<?php
/**
* File MiniTemplator.class.php
* @package MiniTemplator
*/

/**
* A compact template engine for HTML files.
*
* Requires PHP 4.0.4 or newer.
*
* <pre>
* Template syntax:
*
*   Variables:
*     ${VariableName}
*
*   Blocks:
*     &lt;!-- $BeginBlock BlockName --&gt;
*     ... block content ...
*     &lt;!-- $EndBlock BlockName --&gt;
*
*   Include a subtemplate:
*     &lt;!-- $Include RelativeFileName --&gt;
* </pre>
*
* <pre>
* General remarks:
*  - Variable names and block names are case-insensitive.
*  - The same variable may be used multiple times within a template.
*  - Blocks can be nested.
*  - Multiple blocks with the same name may occur within a template.
* </pre>
*
* <pre>
* Public methods:
*   readTemplateFromFile   - Reads the template from a file.
*   setTemplateString      - Assigns a new template string.
*   setVariable            - Sets a template variable.
*   setVariableEsc         - Sets a template variable to an escaped string value.
*   variableExists         - Checks whether a template variable exists.
*   addBlock               - Adds an instance of a template block.
*   blockExists            - Checks whether a block exists.
*   reset                  - Clears all variables and blocks.
*   generateOutput         - Generates the HTML page and writes it to the PHP output stream.
*   generateOutputToFile   - Generates the HTML page and writes it to a file.
*   generateOutputToString - Generates the HTML page and writes it to a string.
* </pre>
*
* Home page: {@link http://www.source-code.biz/MiniTemplator}<br>
* License: This module is released under the GNU/LGPL license ({@link http://www.gnu.org/licenses/lgpl.html}).<br>
* Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland. All rights reserved.<br>
* This product is provided "as is" without warranty of any kind.<br>
*
* Version history:<br>
* 2001-10-24 Christian d'Heureuse (chdh): VBasic version created.<br>
* 2002-01-26 Markus Angst: ported to PHP4.<br>
* 2003-04-07 chdh: changes to adjust to Java version.<br>
* 2003-07-08 chdh: Method variableExists added.
*   Method setVariable changed to trigger an error when the variable does not exist.<br>
* 2004-04-07 chdh: Parameter isOptional added to method setVariable.
*   Licensing changed from GPL to LGPL.<br>
* 2004-04-18 chdh: Method blockExists added.<br>
* 2004-10-28 chdh:<br>
*   Method setVariableEsc added.<br>
*   Multiple blocks with the same name may now occur within a template.<br>
*   No error ("unknown command") is generated any more, if a HTML comment starts with "${".<br>
* 2004-11-06 chdh:<br>
*   "$Include" command implemented.<br>
* 2004-11-20 chdh:<br>
*   "$Include" command changed so that the command text is not copied to the output file.<br>
*/

class MiniTemplator {

//--- public member variables ---------------------------------------------------------------------------------------

/**
* Base path for relative file names of subtemplates (for the $Include command).
* This path is prepended to the subtemplate file names. It must be set before
* readTemplateFromFile or setTemplateString.
* @access public
*/
var $subtemplateBasePath;

//--- private member variables --------------------------------------------------------------------------------------

/**#@+
* @access private
*/

var $maxNestingLevel = 50;            // maximum number of block nestings
var $maxInclTemplateSize = 1000000;   // maximum length of template string when including subtemplates
var $template;                        // Template file data
var $varTab;                          // variables table, array index is variable no
    // Fields:
    //  varName                       // variable name
    //  varValue                      // variable value
var $varTabCnt;                       // no of entries used in VarTab
var $varNameToNoMap;                  // maps variable names to variable numbers
var $varRefTab;                       // variable references table
    // Contains an entry for each variable reference in the template. Ordered by TemplatePos.
    // Fields:
    //  varNo                         // variable no
    //  tPosBegin                     // template position of begin of variable reference
    //  tPosEnd                       // template position of end of variable reference
    //  blockNo                       // block no of the (innermost) block that contains this variable reference
    //  blockVarNo                    // block variable no. Index into BlockInstTab.BlockVarTab
var $varRefTabCnt;                    // no of entries used in VarRefTab
var $blockTab;                        // Blocks table, array index is block no
    // Contains an entry for each block in the template. Ordered by TPosBegin.
    // Fields:
    //  blockName                     // block name
    //  nextWithSameName;             // block no of next block with same name or -1 (blocks are backward linked in relation to template position)
    //  tPosBegin                     // template position of begin of block
    //  tPosContentsBegin             // template pos of begin of block contents
    //  tPosContentsEnd               // template pos of end of block contents
    //  tPosEnd                       // template position of end of block
    //  nestingLevel                  // block nesting level
    //  parentBlockNo                 // block no of parent block
    //  definitionIsOpen              // true while $BeginBlock processed but no $EndBlock
    //  instances                     // number of instances of this block
    //  firstBlockInstNo              // block instance no of first instance of this block or -1
    //  lastBlockInstNo               // block instance no of last instance of this block or -1
    //  currBlockInstNo               // current block instance no, used during generation of output file
    //  blockVarCnt                   // no of variables in block
    //  blockVarNoToVarNoMap          // maps block variable numbers to variable numbers
    //  firstVarRefNo                 // variable reference no of first variable of this block or -1
var $blockTabCnt;                     // no of entries used in BlockTab
var $blockNameToNoMap;                // maps block names to block numbers
var $openBlocksTab;
    // During parsing, this table contains the block numbers of the open parent blocks (nested outer blocks).
    // Indexed by the block nesting level.
var $blockInstTab;                    // block instances table
    // This table contains an entry for each block instance that has been added.
    // Indexed by BlockInstNo.
    // Fields:
    //  blockNo                       // block number
    //  instanceLevel                 // instance level of this block
    //     InstanceLevel is an instance counter per block.
    //     (In contrast to blockInstNo, which is an instance counter over the instances of all blocks)
    //  parentInstLevel               // instance level of parent block
    //  nextBlockInstNo               // pointer to next instance of this block or -1
    //     Forward chain for instances of same block.
    //  blockVarTab                   // block instance variables
var $blockInstTabCnt;                 // no of entries used in BlockInstTab

var $currentNestingLevel;             // Current block nesting level during parsing.
var $templateValid;                   // true if a valid template is prepared
var $outputMode;                      // 0 = to PHP output stream, 1 = to file, 2 = to string
var $outputFileHandle;                // file handle during writing of output file
var $outputError;                     // true when an output error occurred
var $outputString;                    // string buffer for the generated HTML page

/**#@-*/

//--- constructor ---------------------------------------------------------------------------------------------------

/**
* Constructs a MiniTemplator object.
* @access public
*/
function MiniTemplator() {
   $this->templateValid = false; }

//--- template string handling --------------------------------------------------------------------------------------

/**
* Reads the template from a file.
* @param  string   $fileName  name of the file that contains the template.
* @return boolean  true on success, false on error.
* @access public
*/
function readTemplateFromFile ($fileName) {
   if (!$this->readFileIntoString($fileName,$s)) {
      $this->triggerError ("Error while reading template file " . $fileName . ".");
      return false; }
   if (!$this->setTemplateString($s)) return false;
   return true; }

/**
* Assigns a new template string.
* @param  string   $templateString  contents of the template file.
* @return boolean  true on success, false on error.
* @access public
*/
function setTemplateString ($templateString) {
   $this->templateValid = false;
   $this->template = $templateString;
   if (!$this->parseTemplate()) return false;
   $this->reset();
   $this->templateValid = true;
   return true; }

/**
* Loads the template string for a subtemplate (used for the $Include command).
* @return boolean  true on success, false on error.
* @access private
*/
function loadSubtemplate ($subtemplateName, &$s) {
   $subtemplateFileName = $this->combineFileSystemPath($this->subtemplateBasePath,$subtemplateName);
   if (!$this->readFileIntoString($subtemplateFileName,$s)) {
      $this->triggerError ("Error while reading subtemplate file " . $subtemplateFileName . ".");
      return false; }
   return true; }

//--- template parsing ----------------------------------------------------------------------------------------------

/**
* Parses the template.
* @return boolean  true on success, false on error.
* @access private
*/
function parseTemplate() {
   $this->initParsing();
   $this->beginMainBlock();
   if (!$this->parseTemplateCommands()) return false;
   $this->endMainBlock();
   if (!$this->checkBlockDefinitionsComplete()) return false;
   if (!$this->parseTemplateVariables()) return false;
   $this->associateVariablesWithBlocks();
   return true; }

/**
* @access private
*/
function initParsing() {
   $this->varTab = array();
   $this->varTabCnt = 0;
   $this->varNameToNoMap = array();
   $this->varRefTab = array();
   $this->varRefTabCnt = 0;
   $this->blockTab = array();
   $this->blockTabCnt = 0;
   $this->blockNameToNoMap = array();
   $this->openBlocksTab = array(); }

/**
* Registers the main block.
* The main block is an implicitly defined block that covers the whole template.
* @access private
*/
function beginMainBlock() {
   $blockNo = 0;
   $this->registerBlock('@@InternalMainBlock@@', $blockNo);
   $bte =& $this->blockTab[$blockNo];
   $bte['tPosBegin'] = 0;
   $bte['tPosContentsBegin'] = 0;
   $bte['nestingLevel'] = 0;
   $bte['parentBlockNo'] = -1;
   $bte['definitionIsOpen'] = true;
   $this->openBlocksTab[0] = $blockNo;
   $this->currentNestingLevel = 1; }

/**
* Completes the main block registration.
* @access private
*/
function endMainBlock() {
   $bte =& $this->blockTab[0];
   $bte['tPosContentsEnd'] = strlen($this->template);
   $bte['tPosEnd'] = strlen($this->template);
   $bte['definitionIsOpen'] = false;
   $this->currentNestingLevel -= 1; }

/**
* Parses commands within the template in the format "<!-- $command parameters -->".
* @return boolean  true on success, false on error.
* @access private
*/
function parseTemplateCommands() {
   $p = 0;
   while (true) {
      $p0 = strpos($this->template,'<!--',$p);
      if ($p0 === false) break;
      $p = strpos($this->template,'-->',$p0);
      if ($p === false) {
         $this->triggerError ("Invalid HTML comment in template at offset $p0.");
         return false; }
      $p += 3;
      $cmdL = substr($this->template,$p0+4,$p-$p0-7);
      if (!$this->processTemplateCommand($cmdL,$p0,$p,$resumeFromStart))
         return false;
      if ($resumeFromStart) $p = $p0; }
   return true; }

/**
* @return boolean  true on success, false on error.
* @access private
*/
function processTemplateCommand ($cmdL, $cmdTPosBegin, $cmdTPosEnd, &$resumeFromStart) {
   $resumeFromStart = false;
   $p = 0;
   $cmd = '';
   if (!$this->parseWord($cmdL,$p,$cmd)) return true;
   $parms = substr($cmdL,$p);
   switch (strtoupper($cmd)) {
      case '$BEGINBLOCK':
         if (!$this->processBeginBlockCmd($parms,$cmdTPosBegin,$cmdTPosEnd))
            return false;
         break;
      case '$ENDBLOCK':
         if (!$this->processEndBlockCmd($parms,$cmdTPosBegin,$cmdTPosEnd))
            return false;
         break;
      case '$INCLUDE':
         if (!$this->processincludeCmd($parms,$cmdTPosBegin,$cmdTPosEnd))
            return false;
         $resumeFromStart = true;
         break;
      default:
         if ($cmd{0} == '$' && !(strlen($cmd) >= 2 && $cmd{1} == '{')) {
            $this->triggerError ("Unknown command \"$cmd\" in template at offset $cmdTPosBegin.");
            return false; }}
    return true; }

/**
* Processes the $BeginBlock command.
* @return boolean  true on success, false on error.
* @access private
*/
function processBeginBlockCmd ($parms, $cmdTPosBegin, $cmdTPosEnd) {
   $p = 0;
   if (!$this->parseWord($parms,$p,$blockName)) {
      $this->triggerError ("Missing block name in \$BeginBlock command in template at offset $cmdTPosBegin.");
      return false; }
   if (trim(substr($parms,$p)) != '') {
      $this->triggerError ("Extra parameter in \$BeginBlock command in template at offset $cmdTPosBegin.");
      return false; }
   $this->registerBlock ($blockName, $blockNo);
   $btr =& $this->blockTab[$blockNo];
   $btr['tPosBegin'] = $cmdTPosBegin;
   $btr['tPosContentsBegin'] = $cmdTPosEnd;
   $btr['nestingLevel'] = $this->currentNestingLevel;
   $btr['parentBlockNo'] = $this->openBlocksTab[$this->currentNestingLevel-1];
   $this->openBlocksTab[$this->currentNestingLevel] = $blockNo;
   $this->currentNestingLevel += 1;
   if ($this->currentNestingLevel > $this->maxNestingLevel) {
      $this->triggerError ("Block nesting overflow in template at offset $cmdTPosBegin.");
      return false; }
   return true; }

/**
* Processes the $EndBlock command.
* @return boolean  true on success, false on error.
* @access private
*/
function processEndBlockCmd ($parms, $cmdTPosBegin, $cmdTPosEnd) {
   $p = 0;
   if (!$this->parseWord($parms,$p,$blockName)) {
      $this->triggerError ("Missing block name in \$EndBlock command in template at offset $cmdTPosBegin.");
      return false; }
   if (trim(substr($parms,$p)) != '') {
      $this->triggerError ("Extra parameter in \$EndBlock command in template at offset $cmdTPosBegin.");
      return false; }
   if (!$this->lookupBlockName($blockName,$blockNo)) {
      $this->triggerError ("Undefined block name \"$blockName\" in \$EndBlock command in template at offset $cmdTPosBegin.");
      return false; }
   $this->currentNestingLevel -= 1;
   $btr =& $this->blockTab[$blockNo];
   if (!$btr['definitionIsOpen']) {
      $this->triggerError ("Multiple \$EndBlock command for block \"$blockName\" in template at offset $cmdTPosBegin.");
      return false; }
   if ($btr['nestingLevel'] != $this->currentNestingLevel) {
      $this->triggerError ("Block nesting level mismatch at \$EndBlock command for block \"$blockName\" in template at offset $cmdTPosBegin.");
      return false; }
   $btr['tPosContentsEnd'] = $cmdTPosBegin;
   $btr['tPosEnd'] = $cmdTPosEnd;
   $btr['definitionIsOpen'] = false;
   return true; }

/**
* @access private
*/
function registerBlock($blockName, &$blockNo) {
   $blockNo = $this->blockTabCnt++;
   $btr =& $this->blockTab[$blockNo];
   $btr = array();
   $btr['blockName'] = $blockName;
   if (!$this->lookupBlockName($blockName,$btr['nextWithSameName']))
      $btr['nextWithSameName'] = -1;
   $btr['definitionIsOpen'] = true;
   $btr['instances'] = 0;
   $btr['firstBlockInstNo'] = -1;
   $btr['lastBlockInstNo'] = -1;
   $btr['blockVarCnt'] = 0;
   $btr['firstVarRefNo'] = -1;
   $btr['blockVarNoToVarNoMap'] = array();
   $this->blockNameToNoMap[strtoupper($blockName)] = $blockNo; }

/**
* Checks that all block definitions are closed.
* @return boolean  true on success, false on error.
* @access private
*/
function checkBlockDefinitionsComplete() {
   for ($blockNo=0; $blockNo < $this->blockTabCnt; $blockNo++) {
      $btr =& $this->blockTab[$blockNo];
      if ($btr['definitionIsOpen']) {
         $this->triggerError ("Missing \$EndBlock command in template for block " . $btr['blockName'] . ".");
         return false; }}
   if ($this->currentNestingLevel != 0) {
      $this->triggerError ("Block nesting level error at end of template.");
      return false; }
   return true; }

/**
* Processes the $Include command.
* @return boolean  true on success, false on error.
* @access private
*/
function processIncludeCmd ($parms, $cmdTPosBegin, $cmdTPosEnd) {
   $p = 0;
   if (!$this->parseWordOrQuotedString($parms,$p,$subtemplateName)) {
      $this->triggerError ("Missing or invalid subtemplate name in \$Include command in template at offset $cmdTPosBegin.");
      return false; }
   if (trim(substr($parms,$p)) != '') {
      $this->triggerError ("Extra parameter in \$include command in template at offset $cmdTPosBegin.");
      return false; }
   return $this->insertSubtemplate($subtemplateName,$cmdTPosBegin,$cmdTPosEnd); }

/**
* Processes the $Include command.
* @return boolean  true on success, false on error.
* @access private
*/
function insertSubtemplate ($subtemplateName, $tPos1, $tPos2) {
   if (strlen($this->template) > $this->maxInclTemplateSize) {
      $this->triggerError ("Subtemplate include aborted because the internal template string is longer than $this->maxInclTemplateSize characters.");
      return false; }
   if (!$this->loadSubtemplate($subtemplateName,$subtemplate)) return false;
   // (Copying the template to insert a subtemplate is a bit slow. In a future implementation of MiniTemplator,
   // a table could be used that contains references to the string fragments.)
   $this->template = substr($this->template,0,$tPos1) . $subtemplate . substr($this->template,$tPos2);
   return true; }

/**
* Parses variable references within the template in the format "${VarName}".
* @return boolean  true on success, false on error.
* @access private
*/
function parseTemplateVariables() {
   $p = 0;
   while (true) {
      $p = strpos($this->template, '${', $p);
      if ($p === false) break;
      $p0 = $p;
      $p = strpos($this->template, '}', $p);
      if ($p === false) {
         $this->triggerError ("Invalid variable reference in template at offset $p0.");
         return false; }
      $p += 1;
      $varName = trim(substr($this->template, $p0+2, $p-$p0-3));
      if (strlen($varName) == 0) {
         $this->triggerError ("Empty variable name in template at offset $p0.");
         return false; }
      $this->registerVariableReference ($varName, $p0, $p); }
   return true; }

/**
* @access private
*/
function registerVariableReference ($varName, $tPosBegin, $tPosEnd) {
   if (!$this->lookupVariableName($varName,$varNo))
      $this->registerVariable($varName,$varNo);
   $varRefNo = $this->varRefTabCnt++;
   $vrtr =& $this->varRefTab[$varRefNo];
   $vrtr = array();
   $vrtr['tPosBegin'] = $tPosBegin;
   $vrtr['tPosEnd'] = $tPosEnd;
   $vrtr['varNo'] = $varNo; }

/**
* @access private
*/
function registerVariable ($varName, &$varNo) {
   $varNo = $this->varTabCnt++;
   $vtr =& $this->varTab[$varNo];
   $vtr = array();
   $vtr['varName'] = $varName;
   $vtr['varValue'] = '';
   $this->varNameToNoMap[strtoupper($varName)] = $varNo; }

/**
* Associates variable references with blocks.
* @access private
*/
function associateVariablesWithBlocks() {
   $varRefNo = 0;
   $activeBlockNo = 0;
   $nextBlockNo = 1;
   while ($varRefNo < $this->varRefTabCnt) {
      $vrtr =& $this->varRefTab[$varRefNo];
      $varRefTPos = $vrtr['tPosBegin'];
      $varNo = $vrtr['varNo'];
      if ($varRefTPos >= $this->blockTab[$activeBlockNo]['tPosEnd']) {
         $activeBlockNo = $this->blockTab[$activeBlockNo]['parentBlockNo'];
         continue; }
      if ($nextBlockNo < $this->blockTabCnt) {
         if ($varRefTPos >= $this->blockTab[$nextBlockNo]['tPosBegin']) {
            $activeBlockNo = $nextBlockNo;
            $nextBlockNo += 1;
            continue; }}
      $btr =& $this->blockTab[$activeBlockNo];
      if ($varRefTPos < $btr['tPosBegin'])
         $this->programLogicError(1);
      $blockVarNo = $btr['blockVarCnt']++;
      $btr['blockVarNoToVarNoMap'][$blockVarNo] = $varNo;
      if ($btr['firstVarRefNo'] == -1)
         $btr['firstVarRefNo'] = $varRefNo;
      $vrtr['blockNo'] = $activeBlockNo;
      $vrtr['blockVarNo'] = $blockVarNo;
      $varRefNo += 1; }}

//--- build up (template variables and blocks) ----------------------------------------------------------------------

/**
* Clears all variables and blocks.
* This method can be used to produce another HTML page with the same
* template. It is faster than creating another MiniTemplator object,
* because the template does not have to be parsed again.
* All variable values are cleared and all added block instances are deleted.
* @access public
*/
function reset() {
   for ($varNo=0; $varNo<$this->varTabCnt; $varNo++)
      $this->varTab[$varNo]['varValue'] = '';
   for ($blockNo=0; $blockNo<$this->blockTabCnt; $blockNo++) {
      $btr =& $this->blockTab[$blockNo];
      $btr['instances'] = 0;
      $btr['firstBlockInstNo'] = -1;
      $btr['lastBlockInstNo'] = -1; }
   $this->blockInstTab = array();
   $this->blockInstTabCnt = 0; }

/**
* Sets a template variable.
* For variables that are used in blocks, the variable value
* must be set before {@link addBlock} is called.
* @param  string  $variableName   the name of the variable to be set.
* @param  string  $variableValue  the new value of the variable.
* @param  boolean $isOptional     Specifies whether an error should be
*    generated when the variable does not exist in the template. If
*    $isOptional is false and the variable does not exist, an error is
*    generated.
* @return boolean true on success, or false on error (e.g. when no
*    variable with the specified name exists in the template and
*    $isOptional is false).
* @access public
*/
function setVariable ($variableName, $variableValue, $isOptional=false) {
   if (!$this->templateValid) {$this->triggerError ("Template not valid."); return false; }
   if (!$this->lookupVariableName($variableName,$varNo)) {
      if ($isOptional) return true;
      $this->triggerError ("Variable \"$variableName\" not defined in template.");
      return false; }
   $this->varTab[$varNo]['varValue'] = $variableValue;
   return true; }

/**
* Sets a template variable to an escaped string.
* This method is identical to (@link setVariable), except that
* the characters &lt;, &gt;, &amp;, ' and " of variableValue are
* replaced by their corresponding HTML/XML character entity codes.
* For variables that are used in blocks, the variable value
* must be set before {@link addBlock} is called.
* @param  string  $variableName   the name of the variable to be set.
* @param  string  $variableValue  the new value of the variable. Special HTML/XML characters are escaped.
* @param  boolean $isOptional     Specifies whether an error should be
*    generated when the variable does not exist in the template. If
*    $isOptional is false and the variable does not exist, an error is
*    generated.
* @return boolean true on success, or false on error (e.g. when no
*    variable with the specified name exists in the template and
*    $isOptional is false).
* @access public
*/
function setVariableEsc ($variableName, $variableValue, $isOptional=false) {
   return $this->setVariable($variableName,htmlspecialchars($variableValue,ENT_QUOTES),$isOptional); }

/**
* Checks whether a variable with the specified name exists within the template.
* @param  string  $variableName   the name of the variable.
* @return boolean true if the variable exists, or false when no
*    variable with the specified name exists in the template.
* @access public
*/
function variableExists ($variableName) {
   if (!$this->templateValid) {$this->triggerError ("Template not valid."); return false; }
   return $this->lookupVariableName($variableName,$varNo); }

/**
* Adds an instance of a template block.
* If the block contains variables, these variables must be set
* before the block is added.
* If the block contains subblocks (nested blocks), the subblocks
* must be added before this block is added.
* If multiple blocks exist with the specified name, an instance
* is added for each block occurence.
* @param  string   blockName the name of the block to be added.
* @return boolean  true on success, false on error (e.g. when no
*    block with the specified name exists in the template).
* @access public
*/
function addBlock($blockName) {
   if (!$this->templateValid) {$this->triggerError ("Template not valid."); return false; }
   if (!$this->lookupBlockName($blockName,$blockNo)) {
      $this->triggerError ("Block \"$blockName\" not defined in template.");
      return false; }
   while ($blockNo != -1) {
      $this->addBlockByNo($blockNo);
      $blockNo = $this->blockTab[$blockNo]['nextWithSameName']; }
   return true; }

/**
* @access private
*/
function addBlockByNo ($blockNo) {
   $btr =& $this->blockTab[$blockNo];
   $this->registerBlockInstance ($blockInstNo);
   $bitr =& $this->blockInstTab[$blockInstNo];
   if ($btr['firstBlockInstNo'] == -1)
      $btr['firstBlockInstNo'] = $blockInstNo;
   if ($btr['lastBlockInstNo'] != -1)
      $this->blockInstTab[$btr['lastBlockInstNo']]['nextBlockInstNo'] = $blockInstNo;
         // set forward pointer of chain
   $btr['lastBlockInstNo'] = $blockInstNo;
   $parentBlockNo = $btr['parentBlockNo'];
   $blockVarCnt = $btr['blockVarCnt'];
   $bitr['blockNo'] = $blockNo;
   $bitr['instanceLevel'] = $btr['instances']++;
   if ($parentBlockNo == -1)
      $bitr['parentInstLevel'] = -1;
    else
      $bitr['parentInstLevel'] = $this->blockTab[$parentBlockNo]['instances'];
   $bitr['nextBlockInstNo'] = -1;
   $bitr['blockVarTab'] = array();
   // copy instance variables for this block
   for ($blockVarNo=0; $blockVarNo<$blockVarCnt; $blockVarNo++) {
      $varNo = $btr['blockVarNoToVarNoMap'][$blockVarNo];
      $bitr['blockVarTab'][$blockVarNo] = $this->varTab[$varNo]['varValue']; }}

/**
* @access private
*/
function registerBlockInstance (&$blockInstNo) {
   $blockInstNo = $this->blockInstTabCnt++; }

/**
* Checks whether a block with the specified name exists within the template.
* @param  string  $blockName   the name of the block.
* @return boolean true if the block exists, or false when no
*    block with the specified name exists in the template.
* @access public
*/
function blockExists ($blockName) {
   if (!$this->templateValid) {$this->triggerError ("Template not valid."); return false; }
   return $this->lookupBlockName($blockName,$blockNo); }

//--- output generation ---------------------------------------------------------------------------------------------

/**
* Generates the HTML page and writes it to the PHP output stream.
* @return boolean  true on success, false on error.
* @access public
*/
function generateOutput () {
   $this->outputMode = 0;
   if (!$this->generateOutputPage()) return false;
   return true; }

/**
* Generates the HTML page and writes it to a file.
* @param  string   $fileName  name of the output file.
* @return boolean  true on success, false on error.
* @access public
*/
function generateOutputToFile ($fileName) {
   $fh = fopen($fileName,"wb");
   if ($fh === false) return false;
   $this->outputMode = 1;
   $this->outputFileHandle = $fh;
   $ok = $this->generateOutputPage();
   fclose ($fh);
   return $ok; }

/**
* Generates the HTML page and writes it to a string.
* @param  string   $outputString  variable that receives
*                  the contents of the generated HTML page.
* @return boolean  true on success, false on error.
* @access public
*/
function generateOutputToString (&$outputString) {
   $outputString = "Error";
   $this->outputMode = 2;
   $this->outputString = "";
   if (!$this->generateOutputPage()) return false;
   $outputString = $this->outputString;
   return true; }

/**
* @access private
* @return boolean  true on success, false on error.
*/
function generateOutputPage() {
   if (!$this->templateValid) {$this->triggerError ("Template not valid."); return false; }
   if ($this->blockTab[0]['instances'] == 0)
      $this->addBlockByNo (0);        // add main block
   for ($blockNo=0; $blockNo < $this->blockTabCnt; $blockNo++) {
       $btr =& $this->blockTab[$blockNo];
       $btr['currBlockInstNo'] = $btr['firstBlockInstNo']; }
   $this->outputError = false;
   $this->writeBlockInstances (0, -1);
   if ($this->outputError) return false;
   return true; }

/**
* Writes all instances of a block that are contained within a specific
* parent block instance.
* Called recursively.
* @access private
*/
function writeBlockInstances ($blockNo, $parentInstLevel) {
   $btr =& $this->blockTab[$blockNo];
   while (!$this->outputError) {
      $blockInstNo = $btr['currBlockInstNo'];
      if ($blockInstNo == -1) break;
      $bitr =& $this->blockInstTab[$blockInstNo];
      if ($bitr['parentInstLevel'] < $parentInstLevel)
         $this->programLogicError (2);
      if ($bitr['parentInstLevel'] > $parentInstLevel) break;
      $this->writeBlockInstance ($blockInstNo);
      $btr['currBlockInstNo'] = $bitr['nextBlockInstNo']; }}

/**
* @access private
*/
function writeBlockInstance($blockInstNo) {
   $bitr =& $this->blockInstTab[$blockInstNo];
   $blockNo = $bitr['blockNo'];
   $btr =& $this->blockTab[$blockNo];
   $tPos = $btr['tPosContentsBegin'];
   $subBlockNo = $blockNo + 1;
   $varRefNo = $btr['firstVarRefNo'];
   while (!$this->outputError) {
      $tPos2 = $btr['tPosContentsEnd'];
      $kind = 0;                                // assume end-of-block
      if ($varRefNo != -1 && $varRefNo < $this->varRefTabCnt) {  // check for variable reference
         $vrtr =& $this->varRefTab[$varRefNo];
         if ($vrtr['tPosBegin'] < $tPos) {
            $varRefNo += 1;
            continue; }
         if ($vrtr['tPosBegin'] < $tPos2) {
            $tPos2 = $vrtr['tPosBegin'];
            $kind = 1; }}
      if ($subBlockNo < $this->blockTabCnt) {   // check for subblock
         $subBtr =& $this->blockTab[$subBlockNo];
         if ($subBtr['tPosBegin'] < $tPos) {
            $subBlockNo += 1;
            continue; }
         if ($subBtr['tPosBegin'] < $tPos2) {
            $tPos2 = $subBtr['tPosBegin'];
            $kind = 2; }}
      if ($tPos2 > $tPos)
         $this->writeString (substr($this->template,$tPos,$tPos2-$tPos));
      switch ($kind) {
         case 0:         // end of block
            return;
         case 1:         // variable
            $vrtr =& $this->varRefTab[$varRefNo];
            if ($vrtr['blockNo'] != $blockNo)
               $this->programLogicError (4);
            $variableValue = $bitr['blockVarTab'][$vrtr['blockVarNo']];
            $this->writeString ($variableValue);
            $tPos = $vrtr['tPosEnd'];
            $varRefNo += 1;
            break;
         case 2:         // sub block
            $subBtr =& $this->blockTab[$subBlockNo];
            if ($subBtr['parentBlockNo'] != $blockNo)
               $this->programLogicError (3);
            $this->writeBlockInstances ($subBlockNo, $bitr['instanceLevel']);  // recursive call
            $tPos = $subBtr['tPosEnd'];
            $subBlockNo += 1;
            break; }}}

/**
* @access private
*/
function writeString ($s) {
   if ($this->outputError) return;
   switch ($this->outputMode) {
      case 0:            // output to PHP output stream
         if (!print($s))
            $this->outputError = true;
         break;
      case 1:            // output to file
         $rc = fwrite($this->outputFileHandle, $s);
         if ($rc === false) $this->outputError = true;
         break;
      case 2:            // output to string
         $this->outputString .= $s;
         break; }}

//--- name lookup routines ------------------------------------------------------------------------------------------

/**
* Maps variable name to variable number.
* @return boolean  true on success, false if the variable is not found.
* @access private
*/
function lookupVariableName ($varName, &$varNo) {
   $x =& $this->varNameToNoMap[strtoupper($varName)];
   if (!isset($x)) return false;
   $varNo = $x;
   return true; }

/**
* Maps block name to block number.
* If there are multiple blocks with the same name, the block number of the last
* registered block with that name is returned.
* @return boolean  true on success, false when the block is not found.
* @access private
*/
function lookupBlockName ($blockName, &$blockNo) {
   $x =& $this->blockNameToNoMap[strtoupper($blockName)];
   if (!isset($x)) return false;
   $blockNo = $x;
   return true; }

//--- general utility routines -----------------------------------------------------------------------------------------

/**
* Reads a file into a string.
* @return boolean  true on success, false on error.
* @access private
*/
function readFileIntoString ($fileName, &$s) {
   if (function_exists('version_compare') && version_compare(phpversion(),"4.3.0",">=")) {
      $s = file_get_contents($fileName);
      if ($s === false) return false;
      return true; }
   $fh = fopen($fileName,"rb");
   if ($fh === false) return false;
   $fileSize = filesize($fileName);
   if ($fileSize === false) {fclose ($fh); return false; }
   $s = fread($fh,$fileSize);
   fclose ($fh);
   if (strlen($s) != $fileSize) return false;
   return true; }

/**
* @access private
* @return boolean  true on success, false when the end of the string is reached.
*/
function parseWord ($s, &$p, &$w) {
   $sLen = strlen($s);
   while ($p < $sLen && ord($s{$p}) <= 32) $p++;
   if ($p >= $sLen) return false;
   $p0 = $p;
   while ($p < $sLen && ord($s{$p}) > 32) $p++;
   $w = substr($s, $p0, $p - $p0);
   return true; }

/**
* @access private
* @return boolean  true on success, false on error.
*/
function parseQuotedString ($s, &$p, &$w) {
   $sLen = strlen($s);
   while ($p < $sLen && ord($s{$p}) <= 32) $p++;
   if ($p >= $sLen) return false;
   if (substr($s,$p,1) != '"') return false;
   $p++; $p0 = $p;
   while ($p < $sLen && $s{$p} != '"') $p++;
   if ($p >= $sLen) return false;
   $w = substr($s, $p0, $p - $p0);
   $p++;
   return true; }

/**
* @access private
* @return boolean  true on success, false on error.
*/
function parseWordOrQuotedString ($s, &$p, &$w) {
   $sLen = strlen($s);
   while ($p < $sLen && ord($s{$p}) <= 32) $p++;
   if ($p >= $sLen) return false;
   if (substr($s,$p,1) == '"')
      return $this->parseQuotedString($s,$p,$w);
    else
      return $this->parseWord($s,$p,$w); }

/**
* Combine two file system paths.
* @access private
*/
function combineFileSystemPath ($path1, $path2) {
   if ($path1 == '' || $path2 == '') return $path2;
   $s = $path1;
   if (substr($s,-1) != '\\' && substr($s,-1) != '/') $s = $s . "/";
   if (substr($path2,0,1) == '\\' || substr($path2,0,1) == '/')
      $s = $s . substr($path2,1);
    else
      $s = $s . $path2;
   return $s; }

/**
* @access private
*/
function triggerError ($msg) {
   trigger_error ("MiniTemplator error: $msg", E_USER_ERROR); }

/**
* @access private
*/
function programLogicError ($errorId) {
   die ("MiniTemplator: Program logic error $errorId.\n"); }

}
?>
