Add prototype impl of case specialization.
Boolean cases could be translated to ifs, and integer cases to jumps. That's still in progress.
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215
13/ast.cpp
215
13/ast.cpp
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@ -1,5 +1,6 @@
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#include "ast.hpp"
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#include <ostream>
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#include <type_traits>
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#include "binop.hpp"
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#include "error.hpp"
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#include "type_env.hpp"
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@ -218,60 +219,184 @@ void ast_case::translate(global_scope& scope) {
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}
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}
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template <typename T>
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struct case_mappings {
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using tag_type = typename T::tag_type;
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std::map<tag_type, std::vector<instruction_ptr>> defined_cases;
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std::optional<std::vector<instruction_ptr>> default_case;
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std::vector<instruction_ptr>& make_case_for(tag_type tag) {
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auto existing_case = defined_cases.find(tag);
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if(existing_case != defined_cases.end()) return existing_case->second;
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if(default_case)
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throw type_error("attempted pattern match after catch-all");
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return defined_cases[tag];
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}
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std::vector<instruction_ptr>& make_default_case() {
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if(default_case)
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throw type_error("attempted repeated use of catch-all");
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default_case.emplace(std::vector<instruction_ptr>());
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return *default_case;
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}
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std::vector<instruction_ptr>& get_specific_case_for(tag_type tag) {
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auto existing_case = defined_cases.find(tag);
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assert(existing_case != defined_cases.end());
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return existing_case->second;
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}
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std::vector<instruction_ptr>& get_default_case() {
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assert(default_case);
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return *default_case;
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}
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bool case_defined_for(tag_type tag) {
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return defined_cases.find(tag) != defined_cases.end();
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}
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bool default_case_defined() { return default_case.has_value(); }
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size_t defined_cases_count() { return defined_cases.size(); }
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};
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struct case_strategy_bool {
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using tag_type = bool;
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using repr_type = bool;
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tag_type tag_from_repr(repr_type b) { return b; }
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repr_type from_typed_pattern(const pattern_ptr& pt, const type* type) {
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pattern_constr* cpat;
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if(!(cpat = dynamic_cast<pattern_constr*>(pt.get())) ||
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(cpat->constr != "True" && cpat->constr != "False") ||
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cpat->params.size() != 0)
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throw type_error("pattern cannot be converted to a boolean");
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return cpat->constr == "True";
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}
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void compile_branch(
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const branch_ptr& branch,
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const env_ptr& env,
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repr_type repr,
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std::vector<instruction_ptr>& into) {
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branch->expr->compile(env_ptr(new env_offset(1, env)), into);
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}
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size_t case_count(const type* type) {
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return 2;
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}
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instruction_ptr into_instruction(const type* type, case_mappings<case_strategy_bool>& ms) {
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throw std::runtime_error("boolean case unimplemented!");
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}
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};
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struct case_strategy_data {
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using tag_type = int;
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using repr_type = std::pair<const type_data::constructor*, const std::vector<std::string>*>;
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tag_type tag_from_repr(const repr_type& repr) { return repr.first->tag; }
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repr_type from_typed_pattern(const pattern_ptr& pt, const type* type) {
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pattern_constr* cpat;
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if(!(cpat = dynamic_cast<pattern_constr*>(pt.get())))
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throw type_error("pattern cannot be interpreted as constructor.");
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return std::make_pair(
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&static_cast<const type_data*>(type)->constructors.find(cpat->constr)->second,
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&cpat->params);
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}
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void compile_branch(
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const branch_ptr& branch,
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const env_ptr& env,
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const repr_type& repr,
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std::vector<instruction_ptr>& into) {
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env_ptr new_env = env;
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for(auto it = repr.second->rbegin(); it != repr.second->rend(); it++) {
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new_env = env_ptr(new env_var(branch->expr->env->get_mangled_name(*it), new_env));
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}
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into.push_back(instruction_ptr(new instruction_split(repr.second->size())));
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branch->expr->compile(new_env, into);
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into.push_back(instruction_ptr(new instruction_slide(repr.second->size())));
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}
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size_t case_count(const type* type) {
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return static_cast<const type_data*>(type)->constructors.size();
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}
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instruction_ptr into_instruction(const type* type, case_mappings<case_strategy_data>& ms) {
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instruction_jump* jump_instruction = new instruction_jump();
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instruction_ptr inst(jump_instruction);
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auto data_type = static_cast<const type_data*>(type);
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for(auto& constr : data_type->constructors) {
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if(!ms.case_defined_for(constr.second.tag)) continue;
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jump_instruction->branches.push_back(
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std::move(ms.get_specific_case_for(constr.second.tag)));
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jump_instruction->tag_mappings[constr.second.tag] =
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jump_instruction->branches.size() - 1;
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}
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if(ms.default_case_defined()) {
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jump_instruction->branches.push_back(
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std::move(ms.get_default_case()));
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for(auto& constr : data_type->constructors) {
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if(ms.case_defined_for(constr.second.tag)) continue;
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jump_instruction->tag_mappings[constr.second.tag] =
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jump_instruction->branches.size();
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}
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}
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return std::move(inst);
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}
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};
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template <typename T>
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void compile_case(const ast_case& node, const env_ptr& env, const type* type, std::vector<instruction_ptr>& into) {
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T strategy;
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case_mappings<T> cases;
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for(auto& branch : node.branches) {
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pattern_var* vpat;
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if((vpat = dynamic_cast<pattern_var*>(branch->pat.get()))) {
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auto& branch_into = cases.make_default_case();
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env_ptr new_env(new env_var(branch->expr->env->get_mangled_name(vpat->var), env));
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branch->expr->compile(new_env, branch_into);
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} else {
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auto repr = strategy.from_typed_pattern(branch->pat, type);
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auto& branch_into = cases.make_case_for(strategy.tag_from_repr(repr));
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strategy.compile_branch(branch, env, repr, branch_into);
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}
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}
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if(!(cases.defined_cases_count() == strategy.case_count(type) ||
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cases.default_case_defined()))
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throw type_error("incomplete patterns", node.loc);
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into.push_back(strategy.into_instruction(type, cases));
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}
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void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
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type_app* app_type = dynamic_cast<type_app*>(input_type.get());
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type_data* type = dynamic_cast<type_data*>(app_type->constructor.get());
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type_data* data;
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type_internal* internal;
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of->compile(env, into);
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into.push_back(instruction_ptr(new instruction_eval()));
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instruction_jump* jump_instruction = new instruction_jump();
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into.push_back(instruction_ptr(jump_instruction));
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for(auto& branch : branches) {
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std::vector<instruction_ptr> branch_instructions;
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pattern_var* vpat;
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pattern_constr* cpat;
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if((vpat = dynamic_cast<pattern_var*>(branch->pat.get()))) {
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branch->expr->compile(env_ptr(new env_offset(1, env)), branch_instructions);
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for(auto& constr_pair : type->constructors) {
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if(jump_instruction->tag_mappings.find(constr_pair.second.tag) !=
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jump_instruction->tag_mappings.end())
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break;
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jump_instruction->tag_mappings[constr_pair.second.tag] =
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jump_instruction->branches.size();
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}
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jump_instruction->branches.push_back(std::move(branch_instructions));
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} else if((cpat = dynamic_cast<pattern_constr*>(branch->pat.get()))) {
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env_ptr new_env = env;
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for(auto it = cpat->params.rbegin(); it != cpat->params.rend(); it++) {
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new_env = env_ptr(new env_var(branch->expr->env->get_mangled_name(*it), new_env));
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}
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branch_instructions.push_back(instruction_ptr(new instruction_split(
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cpat->params.size())));
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branch->expr->compile(new_env, branch_instructions);
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branch_instructions.push_back(instruction_ptr(new instruction_slide(
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cpat->params.size())));
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int new_tag = type->constructors[cpat->constr].tag;
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if(jump_instruction->tag_mappings.find(new_tag) !=
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jump_instruction->tag_mappings.end())
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throw type_error("technically not a type error: duplicate pattern", cpat->loc);
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jump_instruction->tag_mappings[new_tag] =
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jump_instruction->branches.size();
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jump_instruction->branches.push_back(std::move(branch_instructions));
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if((data = dynamic_cast<type_data*>(app_type->constructor.get()))) {
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compile_case<case_strategy_data>(*this, env, data, into);
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return;
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} else if((internal = dynamic_cast<type_internal*>(app_type->constructor.get()))) {
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if(internal->name == "Bool") {
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compile_case<case_strategy_bool>(*this, env, data, into);
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return;
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}
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}
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for(auto& constr_pair : type->constructors) {
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if(jump_instruction->tag_mappings.find(constr_pair.second.tag) ==
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jump_instruction->tag_mappings.end())
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throw type_error("non-total pattern", loc);
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}
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throw std::runtime_error("no known way to compile case expression");
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}
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void ast_let::print(int indent, std::ostream& to) const {
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