/usr/share/doc/dillo/HtmlParser.txt is in dillo 3.0.5-4build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Last update: Jul 2009
---------------
THE HTML PARSER
---------------
Dillo's parser is more than just a HTML parser, it does XHTML
and plain text also. It has parsing 'modes' that define its
behaviour while working:
typedef enum {
DILLO_HTML_PARSE_MODE_INIT = 0,
DILLO_HTML_PARSE_MODE_STASH,
DILLO_HTML_PARSE_MODE_STASH_AND_BODY,
DILLO_HTML_PARSE_MODE_BODY,
DILLO_HTML_PARSE_MODE_VERBATIM,
DILLO_HTML_PARSE_MODE_PRE
} DilloHtmlParseMode;
The parser works upon a token-grained basis, i.e., the data
stream is parsed into tokens and the parser is fed with them. The
process is simple: whenever the cache has new data, it is
passed to Html_write, which groups data into tokens and calls the
appropriate functions for the token type (tag, space, or word).
Note: when in DILLO_HTML_PARSE_MODE_VERBATIM, the parser
doesn't try to split the data stream into tokens anymore; it
simply collects until the closing tag.
------
TOKENS
------
* A chunk of WHITE SPACE --> Html_process_space
* TAG --> Html_process_tag
The tag-start is defined by two adjacent characters:
first : '<'
second: ALPHA | '/' | '!' | '?'
Note: comments are discarded ( <!-- ... --> )
The tag's end is not as easy to find, nor to deal with!:
1) The HTML 4.01 sec. 3.2.2 states that "Attribute/value
pairs appear before the final '>' of an element's start tag",
but it doesn't define how to discriminate the "final" '>'.
2) '<' and '>' should be escaped as '<' and '>' inside
attribute values.
3) The XML SPEC for XHTML states:
AttrValue ::== '"' ([^<&"] | Reference)* '"' |
"'" ([^<&'] | Reference)* "'"
Current parser honors the XML SPEC.
As it's a common mistake for human authors to mistype or
forget one of the quote marks of an attribute value; the
parser solves the problem with a look-ahead technique
(otherwise the parser could skip significant amounts of
properly-written HTML).
* WORD --> Html_process_word
A word is anything that doesn't start with SPACE, that's
outside of a tag, up to the first SPACE or tag start.
SPACE = ' ' | \n | \r | \t | \f | \v
-----------------
THE PARSING STACK
-----------------
The parsing state of the document is kept in a stack:
class DilloHtml {
[...]
lout::misc::SimpleVector<DilloHtmlState> *stack;
[...]
};
struct _DilloHtmlState {
CssPropertyList *table_cell_props;
DilloHtmlParseMode parse_mode;
DilloHtmlTableMode table_mode;
bool cell_text_align_set;
DilloHtmlListMode list_type;
int list_number;
/* TagInfo index for the tag that's being processed */
int tag_idx;
dw::core::Widget *textblock, *table;
/* This is used to align list items (especially in enumerated lists) */
dw::core::Widget *ref_list_item;
/* This is used for list items etc; if it is set to TRUE, breaks
have to be "handed over" (see Html_add_indented and
Html_eventually_pop_dw). */
bool hand_over_break;
};
Basically, when a TAG is processed, a new state is pushed into
the 'stack' and its 'style' is set to reflect the desired
appearance (details in DwStyle.txt).
That way, when a word is processed later (added to the Dw), all
the information is within the top state.
Closing TAGs just pop the stack.
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