# This is a simple template-handling system. You pass it a big data
# structure with key/value pairs, and a template string to fill out.
#
-# Within a template, it recognizes tags delimited by tildes (~). When
-# the template is filled out, the tags will be replaced with the
-# corresponding data. Tags ending with '?' and '.' mark the start and
-# end of a sub-template (for optional or repeated text), and can be
-# wrapped in HTML comments (which will be removed along with the tags
-# when the template is filled out).
+# Within a template, it recognizes tags of the form ~name [arg...]~,
+# optionally wrapped in HTML comments (which will be removed along with
+# the tag markers when the template is filled out).
+#
+# { and } as the final argument mark those tags as being the start and
+# end of a sub-template (for optional or repeated sections). All other
+# tags represent slots to be directly filled by data values. On a }
+# tag, the name is optional, but must match the corresponding { tag if
+# present.
+#
+# For a value tag, arguments represent encodings to be applied
+# successively. For instance, ~foo html~ will encode it to be safe in
+# HTML ('&' to '&', '<' to '<', and so on).
+#
+# { tags can take one argument, which will call the corresponding
+# tem_auto_* function to munge the data, automating certain common use
+# cases. See the comments on the tem_auto functions for more details.
require_once('code/wfpl/encode.php');
require_once('code/wfpl/file.php');
require_once('code/wfpl/misc.php');
-# Public functions
-# ----------------
+# Top-Level Functions
+# -------------------
-function template($data, $template) {
- return fill_template($data, parse_template($template));
+function template($template, $data) {
+ return fill_template(parse_template($template), $data);
}
-function template_file($data, $filename) {
- return fill_template($data, parse_template_file($filename));
+function template_file($filename, $data) {
+ return fill_template(parse_template_file($filename), $data);
}
function parse_template_file($filename) {
return parse_template(file_get_contents($filename));
}
-# First we take the template string and break it up into an array
-# of strings and sub-arrays. The first item in a sub-array is the name
-# of the value or sub-template.
+# We parse the template string into a tree of strings and sub-templates.
+# A template is a hash with a name string, a pieces array, and possibly
+# an args array.
function parse_template($string) {
- # Don't mess with the $stack/$tem assignments! Since
- # PHP references point to the variable, not the data,
- # it really does have to be written exactly like this.
- $stack[] = array('name' => 'root', 'pieces' => array());
- $tem = &last($stack);
+ $tem =& tem_push();
+ $tem['pieces'] = array();
# note: for some reason this captures '<!--' but not '-->'.
$matches = preg_split("/(<!--)?(~[^~]*~)(?(1)-->)/", $string, -1, PREG_SPLIT_DELIM_CAPTURE);
foreach($matches as $match) {
- if(substr($match,0,1) == '~') {
+ if($match == '~~') $match = '~';
+ if(substr($match,0,1) == '~' and strlen($match) > 2) {
$args = explode(' ', substr($match,1,-1));
if(count($args) == 1 and $args[0] == '}') $name = '';
else $name = array_shift($args);
if(last($args) == '{') { # open block
- array_pop($args);
- $stack[] = array('name' => $name, 'pieces' => array(), 'args' => $args);
- $tem['pieces'][] = &last($stack);
- $tem = &last($stack);
+ array_pop($args); # drop '{'
+ if(!is_string(last($tem['pieces']))) $tem['pieces'][] = '';
+ $tem =& tem_push($tem); # create a new sub-template
+ $tem['parent']['pieces'][] =& $tem; # as a piece of the parent
+ $tem['name'] = $name;
+ $tem['pieces'] = array();
+ $tem['args'] = $args;
} elseif(last($args) == '}') { # close block
- array_pop($args);
- $cur = $stack[count($stack)-1]['name'];
+ array_pop($args); # drop '}'
+ $cur = $tem['name'];
if($name && $name != $cur) {
die("Invalid template: tried to close '$name', but '$cur' is current.");
}
- array_pop($stack); $tem = &last($stack);
+ $tem =& $tem['parent'];
} else { # value slot
$tem['pieces'][] = array('name' => $name, 'args' => $args);
}
return $tem;
}
-# Then we do a depth-first traversal of the template tree,
-# replacing all tags with the data values.
-
-function fill_template($data, $template, $context = NULL, $keychain = NULL) {
- $context[] = $data;
- foreach($template['pieces'] as $piece) {
- if(is_string($piece)) $output .= $piece;
- else {
- if($piece['pieces']) { # sub-template
- $keychain[] = $piece['name'];
- $rows = tem_get_rows($piece, $context, $keychain);
- foreach($rows as $key => $row) {
- $keychain[] = $key;
- $output .= fill_template($row, $piece, $context, $keychain);
- array_pop($keychain);
- }
- array_pop($keychain);
- } else $output .= tem_get_enc($piece, $context);
- }
+function fill_template($template, &$data, &$context = NULL) {
+ if(!$context) {
+ $context =& tem_push($context);
+ $context['data'] =& $data;
}
- return $output;
-}
+ foreach($template['pieces'] as $tem) {
+ if(is_string($tem)) $output .= $tem;
+ elseif($tem['pieces']) { # sub-template
+ $rows =& tem_row_data($tem, $context);
+ foreach($rows as $key => &$row) {
+ $context =& tem_push($context);
+ $context['data'] =& $row;
+ $context['rows'] =& $rows;
+ $output .= fill_template($tem, $row, $context);
+ $context =& $context['parent'];
-# Replace top-level values in $main with top-level templates from $tem.
-function merge_templates($main, $tem) {
- $out = array('name' => $main['name'], 'pieces' => array());
-
- $subs = top_sub_templates($tem);
-
- foreach($main['pieces'] as $piece) {
- if(is_array($piece) and !$piece['pieces'] and $subs[$piece['name']]) {
- $piece = $subs[$piece['name']];
+ }
+ } else { # variable
+ $output .= tem_encoded_data($tem, $context);
}
- $out['pieces'][] = $piece;
}
- return $out;
+ return $output;
}
+# Implementation
+# --------------
-# tem_auto functions
-# ------------------
-#
-# If a { tag has an argument, the corresponding tem_auto function is called.
-# This allows it to mangle the data to automate some common cases.
-# 'sep' (separator) sections will be shown for all but the last parent row.
-# Sample usage:
-# <!--~rows~-->
-# <!--~row~-->
-# row content...
-# <!--~separator sep {~--><hr><!--~separator }"-->
-# <!--~row~-->
-# <!--~rows~-->
-#
-function tem_auto_sep($piece, $context, $keychain) {
- list($name, $index, $this_name) = array_slice($keychain, -3);
- $array = tem_get($name, $context);
- if($index != count($array)-1) return true;
-}
+# To track our position in the template and in the data, we use a linked
+# stack structure. Each node is a hash with a reference to the parent
+# node along with whatever other data you want to add. For each stack,
+# you simply keep a variable with a reference to the top element. Then
+# the push and pop operations are:
-# 'once' sections will be shown once unless the corresponding data value
-# is false. We check only for false; 0 or '' will not work.
+# $top =& tem_push($top);
+# $top =& $top['parent'];
-function tem_auto_once($piece, $context, $keychain) {
- $value = tem_get(array_pop($keychain), $context);
- if($value !== false) return true;
-}
+function &tem_push(&$stack = NULL) {
+ static $refs = array();
-# 'evenodd' sections are given an 'evenodd' attribute whose value
-# alternates between 'even' and 'odd'.
+ # Since a PHP reference is *not* a pointer to data, but a pointer to
+ # a variable (or array slot), we *have* to first put the new node in
+ # $refs, and then reference it from $new.
-function tem_auto_evenodd($piece, $context, $keychain) {
- $rows = tem_get(array_pop($keychain), $context);
- $even = 0;
- $text = array('even', 'odd');
- foreach($rows as $key => $value) {
- $rows[$key]['evenodd'] = $text[$even];
- $even = 1 - $even;
- }
- return $rows;
+ $refs[] = array();
+ $new =& $refs[count($refs)-1];
+ if($stack) $new['parent'] =& $stack;
+ return $new;
}
+# To fill out a template, we do a depth-first traversal of the template
+# tree, replacing all tags with the data values.
+# The data starts out as a nested set of key/value pairs, where the
+# values can be:
-# Internal functions
-# ------------------
-#
-# Of course, nothing stops you from using these, but I don't know
-# why you would want to...
+ # a string to fill a value slot
+ # a hash to fill one instance of a sub-template
+ # an array of hashes to fill multiple instances of a sub-template
+# The middle form will be converted to the last form as we use it.
-# Convert value to array of hashes for use in sub-template expansion.
-# This adds flexibility to how you represent your data.
-function tem_value_as_rows($value) {
+function tem_data_as_rows($value) {
if(is_array($value)) {
# numeric keys, is already array of arrays -- expand sub-template for each.
if(array_key_exists(0, $value)) return $value;
}
}
-# Search the current context and return the value for key.
-function tem_get($key, $context) {
- while($context) {
- $data = array_pop($context);
- if(array_key_exists($key, $data)) return $data[$key];
- }
+# To look up a key, we check each namespace (starting with the
+# innermost one) until a value is found.
+
+function tem_data_scope($key, $context) {
+ $scope = $context;
+ do{
+ if(array_key_exists($key, $scope['data'])) {
+ return $scope;
+ }
+ } while($scope = $scope['parent']);
+
+ # not found; return empty scope.
+ return array('parent' => $context);
+}
+
+function tem_get_data($key, $context) {
+ $scope = tem_data_scope($key, $context);
+ if($scope) return $scope['data'][$key];
}
# Return the value for a tag as a set of rows to fill a sub-template.
# If $tag has an arg, call the tem_auto function to munge the data.
-function tem_get_rows($tag, $context, $keychain)
+function &tem_row_data($tag, $context)
{
+ $key = $tag['name'];
if(count($tag['args'])) {
$func = "tem_auto_" . $tag['args'][0];
- if(function_exists($func)) $value = $func($tag, $context, $keychain);
- else die("ERROR: template auto function '$func' not found.<br>\n");
- } else $value = tem_get($tag['name'], $context);
+ function_exists($func)
+ or die("ERROR: template auto function '$func' not found.<br>\n");
+ }
+ $scope = tem_data_scope($key, $context);
+
+ if($func) $value = $func($key, $scope);
+ else $value = $scope['data'][$key];
- return tem_value_as_rows($value);
+ $rows = tem_data_as_rows($value);
+ if(is_array($value)) $scope['data'][$key] = $rows;
+
+ return $rows;
}
# Return the value for a tag as an encoded string.
-function tem_get_enc($tag, $context)
+function tem_encoded_data($tag, $context)
{
$key = $tag['name'];
- $value = tem_get($key, $context);
+ $value = tem_get_data($key, $context);
foreach($tag['args'] as $encoding) {
$func = "enc_$encoding";
if(function_exists($func)) $value = $func($value, $key);
return $value;
}
+
+
+# Return a hash containing the top-level sub-templates of tem.
function top_sub_templates($tem) {
$subs = array();
foreach($tem['pieces'] as $piece) {
return $subs;
}
+# Replace top-level values in $main with top-level templates from $tem.
+function merge_templates($main, $tem) {
+ $out = array('name' => $main['name'], 'pieces' => array());
+
+ $subs = top_sub_templates($tem);
+
+ foreach($main['pieces'] as $piece) {
+ if(is_array($piece) and !$piece['pieces'] and $subs[$piece['name']]) {
+ $piece = $subs[$piece['name']];
+ }
+ $out['pieces'][] = $piece;
+ }
+ return $out;
+}
+
+
+
+# tem_auto functions
+# ------------------
+#
+# If a { tag has an argument, the corresponding tem_auto function is called.
+# This allows it to mangle the data to automate some common cases.
+
+# 'sep' (separator) sections will be shown for all but the last parent row.
+# Sample usage:
+# <!--~rows~-->
+# <!--~row~-->
+# row content...
+# <!--~separator sep {~--><hr><!--~separator }"-->
+# <!--~row~-->
+# <!--~rows~-->
+#
+function tem_auto_sep($key, $context) {
+ $rows =& $context['parent']['rows'];
+ if(key($rows)) return true;
+ # else we are on the last row (cursor has hit the end and reset).
+}
+
+# 'show' sections will be shown unless the corresponding data value
+# is false. We check only for false; 0 or '' will not work.
+
+function tem_auto_show($key, $context) {
+ if($context['data'][$key] !== false)
+ return tem_data_as_rows(true);
+}
+
+# 'evenodd' sections are given an 'evenodd' attribute whose value
+# alternates between 'even' and 'odd'.
+
+function tem_auto_evenodd($key, $context) {
+ $rows = $context['data'][$key];
+ $even = 0;
+ $text = array('even', 'odd');
+ foreach($rows as $key => $value) {
+ $rows[$key]['evenodd'] = $text[$even];
+ $even = 1 - $even;
+ }
+ return tem_data_as_rows($rows);
+}
+
?>
Got questions, comments, patches, etc.? Contact Jason Woofenden