Annotation of libwww/Library/src/SGML.html, revision 2.14
2.4 timbl 1: <HTML>
2: <HEAD>
2.14 ! frystyk 3: <TITLE>SGML parse and stream definition for libwww</TITLE>
! 4: </HEAD>
2.1 timbl 5: <BODY>
2.11 frystyk 6:
2.14 ! frystyk 7: <H1>SGML and Structured streams</H1>
2.11 frystyk 8:
2.14 ! frystyk 9: <PRE>
! 10: /*
! 11: ** (c) COPYRIGHT CERN 1994.
! 12: ** Please first read the full copyright statement in the file COPYRIGH.
! 13: */
! 14: </PRE>
! 15:
! 16: The SGML parser is a state machine. It is called for every character
! 17: of the input stream. The DTD data structure contains pointers to
! 18: functions which are called to implement the actual effect of the text
! 19: read. When these functions are called, the attribute structures
! 20: pointed to by the DTD are valid, and the function is parsed a pointer
! 21: to the curent tag structure, and an "element stack" which represents
! 22: the state of nesting within SGML elements. See also the <A
! 23: HREF="HTStream.html">the generic Stream definition</A><P>
! 24:
! 25: The following aspects are from Dan Connolly's suggestions: Binary
! 26: search, Strcutured object scheme basically, SGML content enum type.<P>
! 27:
! 28: This module is implemented by <A HREF="SGML.c">SGML.c</A>, and it is a
! 29: part of the <A
! 30: HREF="http://info.cern.ch/hypertext/WWW/Library/User/Guide/Guide.html">
! 31: Library of Common Code</A>.
2.11 frystyk 32:
33: <PRE>
34: #ifndef SGML_H
2.1 timbl 35: #define SGML_H
36:
37: #include "HTUtils.h"
38: #include "HTStream.h"
39:
40: </PRE>
41: <H2>SGML content types</H2>
42: <PRE>typedef enum _SGMLContent{
43: SGML_EMPTY, /* no content */
2.8 timbl 44: SGML_LITERAL, /* character data. Recognized exact close tag only.
2.1 timbl 45: Old www server compatibility only! Not SGML */
46: SGML_CDATA, /* character data. recognize </ only */
47: SGML_RCDATA, /* replaceable character data. recognize </ and &ref; */
48: SGML_MIXED, /* elements and parsed character data. recognize all markup */
49: SGML_ELEMENT /* any data found will be returned as an error*/
50: } SGMLContent;
51:
52:
53: typedef struct {
54: char * name; /* The (constant) name of the attribute */
55: /* Could put type info in here */
56: } attr;
57:
58:
59: /* A tag structure describes an SGML element.
60: ** -----------------------------------------
61: **
62: **
63: ** name is the string which comes after the tag opener "<".
64: **
65: ** attributes points to a zero-terminated array
66: ** of attribute names.
67: **
68: ** litteral determines how the SGML engine parses the charaters
69: ** within the element. If set, tag openers are ignored
70: ** except for that which opens a matching closing tag.
71: **
72: */
73: typedef struct _tag HTTag;
74: struct _tag{
75: char * name; /* The name of the tag */
76: attr * attributes; /* The list of acceptable attributes */
77: int number_of_attributes; /* Number of possible attributes */
78: SGMLContent contents; /* End only on end tag @@ */
79: };
80:
81:
82:
83:
84: /* DTD Information
85: ** ---------------
86: **
87: ** Not the whole DTD, but all this parser usues of it.
88: */
89: typedef struct {
2.2 timbl 90: HTTag * tags; /* Must be in strcmp order by name */
91: int number_of_tags;
92: CONST char ** entity_names; /* Must be in strcmp order by name */
93: int number_of_entities;
2.1 timbl 94: } SGML_dtd;
95:
2.9 frystyk 96: #define MAX_ATTRIBUTES 20 /* Max number of attributes per element */
2.1 timbl 97:
98: /* SGML context passed to parsers
99: */
100: typedef struct _HTSGMLContext *HTSGMLContext; /* Hidden */
101:
102:
103: /*__________________________________________________________________________
104: */
105:
2.6 timbl 106: </PRE>
107: <H2>Structured Object definition</H2>A structured object is something
108: which can reasonably be represented
109: in SGML. I'll rephrase that. A
110: structured object is am ordered tree-structured
111: arrangement of data which is representable
112: as text.The SGML parer outputs to
113: a Structured object. A Structured
114: object can output its contents to
115: another Structured Object. It's a
116: kind of typed stream. The architecure
117: is largely Dan Conolly's. Elements
118: and entities are passed to the sob
119: by number, implying a knowledge of
120: the DTD. Knowledge of the SGML syntax
121: is not here, though.<P>
122: Superclass: HTStream<P>
123: The creation methods will vary on
124: the type of Structured Object.Maybe
125: the callerData is enough info to
2.13 frystyk 126: pass along. <P>
127:
128: <B>NOTE: </B>The <CODE>put_block</CODE> method was <CODE>write</CODE>,
129: but this upset systems which had macros for <CODE>write()</CODE>. See
130: <A HREF="HTStream.html">the generic stream definition</A> for valid
131: return codes.<P>
132:
2.6 timbl 133: <PRE>typedef struct _HTStructured HTStructured;
2.1 timbl 134:
135: typedef struct _HTStructuredClass{
136:
137: char* name; /* Just for diagnostics */
138:
2.13 frystyk 139: int (*_free) PARAMS((
2.1 timbl 140: HTStructured* me));
141:
2.13 frystyk 142: int (*abort) PARAMS((
2.5 timbl 143: HTStructured* me,
144: HTError e));
2.1 timbl 145:
146: void (*put_character) PARAMS((
147: HTStructured* me,
148: char ch));
149:
150: void (*put_string) PARAMS((
151: HTStructured* me,
152: CONST char * str));
153:
2.13 frystyk 154: void (*put_block) PARAMS((
2.2 timbl 155: HTStructured* me,
2.1 timbl 156: CONST char * str,
157: int len));
158:
159: void (*start_element) PARAMS((
160: HTStructured* me,
161: int element_number,
2.2 timbl 162: CONST BOOL* attribute_present,
163: CONST char** attribute_value));
2.1 timbl 164:
165: void (*end_element) PARAMS((
166: HTStructured* me,
167: int element_number));
168:
169: void (*put_entity) PARAMS((
170: HTStructured* me,
171: int entity_number));
172:
2.13 frystyk 173: } HTStructuredClass;
2.1 timbl 174:
2.6 timbl 175: </PRE>
176: <H2>Find a Tag by Name</H2>Returns a pointer to the tag within
177: the DTD.
2.7 timbl 178: <PRE>extern HTTag * SGMLFindTag PARAMS((CONST SGML_dtd* dtd, CONST char * string));
2.1 timbl 179:
180:
2.6 timbl 181: </PRE>
2.10 timbl 182: <H2>Find a Attribute by Name</H2>Returns the number of the
183: atribute or -1 if failure.
184: <PRE>extern int SGMLFindAttribute PARAMS((HTTag* tag, CONST char * string));
185:
186:
187: </PRE>
2.6 timbl 188: <H2>Create an SGML parser</H2>
189: <PRE>/*
2.1 timbl 190: ** On entry,
191: ** dtd must point to a DTD structure as defined above
192: ** callbacks must point to user routines.
193: ** callData is returned in callbacks transparently.
194: ** On exit,
195: ** The default tag starter has been processed.
196: */
197:
198:
199: extern HTStream* SGML_new PARAMS((
200: CONST SGML_dtd * dtd,
201: HTStructured * target));
202:
2.2 timbl 203: extern CONST HTStreamClass SGMLParser;
2.1 timbl 204:
205:
206: #endif /* SGML_H */
2.7 timbl 207:
2.1 timbl 208:
2.3 timbl 209:
210:
2.4 timbl 211:
2.6 timbl 212:
213:
214:
215:
2.8 timbl 216:
217: </PRE></BODY>
2.4 timbl 218: </HTML>
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