Initial implementation of a simple Olson database file format for DST…

… rule parsing. Implements olson_simple_rule_parser().

lib/olson.php

@@ -0,0 +1,106 @@
+<?php 
+/***
+ *** olson_simple_parser($filename)
+ ***
+ *** Parses the olson files for DST rules.
+ *** It's a simple implementation that captures the 
+ *** most up-to-date DST rule for each ruleset.
+ ***
+ *** Returns a multidimensional array, or false on error
+ ***
+ */
+function olson_simple_rule_parser ($filename) {
+
+    $file = fopen($filename, 'r', 0); 
+
+    if (empty($file)) {
+        return false;
+    }
+
+    $rules = array();
+    while ($line = fgets($file)) {
+        // only pay attention to rules lines
+        if(!preg_match('/^Rule\s/', $line)){
+            continue;
+        }
+        $line = preg_replace('/\n$/', '',$line); // chomp
+        $rule = preg_split('/\s+/', $line);
+        list($discard,
+             $name,
+             $from,
+             $to,
+             $type,
+             $in,
+             $on,
+             $at,
+             $save,
+             $letter) = $rule;
+
+
+        $id = $name;
+        if ($save === '0') {
+            $id .= '-reset';
+        } else {
+            $id .= '-set';
+        }
+
+        if (isset($rules[$id])) {
+            if ($rules[$id][2] < $from) {
+                $rules[$id] = $rule;
+            }
+        } else {
+            $rules[$id] = $rule;
+        }
+    }
+
+    // now reformat it a bit to match Moodle's DST table
+    $moodle_rules = array();
+    foreach (array_keys($rules) as $rule) {
+        if (preg_match('/-reset$/', $rule)) {
+            continue; // we skip these
+        }
+
+        list($discard,
+             $name,
+             $from,
+             $to,
+             $type,
+             $in,
+             $on,
+             $at,
+             $save,
+             $letter) = $rules[$rule];
+
+        $moodle_rule = array();
+        $moodle_rule['name'] = $name;
+        $moodle_rule['apply_offset']   = $save; // time offset
+        $moodle_rule['activate_index'] = $on; // the weeknumber 
+        $moodle_rule['activate_day']   = $on; // the weekday
+        $moodle_rule['activate_month'] = $in; // the month
+        $moodle_rule['activate_time']  = $at; // the weeknumber
+
+        // and now the "deactivate" data
+        list($discard,
+             $name,
+             $from,
+             $to,
+             $type,
+             $in,
+             $on,
+             $at,
+             $save,
+             $letter) = $rules[$name.'-reset'];
+
+        $moodle_rule['deactivate_index'] = $on; // the weeknumber 
+        $moodle_rule['deactivate_day']   = $on; // the weekday
+        $moodle_rule['deactivate_month'] = $in; // the month
+        $moodle_rule['deactivate_time']  = $at; // the weeknumber
+
+        $moodle_rules[$name] = $moodle_rule;
+
+    }
+
+    return $moodle_rules;
+}
+
+?>