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Add sax-xml-parser.b example #258

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b0d2007
Add sax-xml-parser.b example
pavel-chumakou Jul 26, 2025
a20ef84
Fix typos, small refactoring
pavel-chumakou Jul 30, 2025
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292 changes: 292 additions & 0 deletions examples/sax-xml-parser.b
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Original file line number Diff line number Diff line change
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// SAX XML Parser
//
// Simple XML-aware parser. CDATA is not supported.
//
// Usage: sax-xml-parser [OPTIONS] <input...>
// OPTIONS:
// -f <file>
// Parse content of the file
// -s <str>
// Parse input string
// -e
// Parse example string: <!DOCTYPE html><html><body><h1>My Heading</h1><p>My paragraph</p></body></html>
// -t <file>
// Extract text from a XML(HTML) file
//
// Written by Pavel Chumakou (pavel@chumakou.com)


parse(str, len, characters, start_tag, end_tag, start_document, end_document)
{
auto text_start; text_start = -1;
auto tag_start; tag_start = -1;
auto tag_name_end; tag_name_end = -1;
auto insideTag; insideTag = 0;

(&*start_document)();

auto i; i = 0; while(i < len)
{
auto current; current = char(str, i);

if (current == '<')
{

if (insideTag == 1)
{
goto continue; // ... <xxx < .... - skip this case
}
tag_start = i;
tag_name_end = -1;
insideTag = 1;
goto continue;
}

if (current == ' ')
{
if ((insideTag == 1) & (tag_name_end < 0))
{
tag_name_end = i;
}
}

if (current == '>')
{
if ((insideTag == 1) & (tag_start + 1 < i))
{
if (char(str, tag_start + 1) == '?' | char(str, tag_start + 1) == '!')
{
// skip <?xml > ... <!DOCTYPE>
text_start = -1;
tag_start = -1;
tag_name_end = -1;
insideTag = 0;
goto continue;
}

auto tag_name_start; tag_name_start = tag_start + 1;
auto openTag; openTag = 1;
if (char(str, tag_start + 1) == '/')
{
openTag = 0; // </xxx ...
tag_name_start++;
}

auto singleTag; singleTag = 0;
auto prevByte; prevByte = char(str, i - 1);
if (prevByte == '/')
{
singleTag = 1; // <xxx />
if (tag_name_end < 0)
{
tag_name_end = i - 1;
}
}

if (tag_name_end < 0)
{
tag_name_end = i;
}

if (text_start >= 0)
{
(&*characters)(str, text_start, tag_start);
text_start = -1;
}

if (singleTag)
{
(&*start_tag)(str, tag_start, i + 1, tag_name_start, tag_name_end, 1);
} else {
if (openTag) {
(&*start_tag)(str, tag_start, i + 1, tag_name_start, tag_name_end, 0);
} else {
(&*end_tag)(str, tag_start, i + 1, tag_name_start, tag_name_end);
}
}

tag_start = -1;
tag_name_end = -1;
insideTag = 0;
}
goto continue;
}

if (current == '\r' | current == '\n' | current == '\t')
{
goto continue;
}

if (insideTag == 0)
{
if (text_start < 0) {
text_start = i;
}
}

continue:
i++;
} // while

if (text_start >= 0) {
(&*characters)(str, text_start, len);
}

(&*end_document)();
}

//// Parse event handlers /////////////

characters(str, start, end)
{
printf("characters: ");
print_substring_n(str, start, end);
}

start_tag(str, tag_start, tag_end, name_start, name_end, is_self_closing)
{
printf("start_tag: ");
print_substring_n(str, name_start, name_end);
}

end_tag(str, tag_start, tag_end, name_start, name_end)
{
printf("end_tag: ");
print_substring_n(str, name_start, name_end);
}

start_document()
{
printf("start_document\n");
}

end_document()
{
printf("end_document\n");
}

//// Extract text event handlers /////

ext_characters(str, start, end)
{
print_substring_n(str, start, end);
}

ext_start_tag(str, tag_start, tag_end, name_start, name_end, is_self_closing){}

ext_end_tag(str, tag_start, tag_end, name_start, name_end){}

ext_start_document() {}

ext_end_document() {}

/////////////////////////////////

print_substring(str, start, end)
{
auto i; i = start; while (i < end)
{
putchar(char(str, i));
i++;
}
}

print_substring_n(str, start, end)
{
print_substring(str, start, end);
putchar('\n');
}

print_usage()
{
printf("SAX XML Parser\n");
printf("Usage: sax-xml-parser [OPTIONS] <input...>\n");
printf("OPTIONS:\n");
printf(" -f <file>\n");
printf(" Parse content of a file\n");
printf(" -s \"<str>\"\n");
printf(" Parse input string\n");
printf(" -e \n");
printf(" Parse example string: <!DOCTYPE html><html><body><h1>My Heading</h1><p>My paragraph</p></body></html>\n");
printf(" -t <file>\n");
printf(" Extract text from a XML(HTML) file\n");
}

buffer;
file_size;

read_file(fname)
{
extrn fopen, ftell, fseek, fread, malloc;
auto fp; fp = fopen(fname, "rb");
if (fp == 0)
{
printf("File %s not found\n", fname);
exit(-1);
}
fseek(fp, 0, 2); // fseek(fp, 0, SEEK_END)
file_size = ftell(fp);
fseek(fp, 0, 0); //fseek(fp, 0, SEEK_SET);
buffer = malloc(file_size);
fread(buffer, 1, file_size, fp);
}

main(argc, argv)
{
extrn malloc, strlen;

if (argc <= 1)
{
print_usage();
return(0);
}

auto opt; opt = argv[1];
if (char(opt, 0) == '-' & char(opt, 1) == 'f')
{
if (argc <= 2)
{
print_usage();
return(0);
}
read_file(argv[2]);
parse(buffer, file_size, &characters, &start_tag, &end_tag, &start_document, &end_document);
return(0);
}

if (char(opt, 0) == '-' & char(opt, 1) == 's')
{
if (argc <= 2)
{
print_usage();
return(0);
}
parse(argv[2], strlen(argv[2]), &characters, &start_tag, &end_tag, &start_document, &end_document);
return(0);
}

if (char(opt, 0) == '-' & char(opt, 1) == 'e')
{
auto str; str = "<!DOCTYPE html><html><body><h1>My Heading</h1><p>My paragraph</p></body></html>";
printf("Parsing example string: %s\n", str);
parse(str, strlen(str), &characters, &start_tag, &end_tag, &start_document, &end_document);
return(0);
}

if (char(opt, 0) == '-' & char(opt, 1) == 't')
{
if (argc <= 2)
{
print_usage();
return(0);
}
read_file(argv[2]);
parse(buffer, file_size, &ext_characters, &ext_start_tag, &ext_end_tag, &ext_start_document, &ext_end_document);
return(0);
}

print_usage();
return(0);

}

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