static int _requiredMaxStackSizeFor(Statement* statement, int depth = 0) {
if (!statement) return 1;
switch (statement->statementType()) {
case STMT_LEAF:
#if DEBUG_SCRIPTVM_CORE
_printIndents(depth);
printf("-> STMT_LEAF\n");
#endif
return 1;
case STMT_LIST: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(depth);
printf("-> STMT_LIST\n");
#endif
Statements* stmts = (Statements*) statement;
int max = 0;
for (int i = 0; stmts->statement(i); ++i) {
int size = _requiredMaxStackSizeFor( stmts->statement(i), depth+1 );
if (max < size) max = size;
}
return max + 1;
}
case STMT_BRANCH: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(depth);
printf("-> STMT_BRANCH\n");
#endif
BranchStatement* branchStmt = (BranchStatement*) statement;
int max = 0;
for (int i = 0; branchStmt->branch(i); ++i) {
int size = _requiredMaxStackSizeFor( branchStmt->branch(i), depth+1 );
if (max < size) max = size;
}
return max + 1;
}
case STMT_LOOP: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(depth);
printf("-> STMT_LOOP\n");
#endif
While* whileStmt = (While*) statement;
if (whileStmt->statements())
return _requiredMaxStackSizeFor( whileStmt->statements() ) + 1;
else
return 1;
}
}
return 1; // actually just to avoid compiler warning
}
VMExecStatus_t ScriptVM::exec(VMParserContext* parserContext, VMExecContext* execContex, VMEventHandler* handler) {
m_parserContext = dynamic_cast<ParserContext*>(parserContext);
if (!m_parserContext) {
std::cerr << "No VM parser context provided. Did you load a script?.\n";
return VMExecStatus_t(VM_EXEC_NOT_RUNNING | VM_EXEC_ERROR);
}
// a ParserContext object is always tied to exactly one ScriptVM object
assert(m_parserContext->functionProvider == this);
ExecContext* ctx = dynamic_cast<ExecContext*>(execContex);
if (!ctx) {
std::cerr << "Invalid VM exec context.\n";
return VMExecStatus_t(VM_EXEC_NOT_RUNNING | VM_EXEC_ERROR);
}
EventHandler* h = dynamic_cast<EventHandler*>(handler);
if (!h) return VM_EXEC_NOT_RUNNING;
m_parserContext->execContext = ctx;
ctx->status = VM_EXEC_RUNNING;
StmtFlags_t flags = STMT_SUCCESS;
int& frameIdx = ctx->stackFrame;
if (frameIdx < 0) { // start condition ...
frameIdx = -1;
ctx->pushStack(h);
}
while (flags == STMT_SUCCESS && frameIdx >= 0) {
if (frameIdx >= ctx->stack.size()) { // should never happen, otherwise it's a bug ...
std::cerr << "CRITICAL: VM stack overflow! (" << frameIdx << ")\n";
flags = StmtFlags_t(STMT_ABORT_SIGNALLED | STMT_ERROR_OCCURRED);
break;
}
ExecContext::StackFrame& frame = ctx->stack[frameIdx];
switch (frame.statement->statementType()) {
case STMT_LEAF: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(frameIdx);
printf("-> STMT_LEAF\n");
#endif
LeafStatement* leaf = (LeafStatement*) frame.statement;
flags = leaf->exec();
ctx->popStack();
break;
}
case STMT_LIST: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(frameIdx);
printf("-> STMT_LIST subidx=%d\n", frame.subindex);
#endif
Statements* stmts = (Statements*) frame.statement;
if (stmts->statement(frame.subindex)) {
ctx->pushStack(
stmts->statement(frame.subindex++)
);
} else {
#if DEBUG_SCRIPTVM_CORE
_printIndents(frameIdx);
printf("[END OF LIST] subidx=%d\n", frame.subindex);
#endif
ctx->popStack();
}
break;
}
case STMT_BRANCH: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(frameIdx);
printf("-> STMT_BRANCH\n");
#endif
if (frame.subindex < 0) ctx->popStack();
else {
BranchStatement* branchStmt = (BranchStatement*) frame.statement;
frame.subindex = branchStmt->evalBranch();
if (frame.subindex >= 0) {
ctx->pushStack(
branchStmt->branch(frame.subindex)
);
frame.subindex = -1;
} else ctx->popStack();
}
break;
}
case STMT_LOOP: {
#if DEBUG_SCRIPTVM_CORE
_printIndents(frameIdx);
printf("-> STMT_LOOP\n");
#endif
While* whileStmt = (While*) frame.statement;
if (whileStmt->evalLoopStartCondition() && whileStmt->statements()) {
ctx->pushStack(
whileStmt->statements()
);
} else ctx->popStack();
}
}
}
if (flags & STMT_SUSPEND_SIGNALLED) {
ctx->status = VM_EXEC_SUSPENDED;
} else {
ctx->status = VM_EXEC_NOT_RUNNING;
if (flags & STMT_ERROR_OCCURRED)
ctx->status = VM_EXEC_ERROR;
ctx->reset();
}
m_parserContext->execContext = NULL;
m_parserContext = NULL;
return ctx->status;
}