93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
/** @file Expression.hpp
|
|
*
|
|
* Author: Roland Conybeare
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include "xo/reflect/TypeDescr.hpp"
|
|
#include "xo/refcnt/Refcounted.hpp"
|
|
#include "exprtype.hpp"
|
|
#include <functional>
|
|
#include <set>
|
|
|
|
namespace xo {
|
|
namespace ast {
|
|
class Variable; /* see Variable.hpp */
|
|
class Lambda; /* see Lamnbda.hpp */
|
|
class Environment; /* see Environment.hpp */
|
|
|
|
/** @class Expression
|
|
* @brief abstract syntax tree for an EGAD program
|
|
*
|
|
* (Expression Graph with Automagic Derivation)
|
|
*
|
|
* Things you can do with an Expression:
|
|
* - evaluate it using an interpreter
|
|
* - execute it on a VM
|
|
* - compile using LLVM
|
|
* see xo-jit/
|
|
*
|
|
* Expressions are immutable. This means they can resused
|
|
* across jit interactions
|
|
*
|
|
* Every expression evaluates to a value with a particular type
|
|
**/
|
|
class Expression : public ref::Refcount {
|
|
public:
|
|
using VisitFn = std::function<void (ref::brw<Expression>)>;
|
|
using TypeDescr = xo::reflect::TypeDescr;
|
|
|
|
public:
|
|
explicit Expression(exprtype extype, TypeDescr valuetype)
|
|
: extype_{extype}, valuetype_{valuetype}{}
|
|
|
|
exprtype extype() const { return extype_; }
|
|
TypeDescr valuetype() const { return valuetype_; }
|
|
|
|
/** visit each Expression node in this AST,
|
|
* and invoke @p fn for each.
|
|
* Returns the number of nodes visited.
|
|
* Preorder: call @p fn for a node before visiting children
|
|
**/
|
|
virtual std::size_t visit_preorder(VisitFn visitor_fn) = 0;
|
|
|
|
/** attach an environment to each lambda expression X in this subtree,
|
|
* that will:
|
|
* - resolve names matching X's arguments (formal parameters) to
|
|
* from @p X.argv
|
|
* - resolve free variables from @p parent
|
|
**/
|
|
virtual void attach_envs(ref::brw<Environment> parent) = 0;
|
|
|
|
/** append to *p_set the set of free variables in this expression.
|
|
* returns the number of free variables introduced
|
|
*
|
|
* @param env stack of lexcically-enclosing lamnbda expressions,
|
|
* in nesting order, i.e. outermost first, innertmost last
|
|
**/
|
|
//virtual std::int32_t find_free_vars(std::vector<ref::brw<Lambda>> env) = 0;
|
|
|
|
/** write human-readable representation to stream **/
|
|
virtual void display(std::ostream & os) const = 0;
|
|
/** human-readable string representation **/
|
|
virtual std::string display_string() const;
|
|
|
|
private:
|
|
/** expression type (constant | apply | ..) for this expression **/
|
|
exprtype extype_ = exprtype::invalid;
|
|
/** type information (when available) for values produced by this
|
|
* expression.
|
|
**/
|
|
TypeDescr valuetype_ = nullptr;
|
|
}; /*Expression*/
|
|
|
|
inline std::ostream &
|
|
operator<<(std::ostream & os, const Expression & x) {
|
|
x.display(os);
|
|
return os;
|
|
}
|
|
} /*namespace ast*/
|
|
} /*namespace xo*/
|
|
|
|
/** end Expression.hpp **/
|