287 lines
10 KiB
C++
287 lines
10 KiB
C++
/* @file lambda_xs.cpp */
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#include "lambda_xs.hpp"
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#include "define_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 "expect_type_xs.hpp"
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#include "xo/expression/Lambda.hpp"
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namespace xo {
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using xo::scm::Lambda;
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using xo::scm::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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case lambdastatetype::lm_4: return "lm_4";
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case lambdastatetype::lm_5: return "lm_5";
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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) : f64 { ... } ;
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* ^ ^ ^ ^ ^ ^
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* | | | | | lm_5
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* | | | | lm_4:expect_expression
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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 "colon|lambda-body";
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case lambdastatetype::lm_3:
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return "type";
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case lambdastatetype::lm_4:
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return "lambda-body";
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case lambdastatetype::lm_5:
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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_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_colon_token(const token_type & tk,
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parserstatemachine * p_psm)
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{
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constexpr const char * c_self_name = "lambda_xs::on_colon_token";
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if (lmxs_type_ == lambdastatetype::lm_2) {
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this->lmxs_type_ = lambdastatetype::lm_3;
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expect_type_xs::start(p_psm);
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/* control reenters via .on_typedescr() */
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} else {
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this->illegal_input_on_token(c_self_name, tk, this->get_expect_str(), p_psm);
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}
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}
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void
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lambda_xs::on_leftbrace_token(const token_type & tk,
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parserstatemachine * p_psm)
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{
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constexpr const char * c_self_name = "lambda_xs::on_leftbrace_token";
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if (lmxs_type_ == lambdastatetype::lm_2)
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this->lmxs_type_ = lambdastatetype::lm_4;
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if (lmxs_type_ == lambdastatetype::lm_4) {
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expect_expr_xs::start(p_psm);
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/* want { to start expr sequence, that finishes on matching } */
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p_psm->on_leftbrace_token(token_type::leftbrace());
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} else {
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this->illegal_input_on_token(c_self_name, tk, this->get_expect_str(), p_psm);
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}
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}
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void
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lambda_xs::on_typedescr(TypeDescr td,
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parserstatemachine * p_psm)
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{
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constexpr const char * c_self_name = "lambda_xs::on_typedescr";
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scope log(XO_DEBUG(p_psm->debug_flag()));
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assert(td);
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if (lmxs_type_ == lambdastatetype::lm_3) {
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this->lmxs_type_ = lambdastatetype::lm_4;
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this->explicit_return_td_ = td;
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this->lambda_td_ = Lambda::assemble_lambda_td(local_env_->argv(),
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explicit_return_td_);
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/* 1. at this point we know function signature (@ref lambda_td_)
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* 2. if this lambda appears on the rhs of a define,
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* propagate function signature to the define.
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* 3. this makes recursive function definitions like this work
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* without relying on type inference:
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* def fact = lambda (n : i64) : i64 {
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* if (n == 0) then
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* 1
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* else
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* n * fact(n - 1)
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* }
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* 4. while parsing the body of the lambda, we want environment
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* to already associate the lambda's signature with variable 'fact',
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* so that when parser encounters 'fact(n - 1)' the expression has
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* known valuetype.
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*/
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if ((p_psm->exprstate_stack_size() >= 3)
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&& (p_psm->lookup_exprstate(1).exs_type() == exprstatetype::expect_rhs_expression)
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&& (p_psm->lookup_exprstate(2).exs_type() == exprstatetype::defexpr)
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&& (p_psm->env_stack_size() >= 2)
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)
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{
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const define_xs * def_xs = dynamic_cast<const define_xs*>(&(p_psm->lookup_exprstate(2)));
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assert(def_xs);
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bp<Variable> def_var = def_xs->lhs_variable();
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if (def_var->valuetype() == nullptr) {
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log && log("assign discovered lambda type T to enclosing define",
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xtag("lhs", def_var),
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xtag("T", print::unq(this->lambda_td_->canonical_name())));
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def_var->assign_valuetype(lambda_td_);
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} else {
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/* don't need to unify here. if def already hasa a type,
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* that's because it was explicitly specified.
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* will discover any conflict after reporting parsed lambda
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* to define_xs
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*/
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}
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}
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expect_expr_xs::start(p_psm);
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/* control reenters via .on_expr() or .on_expr_with_semicolon() */
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} else {
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this->illegal_input_on_type(c_self_name, td, this->get_expect_str(), 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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constexpr const char * c_self_name = "lambda_xs::on_expr";
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if (lmxs_type_ == lambdastatetype::lm_4) {
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this->lmxs_type_ = lambdastatetype::lm_5;
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this->body_ = expr.promote();
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} else {
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this->illegal_input_on_expr(c_self_name, expr, this->get_expect_str(), p_psm);
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}
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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_5) {
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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;
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/* TODO: unify explicit_return_td_ with body_ */
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if (lambda_td_) {
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lm = Lambda::make(name, lambda_td_, local_env_, body_);
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} else {
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lm = Lambda::make_from_env(name, local_env_,
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explicit_return_td_, body_);
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}
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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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bool
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lambda_xs::pretty_print(const xo::print::ppindentinfo & ppii) const
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{
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return ppii.pps()->pretty_struct(ppii, "lambda_xs",
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refrtag("lmxs_type", lmxs_type_));
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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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