Implement C3 class linearization and validate inheritance graphs

2026-10-24 01:16:34 +02:00
parent 323793153c
commit bc5e5f6a8e
4 changed files with 172 additions and 30 deletions
@@ -60,6 +60,8 @@ PH7_PRIVATE ph7_class *PH7_NewRawClass(ph7_vm *pVm, const SyString *pName) {
 	SyHashInit(&pClass->hAttr, &pVm->sAllocator, 0, 0);
 	SyHashInit(&pClass->hDerived, &pVm->sAllocator, 0, 0);
 	SySetInit(&pClass->aInterface, &pVm->sAllocator, sizeof(ph7_class *));
+	SySetInit(&pClass->aBase, &pVm->sAllocator, sizeof(ph7_class *));
+	SySetInit(&pClass->aMro, &pVm->sAllocator, sizeof(ph7_class *));
 	/* All done */
 	return pClass;
 }
@@ -201,6 +203,133 @@ PH7_PRIVATE sxi32 PH7_ClassInstallMethod(ph7_class *pClass, ph7_class_method *pM
 	rc = SyHashInsert(&pClass->hMethod, (const void *)pName->zString, pName->nByte, pMeth);
 	return rc;
 }
+/*
+ * Build [C] + merge(MRO(B1), ..., MRO(Bn), [B1, ..., Bn]).
+ * Resolve declarations rather than hDerived: bytecode initialization may not
+ * have reached a forward-declared base yet. Merge cursors are private so that
+ * neither shared ancestors nor an autoloader can change a base's MRO.
+ */
+PH7_PRIVATE sxi32 PH7_ClassBuildMro(ph7_vm *pVm, ph7_class *pClass) {
+	SySet sBase, sMro;
+	ph7_class *pBase, *pCandidate;
+	SySet *pSeq;
+	sxu32 *aPos = 0;
+	sxu32 i, j, k, nBase, nSeq;
+	sxi32 rc = SXRET_OK;
+	int bPending, bInTail;
+	if(pClass->iFlags & PH7_CLASS_INTERFACE) {
+		return SXRET_OK;
+	}
+	if(pClass->iMroState == 2) {
+		return SXRET_OK;
+	}
+	if(pClass->iMroState == 1) {
+		PH7_VmThrowError(pVm, PH7_CTX_ERR, "Inheritance cycle involving class '%z'", &pClass->sName);
+		return SXERR_INVALID;
+	}
+	/* Set before resolution, which can reenter through an autoloader. */
+	pClass->iMroState = 1;
+	SySetInit(&sBase, &pVm->sAllocator, sizeof(ph7_class *));
+	SySetInit(&sMro, &pVm->sAllocator, sizeof(ph7_class *));
+	if(pClass->pInfo) {
+		for(i = 0; i < SySetUsed(&pClass->pInfo->sExtends); i++) {
+			SyString *pName = (SyString *)SySetAt(&pClass->pInfo->sExtends, i);
+			pBase = PH7_VmExtractClass(pVm, pName->zString, pName->nByte, FALSE);
+			if(pBase == 0) {
+				PH7_VmThrowError(pVm, PH7_CTX_ERR, "Call to non-existent base class '%z'", pName);
+			} else if(pBase == pClass) {
+				PH7_VmThrowError(pVm, PH7_CTX_ERR, "Class '%z' cannot inherit from itself", &pClass->sName);
+			} else if(pBase->iFlags & PH7_CLASS_INTERFACE) {
+				PH7_VmThrowError(pVm, PH7_CTX_ERR, "Class '%z' cannot inherit from interface '%z'", &pClass->sName, pName);
+			} else if(pBase->iFlags & PH7_CLASS_FINAL) {
+				PH7_VmThrowError(pVm, PH7_CTX_ERR, "Class '%z' cannot inherit from final class '%z'", &pClass->sName, pName);
+			}
+			for(j = 0; j < SySetUsed(&sBase); j++) {
+				if(*(ph7_class **)SySetAt(&sBase, j) == pBase) {
+					PH7_VmThrowError(pVm, PH7_CTX_ERR, "Duplicate base class '%z' in class '%z'", &pBase->sName, &pClass->sName);
+				}
+			}
+			rc = SySetPut(&sBase, &pBase);
+			if(rc != SXRET_OK) {
+				goto done;
+			}
+			rc = PH7_ClassBuildMro(pVm, pBase);
+			if(rc != SXRET_OK) {
+				goto done;
+			}
+		}
+	}
+	nBase = SySetUsed(&sBase);
+	nSeq = nBase + 1;
+	aPos = (sxu32 *)SyMemBackendAlloc(&pVm->sAllocator, nSeq * sizeof(sxu32));
+	if(aPos == 0) {
+		rc = SXERR_MEM;
+		goto done;
+	}
+	SyZero(aPos, nSeq * sizeof(sxu32));
+	rc = SySetPut(&sMro, &pClass);
+	if(rc != SXRET_OK) {
+		goto done;
+	}
+	for(;;) {
+		bPending = FALSE;
+		pCandidate = 0;
+		for(i = 0; i < nSeq; i++) {
+			pSeq = i == nBase ? &sBase : &(*(ph7_class **)SySetAt(&sBase, i))->aMro;
+			if(aPos[i] >= SySetUsed(pSeq)) {
+				continue;
+			}
+			bPending = TRUE;
+			pCandidate = *(ph7_class **)SySetAt(pSeq, aPos[i]);
+			bInTail = FALSE;
+			for(j = 0; j < nSeq && !bInTail; j++) {
+				pSeq = j == nBase ? &sBase : &(*(ph7_class **)SySetAt(&sBase, j))->aMro;
+				for(k = aPos[j] + 1; k < SySetUsed(pSeq); k++) {
+					if(*(ph7_class **)SySetAt(pSeq, k) == pCandidate) {
+						bInTail = TRUE;
+						break;
+					}
+				}
+			}
+			if(!bInTail) {
+				break;
+			}
+			pCandidate = 0;
+		}
+		if(!bPending) {
+			break;
+		}
+		if(pCandidate == 0) {
+			PH7_VmThrowError(pVm, PH7_CTX_ERR, "Inconsistent C3 hierarchy for class '%z'", &pClass->sName);
+			rc = SXERR_INVALID;
+			goto done;
+		}
+		rc = SySetPut(&sMro, &pCandidate);
+		if(rc != SXRET_OK) {
+			goto done;
+		}
+		for(i = 0; i < nSeq; i++) {
+			pSeq = i == nBase ? &sBase : &(*(ph7_class **)SySetAt(&sBase, i))->aMro;
+			if(aPos[i] < SySetUsed(pSeq) && *(ph7_class **)SySetAt(pSeq, aPos[i]) == pCandidate) {
+				aPos[i]++;
+			}
+		}
+	}
+	/* Publish only a complete linearization. */
+	SySetRelease(&pClass->aBase);
+	SySetRelease(&pClass->aMro);
+	pClass->aBase = sBase;
+	pClass->aMro = sMro;
+	pClass->iMroState = 2;
+done:
+	SyMemBackendFree(&pVm->sAllocator, aPos);
+	if(rc != SXRET_OK) {
+		SySetRelease(&sBase);
+		SySetRelease(&sMro);
+		pClass->iMroState = 0;
+	}
+	return rc;
+}
 /*
 * Perform an inheritance operation.
 * According to the PHP language reference manual