71 lines
2.6 KiB
C++
71 lines
2.6 KiB
C++
#include "ast.hpp"
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#include "type_checker.hpp"
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#include "error.hpp"
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namespace lily {
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type* ast_num::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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return mgr.require_type("Int");
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}
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type* ast_var::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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return env->get_identifier_type(name);
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}
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type* ast_app::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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type* ltype = left->check(mgr, env);
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type* rtype = right->check(mgr, env);
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// We LHS has to be a function, so unify LHS with that.
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type_func* f = mgr.create_type<type_func>(nullptr, nullptr);
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// Input type of function is known - it's rtype.
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f->left = rtype;
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// Output is not known - create parameter for it.
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type* new_param = mgr.create_type<type_parameter>();
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f->right = new_param;
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// Unify ltype with the function (we know it has to be one!)
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if(!ltype->unify_with(f))
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throw error("unable to unify application type");
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return new_param;
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}
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type* ast_op::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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type* ltype = left->check(mgr, env);
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type* rtype = right->check(mgr, env);
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// We know the thing has to be a nunmber, so we unify with number type.
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type* inttype = mgr.require_type("Int");
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if(!ltype->unify_with(inttype))
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throw error("left hand side of operator must be a number.");
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if(!rtype->unify_with(inttype))
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throw error("right hand side of operator must be a number.");
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// We return an integer.
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return inttype;
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}
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type* ast_let::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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if(env->identifier_exists(name))
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throw error("invalid redefinition of variable.");
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type* etype = expr->check(mgr, env);
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auto new_env = env->with_type(name, etype);
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return in->check(mgr, new_env);
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}
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type* ast_letrec::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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if(env->identifier_exists(name))
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throw error("invalid redefinition of variable.");
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type* variable_type = mgr.create_type<type_parameter>();
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auto new_env = env->with_type(name, variable_type);
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type* etype = expr->check(mgr, new_env);
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if(!variable_type->unify_with(etype))
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throw error("incompatible type for variable");
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return in->check(mgr, new_env);
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}
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type* ast_case::check(type_manager& mgr, std::shared_ptr<type_env> env) {
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throw error("unimplemented");
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}
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}
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