Annotation of libwww/Library/src/SGML.html, revision 2.15
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:
2.15 ! roeber 37: #include "sysdep.h"
2.1 timbl 38: #include "HTUtils.h"
39: #include "HTStream.h"
40:
41: </PRE>
42: <H2>SGML content types</H2>
43: <PRE>typedef enum _SGMLContent{
44: SGML_EMPTY, /* no content */
2.8 timbl 45: SGML_LITERAL, /* character data. Recognized exact close tag only.
2.1 timbl 46: Old www server compatibility only! Not SGML */
47: SGML_CDATA, /* character data. recognize </ only */
48: SGML_RCDATA, /* replaceable character data. recognize </ and &ref; */
49: SGML_MIXED, /* elements and parsed character data. recognize all markup */
50: SGML_ELEMENT /* any data found will be returned as an error*/
51: } SGMLContent;
52:
53:
54: typedef struct {
55: char * name; /* The (constant) name of the attribute */
56: /* Could put type info in here */
57: } attr;
58:
59:
60: /* A tag structure describes an SGML element.
61: ** -----------------------------------------
62: **
63: **
64: ** name is the string which comes after the tag opener "<".
65: **
66: ** attributes points to a zero-terminated array
67: ** of attribute names.
68: **
69: ** litteral determines how the SGML engine parses the charaters
70: ** within the element. If set, tag openers are ignored
71: ** except for that which opens a matching closing tag.
72: **
73: */
74: typedef struct _tag HTTag;
75: struct _tag{
76: char * name; /* The name of the tag */
77: attr * attributes; /* The list of acceptable attributes */
78: int number_of_attributes; /* Number of possible attributes */
79: SGMLContent contents; /* End only on end tag @@ */
80: };
81:
82:
83:
84:
85: /* DTD Information
86: ** ---------------
87: **
88: ** Not the whole DTD, but all this parser usues of it.
89: */
90: typedef struct {
2.2 timbl 91: HTTag * tags; /* Must be in strcmp order by name */
92: int number_of_tags;
93: CONST char ** entity_names; /* Must be in strcmp order by name */
94: int number_of_entities;
2.1 timbl 95: } SGML_dtd;
96:
2.9 frystyk 97: #define MAX_ATTRIBUTES 20 /* Max number of attributes per element */
2.1 timbl 98:
99: /* SGML context passed to parsers
100: */
101: typedef struct _HTSGMLContext *HTSGMLContext; /* Hidden */
102:
103:
104: /*__________________________________________________________________________
105: */
106:
2.6 timbl 107: </PRE>
108: <H2>Structured Object definition</H2>A structured object is something
109: which can reasonably be represented
110: in SGML. I'll rephrase that. A
111: structured object is am ordered tree-structured
112: arrangement of data which is representable
113: as text.The SGML parer outputs to
114: a Structured object. A Structured
115: object can output its contents to
116: another Structured Object. It's a
117: kind of typed stream. The architecure
118: is largely Dan Conolly's. Elements
119: and entities are passed to the sob
120: by number, implying a knowledge of
121: the DTD. Knowledge of the SGML syntax
122: is not here, though.<P>
123: Superclass: HTStream<P>
124: The creation methods will vary on
125: the type of Structured Object.Maybe
126: the callerData is enough info to
2.13 frystyk 127: pass along. <P>
128:
129: <B>NOTE: </B>The <CODE>put_block</CODE> method was <CODE>write</CODE>,
130: but this upset systems which had macros for <CODE>write()</CODE>. See
131: <A HREF="HTStream.html">the generic stream definition</A> for valid
132: return codes.<P>
133:
2.6 timbl 134: <PRE>typedef struct _HTStructured HTStructured;
2.1 timbl 135:
136: typedef struct _HTStructuredClass{
137:
138: char* name; /* Just for diagnostics */
139:
2.13 frystyk 140: int (*_free) PARAMS((
2.1 timbl 141: HTStructured* me));
142:
2.13 frystyk 143: int (*abort) PARAMS((
2.5 timbl 144: HTStructured* me,
145: HTError e));
2.1 timbl 146:
147: void (*put_character) PARAMS((
148: HTStructured* me,
149: char ch));
150:
151: void (*put_string) PARAMS((
152: HTStructured* me,
153: CONST char * str));
154:
2.13 frystyk 155: void (*put_block) PARAMS((
2.2 timbl 156: HTStructured* me,
2.1 timbl 157: CONST char * str,
158: int len));
159:
160: void (*start_element) PARAMS((
161: HTStructured* me,
162: int element_number,
2.2 timbl 163: CONST BOOL* attribute_present,
164: CONST char** attribute_value));
2.1 timbl 165:
166: void (*end_element) PARAMS((
167: HTStructured* me,
168: int element_number));
169:
170: void (*put_entity) PARAMS((
171: HTStructured* me,
172: int entity_number));
173:
2.13 frystyk 174: } HTStructuredClass;
2.1 timbl 175:
2.6 timbl 176: </PRE>
177: <H2>Find a Tag by Name</H2>Returns a pointer to the tag within
178: the DTD.
2.7 timbl 179: <PRE>extern HTTag * SGMLFindTag PARAMS((CONST SGML_dtd* dtd, CONST char * string));
2.1 timbl 180:
181:
2.6 timbl 182: </PRE>
2.10 timbl 183: <H2>Find a Attribute by Name</H2>Returns the number of the
184: atribute or -1 if failure.
185: <PRE>extern int SGMLFindAttribute PARAMS((HTTag* tag, CONST char * string));
186:
187:
188: </PRE>
2.6 timbl 189: <H2>Create an SGML parser</H2>
190: <PRE>/*
2.1 timbl 191: ** On entry,
192: ** dtd must point to a DTD structure as defined above
193: ** callbacks must point to user routines.
194: ** callData is returned in callbacks transparently.
195: ** On exit,
196: ** The default tag starter has been processed.
197: */
198:
199:
200: extern HTStream* SGML_new PARAMS((
201: CONST SGML_dtd * dtd,
202: HTStructured * target));
203:
2.2 timbl 204: extern CONST HTStreamClass SGMLParser;
2.1 timbl 205:
206:
207: #endif /* SGML_H */
2.7 timbl 208:
2.1 timbl 209:
2.3 timbl 210:
211:
2.4 timbl 212:
2.6 timbl 213:
214:
215:
216:
2.8 timbl 217:
218: </PRE></BODY>
2.4 timbl 219: </HTML>
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