* template.php: switch to generic linked stack.

diff --git a/template.php b/template.php
index 0e1688c..03f11ea 100644 (file)
--- a/template.php
+++ b/template.php
@@ -42,8 +42,8 @@ require_once('code/wfpl/file.php');
 require_once('code/wfpl/misc.php');
 
 
-# Public functions
-# ----------------
+# Top-Level Functions
+# -------------------
 
 function template($template, $data) {
        return fill_template(parse_template($template), $data);
@@ -57,16 +57,39 @@ function parse_template_file($filename) {
        return parse_template(file_get_contents($filename));
 }
 
+# See also parse_template and fill_template.
+
+
+# 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:
+
+# $top =& tem_push($top);
+# $top =& $top['parent'];
+
+function &tem_push(&$stack = NULL) {
+       static $refs = array();
+
+       # 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.
+
+       $refs[] = array();
+       $new =& $refs[count($refs)-1];
+       if($stack) $new['parent'] =& $stack;
+       return $new;
+}
+
+
 # First we take the template string and convert it 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 $match) {
@@ -78,16 +101,20 @@ function parse_template($string) {
 
                        if(last($args) == '{') {  # open block
                                array_pop($args);
-                               $stack[] = array('name' => $name, 'pieces' => array(), 'args' => $args);
-                               $tem['pieces'][] = &last($stack);
-                               $tem = &last($stack);
+                               # create a new sub-template
+                               # and add it to the parent.
+                               $tem =& tem_push($tem);
+                               $tem['parent']['pieces'][] =& $tem;
+                               $tem['name'] = $name;
+                               $tem['pieces'] = array();
+                               $tem['args'] = $args;
                        } elseif(last($args) == '}') {  # close block
                                array_pop($args);
-                               $cur = $stack[count($stack)-1]['name'];
+                               $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' => $args);
                        }
@@ -125,29 +152,6 @@ function tem_data_as_rows($value) {
        }
 }
 
-
-
-# We use dynamic scoping, so we keep a stack of namespaces.
-# Each scope references a hash and the parent scope.
-
-function &tem_scope(&$data, $push = true) {
-       static $stack = array();
-
-       if($push) {
-               $parent =& last($stack);
-               $stack[] = array();
-
-               $scope =& last($stack);
-               $scope['data'] =& $data;
-               if($parent) $scope['parent'] =& $parent;
-       } else { # pop
-               array_pop($stack);
-       }
-       return last($stack);
-}
-
-function &tem_end_scope() { return tem_scope($x, false); }
-
 # To look up a key, we check each namespace (starting with the
 # innermost one) until a value is found.
 
@@ -203,16 +207,21 @@ function tem_get_enc($tag, $context)
 }
 
 function fill_template($template, &$data, &$context = NULL) {
-       if(!$context) $context =& tem_scope($data);
+       if(!$context) {
+               $context =& tem_push($context);
+               $context['data'] =& $data;
+       }
+
        foreach($template['pieces'] as $tem) {
                if(is_string($tem)) $output .= $tem;
                elseif($tem['pieces']) {  # sub-template
                        $rows =& tem_get_rows($tem, $context);
                        foreach($rows as $key => &$row) {
-                               $context =& tem_scope($row);
+                               $context =& tem_push($context);
+                               $context['data'] =& $row;
                                $context['rows'] =& $rows;
                                        $output .= fill_template($tem, $row, $context);
-                               $context =& tem_end_scope();
+                               $context =& $context['parent'];
 
                        }
                } else {  # variable