src/document/css/stylesheet.h

   1
   2 #ifndef EL__DOCUMENT_CSS_STYLESHEET_H
   3 #define EL__DOCUMENT_CSS_STYLESHEET_H
   4
   5 #include "protocol/uri.h"
   6 #include "util/lists.h"
   7
   8 /* #define DEBUG_CSS */
   9
  10 /** @file
  11  * @todo TODO: We need a memory efficient and fast way to define how
  12  * properties cascade. What we are interested in is making it fast and
  13  * easy to find all properties we need.
  14  *
  15  * @code
  16  *      struct css_cascade {
  17  *              struct css_cascade *parent;
  18  *              struct list_head properties;
  19  *
  20  *                      - Can later be turned into a table to not waste memory:
  21  *                        struct css_property properties[1];
  22  *      };
  23  * @endcode
  24  *
  25  * And the selector should then only map a document element into this
  26  * data structure.
  27  *
  28  * All the CSS applier has to do is require the css_cascade of the current
  29  * element and it should nicely inherit any style from parent cascades.
  30  * Question is in what direction to apply. It should be possible for the user
  31  * to overwrite any document provided stylesheet using "!important" so we need
  32  * to keep track in some table what properties was already applied so we only
  33  * overwrite when we have to. --jonas
  34  *
  35  * XXX: This is one of the TODOs where I have no clue what is it talking about
  36  * in particular. Is it obsolete now when we grok 'td.foo p#x>a:hover' without
  37  * hesitation? --pasky */
  38
  39 /** A set of struct css_selector.  This is currently represented as a
  40  * list but that may be changed later.  Therefore please try not to
  41  * access the contents directly; instead define new wrapper macros.
  42  *
  43  * According to CSS2 section 7.1 "Cascading order", if two rules have
  44  * the same weight, then the latter specified wins.  Regardless, the
  45  * order of rules need not be represented in struct css_selector_set,
  46  * because all rules for the same selector have already been merged
  47  * into one struct css_selector.  */
  48 struct css_selector_set {
  49         unsigned char may_contain_rel_ancestor_or_parent;
  50
  51         /** The list of selectors in this set.
  52          *
  53          * Sets are currently represented as lists that
  54          * find_css_selector() then has to search linearly.
  55          * Hashing was also tested but did not help in practice:
  56          * each find_css_selector() call runs approximately one
  57          * strcasecmp(), and a hash function is unlikely to be
  58          * faster than that.  See ELinks bug 789 for details.
  59          *
  60          * Keep this away from the beginning of the structure,
  61          * so that nobody can cast the struct css_selector_set *
  62          * to LIST_OF(struct css_selector) * and get away with it.  */
  63         LIST_OF(struct css_selector) list;
  64 };
  65 #define INIT_CSS_SELECTOR_SET(set) { 0, { D_LIST_HEAD(set.list) } }
  66
  67 /** The struct css_selector is used for mapping elements (or nodes) in the
  68  * document structure to properties. See README for some hints about how the
  69  * trees of these span. */
  70 struct css_selector {
  71         LIST_HEAD(struct css_selector);
  72
  73         /** This defines relation between this selector fragment and its
  74          * parent in the selector tree.
  75          * Update with set_css_selector_relation().  */
  76         enum css_selector_relation {
  77                 CSR_ROOT, /**< First class stylesheet member. */
  78                 CSR_SPECIFITY, /**< Narrowing-down, i.e. the "x" in "foo#x". */
  79                 CSR_ANCESTOR, /**< Ancestor, i.e. the "p" in "p a". */
  80                 CSR_PARENT, /**< Direct parent, i.e. the "div" in "div>img". */
  81         } relation;
  82         struct css_selector_set leaves;
  83
  84         enum css_selector_type {
  85                 CST_ELEMENT,
  86                 CST_ID,
  87                 CST_CLASS,
  88                 CST_PSEUDO,
  89                 CST_INVALID, /**< Auxiliary for the parser */
  90         } type;
  91         unsigned char *name;
  92
  93         LIST_OF(struct css_property) properties;
  94 };
  95
  96
  97 struct css_stylesheet;
  98 typedef void (*css_stylesheet_importer_T)(struct css_stylesheet *, struct uri *,
  99                                           const unsigned char *url, int urllen);
 100
 101 /** The struct css_stylesheet describes all the useful data that was extracted
 102  * from the CSS source. Currently we don't cache anything but the default user
 103  * stylesheet so it can contain stuff from both @<style> tags and @@import'ed
 104  * CSS documents. */
 105 struct css_stylesheet {
 106         /** The import callback function.  The caller must check the
 107          * media types first.  */
 108         css_stylesheet_importer_T import;
 109
 110         /** The import callback's data. */
 111         void *import_data;
 112
 113         /** The set of basic element selectors (which can then somehow
 114          * tree up on inside). */
 115         struct css_selector_set selectors;
 116
 117         /** How deeply nested are we. Limited by MAX_REDIRECTS. */
 118         int import_level;
 119 };
 120
 121 #define INIT_CSS_STYLESHEET(css, import) \
 122         { import, NULL, INIT_CSS_SELECTOR_SET(css.selectors) }
 123
 124 /** Dynamically allocates a stylesheet. */
 125 struct css_stylesheet *init_css_stylesheet(css_stylesheet_importer_T importer,
 126                                            void *import_data);
 127
 128 /** Mirror given CSS stylesheet @a css1 to an identical copy of itself
 129  * (including all the selectors), @a css2. */
 130 void mirror_css_stylesheet(struct css_stylesheet *css1,
 131                            struct css_stylesheet *css2);
 132
 133 /** Releases all the content of the stylesheet (but not the stylesheet
 134  * itself). */
 135 void done_css_stylesheet(struct css_stylesheet *css);
 136
 137
 138 /** Returns a new freshly made selector adding it to the given selector
 139  * set, or NULL. */
 140 struct css_selector *get_css_selector(struct css_selector_set *set,
 141                                       enum css_selector_type type,
 142                                       enum css_selector_relation rel,
 143                                       const unsigned char *name, int namelen);
 144
 145 #define get_css_base_selector(stylesheet, type, rel, name, namelen) \
 146         get_css_selector((stylesheet) ? &(stylesheet)->selectors : NULL, \
 147                          type, rel, name, namelen)
 148
 149 /** Looks up the selector of the name @a name and length @a namelen in
 150  * the given set of selectors. */
 151 struct css_selector *find_css_selector(struct css_selector_set *set,
 152                                        enum css_selector_type type,
 153                                        enum css_selector_relation rel,
 154                                        const unsigned char *name, int namelen);
 155
 156 #define find_css_base_selector(stylesheet, type, rel, name, namelen) \
 157         find_css_selector(&stylesheet->selectors, rel, type, name, namelen)
 158
 159 /** Initialize the selector structure. This is a rather low-level
 160  * function from your POV. */
 161 struct css_selector *init_css_selector(struct css_selector_set *set,
 162                                        enum css_selector_type type,
 163                                        enum css_selector_relation relation,
 164                                        const unsigned char *name, int namelen);
 165
 166 /** Add all properties from the list to the given @a selector. */
 167 void add_selector_properties(struct css_selector *selector,
 168                              LIST_OF(struct css_property) *properties);
 169
 170 /** Join @a sel2 to @a sel1, @a sel1 taking precedence in all conflicts. */
 171 void merge_css_selectors(struct css_selector *sel1, struct css_selector *sel2);
 172
 173 /** Use this function instead of modifying css_selector.relation directly.  */
 174 void set_css_selector_relation(struct css_selector *,
 175                                enum css_selector_relation);
 176
 177 /** Destroy a selector. done_css_stylesheet() normally does that for you. */
 178 void done_css_selector(struct css_selector *selector);
 179
 180 void init_css_selector_set(struct css_selector_set *set);
 181 void done_css_selector_set(struct css_selector_set *set);
 182 #define css_selector_set_empty(set) list_empty((set)->list)
 183 #define css_selector_set_front(set) ((struct css_selector *) ((set)->list.next))
 184 void add_css_selector_to_set(struct css_selector *, struct css_selector_set *);
 185 void del_css_selector_from_set(struct css_selector *);
 186 #define css_selector_is_in_set(selector) ((selector)->next != NULL)
 187 #define foreach_css_selector(selector, set) foreach (selector, (set)->list)
 188
 189 #ifdef DEBUG_CSS
 190 /** Dumps the selector tree to stderr. */
 191 void dump_css_selector_tree(struct css_selector_set *set);
 192 #endif
 193
 194 #endif