pjs/lib/libdom/domstyle.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

#include "domstyle.h"

static int
CompareSelectors(const void *v1, const void *v2)
{
    DOM_StyleSelector *s1 = (DOM_StyleSelector *)v1,
        *s2 = (DOM_StyleSelector *)v2;

    return s1->type == s2->type &&

        /* compare base selector */
        !XP_STRCMP(s1->selector, s2->selector) &&

        /* if both have a psuedo, they have to match, else both must be NULL */
        (s1->pseudo && s2->pseudo ?
         XP_STRCMP(s1->pseudo, s2->pseudo) :
         !(s1 || s2));
}

DOM_StyleDatabase *
DOM_NewStyleDatabase(JSContext *cx)
{
    DOM_StyleDatabase *db = XP_NEW_ZAP(DOM_StyleDatabase);
    if (!db)
        return NULL;

    db->ht = PL_NewHashTable(32, PL_HashString, PL_CompareStrings,
                             CompareSelectors, NULL, NULL);
    if (!db->ht) {
        XP_FREE(db);
        return NULL;
    }

    return db;
}

void
DOM_DestroyStyleDatabase(JSContext *cx, DOM_StyleDatabase *db)
{
    PL_HashTableDestroy(db->ht);
    XP_FREE(db);
}

static JSBool
InsertBaseSelector(JSContext *cx, DOM_StyleDatabase *db,
                   DOM_StyleSelector *sel)
{
    return PL_HashTableAdd(db->ht, sel->selector, sel) != NULL;
}

static DOM_StyleSelector *
GetBaseSelector(JSContext *cx, DOM_StyleDatabase *db, DOM_StyleToken type,
                DOM_StyleToken pseudo)
{
    DOM_StyleSelector *sel = NULL;
    /* sel = HASH_LOOKUP(db->hashtable, type); */
    return sel;
}

static void
DestroySelector(JSContext *cx, DOM_StyleSelector *sel)
{
    XP_FREE((char *)sel->selector);
    if (sel->pseudo)
        XP_FREE((char *)sel->pseudo);
    if (sel->rules) {
        DOM_StyleRule *iter, *next;
        iter = sel->rules;
        do {
            next = iter->next;
            XP_FREE((char *)iter->entry.name);
            XP_FREE((char *)iter->entry.value);
            XP_FREE(iter);
            iter = next;
        } while (iter);
    }
    XP_FREE(sel);
}

static DOM_StyleSelector *
NewSelector(JSContext *cx, DOM_StyleToken selector, DOM_StyleToken pseudo)
{
    DOM_StyleSelector *sel;
    sel = XP_NEW_ZAP(DOM_StyleSelector);
    if (!sel)
        return NULL;
    if (selector[0] == '.') {
        sel->type = SELECTOR_CLASS;
        selector++;
    } else if (selector[0] == '#') {
        sel->type = SELECTOR_ID;
        selector++;
    } else {
        sel->type = SELECTOR_TAG;
    }

    sel->selector = XP_STRDUP(selector);
    if (!sel->selector) {
        DestroySelector(cx, sel);
        return NULL;
    }

    if (pseudo) {
        sel->pseudo = XP_STRDUP(pseudo);
        if (!sel->pseudo) {
            DestroySelector(cx, sel);
            return NULL;
        }
    }
    
    return sel;
}

/* the pseudoclass, if any, is stored in a magic attribute */
static DOM_StyleToken
GetPseudo(JSContext *cx, DOM_Element *element)
{
    DOM_AttributeEntry *entry;

    if (!DOM_GetElementAttribute(cx, element, ":pseudoclass", &entry))
        /* report error? */
        return NULL;
    return entry ? entry->value : NULL;
}

#define PSEUDO_MATCHES(p1, p2) (!XP_STRCMP((p1), (p2)))

#ifdef DEBUG_shaver
#define MATCH()                                                               \
        fprintf(stderr, "selector %s:%s matches element %s\n",                \
                sel->selector, sel->pseudo ? sel->pseudo : "",                \
                element->tagName);
#else
#define MATCH()
#endif

#ifdef DEBUG_shaver
#define NO_MATCH()                                                            \
        fprintf(stderr, "selector %s:%s doesn't match element %s\n",          \
                sel->selector, sel->pseudo ? sel->pseudo : "",                \
                element->tagName);
#else
#define NO_MATCH()
#endif

static JSBool
SelectorMatchesToken(JSContext *cx, DOM_StyleSelector *sel,
                     DOM_StyleToken token, DOM_StyleToken pseudo)
{
    /* XXX handle #ID and .class */
    return !XP_STRCMP(sel->selector, token);
}

#define ELEMENT_IS_TYPE(element, type) \
  (!XP_STRCMP(((element))->tagName, (type)))

static JSBool
SelectorMatchesElement(JSContext *cx, DOM_Element *element,
                       DOM_StyleSelector *sel)
{
    /* XXX handle class and ID */
    if (ELEMENT_IS_TYPE(element, sel->selector)) {
        /* check pseudo, if any */
        if (sel->pseudo) {
            DOM_StyleToken elementPseudo = GetPseudo(cx, element);
            if (PSEUDO_MATCHES(sel->pseudo, elementPseudo)) {
                MATCH();
                return JS_TRUE;
            }
        } else {
            MATCH();
            return JS_TRUE;
        }
    }
    return JS_FALSE;
}

#define SELECTOR_SCORE(sel, specificity) (specificity)

static DOM_AttributeEntry *
RuleValueFor(JSContext *cx, DOM_StyleRule *rule, DOM_StyleToken property)
{
    DOM_StyleRule *iter = rule;
    do {
        if (!XP_STRCMP(iter->entry.name, property))
            return &iter->entry;
        iter = iter->next;
    } while (iter);
    return NULL;
}

/* Find the parent element of appropriate type for given element */
static DOM_Element *
AncestorOfType(JSContext *cx, DOM_Element *element, DOM_StyleSelector *sel)
{
    do {
        /* check type */
        if (SelectorMatchesElement(cx, element, sel))
            return element;
        element = (DOM_Element *)element->node.parent;
    } while (element);

    return NULL;
}

/*
 * Determine if the given selector is a best-yet match for element, and
 * recurse/iterate appropriately over enclosing and sibling elements.
 */
static JSBool
CheckSelector(JSContext *cx, DOM_Element *element, DOM_StyleSelector *sel,
              DOM_StyleToken property, DOM_AttributeEntry **entryp,
              uintN *best, uintN specificity)
{
    DOM_AttributeEntry *entry;
    DOM_Element *next;

    /* check self */
    if (SelectorMatchesElement(cx, element, sel)) {
        /* if we have rules, maybe get an entry from them */
        if (sel->rules) {
            uintN score = SELECTOR_SCORE(sel, specificity);
            if (score > *best) {        /* are we the best so far? */
                entry = RuleValueFor(cx, sel->rules, property);
                if (entry) {    /* do we have a value for this property? */
#ifdef DEBUG_shaver
                    fprintf(stderr, "- score %d, value %s\n",
                            score, entry->value);
#endif
                    *best = score;
                    *entryp = entry;
                }
            }
        }

        /* now, check our enclosing selector */
        if (sel->enclosing) {
            next = AncestorOfType(cx, element, sel->enclosing);
            if (next)
                if (!CheckSelector(cx, next, sel->enclosing, property, entryp,
                                   best, specificity + 1))
                    return JS_FALSE;
        }
    }

    /* check our sibling */
    if (sel->sibling)
        if (!CheckSelector(cx, element, sel->sibling, property, entryp,
                           best, specificity))
            return JS_FALSE;

    return JS_TRUE;
}

JSBool
DOM_StyleGetProperty(JSContext *cx, DOM_StyleDatabase *db,
                     DOM_Node *node, DOM_StyleToken property,
                     DOM_StyleToken pseudo, DOM_AttributeEntry **entryp)
{
    DOM_StyleSelector *sel;
    DOM_Element *element;
    uintN best = 0;
    
    if (node->type != NODE_TYPE_ELEMENT) {
        element = (DOM_Element *)node->parent;
        XP_ASSERT(element->node.type == NODE_TYPE_ELEMENT);
    } else {
        element = (DOM_Element *)node;
    }

    *entryp = NULL;

    sel = GetBaseSelector(cx, db, element->tagName, GetPseudo(cx, element));
    if (!sel)
        return JS_TRUE;

    /*
     * CheckSelector will recursively find the best match for a given
     * property.
     */
    return CheckSelector(cx, element, sel, property, entryp, &best, 1);
}

DOM_StyleSelector *
DOM_StyleFindSelector(JSContext *cx, DOM_StyleDatabase *db,
                      DOM_StyleSelector *base, DOM_StyleToken enclosing,
                      DOM_StyleToken pseudo)
{
    DOM_StyleSelector *sel;

    /* looking for the base one */
    if (!base) {
        sel = GetBaseSelector(cx, db, enclosing, pseudo);
        if (!sel)
            sel = NewSelector(cx, enclosing, pseudo);
        if (sel)
            InsertBaseSelector(cx, db, sel);
        return sel;
    }
    
    if (!base->enclosing) {
        sel = NewSelector(cx, enclosing, pseudo);
        if (!sel)
            return NULL;
        base->enclosing = sel;
        return sel;
    }
    
    /* check existing enclosing selectors */
    sel = base->enclosing;
    do {
        if (SelectorMatchesToken(cx, sel, enclosing, pseudo))
            return sel;
        sel = sel->sibling;
    } while (sel);

    /* nothing found that matches, so create a new one */
    sel = NewSelector(cx, enclosing, pseudo);
    if (!sel)
        return NULL;
    sel->sibling = base->enclosing;
    base->enclosing = sel;

    return sel;
}