net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/ast/Expression.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  14 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  15 import net.sourceforge.phpdt.internal.compiler.impl.Constant;
  16 import net.sourceforge.phpdt.internal.compiler.lookup.BaseTypeBinding;
  17 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  18 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  19
  20 public class Expression extends Statement {
  21
  22         //some expression may not be used - from a java semantic point
  23         //of view only - as statements. Other may. In order to avoid the creation
  24         //of wrappers around expression in order to tune them as expression
  25         //Expression is a subclass of Statement. See the message isValidJavaStatement()
  26
  27         public int implicitConversion;
  28         public TypeBinding resolvedType;
  29
  30         public Constant constant;
  31
  32         public Expression() {
  33                 super();
  34         }
  35
  36         public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {
  37
  38                 return flowInfo;
  39         }
  40
  41         public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo, boolean valueRequired) {
  42
  43                 return analyseCode(currentScope, flowContext, flowInfo);
  44         }
  45
  46         /**
  47          * Constant usable for bytecode pattern optimizations, but cannot be inlined
  48          * since it is not strictly equivalent to the definition of constant expressions.
  49          * In particular, some side-effects may be required to occur (only the end value
  50          * is known).
  51          * Constant is known to be of boolean type
  52          */
  53         public Constant optimizedBooleanConstant() {
  54
  55                 return this.constant;
  56         }
  57
  58         public static final boolean isConstantValueRepresentable(
  59                 Constant constant,
  60                 int constantTypeID,
  61                 int targetTypeID) {
  62
  63                 //true if there is no loss of precision while casting.
  64                 // constantTypeID == constant.typeID
  65                 if (targetTypeID == constantTypeID)
  66                         return true;
  67                 switch (targetTypeID) {
  68                         case T_char :
  69                                 switch (constantTypeID) {
  70                                         case T_char :
  71                                                 return true;
  72                                         case T_double :
  73                                                 return constant.doubleValue() == constant.charValue();
  74                                         case T_float :
  75                                                 return constant.floatValue() == constant.charValue();
  76                                         case T_int :
  77                                                 return constant.intValue() == constant.charValue();
  78                                         case T_short :
  79                                                 return constant.shortValue() == constant.charValue();
  80                                         case T_byte :
  81                                                 return constant.byteValue() == constant.charValue();
  82                                         case T_long :
  83                                                 return constant.longValue() == constant.charValue();
  84                                         default :
  85                                                 return false;//boolean
  86                                 }
  87
  88                         case T_float :
  89                                 switch (constantTypeID) {
  90                                         case T_char :
  91                                                 return constant.charValue() == constant.floatValue();
  92                                         case T_double :
  93                                                 return constant.doubleValue() == constant.floatValue();
  94                                         case T_float :
  95                                                 return true;
  96                                         case T_int :
  97                                                 return constant.intValue() == constant.floatValue();
  98                                         case T_short :
  99                                                 return constant.shortValue() == constant.floatValue();
 100                                         case T_byte :
 101                                                 return constant.byteValue() == constant.floatValue();
 102                                         case T_long :
 103                                                 return constant.longValue() == constant.floatValue();
 104                                         default :
 105                                                 return false;//boolean
 106                                 }
 107
 108                         case T_double :
 109                                 switch (constantTypeID) {
 110                                         case T_char :
 111                                                 return constant.charValue() == constant.doubleValue();
 112                                         case T_double :
 113                                                 return true;
 114                                         case T_float :
 115                                                 return constant.floatValue() == constant.doubleValue();
 116                                         case T_int :
 117                                                 return constant.intValue() == constant.doubleValue();
 118                                         case T_short :
 119                                                 return constant.shortValue() == constant.doubleValue();
 120                                         case T_byte :
 121                                                 return constant.byteValue() == constant.doubleValue();
 122                                         case T_long :
 123                                                 return constant.longValue() == constant.doubleValue();
 124                                         default :
 125                                                 return false; //boolean
 126                                 }
 127
 128                         case T_byte :
 129                                 switch (constantTypeID) {
 130                                         case T_char :
 131                                                 return constant.charValue() == constant.byteValue();
 132                                         case T_double :
 133                                                 return constant.doubleValue() == constant.byteValue();
 134                                         case T_float :
 135                                                 return constant.floatValue() == constant.byteValue();
 136                                         case T_int :
 137                                                 return constant.intValue() == constant.byteValue();
 138                                         case T_short :
 139                                                 return constant.shortValue() == constant.byteValue();
 140                                         case T_byte :
 141                                                 return true;
 142                                         case T_long :
 143                                                 return constant.longValue() == constant.byteValue();
 144                                         default :
 145                                                 return false; //boolean
 146                                 }
 147
 148                         case T_short :
 149                                 switch (constantTypeID) {
 150                                         case T_char :
 151                                                 return constant.charValue() == constant.shortValue();
 152                                         case T_double :
 153                                                 return constant.doubleValue() == constant.shortValue();
 154                                         case T_float :
 155                                                 return constant.floatValue() == constant.shortValue();
 156                                         case T_int :
 157                                                 return constant.intValue() == constant.shortValue();
 158                                         case T_short :
 159                                                 return true;
 160                                         case T_byte :
 161                                                 return constant.byteValue() == constant.shortValue();
 162                                         case T_long :
 163                                                 return constant.longValue() == constant.shortValue();
 164                                         default :
 165                                                 return false; //boolean
 166                                 }
 167
 168                         case T_int :
 169                                 switch (constantTypeID) {
 170                                         case T_char :
 171                                                 return constant.charValue() == constant.intValue();
 172                                         case T_double :
 173                                                 return constant.doubleValue() == constant.intValue();
 174                                         case T_float :
 175                                                 return constant.floatValue() == constant.intValue();
 176                                         case T_int :
 177                                                 return true;
 178                                         case T_short :
 179                                                 return constant.shortValue() == constant.intValue();
 180                                         case T_byte :
 181                                                 return constant.byteValue() == constant.intValue();
 182                                         case T_long :
 183                                                 return constant.longValue() == constant.intValue();
 184                                         default :
 185                                                 return false; //boolean
 186                                 }
 187
 188                         case T_long :
 189                                 switch (constantTypeID) {
 190                                         case T_char :
 191                                                 return constant.charValue() == constant.longValue();
 192                                         case T_double :
 193                                                 return constant.doubleValue() == constant.longValue();
 194                                         case T_float :
 195                                                 return constant.floatValue() == constant.longValue();
 196                                         case T_int :
 197                                                 return constant.intValue() == constant.longValue();
 198                                         case T_short :
 199                                                 return constant.shortValue() == constant.longValue();
 200                                         case T_byte :
 201                                                 return constant.byteValue() == constant.longValue();
 202                                         case T_long :
 203                                                 return true;
 204                                         default :
 205                                                 return false; //boolean
 206                                 }
 207
 208                         default :
 209                                 return false; //boolean
 210                 }
 211         }
 212
 213         /**
 214          * Expression statements are plain expressions, however they generate like
 215          * normal expressions with no value required.
 216          *
 217          * @param currentScope net.sourceforge.phpdt.internal.compiler.lookup.BlockScope
 218          * @param codeStream net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
 219          */
 220 //      public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 221 //
 222 //              if ((bits & IsReachableMASK) == 0) {
 223 //                      return;
 224 //              }
 225 //              generateCode(currentScope, codeStream, false);
 226 //      }
 227
 228         /**
 229          * Every expression is responsible for generating its implicit conversion when necessary.
 230          *
 231          * @param currentScope net.sourceforge.phpdt.internal.compiler.lookup.BlockScope
 232          * @param codeStream net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
 233          * @param valueRequired boolean
 234          */
 235 //      public void generateCode(
 236 //              BlockScope currentScope,
 237 //              CodeStream codeStream,
 238 //              boolean valueRequired) {
 239 //
 240 //              if (constant != NotAConstant) {
 241 //                      // generate a constant expression
 242 //                      int pc = codeStream.position;
 243 //                      codeStream.generateConstant(constant, implicitConversion);
 244 //                      codeStream.recordPositionsFrom(pc, this.sourceStart);
 245 //              } else {
 246 //                      // actual non-constant code generation
 247 //                      throw new ShouldNotImplement(ProjectPrefUtil.bind("ast.missingCode")); //$NON-NLS-1$
 248 //              }
 249 //      }
 250
 251         /**
 252          * Default generation of a boolean value
 253          */
 254 //      public void generateOptimizedBoolean(
 255 //              BlockScope currentScope,
 256 //              CodeStream codeStream,
 257 //              Label trueLabel,
 258 //              Label falseLabel,
 259 //              boolean valueRequired) {
 260 //
 261 //              // a label valued to nil means: by default we fall through the case...
 262 //              // both nil means we leave the value on the stack
 263 //
 264 //              if ((constant != Constant.NotAConstant) && (constant.typeID() == T_boolean)) {
 265 //                      int pc = codeStream.position;
 266 //                      if (constant.booleanValue() == true) {
 267 //                              // constant == true
 268 //                              if (valueRequired) {
 269 //                                      if (falseLabel == null) {
 270 //                                              // implicit falling through the FALSE case
 271 //                                              if (trueLabel != null) {
 272 //                                                      codeStream.goto_(trueLabel);
 273 //                                              }
 274 //                                      }
 275 //                              }
 276 //                      } else {
 277 //                              if (valueRequired) {
 278 //                                      if (falseLabel != null) {
 279 //                                              // implicit falling through the TRUE case
 280 //                                              if (trueLabel == null) {
 281 //                                                      codeStream.goto_(falseLabel);
 282 //                                              }
 283 //                                      }
 284 //                              }
 285 //                      }
 286 //                      codeStream.recordPositionsFrom(pc, this.sourceStart);
 287 //                      return;
 288 //              }
 289 //              generateCode(currentScope, codeStream, valueRequired);
 290 //              // branching
 291 //              int position = codeStream.position;
 292 //              if (valueRequired) {
 293 //                      if (falseLabel == null) {
 294 //                              if (trueLabel != null) {
 295 //                                      // Implicit falling through the FALSE case
 296 //                                      codeStream.ifne(trueLabel);
 297 //                              }
 298 //                      } else {
 299 //                              if (trueLabel == null) {
 300 //                                      // Implicit falling through the TRUE case
 301 //                                      codeStream.ifeq(falseLabel);
 302 //                              } else {
 303 //                                      // No implicit fall through TRUE/FALSE --> should never occur
 304 //                              }
 305 //                      }
 306 //              }
 307 //              // reposition the endPC
 308 //              codeStream.updateLastRecordedEndPC(position);
 309 //      }
 310 //
 311 //      /* Optimized (java) code generation for string concatenations that involve StringBuffer
 312 //       * creation: going through this path means that there is no need for a new StringBuffer
 313 //       * creation, further operands should rather be only appended to the current one.
 314 //       * By default: no optimization.
 315 //       */
 316 //      public void generateOptimizedStringBuffer(
 317 //              BlockScope blockScope,
 318 //              net.sourceforge.phpdt.internal.compiler.codegen.CodeStream codeStream,
 319 //              int typeID) {
 320 //
 321 //              generateCode(blockScope, codeStream, true);
 322 //              codeStream.invokeStringBufferAppendForType(typeID);
 323 //      }
 324
 325         /* Optimized (java) code generation for string concatenations that involve StringBuffer
 326          * creation: going through this path means that there is no need for a new StringBuffer
 327          * creation, further operands should rather be only appended to the current one.
 328          */
 329 //      public void generateOptimizedStringBufferCreation(
 330 //              BlockScope blockScope,
 331 //              CodeStream codeStream,
 332 //              int typeID) {
 333 //
 334 //              // Optimization only for integers and strings
 335 //              if (typeID == T_Object) {
 336 //                      // in the case the runtime value of valueOf(Object) returns null, we have to use append(Object) instead of directly valueOf(Object)
 337 //                      // append(Object) returns append(valueOf(Object)), which means that the null case is handled by append(String).
 338 //                      codeStream.newStringBuffer();
 339 //                      codeStream.dup();
 340 //                      codeStream.invokeStringBufferDefaultConstructor();
 341 //                      generateCode(blockScope, codeStream, true);
 342 //                      codeStream.invokeStringBufferAppendForType(T_Object);
 343 //                      return;
 344 //              }
 345 //              codeStream.newStringBuffer();
 346 //              codeStream.dup();
 347 //              if (typeID == T_String || typeID == T_null) {
 348 //                      if (constant != NotAConstant) {
 349 //                              codeStream.ldc(constant.stringValue());
 350 //                      } else {
 351 //                              generateCode(blockScope, codeStream, true);
 352 //                              codeStream.invokeStringValueOf(T_Object);
 353 //                      }
 354 //              } else {
 355 //                      generateCode(blockScope, codeStream, true);
 356 //                      codeStream.invokeStringValueOf(typeID);
 357 //              }
 358 //              codeStream.invokeStringBufferStringConstructor();
 359 //      }
 360
 361         // Base types need that the widening is explicitly done by the compiler using some bytecode like i2f
 362         public void implicitWidening(
 363                 TypeBinding runtimeTimeType,
 364                 TypeBinding compileTimeType) {
 365
 366                 if (runtimeTimeType == null || compileTimeType == null)
 367                         return;
 368
 369 //              if (compileTimeType.id == T_null) {
 370 //                      // this case is possible only for constant null
 371 //                      // The type of runtime is a reference type
 372 //                      // The code gen use the constant id thus any value
 373 //                      // for the runtime id (akak the <<4) could be used.
 374 //                      // T_Object is used as some general T_reference
 375 //                      implicitConversion = (T_Object << 4) + T_null;
 376 //                      return;
 377 //              }
 378
 379                 switch (runtimeTimeType.id) {
 380                         case T_byte :
 381                         case T_short :
 382                         case T_char :
 383                                 implicitConversion = (T_int << 4) + compileTimeType.id;
 384                                 break;
 385                         case T_String :
 386                         case T_float :
 387                         case T_boolean :
 388                         case T_double :
 389                         case T_int : //implicitConversion may result in i2i which will result in NO code gen
 390                         case T_long :
 391                                 implicitConversion = (runtimeTimeType.id << 4) + compileTimeType.id;
 392                                 break;
 393                         default : //nothing on regular object ref
 394                 }
 395         }
 396
 397         public boolean isCompactableOperation() {
 398
 399                 return false;
 400         }
 401
 402         //Return true if the conversion is done AUTOMATICALLY by the vm
 403         //while the javaVM is an int based-machine, thus for example pushing
 404         //a byte onto the stack , will automatically creates a int on the stack
 405         //(this request some work d be done by the VM on signed numbers)
 406         public boolean isConstantValueOfTypeAssignableToType(
 407                 TypeBinding constantType,
 408                 TypeBinding targetType) {
 409
 410                 if (constant == Constant.NotAConstant)
 411                         return false;
 412                 if (constantType == targetType)
 413                         return true;
 414                 if (constantType.isBaseType() && targetType.isBaseType()) {
 415                         //No free assignment conversion from anything but to integral ones.
 416                         if ((constantType == IntBinding
 417                                 || BaseTypeBinding.isWidening(T_int, constantType.id))
 418                                 && (BaseTypeBinding.isNarrowing(targetType.id, T_int))) {
 419                                 //use current explicit conversion in order to get some new value to compare with current one
 420                                 return isConstantValueRepresentable(constant, constantType.id, targetType.id);
 421                         }
 422                 }
 423                 return false;
 424         }
 425
 426         public boolean isTypeReference() {
 427                 return false;
 428         }
 429         public StringBuffer print(int indent, StringBuffer output) {
 430                 printIndent(indent, output);
 431                 return printExpression(indent, output);
 432         }
 433
 434         public StringBuffer printExpression(int indent, StringBuffer output) {
 435           output.append(super.toString(0));
 436           return output;
 437         }
 438
 439         public StringBuffer printStatement(int indent, StringBuffer output) {
 440                 return print(indent, output).append(";"); //$NON-NLS-1$
 441         }
 442         public void resolve(BlockScope scope) {
 443                 // drops the returning expression's type whatever the type is.
 444
 445                 this.resolveType(scope);
 446                 return;
 447         }
 448
 449         public TypeBinding resolveType(BlockScope scope) {
 450                 // by default... subclasses should implement a better TC if required.
 451
 452                 return null;
 453         }
 454
 455         public TypeBinding resolveTypeExpecting(
 456                 BlockScope scope,
 457                 TypeBinding expectedType) {
 458
 459                 TypeBinding expressionType = this.resolveType(scope);
 460                 if (expressionType == null) return null;
 461                 if (expressionType == expectedType) return expressionType;
 462
 463                 if (!expressionType.isCompatibleWith(expectedType)) {
 464                         scope.problemReporter().typeMismatchError(expressionType, expectedType, this);
 465                         return null;
 466                 }
 467                 return expressionType;
 468         }
 469
 470         public String toString(int tab) {
 471
 472                 //Subclass re-define toStringExpression
 473                 String s = tabString(tab);
 474                 if (constant != null)
 475                         //before TC has runned
 476                         if (constant != NotAConstant)
 477                                 //after the TC has runned
 478                                 s += " /*cst:" + constant.toString() + "*/ "; //$NON-NLS-1$ //$NON-NLS-2$
 479                 return s + toStringExpression(tab);
 480         }
 481
 482         //Subclass re-define toStringExpression
 483         //This method is abstract and should never be called
 484         //but we provide some code that is running.....just in case
 485         //of developpement time (while every  thing is not built)
 486         public String toStringExpression() {
 487
 488                 return super.toString(0);
 489         }
 490
 491         public String toStringExpression(int tab) {
 492                 // default is regular toString expression (qualified allocation expressions redifine this method)
 493                 return this.toStringExpression();
 494         }
 495
 496         public Expression toTypeReference() {
 497                 //by default undefined
 498
 499                 //this method is meanly used by the parser in order to transform
 500                 //an expression that is used as a type reference in a cast ....
 501                 //--appreciate the fact that castExpression and ExpressionWithParenthesis
 502                 //--starts with the same pattern.....
 503
 504                 return this;
 505         }
 506 }