includes/cbt/CBTCompiler.php

   1 <?php
   2
   3 /**
   4  * This file contains functions to convert callback templates to other languages.
   5  * The template should first be pre-processed with CBTProcessor to remove static
   6  * sections.
   7  */
   8
   9
  10 require_once( dirname( __FILE__ ) . '/CBTProcessor.php' );
  11
  12 /**
  13  * Push a value onto the stack
  14  * Argument 1: value
  15  */
  16 define( 'CBT_PUSH', 1 );
  17
  18 /**
  19  * Pop, concatenate argument, push
  20  * Argument 1: value
  21  */
  22 define( 'CBT_CAT', 2 );
  23
  24 /**
  25  * Concatenate where the argument is on the stack, instead of immediate
  26  */
  27 define( 'CBT_CATS', 3 );
  28
  29 /**
  30  * Call a function, push the return value onto the stack and put it in the cache
  31  * Argument 1: argument count
  32  *
  33  * The arguments to the function are on the stack
  34  */
  35 define( 'CBT_CALL', 4 );
  36
  37 /**
  38  * Pop, htmlspecialchars, push
  39  */
  40 define( 'CBT_HX', 5 );
  41
  42 class CBTOp {
  43         var $opcode;
  44         var $arg1;
  45         var $arg2;
  46
  47         function CBTOp( $opcode, $arg1, $arg2 ) {
  48                 $this->opcode = $opcode;
  49                 $this->arg1 = $arg1;
  50                 $this->arg2 = $arg2;
  51         }
  52
  53         function name() {
  54                 $opcodeNames = array(
  55                         CBT_PUSH => 'PUSH',
  56                         CBT_CAT => 'CAT',
  57                         CBT_CATS => 'CATS',
  58                         CBT_CALL => 'CALL',
  59                         CBT_HX => 'HX',
  60                 );
  61                 return $opcodeNames[$this->opcode];
  62         }
  63 };
  64
  65 class CBTCompiler {
  66         var $mOps = array();
  67         var $mCode;
  68
  69         function CBTCompiler( $text ) {
  70                 $this->mText = $text;
  71         }
  72
  73         /**
  74          * Compile the text.
  75          * Returns true on success, error message on failure
  76          */
  77         function compile() {
  78                 $this->mLastError = false;
  79                 $this->mOps = array();
  80
  81                 $this->doText( 0, strlen( $this->mText ) );
  82
  83                 if ( $this->mLastError !== false ) {
  84                         $pos = $this->mErrorPos;
  85
  86                         // Find the line number at which the error occurred
  87                         $startLine = 0;
  88                         $endLine = 0;
  89                         $line = 0;
  90                         do {
  91                                 if ( $endLine ) {
  92                                         $startLine = $endLine + 1;
  93                                 }
  94                                 $endLine = strpos( $this->mText, "\n", $startLine );
  95                                 ++$line;
  96                         } while ( $endLine !== false && $endLine < $pos );
  97
  98                         $text = "Template error at line $line: $this->mLastError\n<pre>\n";
  99
 100                         $context = rtrim( str_replace( "\t", " ", substr( $this->mText, $startLine, $endLine - $startLine ) ) );
 101                         $text .= htmlspecialchars( $context ) . "\n" . str_repeat( ' ', $pos - $startLine ) . "^\n</pre>\n";
 102                 } else {
 103                         $text = true;
 104                 }
 105
 106                 return $text;
 107         }
 108
 109         /** Shortcut for doOpenText( $start, $end, false */
 110         function doText( $start, $end ) {
 111                 return $this->doOpenText( $start, $end, false );
 112         }
 113
 114         function phpQuote( $text ) {
 115                 return "'" . strtr( $text, array( "\\" => "\\\\", "'" => "\\'" ) ) . "'";
 116         }
 117
 118         function op( $opcode, $arg1 = null, $arg2 = null) {
 119                 return new CBTOp( $opcode, $arg1, $arg2 );
 120         }
 121
 122         /**
 123          * Recursive workhorse for text mode.
 124          *
 125          * Processes text mode starting from offset $p, until either $end is
 126          * reached or a closing brace is found. If $needClosing is false, a
 127          * closing brace will flag an error, if $needClosing is true, the lack
 128          * of a closing brace will flag an error.
 129          *
 130          * The parameter $p is advanced to the position after the closing brace,
 131          * or after the end. A CBTValue is returned.
 132          *
 133          * @private
 134          */
 135         function doOpenText( &$p, $end, $needClosing = true ) {
 136                 $in =& $this->mText;
 137                 $start = $p;
 138                 $atStart = true;
 139
 140                 $foundClosing = false;
 141                 while ( $p < $end ) {
 142                         $matchLength = strcspn( $in, CBT_BRACE, $p, $end - $p );
 143                         $pToken = $p + $matchLength;
 144
 145                         if ( $pToken >= $end ) {
 146                                 // No more braces, output remainder
 147                                 if ( $atStart ) {
 148                                         $this->mOps[] = $this->op( CBT_PUSH, substr( $in, $p ) );
 149                                         $atStart = false;
 150                                 } else {
 151                                         $this->mOps[] = $this->op( CBT_CAT, substr( $in, $p ) );
 152                                 }
 153                                 $p = $end;
 154                                 break;
 155                         }
 156
 157                         // Output the text before the brace
 158                         if ( $atStart ) {
 159                                 $this->mOps[] = $this->op( CBT_PUSH, substr( $in, $p, $matchLength ) );
 160                                 $atStart = false;
 161                         } else {
 162                                 $this->mOps[] = $this->op( CBT_CAT, substr( $in, $p, $matchLength ) );
 163                         }
 164
 165                         // Advance the pointer
 166                         $p = $pToken + 1;
 167
 168                         // Check for closing brace
 169                         if ( $in[$pToken] == '}' ) {
 170                                 $foundClosing = true;
 171                                 break;
 172                         }
 173
 174                         // Handle the "{fn}" special case
 175                         if ( $pToken > 0 && $in[$pToken-1] == '"' ) {
 176                                 $this->doOpenFunction( $p, $end );
 177                                 if ( $p < $end && $in[$p] == '"' ) {
 178                                         $this->mOps[] = $this->op( CBT_HX );
 179                                 }
 180                         } else {
 181                                 $this->doOpenFunction( $p, $end );
 182                         }
 183                         if ( $atStart ) {
 184                                 $atStart = false;
 185                         } else {
 186                                 $this->mOps[] = $this->op( CBT_CATS );
 187                         }
 188                 }
 189                 if ( $foundClosing && !$needClosing ) {
 190                         $this->error( 'Errant closing brace', $p );
 191                 } elseif ( !$foundClosing && $needClosing ) {
 192                         $this->error( 'Unclosed text section', $start );
 193                 } else {
 194                         if ( $atStart ) {
 195                                 $this->mOps[] = $this->op( CBT_PUSH, '' );
 196                         }
 197                 }
 198         }
 199
 200         /**
 201          * Recursive workhorse for function mode.
 202          *
 203          * Processes function mode starting from offset $p, until either $end is
 204          * reached or a closing brace is found. If $needClosing is false, a
 205          * closing brace will flag an error, if $needClosing is true, the lack
 206          * of a closing brace will flag an error.
 207          *
 208          * The parameter $p is advanced to the position after the closing brace,
 209          * or after the end. A CBTValue is returned.
 210          *
 211          * @private
 212          */
 213         function doOpenFunction( &$p, $end, $needClosing = true ) {
 214                 $in =& $this->mText;
 215                 $start = $p;
 216                 $argCount = 0;
 217
 218                 $foundClosing = false;
 219                 while ( $p < $end ) {
 220                         $char = $in[$p];
 221                         if ( $char == '{' ) {
 222                                 // Switch to text mode
 223                                 ++$p;
 224                                 $this->doOpenText( $p, $end );
 225                                 ++$argCount;
 226                         } elseif ( $char == '}' ) {
 227                                 // Block end
 228                                 ++$p;
 229                                 $foundClosing = true;
 230                                 break;
 231                         } elseif ( false !== strpos( CBT_WHITE, $char ) ) {
 232                                 // Whitespace
 233                                 // Consume the rest of the whitespace
 234                                 $p += strspn( $in, CBT_WHITE, $p, $end - $p );
 235                         } else {
 236                                 // Token, find the end of it
 237                                 $tokenLength = strcspn( $in, CBT_DELIM, $p, $end - $p );
 238                                 $this->mOps[] = $this->op( CBT_PUSH, substr( $in, $p, $tokenLength ) );
 239
 240                                 // Execute the token as a function if it's not the function name
 241                                 if ( $argCount ) {
 242                                         $this->mOps[] = $this->op( CBT_CALL, 1 );
 243                                 }
 244
 245                                 $p += $tokenLength;
 246                                 ++$argCount;
 247                         }
 248                 }
 249                 if ( !$foundClosing && $needClosing ) {
 250                         $this->error( 'Unclosed function', $start );
 251                         return '';
 252                 }
 253
 254                 $this->mOps[] = $this->op( CBT_CALL, $argCount );
 255         }
 256
 257         /**
 258          * Set a flag indicating that an error has been found.
 259          */
 260         function error( $text, $pos = false ) {
 261                 $this->mLastError = $text;
 262                 if ( $pos === false ) {
 263                         $this->mErrorPos = $this->mCurrentPos;
 264                 } else {
 265                         $this->mErrorPos = $pos;
 266                 }
 267         }
 268
 269         function getLastError() {
 270                 return $this->mLastError;
 271         }
 272
 273         function opsToString() {
 274                 $s = '';
 275                 foreach( $this->mOps as $op ) {
 276                         $s .= $op->name();
 277                         if ( !is_null( $op->arg1 ) ) {
 278                                 $s .= ' ' . var_export( $op->arg1, true );
 279                         }
 280                         if ( !is_null( $op->arg2 ) ) {
 281                                 $s .= ' ' . var_export( $op->arg2, true );
 282                         }
 283                         $s .= "\n";
 284                 }
 285                 return $s;
 286         }
 287
 288         function generatePHP( $functionObj ) {
 289                 $fname = 'CBTCompiler::generatePHP';
 290                 wfProfileIn( $fname );
 291                 $stack = array();
 292
 293                 foreach( $this->mOps as $op ) {
 294                         switch( $op->opcode ) {
 295                                 case CBT_PUSH:
 296                                         $stack[] = $this->phpQuote( $op->arg1 );
 297                                         break;
 298                                 case CBT_CAT:
 299                                         $val = array_pop( $stack );
 300                                         array_push( $stack, "$val . " . $this->phpQuote( $op->arg1 ) );
 301                                         break;
 302                                 case CBT_CATS:
 303                                         $right = array_pop( $stack );
 304                                         $left = array_pop( $stack );
 305                                         array_push( $stack, "$left . $right" );
 306                                         break;
 307                                 case CBT_CALL:
 308                                         $args = array_slice( $stack, count( $stack ) - $op->arg1, $op->arg1 );
 309                                         $stack = array_slice( $stack, 0, count( $stack ) - $op->arg1 );
 310
 311                                         // Some special optimised expansions
 312                                         if ( $op->arg1 == 0 ) {
 313                                                 $result = '';
 314                                         } else {
 315                                                 $func = array_shift( $args );
 316                                                 if ( substr( $func, 0, 1 ) == "'" &&  substr( $func, -1 ) == "'" ) {
 317                                                         $func = substr( $func, 1, strlen( $func ) - 2 );
 318                                                         if ( $func == "if" ) {
 319                                                                 if ( $op->arg1 < 3 ) {
 320                                                                         // This should have been caught during processing
 321                                                                         return "Not enough arguments to if";
 322                                                                 } elseif ( $op->arg1 == 3 ) {
 323                                                                         $result = "(({$args[0]} != '') ? ({$args[1]}) : '')";
 324                                                                 } else {
 325                                                                         $result = "(({$args[0]} != '') ? ({$args[1]}) : ({$args[2]}))";
 326                                                                 }
 327                                                         } elseif ( $func == "true" ) {
 328                                                                 $result = "true";
 329                                                         } elseif( $func == "lbrace" || $func == "{" ) {
 330                                                                 $result = "{";
 331                                                         } elseif( $func == "rbrace" || $func == "}" ) {
 332                                                                 $result = "}";
 333                                                         } elseif ( $func == "escape" || $func == "~" ) {
 334                                                                 $result = "htmlspecialchars({$args[0]})";
 335                                                         } else {
 336                                                                 // Known function name
 337                                                                 $result = "{$functionObj}->{$func}(" . implode( ', ', $args ) . ')';
 338                                                         }
 339                                                 } else {
 340                                                         // Unknown function name
 341                                                         $result = "call_user_func(array($functionObj, $func), " . implode( ', ', $args ) . ' )';
 342                                                 }
 343                                         }
 344                                         array_push( $stack, $result );
 345                                         break;
 346                                 case CBT_HX:
 347                                         $val = array_pop( $stack );
 348                                         array_push( $stack, "htmlspecialchars( $val )" );
 349                                         break;
 350                                 default:
 351                                         return "Unknown opcode {$op->opcode}\n";
 352                         }
 353                 }
 354                 wfProfileOut( $fname );
 355                 if ( count( $stack ) !== 1 ) {
 356                         return "Error, stack count incorrect\n";
 357                 }
 358                 return '
 359                         global $cbtExecutingGenerated;
 360                         ++$cbtExecutingGenerated;
 361                         $output = ' . $stack[0] . ';
 362                         --$cbtExecutingGenerated;
 363                         return $output;
 364                         ';
 365         }
 366 }