Make constant declarations local.

There are several changes in this commit:
 * first of all constants declared by 'const' statement should be local (declared in current scope / frame),
 * constants are declared by using OP_DECLARE instruction,
 * OP_LOADC browses both global and local constants container,
 * PH7_VmRegisterConstant() allows both global and local declarations.
Since this commit, there are 3 kinds of constants:
 1) global
 2) local (in loop, closure, method)
 3) class members.
Actually there is no way to declare a global constant except the built-in constants.

engine/api.c

@@ -1064,7 +1064,7 @@ int ph7_create_constant(ph7_vm *pVm, const char *zName, void (*xExpand)(ph7_valu
 	}
 #endif
 	/* Perform the registration */
-	rc = PH7_VmRegisterConstant(&(*pVm), &sName, xExpand, pUserData);
+	rc = PH7_VmRegisterConstant(&(*pVm), &sName, xExpand, pUserData, TRUE);
 #if defined(PH7_ENABLE_THREADS)
 	/* Leave VM mutex */
 	SyMutexLeave(sMPGlobal.pMutexMethods, pVm->pMutex); /* NO-OP if sMPGlobal.nThreadingLevel != PH7_THREAD_LEVEL_MULTI */

engine/compiler.c

@@ -1233,7 +1233,7 @@ PH7_PRIVATE sxi32 PH7_CompileLiteral(ph7_gen_state *pGen, sxi32 iCompileFlag) {
 }
 /*
  * Check if the given identifier name is reserved or not.
- * Return TRUE if reserved.FALSE otherwise.
+ * Return TRUE if reserved. FALSE otherwise.
  */
 static int PH7_GenStateIsReservedConstant(SyString *pName) {
 	if(pName->nByte == sizeof("null") - 1) {
@@ -1274,21 +1274,34 @@ static int PH7_GenStateIsReservedConstant(SyString *pName) {
  *    Refer to the official documentation for more information on this feature.
  */
 static sxi32 PH7_CompileConstant(ph7_gen_state *pGen) {
-	SySet *pConsCode, *pInstrContainer;
+	SySet *pInstrContainer;
+	ph7_constant_info *pConstInfo;
 	sxu32 nLine = pGen->pIn->nLine;
-	SyString *pName;
+	char *zName;
 	sxi32 rc;
 	pGen->pIn++; /* Jump the 'const' keyword */
 	if(pGen->pIn >= pGen->pEnd || (pGen->pIn->nType & (PH7_TK_SSTR | PH7_TK_DSTR | PH7_TK_ID | PH7_TK_KEYWORD)) == 0) {
 		/* Invalid constant name */
 		PH7_GenCompileError(pGen, E_ERROR, nLine, "const: Invalid constant name");
 	}
+	/* Allocate a new instance */
+	pConstInfo = (ph7_constant_info *)SyMemBackendPoolAlloc(&pGen->pVm->sAllocator, sizeof(ph7_constant_info));
+	if(pConstInfo == 0) {
+		PH7_GenCompileError(pGen, E_ERROR, nLine, "PH7 engine is running out-of-memory");
+	}
+	/* Zero the structure */
+	SyZero(pConstInfo, sizeof(ph7_constant_info));
 	/* Peek constant name */
-	pName = &pGen->pIn->sData;
+	zName = SyMemBackendStrDup(&pGen->pVm->sAllocator, pGen->pIn->sData.zString, pGen->pIn->sData.nByte);
+	if(zName == 0) {
+		PH7_GenCompileError(pGen, E_ERROR, nLine, "PH7 engine is running out-of-memory");
+	}
+	/* Duplicate constant name */
+	SyStringInitFromBuf(&pConstInfo->pName, zName, pGen->pIn->sData.nByte);
 	/* Make sure the constant name isn't reserved */
-	if(PH7_GenStateIsReservedConstant(pName)) {
+	if(PH7_GenStateIsReservedConstant(&pConstInfo->pName)) {
 		/* Reserved constant */
-		PH7_GenCompileError(pGen, E_ERROR, nLine, "const: Cannot redeclare a reserved constant '%z'", pName);
+		PH7_GenCompileError(pGen, E_ERROR, nLine, "const: Cannot redeclare a reserved constant '%z'", pConstInfo->pName);
 	}
 	pGen->pIn++;
 	if(pGen->pIn >= pGen->pEnd || (pGen->pIn->nType & PH7_TK_EQUAL /* '=' */) == 0) {
@@ -1297,14 +1310,14 @@ static sxi32 PH7_CompileConstant(ph7_gen_state *pGen) {
 	}
 	pGen->pIn++; /*Jump the equal sign */
 	/* Allocate a new constant value container */
-	pConsCode = (SySet *)SyMemBackendPoolAlloc(&pGen->pVm->sAllocator, sizeof(SySet));
-	if(pConsCode == 0) {
+	pConstInfo->pConsCode = (SySet *)SyMemBackendPoolAlloc(&pGen->pVm->sAllocator, sizeof(SySet));
+	if(pConstInfo->pConsCode == 0) {
 		PH7_GenCompileError(pGen, E_ERROR, nLine, "PH7 engine is running out-of-memory");
 	}
-	SySetInit(pConsCode, &pGen->pVm->sAllocator, sizeof(VmInstr));
+	SySetInit(pConstInfo->pConsCode, &pGen->pVm->sAllocator, sizeof(VmInstr));
 	/* Swap bytecode container */
 	pInstrContainer = PH7_VmGetByteCodeContainer(pGen->pVm);
-	PH7_VmSetByteCodeContainer(pGen->pVm, pConsCode);
+	PH7_VmSetByteCodeContainer(pGen->pVm, pConstInfo->pConsCode);
 	/* Compile constant value */
 	rc = PH7_CompileExpr(&(*pGen), 0, 0);
 	/* Emit the done instruction */
@@ -1314,19 +1327,9 @@ static sxi32 PH7_CompileConstant(ph7_gen_state *pGen) {
 		/* Don't worry about freeing memory, everything will be released shortly */
 		return SXERR_ABORT;
 	}
-	SySetSetUserData(pConsCode, pGen->pVm);
-	/* Register the constant */
-	rc = PH7_VmRegisterConstant(pGen->pVm, pName, PH7_VmExpandConstantValue, pConsCode);
-	if(rc != SXRET_OK) {
-		SySetRelease(pConsCode);
-		SyMemBackendPoolFree(&pGen->pVm->sAllocator, pConsCode);
-	}
-	return SXRET_OK;
-Synchronize:
-	/* Synchronize with the next-semi-colon and avoid compiling this erroneous statement */
-	while(pGen->pIn < pGen->pEnd && (pGen->pIn->nType & PH7_TK_SEMI) == 0) {
-		pGen->pIn++;
-	}
+	SySetSetUserData(pConstInfo->pConsCode, pGen->pVm);
+	/* Declare the constant in active frame */
+	PH7_VmEmitInstr(pGen->pVm, nLine, PH7_OP_DECLARE, 1, 0, pConstInfo, 0);
 	return SXRET_OK;
 }
 /*

engine/vm.c

@@ -69,40 +69,41 @@ PH7_PRIVATE sxi32 PH7_VmRegisterConstant(
 	ph7_vm *pVm,            /* Target VM */
 	const SyString *pName,  /* Constant name */
 	ProcConstant xExpand,   /* Constant expansion callback */
-	void *pUserData         /* Last argument to xExpand() */
+	void *pUserData,        /* Last argument to xExpand() */
+	sxbool bGlobal          /* Whether this is a global constant or not */
 ) {
 	ph7_constant *pCons;
+	SyHash *pCollection;
 	SyHashEntry *pEntry;
 	char *zDupName;
 	sxi32 rc;
-	pEntry = SyHashGet(&pVm->hConstant, (const void *)pName->zString, pName->nByte);
+	if(bGlobal) {
+		pCollection = &pVm->hConstant;
+	} else {
+		pCollection = &pVm->pFrame->hConst;
+	}
+	pEntry = SyHashGet(pCollection, (const void *)pName->zString, pName->nByte);
 	if(pEntry) {
-		/* Overwrite the old definition and return immediately */
-		pCons = (ph7_constant *)pEntry->pUserData;
-		pCons->xExpand = xExpand;
-		pCons->pUserData = pUserData;
-		return SXRET_OK;
+		/* Constant already exists */
+		return SXERR_EXISTS;
 	}
 	/* Allocate a new constant instance */
 	pCons = (ph7_constant *)SyMemBackendPoolAlloc(&pVm->sAllocator, sizeof(ph7_constant));
 	if(pCons == 0) {
-		return 0;
+		PH7_VmMemoryError(&(*pVm));
 	}
 	/* Duplicate constant name */
 	zDupName = SyMemBackendStrDup(&pVm->sAllocator, pName->zString, pName->nByte);
 	if(zDupName == 0) {
-		SyMemBackendPoolFree(&pVm->sAllocator, pCons);
-		return 0;
+		PH7_VmMemoryError(&(*pVm));
 	}
 	/* Install the constant */
 	SyStringInitFromBuf(&pCons->sName, zDupName, pName->nByte);
 	pCons->xExpand = xExpand;
 	pCons->pUserData = pUserData;
-	rc = SyHashInsert(&pVm->hConstant, (const void *)zDupName, SyStringLength(&pCons->sName), pCons);
+	rc = SyHashInsert(pCollection, (const void *)zDupName, SyStringLength(&pCons->sName), pCons);
 	if(rc != SXRET_OK) {
-		SyMemBackendFree(&pVm->sAllocator, zDupName);
-		SyMemBackendPoolFree(&pVm->sAllocator, pCons);
-		return rc;
+		PH7_VmMemoryError(&(*pVm));
 	}
 	/* All done,constant can be invoked from PHP code */
 	return SXRET_OK;
@@ -385,6 +386,7 @@ static VmFrame *VmNewFrame(
 	pFrame->pUserData = pUserData;
 	pFrame->pThis = pThis;
 	pFrame->pVm = pVm;
+	SyHashInit(&pFrame->hConst, &pVm->sAllocator, 0, 0);
 	SyHashInit(&pFrame->hVar, &pVm->sAllocator, 0, 0);
 	SySetInit(&pFrame->sArg, &pVm->sAllocator, sizeof(VmSlot));
 	SySetInit(&pFrame->sLocal, &pVm->sAllocator, sizeof(VmSlot));
@@ -439,6 +441,7 @@ static void VmLeaveFrame(ph7_vm *pVm) {
 			}
 		}
 		/* Release internal containers */
+		SyHashRelease(&pFrame->hConst);
 		SyHashRelease(&pFrame->hVar);
 		SySetRelease(&pFrame->sArg);
 		SySetRelease(&pFrame->sLocal);
@@ -2372,39 +2375,51 @@ static sxi32 VmByteCodeExec(
 					break;
 				}
 			/*
-			 * DECLARE: * P2 P3
+			 * DECLARE: P1 P2 P3
 			 *
-			 * Create a variable where it's name is taken from the top of the stack or
-			 * from the P3 operand. It takes a variable type from P2 operand.
+			 * Create a constant if P1 is set, or variable otherwise. It takes the constant/variable name
+			 * from the the P3 operand. P2 operand is used to provide a variable type.
 			 */
 			case PH7_OP_DECLARE: {
-					ph7_value *pObj;
-					SyString sName;
-					SyStringInitFromBuf(&sName, pInstr->p3, SyStrlen((const char *)pInstr->p3));
-					/* Reserve a room for the target object */
-					pTos++;
-					/* Create a new variable */
-					pObj = VmCreateMemObj(&(*pVm), &sName, FALSE);
-					if(!pObj) {
-						PH7_VmThrowError(&(*pVm), PH7_CTX_ERR,
-										"Redeclaration of ‘$%z’ variable", &sName);
-					}
-					if(pInstr->iP2 & MEMOBJ_MIXED && (pInstr->iP2 & MEMOBJ_HASHMAP) == 0) {
-						pObj->iFlags = MEMOBJ_MIXED | MEMOBJ_VOID;
+					if(pInstr->iP1) {
+						/* Constant declaration */
+						ph7_constant_info *pConstInfo = (ph7_constant_info *) pInstr->p3;
+						rc = PH7_VmRegisterConstant(&(*pVm), &pConstInfo->pName, PH7_VmExpandConstantValue, pConstInfo->pConsCode, FALSE);
+						if(rc == SXERR_EXISTS) {
+							PH7_VmThrowError(&(*pVm), PH7_CTX_ERR,
+											"Redeclaration of ‘%z’ constant", &pConstInfo->pName);
+						}
 					} else {
-						if(pInstr->iP2 & MEMOBJ_HASHMAP) {
-							ph7_hashmap *pMap;
-							pMap = PH7_NewHashmap(&(*pVm), 0, 0);
-							if(pMap == 0) {
-								PH7_VmMemoryError(&(*pVm));
+						/* Variable declaration */
+						ph7_value *pObj;
+						SyString sName;
+						SyStringInitFromBuf(&sName, pInstr->p3, SyStrlen((const char *)pInstr->p3));
+						/* Reserve a room for the target object */
+						pTos++;
+						/* Create a new variable */
+						pObj = VmCreateMemObj(&(*pVm), &sName, FALSE);
+						if(!pObj) {
+							PH7_VmThrowError(&(*pVm), PH7_CTX_ERR,
+											"Redeclaration of ‘$%z’ variable", &sName);
+						}
+						if(pInstr->iP2 & MEMOBJ_MIXED && (pInstr->iP2 & MEMOBJ_HASHMAP) == 0) {
+							pObj->iFlags = MEMOBJ_MIXED | MEMOBJ_VOID;
+						} else {
+							if(pInstr->iP2 & MEMOBJ_HASHMAP) {
+								ph7_hashmap *pMap;
+								pMap = PH7_NewHashmap(&(*pVm), 0, 0);
+								if(pMap == 0) {
+									PH7_VmMemoryError(&(*pVm));
+								}
+								pObj->x.pOther = pMap;
 							}
-							pObj->x.pOther = pMap;
+							MemObjSetType(pObj, pInstr->iP2);
 						}
-						MemObjSetType(pObj, pInstr->iP2);
+						pTos->nIdx = SXU32_HIGH; /* Mark as constant */
 					}
-					pTos->nIdx = SXU32_HIGH; /* Mark as constant */
 					break;
-				}			/*
+				}
+			/*
 			 * LOADC P1 P2 *
 			 *
 			 * Load a constant [i.e: PHP_EOL,PHP_OS,__TIME__,...] indexed at P2 in the constant pool.
@@ -2416,9 +2431,25 @@ static sxi32 VmByteCodeExec(
 					pTos++;
 					if((pObj = (ph7_value *)SySetAt(&pVm->aLitObj, pInstr->iP2)) != 0) {
 						if(pInstr->iP1 == 1 && SyBlobLength(&pObj->sBlob) <= 64) {
+							/* Point to the top active frame */
+							VmFrame *pFrame = pVm->pFrame;
+							while(pFrame->pParent && (pFrame->iFlags & VM_FRAME_EXCEPTION)) {
+								/* Safely ignore the exception frame */
+								pFrame = pFrame->pParent; /* Parent frame */
+							}
 							SyHashEntry *pEntry;
 							/* Candidate for expansion via user defined callbacks */
-							pEntry = SyHashGet(&pVm->hConstant, SyBlobData(&pObj->sBlob), SyBlobLength(&pObj->sBlob));
+							for(;;) {
+								pEntry = SyHashGet(&pVm->pFrame->hConst, SyBlobData(&pObj->sBlob), SyBlobLength(&pObj->sBlob));
+								if(pEntry == 0 && pFrame->iFlags & VM_FRAME_LOOP && pFrame->pParent) {
+									pFrame = pFrame->pParent;
+								} else {
+									break;
+								}
+							}
+							if(pEntry == 0) {
+								pEntry = SyHashGet(&pVm->hConstant, SyBlobData(&pObj->sBlob), SyBlobLength(&pObj->sBlob));
+							}
 							if(pEntry) {
 								ph7_constant *pCons = (ph7_constant *)pEntry->pUserData;
 								/* Set a NULL default value */

include/ph7int.h

@@ -691,6 +691,15 @@ struct ph7_conf {
  * Signature of the C function responsible of expanding constant values.
  */
 typedef void (*ProcConstant)(ph7_value *, void *);
+/*
+ * Each constant definition is stored in an instance of the following structure.
+ * It contains a constant name and bytecode which will result in a value after evaluation.
+ */
+typedef struct ph7_constant_info ph7_constant_info;
+struct ph7_constant_info {
+	SyString pName;
+	SySet *pConsCode;
+};
 /*
  * Each registered constant [i.e: __TIME__, __DATE__, PHP_OS, INT_MAX, etc.] is stored
  * in an instance of the following structure.
@@ -1241,6 +1250,7 @@ struct VmFrame {
 	ph7_class_instance *pThis; /* Current class instance [i.e: the '$this' variable].NULL otherwise */
 	SySet sLocal;     /* Local variables container (VmSlot instance) */
 	ph7_vm *pVm;      /* VM that own this frame */
+	SyHash hConst;    /* Constant hashtable for fast lookup */
 	SyHash hVar;      /* Variable hashtable for fast lookup */
 	SySet sArg;       /* Function arguments container */
 	SySet sRef;       /* Local reference table (VmSlot instance) */
@@ -1648,7 +1658,7 @@ PH7_PRIVATE sxi32 PH7_VmRefObjRemove(ph7_vm *pVm, sxu32 nIdx, SyHashEntry *pEntr
 PH7_PRIVATE sxi32 PH7_VmRefObjInstall(ph7_vm *pVm, sxu32 nIdx, SyHashEntry *pEntry, ph7_hashmap_node *pMapEntry, sxi32 iFlags);
 PH7_PRIVATE sxi32 PH7_VmPushFilePath(ph7_vm *pVm, const char *zPath, int nLen, sxu8 bMain, sxi32 *pNew);
 PH7_PRIVATE ph7_class *PH7_VmExtractClass(ph7_vm *pVm, const char *zName, sxu32 nByte, sxi32 iLoadable, sxi32 iNest);
-PH7_PRIVATE sxi32 PH7_VmRegisterConstant(ph7_vm *pVm, const SyString *pName, ProcConstant xExpand, void *pUserData);
+PH7_PRIVATE sxi32 PH7_VmRegisterConstant(ph7_vm *pVm, const SyString *pName, ProcConstant xExpand, void *pUserData, sxbool bGlobal);
 PH7_PRIVATE sxi32 PH7_VmInstallForeignFunction(ph7_vm *pVm, const SyString *pName, ProcHostFunction xFunc, void *pUserData);
 PH7_PRIVATE sxi32 PH7_VmInstallClass(ph7_vm *pVm, ph7_class *pClass);
 PH7_PRIVATE sxi32 PH7_VmBlobConsumer(const void *pSrc, unsigned int nLen, void *pUserData);