cpp-peglib/language/interpreter.hpp
2015-06-01 17:56:39 -04:00

229 lines
6.9 KiB
C++
Executable File

#include <map>
#include <string>
#include <peglib.h>
struct Environment;
struct Value
{
enum Type { Undefined, Bool, Long, String, Array, Function };
struct ArrayValue {
std::vector<Value> values;
};
struct FunctionValue {
std::vector<std::string> params;
std::function<Value (std::shared_ptr<Environment> env)> eval;
};
explicit Value() : type(Undefined) {}
explicit Value(bool b) : type(Bool) { v = b; }
explicit Value(long l) : type(Long) { v = l; }
explicit Value(const std::string& s) : type(String) { v = s; }
explicit Value(const ArrayValue& a) : type(Array) { v = a; }
explicit Value(const FunctionValue& f) : type(Function) { v = f; }
bool to_bool() const {
switch (type) {
case Bool: return v.get<bool>();
case Long: return v.get<long>() != 0;
}
throw std::runtime_error("type error.");
}
long to_long() const {
switch (type) {
case Bool: return v.get<bool>();
case Long: return v.get<long>();
}
throw std::runtime_error("type error.");
}
std::string to_string() const {
switch (type) {
case String: return v.get<std::string>();
}
throw std::runtime_error("type error.");
}
ArrayValue to_array() const {
switch (type) {
case Array: return v.get<ArrayValue>();
}
throw std::runtime_error("type error.");
}
FunctionValue to_function() const {
switch (type) {
case Function: return v.get<FunctionValue>();
}
throw std::runtime_error("type error.");
}
std::string str() const {
switch (type) {
case Undefined: return "undefined";
case Bool: return to_bool() ? "true" : "false";
case Long: return std::to_string(to_long()); break;
case String: return to_string();
case Function: return "[function]";
case Array: return "[array]";
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
std::ostream& out(std::ostream& os) const {
switch (type) {
case Undefined: os << "undefined"; break;
case Bool: os << (to_bool() ? "true" : "false"); break;
case Long: os << to_long(); break;
case String: os << "'" << to_string() << "'"; break;
case Function: os << "[function]"; break;
case Array: os << "[array]"; break;
default: throw std::logic_error("invalid internal condition.");
}
return os;
}
bool operator==(const Value& rhs) const {
switch (type) {
case Undefined: return true;
case Bool: return to_bool() == rhs.to_bool();
case Long: return to_long() == rhs.to_long();
case String: return to_string() == rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
bool operator!=(const Value& rhs) const {
switch (type) {
case Undefined: return false;
case Bool: return to_bool() != rhs.to_bool();
case Long: return to_long() != rhs.to_long();
case String: return to_string() != rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
bool operator<=(const Value& rhs) const {
switch (type) {
case Undefined: return false;
case Bool: return to_bool() <= rhs.to_bool();
case Long: return to_long() <= rhs.to_long();
case String: return to_string() <= rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
bool operator<(const Value& rhs) const {
switch (type) {
case Undefined: return false;
case Bool: return to_bool() < rhs.to_bool();
case Long: return to_long() < rhs.to_long();
case String: return to_string() < rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
bool operator>=(const Value& rhs) const {
switch (type) {
case Undefined: return false;
case Bool: return to_bool() >= rhs.to_bool();
case Long: return to_long() >= rhs.to_long();
case String: return to_string() >= rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
bool operator>(const Value& rhs) const {
switch (type) {
case Undefined: return false;
case Bool: return to_bool() > rhs.to_bool();
case Long: return to_long() > rhs.to_long();
case String: return to_string() > rhs.to_string();
default: throw std::logic_error("invalid internal condition.");
}
// NOTREACHED
}
private:
friend std::ostream& operator<<(std::ostream&, const Value&);
int type;
peglib::any v;
};
std::ostream& operator<<(std::ostream& os, const Value& val);
struct Environment
{
Environment() = default;
void push_outer(std::shared_ptr<Environment> outer) {
outers_.push_back(outer);
}
bool has(const std::string& s) const {
if (dic_.find(s) != dic_.end()) {
return true;
}
for (auto& outer: outers_) {
if (outer->has(s)) {
return true;
}
}
return false;
}
Value get(const std::string& s) const {
assert(has(s));
if (dic_.find(s) != dic_.end()) {
return dic_.at(s);
}
for (auto& outer: outers_) {
if (outer->has(s)) {
return outer->get(s);
}
}
// NOT REACHED
}
void set(const std::string& s, const Value& val) {
if (dic_.find(s) != dic_.end()) {
dic_[s] = val;
}
for (auto& outer: outers_) {
if (outer->has(s)) {
outer->set(s, val);
return;
}
}
dic_[s] = val;
}
void setup_built_in_functions() {
auto func_pretty_print = Value::FunctionValue {
{ "arg" },
[](std::shared_ptr<Environment> env) {
std::cout << env->get("arg").str() << std::endl;
return Value();
}
};
set("pp", Value(func_pretty_print));
}
private:
std::vector<std::shared_ptr<Environment>> outers_;
std::map<std::string, Value> dic_;
};
bool run(const std::string& path, std::shared_ptr<Environment> env, const char* expr, size_t len, Value& val, std::string& msg, bool print_ast);