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/*
* Copyright © 1997-2016 World Wide Web Consortium
* See http://www.w3.org/Consortium/Legal/copyright-software
*
* Author: Bert Bos <bert@w3.org>
* Created: 1997
**/
#include "config.h"
#include <assert.h>
#include <stdlib.h>
#if STDC_HEADERS
# include <string.h>
#else
# ifndef HAVE_STRCHR
# define strchr index
# define strrchr rindex
# endif
# ifndef HAVE_STRDUP
# include "strdup.e"
# endif
#endif
#include <ctype.h>
#include <stdio.h>
#include <stdbool.h>
#include "export.h"
#include "heap.e"
#include "types.e"
#include "dtd.e"
#include "errexit.e"
#include "scan.e"
EXPORT typedef enum {
Element, Text, Comment, Declaration, Procins, Root
} Nodetype;
EXPORT typedef struct _node {
Nodetype tp;
string name;
pairlist attribs;
string text;
string url;
struct _node *parent;
struct _node *sister;
struct _node *children;
} Node, *Tree;
/* create -- create an empty tree */
EXPORT Tree create(void)
{
Tree t = malloc(sizeof(*t));
assert(t != NULL);
t->tp = Root;
t->name = "";
t->sister = t->children = NULL;
return t;
}
/* tree_delete -- recursively free the memory occupied by a tree */
EXPORT void tree_delete(Tree t)
{
if (t != NULL) {
switch (t->tp) {
case Element:
dispose(t->name);
pairlist_delete(t->attribs);
tree_delete(t->sister);
tree_delete(t->children);
break;
case Text:
dispose(t->text);
assert(t->children == NULL);
tree_delete(t->sister);
break;
case Comment:
dispose(t->text);
assert(t->children == NULL);
tree_delete(t->sister);
break;
case Declaration:
dispose(t->name);
dispose(t->text);
dispose(t->url);
assert(t->children == NULL);
tree_delete(t->sister);
break;
case Procins:
dispose(t->text);
assert(t->children == NULL);
tree_delete(t->sister);
break;
case Root:
assert(t->sister == NULL);
tree_delete(t->children);
break;
default:
assert(!"Cannot happen");
}
dispose(t);
}
}
/* get_root -- return root of tree */
EXPORT Tree get_root(Tree t)
{
while (t->tp != Root) t = t->parent;
return t;
}
/* get_attrib -- return a ptr to the value of a named attibute, or false */
EXPORT conststring get_attrib(const Node *e, const conststring attname)
{
assert(e->tp == Element);
return pairlist_get(e->attribs, attname);
}
/* set_attrib -- set an attribute to a value */
EXPORT void set_attrib(Node *e, string name, conststring value)
{
assert(e->tp == Element);
pairlist_set(&e->attribs, name, value);
}
/* delete_attrib -- remove attribute from element, false if not found */
EXPORT bool delete_attrib(Node *e, const conststring name)
{
assert(e->tp == Element);
return pairlist_unset(&e->attribs, name);
}
/* get_by_id -- recursively get the element node with the id in subtree n */
static Tree get_by_id(Node *n, const conststring id)
{
conststring val;
Tree h, p;
assert(n->tp == Element);
if ((val = get_attrib(n, "id")) && eq(val, id)) return n;
for (h = n->children; h; h = h->sister)
if (h->tp == Element && (p = get_by_id(h, id))) return p;
return NULL;
}
/* get_elt_by_id -- get the element node with the ID attribute id */
EXPORT Tree get_elt_by_id(Node *n, const conststring id)
{
/* To do: should this use a hash table? */
Tree h, p;
h = get_root(n);
for (h = h->children; h; h = h->sister)
if (h->tp == Element && (p = get_by_id(h, id))) return p;
return NULL;
}
/* wrap_contents -- wrap contents of a node in an element, return new elt */
EXPORT Tree wrap_contents(Node *n, const string elem, pairlist attr)
{
Node *h, *k;
new(h);
h->tp = Element;
h->name = newstring(elem);
h->attribs = attr;
h->sister = NULL;
h->parent = n;
h->children = n->children;
n->children = h;
for (k = h->children; k; k = k->sister) k->parent = h;
return h;
}
/* wrap_elt -- wrap an element in a new element, return the new element */
EXPORT Tree wrap_elt(Node *n, const conststring elem, pairlist attr)
{
Node *h, *k;
new(h);
h->tp = Element;
h->name = newstring(elem);
h->attribs = attr;
h->sister = n->sister;
h->parent = n->parent;
h->children = n;
n->sister = NULL;
n->parent = h;
if (h->parent->children == n) {
h->parent->children = h;
} else {
k = h->parent->children;
while (k->sister != n) {assert(k->sister->sister); k = k->sister;}
k->sister = h;
}
return h;
}
/* rename_elt -- change the name of an element to elem */
EXPORT void rename_elt(Node *n, const string elem)
{
assert(n->tp == Element);
n->name = newstring(elem);
}
/* push -- add a child node to the tree */
static Tree push(Tree t, Node *n)
{
if (t->children == NULL) {
t->children = n;
} else {
Tree h = t->children;
while (h->sister != NULL) h = h->sister;
h->sister = n;
}
n->parent = t;
return n;
}
/* pop -- go up one level */
static Tree pop(Tree t)
{
assert(t != NULL);
assert(t->tp != Root);
return t->parent;
}
/* append -- add at end of children */
static Tree append(Tree t, Node *n)
{
assert(t != NULL);
if (t->children == NULL) {
t->children = n;
} else {
Tree h = t->children;
while (h->sister != NULL) h = h->sister;
h->sister = n;
}
n->parent = t;
return t;
}
/* lookup -- lookup info about an element case-insensitively */
static const ElementType *lookup(const string e)
{
char h[MAXNAMELEN+2];
strncpy(h, e, sizeof(h) - 1);
h[sizeof(h)-1] = '\0';
down(h);
return lookup_element(h, strlen(h));
}
/* is_known -- true if the element is an HTML 4 element */
EXPORT bool is_known(const string e)
{
return lookup(e) != NULL;
}
/* is_pre -- true if the element has preformatted content */
EXPORT bool is_pre(const string e)
{
const ElementType *info = lookup(e);
return info && info->pre;
}
/* need_stag -- true if the element's start tag is required */
EXPORT bool need_stag(const string e)
{
const ElementType *info = lookup(e);
return !info || info->stag;
}
/* need_etag -- true if the element's end tag is required */
EXPORT bool need_etag(const string e)
{
const ElementType *info = lookup(e);
return !info || info->etag;
}
/* is_empty -- true if element is empty */
EXPORT bool is_empty(const string e)
{
const ElementType *info = lookup(e);
return info && info->empty;
}
/* has_parent -- true if c accepts p as a parent */
EXPORT bool has_parent(const string c, const string p)
{
const ElementType *info = lookup_element(c, strlen(c));
int i;
if (!info) return false;
for (i = 0; info->parents[i]; i++)
if (eq(info->parents[i], p)) return true;
return false;
}
/* preferred_parent -- return first possible parent of e */
static string preferred_parent(const string e)
{
const ElementType *info = lookup_element(e, strlen(e));
assert(info != NULL); /* element is known */
assert(info->parents[0] != NULL); /* element is not root */
return info->parents[0];
}
/* is_root -- true if e has no possible parents */
static bool is_root(const string e)
{
const ElementType *info = lookup_element(e, strlen(e));
assert(info != NULL); /* element is known */
return info->parents[0] == NULL;
}
/* is_mixed -- true if e accepts text content */
EXPORT bool is_mixed(const string e)
{
const ElementType *info = lookup(e);
return !info || info->mixed;
}
/* break_before -- true if element looks better with a newline before it */
EXPORT bool break_before(const string e)
{
const ElementType *info = lookup(e);
return info && info->break_before;
}
/* break_after -- true if element looks better with a newline after it */
EXPORT bool break_after(const string e)
{
const ElementType *info = lookup(e);
return info && info->break_after;
}
/* is_cdata_elt -- true if element has character data content */
EXPORT bool is_cdata_elt(const string e)
{
const ElementType *info = lookup(e);
return info && info->cdata;
}
/* build_path -- try to add omittable start tags to make elem acceptable */
static bool build_path(Tree *t, string elem)
{
const ElementType *info;
Node *n;
int i;
assert(is_known(elem));
assert(is_known((*t)->name));
/* Check if we are done */
if (has_parent(elem, (*t)->name)) return true;
/* Try recursively if any possible parent can be a child of t */
info = lookup(elem);
for (i = 0; info->parents[i]; i++) {
if (!need_stag(info->parents[i]) && build_path(t, info->parents[i])) {
/* Success, so add this parent and return true */
n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Element;
n->name = newstring(info->parents[i]);
assert(islower(n->name[0]));
n->attribs = NULL;
n->sister = n->children = NULL;
*t = push(*t, n);
return true;
}
}
return false;
}
/* tree_push -- add an element to the tree, without checking the DTD */
EXPORT Tree tree_push(Tree t, string elem, pairlist attr)
{
Node *n;
new(n);
n->tp = Element;
n->name = newstring(elem);
n->attribs = attr;
n->sister = n->children = NULL;
return push(t, n);
}
/* html_push -- add an element to the tree, open or close missing elements */
EXPORT Tree html_push(Tree t, string elem, pairlist attr)
{
pairlist a;
Node *h, *n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Element;
n->name = down(newstring(elem));
for (a = attr; a; a = a->next) down(a->name);
n->attribs = attr;
n->sister = n->children = NULL;
/* Unknown elements are just pushed where they are */
if (!is_known(n->name)) return push(t, n);
if (is_root(n->name)) {
while (t->tp != Root) t = pop(t); /* Make sure root is at root */
} else if (is_known(t->name) && build_path(&t, n->name)) {
; /* Added missing start tags */
} else {
/* Check if there is a possible parent further up the tree */
for (h=t; h->tp!=Root && is_known(h->name) && !has_parent(n->name,h->name);
h = h->parent) ;
/* Close omitted end tags */
if (h->tp != Root) while (t != h) t = pop(t);
/* If no valid parent, fabricate one */
if (t->tp == Root || (is_known(t->name) && !has_parent(n->name, t->name)))
t = html_push(t, preferred_parent(n->name), NULL);
}
t = push(t, n);
if (is_empty(n->name)) t = pop(t);
if (is_cdata_elt(n->name)) set_cdata_element(n->name); /* Change scanner */
return t;
}
/* tree_pop -- close an open element, without checking the DTD */
EXPORT Tree tree_pop(Tree t, string elem)
{
assert(t != NULL);
if (t->tp == Root) errexit("End tag </%s> without matching start tag\n", elem);
assert(t->tp == Element);
if (*elem == '\0') return pop(t); /* Empty end tag </> */
if (eq(t->name, elem)) return pop(t);
errexit("End tag </%s> doesn't match start tag <%s>\n", elem, t->name);
return NULL; /* Keep lint happy */
}
/* html_pop -- close an open element */
EXPORT Tree html_pop(Tree t, string elem)
{
Tree h = t;
assert(t != NULL);
down(elem);
if (*elem == '\0') { /* </> */
if (t->tp != Root) t = pop(t);
} else { /* </name> */
for (h = t; h->tp != Root && !eq(h->name, elem); h = h->parent) ;
if (h->tp != Root) { /* Found open element */
while (t != h) t = pop(t);
t = pop(t);
}
}
return t;
}
/* append_comment -- add a comment to the tree */
EXPORT Tree append_comment(Tree t, string comment)
{
Node *n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Comment;
n->text = comment;
n->sister = n->children = NULL;
return append(t, n);
}
/* append_declaration -- add a declaration to the tree */
EXPORT Tree append_declaration(Tree t, string gi,
string fpi, string url)
{
Node *n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Declaration;
n->name = down(gi);
n->text = fpi;
n->url = url;
n->sister = n->children = NULL;
return append(t, n);
}
/* append_procins -- append a processing instruction */
EXPORT Tree append_procins(Tree t, string procins)
{
Node *n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Procins;
n->text = procins;
n->sister = n->children = NULL;
return append(t, n);
}
/* tree_append_text -- append a text chunk, without checking the DTD */
EXPORT Tree tree_append_text(Tree t, string text)
{
Node *n;
assert(text);
new(n);
n->tp = Text;
n->text = text;
n->sister = n->children = NULL;
return append(t, n);
}
/* append_text -- append a text chunk to the document tree */
EXPORT Tree append_text(Tree t, string text)
{
Node *n;
string new_parent;
if (only_space(text) && (t->tp == Root || !is_mixed(t->name))) {
/* Drop text, since it is non-significant whitespace */
return t;
}
if (t->tp == Root || !is_mixed(t->name)) {
/* Need heuristics to make a valid tree */
new_parent = preferred_parent("%data");
/* Close omitted end tags until text or preferred parent fits */
while (t->tp != Root && !is_mixed(t->name) && !need_etag(t->name)
&& !has_parent(new_parent, t->name))
t = pop(t);
/* Fabricate a parent if needed */
if (t->tp == Root || !is_mixed(t->name))
t = html_push(t, new_parent, NULL);
}
n = malloc(sizeof(*n));
assert(n != NULL);
n->tp = Text;
n->text = text;
assert(n->text != NULL);
n->sister = n->children = NULL;
return append(t, n);
}
static void dump2(Tree n, FILE *f)
{
pairlist h;
Tree l;
switch (n->tp) {
case Text: fprintf(f, "%s", n->text); break;
case Comment: fprintf(f, "<!--%s-->", n->text); break;
case Declaration:
fprintf(f, "<!DOCTYPE %s", n->name);
if (n->text) fprintf(f, " PUBLIC \"%s\">", n->text);
if (n->url) fprintf(f, " %s\"%s\">", n->text ? "" : "SYSTEM ", n->url);
fprintf(f, ">");
break;
case Procins: fprintf(f, "<?%s>", n->text); break;
case Element:
fprintf(f, "<%s", n->name);
for (h = n->attribs; h != NULL; h = h->next) {
fprintf(f, " %s", h->name);
if (h->value != NULL) fprintf(f, "=\"%s\"", h->value);
}
if (is_empty(n->name)) {
assert(n->children == NULL);
fprintf(f, " />");
} else {
fprintf(f, ">");
for (l = n->children; l != NULL; l = l->sister) dump2(l, f);
fprintf(f, "</%s>", n->name);
}
break;
default:
assert(!"Cannot happen");
}
}
/* dumptree -- write out the tree below t (t's children, not t itself)*/
EXPORT void dumptree(Tree t, FILE *f)
{
Tree h;
for (h = t->children; h != NULL; h = h->sister) dump2(h, f);
}
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