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