3 # Copyright (C) 2008,2009 Joshua Grams <josh@qualdan.com>
5 # This program is free software: you can redistribute it and/or modify
6 # it under the terms of the GNU General Public License as published by
7 # the Free Software Foundation, either version 3 of the License, or
8 # (at your option) any later version.
10 # This program is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU General Public License for more details.
15 # You should have received a copy of the GNU General Public License
16 # along with this program. If not, see <http://www.gnu.org/licenses/>.
19 # This is a simple template-handling system. You pass it a big data
20 # structure with key/value pairs, and a template string to fill out.
22 # Within a template, it recognizes tags of the form ~name [arg...]~,
23 # optionally wrapped in HTML comments (which will be removed along with
24 # the tag markers when the template is filled out).
26 # { and } as the final argument mark those tags as being the start and
27 # end of a sub-template (for optional or repeated sections). All other
28 # tags represent slots to be directly filled by data values. On a }
29 # tag, the name is optional, but must match the corresponding { tag if
32 # For a value tag, arguments represent encodings to be applied
33 # successively. For instance, ~foo html~ will encode it to be safe in
34 # HTML ('&' to '&', '<' to '<', and so on).
36 # { tags can take one argument, which will call the corresponding
37 # tem_auto_* function to munge the data, automating certain common use
38 # cases. See the comments on the tem_auto functions for more details.
40 require_once('code/wfpl/encode.php');
41 require_once('code/wfpl/file.php');
42 require_once('code/wfpl/misc.php');
48 function template($template, $data) {
49 return fill_template(parse_template($template), $data);
52 function template_file($filename, $data) {
53 return fill_template(parse_template_file($filename), $data);
56 function parse_template_file($filename) {
57 return parse_template(file_get_contents($filename));
60 # First we take the template string and convert it into a tree of
61 # strings and sub-templates. A template is a hash with a name string,
62 # a pieces array, and possibly an args array.
64 function parse_template($string) {
65 # Don't mess with the $stack/$tem assignments! Since
66 # PHP references point to the variable, not the data,
67 # it really does have to be written exactly like this.
68 $stack[] = array('name' => 'root', 'pieces' => array());
70 # note: for some reason this captures '<!--' but not '-->'.
71 $matches = preg_split("/(<!--)?(~[^~]*~)(?(1)-->)/", $string, -1, PREG_SPLIT_DELIM_CAPTURE);
72 foreach($matches as $match) {
73 if(substr($match,0,1) == '~') {
74 $args = explode(' ', substr($match,1,-1));
76 if(count($args) == 1 and $args[0] == '}') $name = '';
77 else $name = array_shift($args);
79 if(last($args) == '{') { # open block
81 $stack[] = array('name' => $name, 'pieces' => array(), 'args' => $args);
82 $tem['pieces'][] = &last($stack);
84 } elseif(last($args) == '}') { # close block
86 $cur = $stack[count($stack)-1]['name'];
87 if($name && $name != $cur) {
88 die("Invalid template: tried to close '$name', but '$cur' is current.");
90 array_pop($stack); $tem = &last($stack);
92 $tem['pieces'][] = array('name' => $name, 'args' => $args);
94 } elseif($match and $match != '<!--') { # static string
95 $tem['pieces'][] = $match;
101 # To fill out a template, we do a depth-first traversal of the template
102 # tree, replacing all tags with the data values.
104 # The data starts out as a nested set of key/value pairs, where the
107 # a string to fill a value slot
108 # a hash to fill one instance of a sub-template
109 # an array of hashes to fill multiple instances of a sub-template
111 # The middle form will be converted to the last form as we use it.
113 function tem_data_as_rows($value) {
114 if(is_array($value)) {
115 # numeric keys, is already array of arrays -- expand sub-template for each.
116 if(array_key_exists(0, $value)) return $value;
117 # key/value pairs -- expand sub-template once.
118 else return array($value);
120 # value -- expand sub-template once using only parent values
121 return array(array());
123 # empty value -- don't expand sub-template
130 # We use dynamic scoping, so we keep a stack of namespaces.
131 # Each scope references a hash and the parent scope.
133 function &tem_scope(&$data, $push = true) {
134 static $stack = array();
137 $parent =& last($stack);
140 $scope =& last($stack);
141 $scope['data'] =& $data;
142 if($parent) $scope['parent'] =& $parent;
149 function &tem_end_scope() { return tem_scope($x, false); }
151 # To look up a key, we check each namespace (starting with the
152 # innermost one) until a value is found.
154 function tem_find_scope($key, $context) {
157 if(array_key_exists($key, $scope['data'])) {
160 } while($scope = $scope['parent']);
162 # not found; return empty scope.
163 return array('parent' => $context);
166 function tem_get($key, $context) {
167 $scope = tem_find_scope($key, $context);
168 if($scope) return $scope['data'][$key];
171 # Return the value for a tag as a set of rows to fill a sub-template.
172 # If $tag has an arg, call the tem_auto function to munge the data.
173 function &tem_get_rows($tag, $context)
176 if(count($tag['args'])) {
177 $func = "tem_auto_" . $tag['args'][0];
178 function_exists($func)
179 or die("ERROR: template auto function '$func' not found.<br>\n");
181 $scope = tem_find_scope($key, $context);
183 if($func) $value = $func($key, $scope);
184 else $value = $scope['data'][$key];
186 $rows = tem_data_as_rows($value);
187 if(is_array($value)) $scope['data'][$key] = $rows;
192 # Return the value for a tag as an encoded string.
193 function tem_get_enc($tag, $context)
196 $value = tem_get($key, $context);
197 foreach($tag['args'] as $encoding) {
198 $func = "enc_$encoding";
199 if(function_exists($func)) $value = $func($value, $key);
200 else die("ERROR: encoder function '$func' not found.<br>\n");
205 function fill_template($template, &$data, &$context = NULL) {
206 if(!$context) $context =& tem_scope($data);
207 foreach($template['pieces'] as $tem) {
208 if(is_string($tem)) $output .= $tem;
209 elseif($tem['pieces']) { # sub-template
210 $rows =& tem_get_rows($tem, $context);
211 foreach($rows as $key => &$row) {
212 $context =& tem_scope($row);
213 $context['rows'] =& $rows;
214 $output .= fill_template($tem, $row, $context);
215 $context =& tem_end_scope();
219 $output .= tem_get_enc($tem, $context);
227 # Return a hash containing the top-level sub-templates of tem.
228 function top_sub_templates($tem) {
230 foreach($tem['pieces'] as $piece) {
231 if(is_array($piece) and $piece['pieces']) {
232 $subs[$piece['name']] = $piece;
238 # Replace top-level values in $main with top-level templates from $tem.
239 function merge_templates($main, $tem) {
240 $out = array('name' => $main['name'], 'pieces' => array());
242 $subs = top_sub_templates($tem);
244 foreach($main['pieces'] as $piece) {
245 if(is_array($piece) and !$piece['pieces'] and $subs[$piece['name']]) {
246 $piece = $subs[$piece['name']];
248 $out['pieces'][] = $piece;
258 # If a { tag has an argument, the corresponding tem_auto function is called.
259 # This allows it to mangle the data to automate some common cases.
261 # 'sep' (separator) sections will be shown for all but the last parent row.
266 # <!--~separator sep {~--><hr><!--~separator }"-->
270 function tem_auto_sep($key, $context) {
271 $rows =& $context['parent']['rows'];
272 if(key($rows)) return true;
273 # else we are on the last row (cursor has hit the end and reset).
276 # 'once' sections will be shown once unless the corresponding data value
277 # is false. We check only for false; 0 or '' will not work.
279 function tem_auto_once($key, $context) {
280 if($context['data'][$key] !== false)
281 return tem_data_as_rows(true);
284 # 'evenodd' sections are given an 'evenodd' attribute whose value
285 # alternates between 'even' and 'odd'.
287 function tem_auto_evenodd($key, $context) {
288 $rows = $context['data'][$key];
290 $text = array('even', 'odd');
291 foreach($rows as $key => $value) {
292 $rows[$key]['evenodd'] = $text[$even];
295 return tem_data_as_rows($rows);