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+ October 2001, --Jcid
+ Last update: Dec 2004
+
+ ---------------
+ 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,
+ 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 gets
+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 '&lt;' and '&gt;' 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 significative amounts of
+ well written HTML).
+
+
+
+ * WORD --> Html_process_word
+
+ A word is anything that doesn't start with SPACE, and 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:
+
+ struct _DilloHtml {
+ [...]
+ DilloHtmlState *stack;
+ gint stack_top; /* Index to the top of the stack [0 based] */
+ gint stack_max;
+ [...]
+ };
+
+ struct _DilloHtmlState {
+ char *tag;
+ DwStyle *style, *table_cell_style;
+ DilloHtmlParseMode parse_mode;
+ DilloHtmlTableMode table_mode;
+ gint list_level;
+ gint list_number;
+ DwWidget *page, *table;
+ gint32 current_bg_color;
+ };
+
+
+ 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.
+
+