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

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v0.5
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v05.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.impl.*;
  14 import net.sourceforge.phpdt.internal.compiler.codegen.*;
  15 import net.sourceforge.phpdt.internal.compiler.flow.*;
  16 import net.sourceforge.phpdt.internal.compiler.lookup.*;
  17 import net.sourceforge.phpdt.internal.compiler.problem.*;
  18 import net.sourceforge.phpdt.internal.compiler.util.Util;
  19
  20 public abstract 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
  29         public Constant constant;
  30
  31         public Expression() {
  32                 super();
  33         }
  34
  35         public FlowInfo analyseCode(
  36                 BlockScope currentScope,
  37                 FlowContext flowContext,
  38                 FlowInfo flowInfo,
  39                 boolean valueRequired) {
  40
  41                 return analyseCode(currentScope, flowContext, flowInfo);
  42         }
  43
  44         public Constant conditionalConstant() {
  45
  46                 return constant;
  47         }
  48
  49         public static final boolean isConstantValueRepresentable(
  50                 Constant constant,
  51                 int constantTypeID,
  52                 int targetTypeID) {
  53
  54                 //true if there is no loss of precision while casting.
  55                 // constantTypeID == constant.typeID
  56                 if (targetTypeID == constantTypeID)
  57                         return true;
  58                 switch (targetTypeID) {
  59                         case T_char :
  60                                 switch (constantTypeID) {
  61                                         case T_char :
  62                                                 return true;
  63                                         case T_double :
  64                                                 return constant.doubleValue() == constant.charValue();
  65                                         case T_float :
  66                                                 return constant.floatValue() == constant.charValue();
  67                                         case T_int :
  68                                                 return constant.intValue() == constant.charValue();
  69                                         case T_short :
  70                                                 return constant.shortValue() == constant.charValue();
  71                                         case T_byte :
  72                                                 return constant.byteValue() == constant.charValue();
  73                                         case T_long :
  74                                                 return constant.longValue() == constant.charValue();
  75                                         default :
  76                                                 return false;//boolean
  77                                 }
  78
  79                         case T_float :
  80                                 switch (constantTypeID) {
  81                                         case T_char :
  82                                                 return constant.charValue() == constant.floatValue();
  83                                         case T_double :
  84                                                 return constant.doubleValue() == constant.floatValue();
  85                                         case T_float :
  86                                                 return true;
  87                                         case T_int :
  88                                                 return constant.intValue() == constant.floatValue();
  89                                         case T_short :
  90                                                 return constant.shortValue() == constant.floatValue();
  91                                         case T_byte :
  92                                                 return constant.byteValue() == constant.floatValue();
  93                                         case T_long :
  94                                                 return constant.longValue() == constant.floatValue();
  95                                         default :
  96                                                 return false;//boolean
  97                                 }
  98
  99                         case T_double :
 100                                 switch (constantTypeID) {
 101                                         case T_char :
 102                                                 return constant.charValue() == constant.doubleValue();
 103                                         case T_double :
 104                                                 return true;
 105                                         case T_float :
 106                                                 return constant.floatValue() == constant.doubleValue();
 107                                         case T_int :
 108                                                 return constant.intValue() == constant.doubleValue();
 109                                         case T_short :
 110                                                 return constant.shortValue() == constant.doubleValue();
 111                                         case T_byte :
 112                                                 return constant.byteValue() == constant.doubleValue();
 113                                         case T_long :
 114                                                 return constant.longValue() == constant.doubleValue();
 115                                         default :
 116                                                 return false; //boolean
 117                                 }
 118
 119                         case T_byte :
 120                                 switch (constantTypeID) {
 121                                         case T_char :
 122                                                 return constant.charValue() == constant.byteValue();
 123                                         case T_double :
 124                                                 return constant.doubleValue() == constant.byteValue();
 125                                         case T_float :
 126                                                 return constant.floatValue() == constant.byteValue();
 127                                         case T_int :
 128                                                 return constant.intValue() == constant.byteValue();
 129                                         case T_short :
 130                                                 return constant.shortValue() == constant.byteValue();
 131                                         case T_byte :
 132                                                 return true;
 133                                         case T_long :
 134                                                 return constant.longValue() == constant.byteValue();
 135                                         default :
 136                                                 return false; //boolean
 137                                 }
 138
 139                         case T_short :
 140                                 switch (constantTypeID) {
 141                                         case T_char :
 142                                                 return constant.charValue() == constant.shortValue();
 143                                         case T_double :
 144                                                 return constant.doubleValue() == constant.shortValue();
 145                                         case T_float :
 146                                                 return constant.floatValue() == constant.shortValue();
 147                                         case T_int :
 148                                                 return constant.intValue() == constant.shortValue();
 149                                         case T_short :
 150                                                 return true;
 151                                         case T_byte :
 152                                                 return constant.byteValue() == constant.shortValue();
 153                                         case T_long :
 154                                                 return constant.longValue() == constant.shortValue();
 155                                         default :
 156                                                 return false; //boolean
 157                                 }
 158
 159                         case T_int :
 160                                 switch (constantTypeID) {
 161                                         case T_char :
 162                                                 return constant.charValue() == constant.intValue();
 163                                         case T_double :
 164                                                 return constant.doubleValue() == constant.intValue();
 165                                         case T_float :
 166                                                 return constant.floatValue() == constant.intValue();
 167                                         case T_int :
 168                                                 return true;
 169                                         case T_short :
 170                                                 return constant.shortValue() == constant.intValue();
 171                                         case T_byte :
 172                                                 return constant.byteValue() == constant.intValue();
 173                                         case T_long :
 174                                                 return constant.longValue() == constant.intValue();
 175                                         default :
 176                                                 return false; //boolean
 177                                 }
 178
 179                         case T_long :
 180                                 switch (constantTypeID) {
 181                                         case T_char :
 182                                                 return constant.charValue() == constant.longValue();
 183                                         case T_double :
 184                                                 return constant.doubleValue() == constant.longValue();
 185                                         case T_float :
 186                                                 return constant.floatValue() == constant.longValue();
 187                                         case T_int :
 188                                                 return constant.intValue() == constant.longValue();
 189                                         case T_short :
 190                                                 return constant.shortValue() == constant.longValue();
 191                                         case T_byte :
 192                                                 return constant.byteValue() == constant.longValue();
 193                                         case T_long :
 194                                                 return true;
 195                                         default :
 196                                                 return false; //boolean
 197                                 }
 198
 199                         default :
 200                                 return false; //boolean
 201                 }
 202         }
 203
 204         /**
 205          * Expression statements are plain expressions, however they generate like
 206          * normal expressions with no value required.
 207          *
 208          * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
 209          * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
 210          */
 211         public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 212
 213                 if ((bits & IsReachableMASK) == 0) {
 214                         return;
 215                 }
 216                 generateCode(currentScope, codeStream, false);
 217         }
 218
 219         /**
 220          * Every expression is responsible for generating its implicit conversion when necessary.
 221          *
 222          * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
 223          * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
 224          * @param valueRequired boolean
 225          */
 226         public void generateCode(
 227                 BlockScope currentScope,
 228                 CodeStream codeStream,
 229                 boolean valueRequired) {
 230
 231                 if (constant != NotAConstant) {
 232                         // generate a constant expression
 233                         int pc = codeStream.position;
 234                         codeStream.generateConstant(constant, implicitConversion);
 235                         codeStream.recordPositionsFrom(pc, this.sourceStart);
 236                 } else {
 237                         // actual non-constant code generation
 238                         throw new ShouldNotImplement(Util.bind("ast.missingCode")); //$NON-NLS-1$
 239                 }
 240         }
 241
 242         /**
 243          * Default generation of a boolean value
 244          */
 245         public void generateOptimizedBoolean(
 246                 BlockScope currentScope,
 247                 CodeStream codeStream,
 248                 Label trueLabel,
 249                 Label falseLabel,
 250                 boolean valueRequired) {
 251
 252                 // a label valued to nil means: by default we fall through the case...
 253                 // both nil means we leave the value on the stack
 254
 255                 if ((constant != Constant.NotAConstant) && (constant.typeID() == T_boolean)) {
 256                         int pc = codeStream.position;
 257                         if (constant.booleanValue() == true) {
 258                                 // constant == true
 259                                 if (valueRequired) {
 260                                         if (falseLabel == null) {
 261                                                 // implicit falling through the FALSE case
 262                                                 if (trueLabel != null) {
 263                                                         codeStream.goto_(trueLabel);
 264                                                 }
 265                                         }
 266                                 }
 267                         } else {
 268                                 if (valueRequired) {
 269                                         if (falseLabel != null) {
 270                                                 // implicit falling through the TRUE case
 271                                                 if (trueLabel == null) {
 272                                                         codeStream.goto_(falseLabel);
 273                                                 }
 274                                         }
 275                                 }
 276                         }
 277                         codeStream.recordPositionsFrom(pc, this.sourceStart);
 278                         return;
 279                 }
 280                 generateCode(currentScope, codeStream, valueRequired);
 281                 // branching
 282                 int position = codeStream.position;
 283                 if (valueRequired) {
 284                         if (falseLabel == null) {
 285                                 if (trueLabel != null) {
 286                                         // Implicit falling through the FALSE case
 287                                         codeStream.ifne(trueLabel);
 288                                 }
 289                         } else {
 290                                 if (trueLabel == null) {
 291                                         // Implicit falling through the TRUE case
 292                                         codeStream.ifeq(falseLabel);
 293                                 } else {
 294                                         // No implicit fall through TRUE/FALSE --> should never occur
 295                                 }
 296                         }
 297                 }
 298                 // reposition the endPC
 299                 codeStream.updateLastRecordedEndPC(position);
 300         }
 301
 302         /* Optimized (java) code generation for string concatenations that involve StringBuffer
 303          * creation: going through this path means that there is no need for a new StringBuffer
 304          * creation, further operands should rather be only appended to the current one.
 305          * By default: no optimization.
 306          */
 307         public void generateOptimizedStringBuffer(
 308                 BlockScope blockScope,
 309                 net.sourceforge.phpdt.internal.compiler.codegen.CodeStream codeStream,
 310                 int typeID) {
 311
 312                 generateCode(blockScope, codeStream, true);
 313                 codeStream.invokeStringBufferAppendForType(typeID);
 314         }
 315
 316         /* Optimized (java) code generation for string concatenations that involve StringBuffer
 317          * creation: going through this path means that there is no need for a new StringBuffer
 318          * creation, further operands should rather be only appended to the current one.
 319          */
 320         public void generateOptimizedStringBufferCreation(
 321                 BlockScope blockScope,
 322                 CodeStream codeStream,
 323                 int typeID) {
 324
 325                 // Optimization only for integers and strings
 326                 if (typeID == T_Object) {
 327                         // in the case the runtime value of valueOf(Object) returns null, we have to use append(Object) instead of directly valueOf(Object)
 328                         // append(Object) returns append(valueOf(Object)), which means that the null case is handled by append(String).
 329                         codeStream.newStringBuffer();
 330                         codeStream.dup();
 331                         codeStream.invokeStringBufferDefaultConstructor();
 332                         generateCode(blockScope, codeStream, true);
 333                         codeStream.invokeStringBufferAppendForType(T_Object);
 334                         return;
 335                 }
 336                 codeStream.newStringBuffer();
 337                 codeStream.dup();
 338                 if ((typeID == T_String) || (typeID == T_null)) {
 339                         if (constant != NotAConstant) {
 340                                 codeStream.ldc(constant.stringValue());
 341                         } else {
 342                                 generateCode(blockScope, codeStream, true);
 343                                 codeStream.invokeStringValueOf(T_Object);
 344                         }
 345                 } else {
 346                         generateCode(blockScope, codeStream, true);
 347                         codeStream.invokeStringValueOf(typeID);
 348                 }
 349                 codeStream.invokeStringBufferStringConstructor();
 350         }
 351
 352         // Base types need that the widening is explicitly done by the compiler using some bytecode like i2f
 353         public void implicitWidening(
 354                 TypeBinding runtimeTimeType,
 355                 TypeBinding compileTimeType) {
 356
 357                 if (runtimeTimeType == null || compileTimeType == null)
 358                         return;
 359
 360                 if (compileTimeType.id == T_null) {
 361                         // this case is possible only for constant null
 362                         // The type of runtime is a reference type
 363                         // The code gen use the constant id thus any value
 364                         // for the runtime id (akak the <<4) could be used.
 365                         // T_Object is used as some general T_reference
 366                         implicitConversion = (T_Object << 4) + T_null;
 367                         return;
 368                 }
 369
 370                 switch (runtimeTimeType.id) {
 371                         case T_byte :
 372                         case T_short :
 373                         case T_char :
 374                                 implicitConversion = (T_int << 4) + compileTimeType.id;
 375                                 break;
 376                         case T_String :
 377                         case T_float :
 378                         case T_boolean :
 379                         case T_double :
 380                         case T_int : //implicitConversion may result in i2i which will result in NO code gen
 381                         case T_long :
 382                                 implicitConversion = (runtimeTimeType.id << 4) + compileTimeType.id;
 383                                 break;
 384                         default : //nothing on regular object ref
 385                 }
 386         }
 387
 388         public boolean isCompactableOperation() {
 389
 390                 return false;
 391         }
 392
 393         //Return true if the conversion is done AUTOMATICALLY by the vm
 394         //while the javaVM is an int based-machine, thus for example pushing
 395         //a byte onto the stack , will automatically creates a int on the stack
 396         //(this request some work d be done by the VM on signed numbers)
 397         public boolean isConstantValueOfTypeAssignableToType(
 398                 TypeBinding constantType,
 399                 TypeBinding targetType) {
 400
 401                 if (constant == Constant.NotAConstant)
 402                         return false;
 403                 if (constantType == targetType)
 404                         return true;
 405                 if (constantType.isBaseType() && targetType.isBaseType()) {
 406                         //No free assignment conversion from anything but to integral ones.
 407                         if ((constantType == IntBinding
 408                                 || BaseTypeBinding.isWidening(T_int, constantType.id))
 409                                 && (BaseTypeBinding.isNarrowing(targetType.id, T_int))) {
 410                                 //use current explicit conversion in order to get some new value to compare with current one
 411                                 return isConstantValueRepresentable(constant, constantType.id, targetType.id);
 412                         }
 413                 }
 414                 return false;
 415         }
 416
 417         public boolean isTypeReference() {
 418                 return false;
 419         }
 420
 421         public void resolve(BlockScope scope) {
 422                 // drops the returning expression's type whatever the type is.
 423
 424                 this.resolveType(scope);
 425                 return;
 426         }
 427
 428         public TypeBinding resolveType(BlockScope scope) {
 429                 // by default... subclasses should implement a better TC if required.
 430
 431                 return null;
 432         }
 433
 434         public TypeBinding resolveTypeExpecting(
 435                 BlockScope scope,
 436                 TypeBinding expectedTb) {
 437
 438                 TypeBinding thisTb = this.resolveType(scope);
 439                 if (thisTb == null)
 440                         return null;
 441                 if (!scope.areTypesCompatible(thisTb, expectedTb)) {
 442                         scope.problemReporter().typeMismatchError(thisTb, expectedTb, this);
 443                         return null;
 444                 }
 445                 return thisTb;
 446         }
 447
 448         public String toString(int tab) {
 449
 450                 //Subclass re-define toStringExpression
 451                 String s = tabString(tab);
 452                 if (constant != null)
 453                         //before TC has runned
 454                         if (constant != NotAConstant)
 455                                 //after the TC has runned
 456                                 s += " /*cst:" + constant.toString() + "*/ "; //$NON-NLS-1$ //$NON-NLS-2$
 457                 return s + toStringExpression(tab);
 458         }
 459
 460         //Subclass re-define toStringExpression
 461         //This method is abstract and should never be called
 462         //but we provide some code that is running.....just in case
 463         //of developpement time (while every  thing is not built)
 464         public String toStringExpression() {
 465
 466                 return super.toString(0);
 467         }
 468
 469         public String toStringExpression(int tab) {
 470                 // default is regular toString expression (qualified allocation expressions redifine this method)
 471                 return this.toStringExpression();
 472         }
 473
 474         public Expression toTypeReference() {
 475                 //by default undefined
 476
 477                 //this method is meanly used by the parser in order to transform
 478                 //an expression that is used as a type reference in a cast ....
 479                 //--appreciate the fact that castExpression and ExpressionWithParenthesis
 480                 //--starts with the same pattern.....
 481
 482                 return this;
 483         }
 484 }