98 lines
3 KiB
C++
98 lines
3 KiB
C++
/** @file Variable.hpp
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*
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* Author: Roland Conybeare
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**/
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#pragma once
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#include "Expression.hpp"
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#include "binding_path.hpp"
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namespace xo {
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namespace scm {
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/** @class Variable
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* @brief syntax for a variable reference
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**/
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class Variable : public Expression {
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public:
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/** Generate unique symbol-name beginning with @p prefix.
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* Relies on static counter
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**/
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static std::string gensym(const std::string & prefix);
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/** create expression representing a variable
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* identified by @p name, that can take on values
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* described by @p var_type.
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**/
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static rp<Variable> make(const std::string & name,
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TypeDescr var_type) {
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return new Variable(name, var_type);
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}
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/** return copy of @p x: same var, different object identity **/
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static rp<Variable> copy(bp<Variable> x) {
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return new Variable(x->name(), x->valuetype());
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}
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/** downcast from Expression **/
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static bp<Variable> from(bp<Expression> x) {
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return bp<Variable>::from(x);
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}
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void assign_name(const std::string & name) { name_ = name; }
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const std::string & name() const { return name_; }
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virtual std::set<std::string> get_free_variables() const override {
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std::set<std::string> retval;
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retval.insert(this->name_);
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return retval;
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}
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virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
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visitor_fn(this);
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return 1;
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}
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virtual std::size_t visit_layer(VisitFn visitor_fn) override {
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visitor_fn(this);
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return 1;
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}
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virtual rp<Expression> xform_layer(TransformFn xform_fn) override {
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return xform_fn(this);
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}
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virtual void attach_envs(bp<SymbolTable> /*p*/) override;
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virtual void display(std::ostream & os) const override;
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virtual std::uint32_t pretty_print(const ppindentinfo & ppii) const override;
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private:
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Variable(const std::string & name,
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TypeDescr var_type)
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: Expression(exprtype::variable, var_type),
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name_{name} {}
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private:
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/** variable name **/
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std::string name_;
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/** Eventually: navigate environment via this path to find runtime memory
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* location for this variable.
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*
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* Establish via @ref attach_envs
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**/
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binding_path path_;
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}; /*Variable*/
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inline rp<Variable>
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make_var(const std::string & name,
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reflect::TypeDescr var_type) {
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return Variable::make(name, var_type);
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}
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} /*namespace scm*/
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} /*namespace xo*/
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/** end Variable.hpp **/
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