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// Simple WebAssembly interpreter, designed to be embeddable in JavaScript, so it
// can function as a polyfill.
#include "wasm.h"
using namespace cashew;
using namespace wasm;
namespace wasm {
// An instance of a WebAssembly module
class ModuleInstance {
public:
ModuleInstance(Module& wasm) : wasm(wasm) {
for (auto function : wasm.functions) {
functions[function->name] = function;
}
}
Literal callFunction(const char *name) {
return callFunction(IString(name));
}
Literal callFunction(IString name) {
// Stuff that flows around during executing expressions: a literal, or a change in control flow
class Flow {
public:
Flow() {}
Flow(Literal value) : value(value) {}
Literal value;
IString breakTo; // if non-null, a break is going on
bool breaking() { return breakTo.is(); }
void clearIf(IString target) {
if (breakTo == target) {
breakTo.clear();
}
}
};
// Execute a statement
class ExpressionRunner : public WasmVisitor<Flow> {
private:
std::vector<Literal> arguments; // filled in before a call, cleared by the call
public:
Flow visitBlock(Block *curr) override {
Flow flow;
for (auto expression : curr->list) {
flow = visit(expression);
if (flow.breaking()) {
flow.clearIf(curr->name);
return flow;
}
}
return flow;
}
Flow visitIf(If *curr) override {
Flow flow = visit(curr->condition);
if (flow.breaking()) return flow;
if (flow.value.geti32()) return visit(curr->ifTrue);
if (curr->ifFalse) return visit(curr->ifFalse);
return Flow();
}
Flow visitLoop(Loop *curr) override {
while (1) {
Flow flow = visit(curr->body);
if (flow.breaking()) {
if (flow.breakTo == curr->in) continue; // lol
flow.clearIf(curr->out);
return flow;
}
}
}
Flow visitLabel(Label *curr) override {
Flow flow = visit(curr->body);
flow.clearIf(curr->name);
return flow;
}
Flow visitBreak(Break *curr) override {
if (curr->condition) {
Flow flow = visit(curr->condition);
if (flow.breaking()) return flow;
if (!flow.value.geti32()) return Flow();
}
Flow flow = visit(curr->value);
if (!flow.breaking()) {
flow.breakTo = curr->name;
}
return flow;
}
Flow visitSwitch(Switch *curr) override {
abort();
}
Flow visitCall(Call *curr) override {
}
Flow visitCallImport(CallImport *curr) override {
}
Flow visitCallIndirect(CallIndirect *curr) override {
}
Flow visitGetLocal(GetLocal *curr) override {
}
Flow visitSetLocal(SetLocal *curr) override {
}
Flow visitLoad(Load *curr) override {
}
Flow visitStore(Store *curr) override {
}
Flow visitConst(Const *curr) override {
return Flow(curr->value); // heh
}
Flow visitUnary(Unary *curr) override {
}
Flow visitBinary(Binary *curr) override {
}
Flow visitCompare(Compare *curr) override {
}
Flow visitConvert(Convert *curr) override {
}
Flow visitHost(Host *curr) override {
}
Flow visitNop(Nop *curr) override {
}
};
return ExpressionRunner().visit(functions[name]->body).value;
}
private:
Module& wasm;
std::map<IString, Function*> functions;
};
} // namespace wasm
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