case Left: {
  87. 				Tag tmp;
  88. 				if (!read_tag_name(&tmp, &p)) {
  89. 					goto error;
  90. 				}
  91. 				if (tmp.name == 'a' && btag->name == 'b') {
  92. 					goto error;
  93. 				}
  94. 				if (tmp.name == btag->name && tmp.type == End) {
  95. 					goto success;
  96. 				}
  97. 				if (!read_tag(&tmp, &p)) {
  98. 					goto error;
  99. 				}
  100. 				m = First;
  101. 			} break;
  102. 		}
  103. 	}
  104. error:
  105. 	*src = p;
  106. 	return NULL;
  107. success:
  108. 	*src = p;
  109. 	return btag;
  110. }
  111.  
  112. static int
  113. parse(char* src) {
  114. 	Mode m = First;
  115. 	char* p = src;
  116.  
  117. 	for (; ; ++p) {
  118. 		char ch = *p;
  119. 		if (ch == '\0') {
  120. 			if (m == Text || m == First)
  121. 				goto success;
  122. 			goto error;
  123. 		}
  124.  
  125. 		switch (m) {
  126. 			default: goto error; break;
  127. 			case First:
  128. 				if (istarch(ch)) m = Text;
  129. 				else if (ch == '<') m = Left;
  130. 				else goto error;
  131. 			break;
  132. 			case Text:
  133. 				if (ch == '<') m = Left;
  134. 			break;
  135. 			case Left: {
  136. 				Tag t;
  137. 				if (!read_tag(read_tag_name(&t, &p), &p)) {
  138. 					goto error;
  139. 				}
  140. 				m = First;
  141. 			} break;
  142. 		}
  143. 	}
  144. error:
  145. 	return 0;
  146. success:
  147. 	return 1;
  148. }
  149.  
  150. int main(void) {
  151. 	char buf[1024];
  152.  
  153. 	while (fgets(buf, sizeof buf, stdin)) {
  154. 		size_t len = strlen(buf);
  155. 		if (buf[len-1] == '\n')
  156. 			buf[len-1] = '\0';
  157. 		printf("%d '%s'\n", parse(buf), buf);
  158. 	}
  159. 	return 0;
  160. }
  161.  
Success #stdin #stdout 0s 2012KB
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<a>ruby<b>php</b>python</a><a><b></b></a><a></a>
<a>ruby<b>php</b>python</a><a></b></a><a></a>
<a>ruby<b>php</b>python</a><a><b></a><a></a>
<a>ruby<b>php</b>python</a><a><b></b></a><a>
vvvc<a>ruby<b>php</b>python</a><a><b></b></a><a></a>
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1 '<a>ruby<b>php</b>python</a><a><b></b></a><a></a>'
0 '<a>ruby<b>php</b>python</a><a></b></a><a></a>'
0 '<a>ruby<b>php</b>python</a><a><b></a><a></a>'
0 '<a>ruby<b>php</b>python</a><a><b></b></a><a>'
1 'vvvc<a>ruby<b>php</b>python</a><a><b></b></a><a></a> '
https://ideone.com/BgrYRy
language:
C (gcc 8.3)
created:
9 years ago
visibility:
secret

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