159 lines
4.8 KiB
C++
159 lines
4.8 KiB
C++
/* @file lambda_xs.cpp */
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#include "lambda_xs.hpp"
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#include "parserstatemachine.hpp"
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#include "exprstatestack.hpp"
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#include "expect_formal_arglist_xs.hpp"
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#include "expect_expr_xs.hpp"
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#include "xo/expression/Lambda.hpp"
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namespace xo {
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using xo::ast::Lambda;
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using xo::ast::LocalEnv;
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namespace scm {
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const char *
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lambdastatetype_descr(lambdastatetype x) {
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switch(x) {
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case lambdastatetype::invalid: return "invalid";
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case lambdastatetype::lm_0: return "lm_0";
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case lambdastatetype::lm_1: return "lm_1";
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case lambdastatetype::lm_2: return "lm_2";
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case lambdastatetype::lm_3: return "lm_3";
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default: break;
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}
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return "???lambdastatetype";
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}
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// ----- lambda_xs - ----
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std::unique_ptr<lambda_xs>
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lambda_xs::make() {
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return std::make_unique<lambda_xs>(lambda_xs());
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}
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void
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lambda_xs::start(parserstatemachine * p_psm)
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{
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p_psm->push_exprstate(lambda_xs::make());
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p_psm->top_exprstate()
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.on_lambda_token(token_type::lambda(), p_psm);
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}
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lambda_xs::lambda_xs() : exprstate(exprstatetype::lambdaexpr) {}
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const char *
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lambda_xs::get_expect_str() const
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{
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/*
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* lambda (x : f64) { ... } ;
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* ^ ^ ^ ^
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* | | | lm_3
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* | | lm_2
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* | lm_1:
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* expect_expression
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*/
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switch (this->lmxs_type_) {
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case lambdastatetype::invalid:
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case lambdastatetype::lm_0:
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case lambdastatetype::n_lambdastatetype:
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assert(false); // impossible
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return nullptr;
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case lambdastatetype::lm_1:
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return "lambda-params";
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case lambdastatetype::lm_2:
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return "lambda-body";
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case lambdastatetype::lm_3:
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return "semicolon";
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}
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return "?expect";
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}
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void
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lambda_xs::on_lambda_token(const token_type & tk,
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parserstatemachine * p_psm)
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{
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if (lmxs_type_ == lambdastatetype::lm_0) {
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this->lmxs_type_ = lambdastatetype::lm_1;
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expect_formal_arglist_xs::start(p_psm);
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} else {
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exprstate::on_lambda_token(tk, p_psm);
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}
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}
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void
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lambda_xs::on_formal_arglist(const std::vector<rp<Variable>> & argl,
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parserstatemachine * p_psm)
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{
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if (lmxs_type_ == lambdastatetype::lm_1) {
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this->lmxs_type_ = lambdastatetype::lm_2;
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this->parent_env_ = p_psm->top_envframe().promote();
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this->local_env_ = LocalEnv::make(argl, parent_env_);
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p_psm->push_envframe(local_env_);
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expect_expr_xs::start(p_psm);
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} else {
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exprstate::on_formal_arglist(argl, p_psm);
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}
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}
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void
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lambda_xs::on_expr(bp<Expression> expr,
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parserstatemachine * p_psm)
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{
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if (lmxs_type_ == lambdastatetype::lm_2) {
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this->lmxs_type_ = lambdastatetype::lm_3;
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this->body_ = expr.promote();
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} else {
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exprstate::on_expr(expr, p_psm);
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}
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}
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void
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lambda_xs::on_expr_with_semicolon(bp<Expression> expr,
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parserstatemachine * p_psm)
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{
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this->on_expr(expr, p_psm);
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this->on_semicolon_token(token_type::semicolon(), p_psm);
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}
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void
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lambda_xs::on_semicolon_token(const token_type & tk,
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parserstatemachine * p_psm)
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{
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if (lmxs_type_ == lambdastatetype::lm_3) {
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/* done! */
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std::unique_ptr<exprstate> self = p_psm->pop_exprstate();
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std::string name = Variable::gensym("lambda");
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/* top env frame recorded arguments to this lambda */
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p_psm->pop_envframe();
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rp<Lambda> lm = Lambda::make_from_env(name, local_env_, body_);
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p_psm->top_exprstate().on_expr(lm, p_psm);
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p_psm->top_exprstate().on_semicolon_token(tk, p_psm);
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return;
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}
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exprstate::on_semicolon_token(tk, p_psm);
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}
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void
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lambda_xs::print(std::ostream & os) const {
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os << "<lambda_xs"
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<< xtag("lmxs_type", lmxs_type_)
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<< ">";
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}
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} /*namespace scm*/
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} /*namespace xo*/
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/* end lambda_xs.cpp */
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