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Diffstat (limited to 'src/edit_var.erl')
| -rw-r--r-- | src/edit_var.erl | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/edit_var.erl b/src/edit_var.erl new file mode 100644 index 0000000..0af74b4 --- /dev/null +++ b/src/edit_var.erl @@ -0,0 +1,171 @@ +%%%---------------------------------------------------------------------- +%%% File : edit_var.erl +%%% Author : Luke Gorrie <luke@bluetail.com> +%%% Purpose : Variable management server - transient and persistent +%%% Created : 21 Jan 2001 by Luke Gorrie <luke@bluetail.com> +%%%---------------------------------------------------------------------- + +%%% This module implements "setq"-like variables. But, this seems a bit +%%% distasteful because of concurrent updates and so on. Maybe there is +%%% better way to do variables in general (or just program-internal +%%% variables). + +-module(edit_var). +-author('luke@bluetail.com'). + +%%-compile(export_all). +%%-export([Function/Arity, ...]). + +-behaviour(gen_server). + +%% External exports +-export([start_link/0]). + +-export([lookup/1, lookup/2, set/2, permanent/2, add_to_list/2]). + +%% gen_server callbacks +-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). + +-record(state, {ets, dets}). + +%%%---------------------------------------------------------------------- +%%% API +%%%---------------------------------------------------------------------- +start_link() -> + gen_server:start_link({local, edit_var}, edit_var, [], []). + +%% Return: Value | undefined +lookup(Name) -> + lookup(Name, undefined). + +lookup(Name, Default) -> + gen_server:call(?MODULE, {lookup, Name, Default}). + +set(Name, Value) -> + gen_server:call(?MODULE, {set, Name, Value}). + +%% permanent(Name, true | false) +permanent(Name, Flag) -> + gen_server:call(?MODULE, {permanent, Name, Flag}). + +add_to_list(Name, Value) -> + List = lookup(Name, []), + edit_var:set(Name, include(List, Value)). + +include([], Value) -> [Value]; +include([Value|T], Value) -> [Value|T]; +include([H|T], Value) -> [H|include(T, Value)]. + +%%%---------------------------------------------------------------------- +%%% Callback functions from gen_server +%%%---------------------------------------------------------------------- + +%%---------------------------------------------------------------------- +%% Func: init/1 +%% Returns: {ok, State} | +%% {ok, State, Timeout} | +%% ignore | +%% {stop, Reason} +%%---------------------------------------------------------------------- +init([]) -> + Filename = filename:join(os:getenv("HOME"), "edit_var.dets"), + Ets = ets:new(edit_mem_var, [set, public, named_table]), + {ok, Dets} = dets:open_file(edit_disk_var, + [{type, set}, + {file, Filename}]), + load_file(Dets, Ets), + State = #state{ets=Ets, + dets=Dets}, + {ok, State}. + +%%---------------------------------------------------------------------- +%% Func: handle_call/3 +%% Returns: {reply, Reply, State} | +%% {reply, Reply, State, Timeout} | +%% {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, Reply, State} | (terminate/2 is called) +%% {stop, Reason, State} (terminate/2 is called) +%%---------------------------------------------------------------------- +handle_call({lookup, Name, Default}, From, State) -> + {reply, do_lookup(State, Name, Default), State}; + +handle_call({set, Name, Value}, From, State) -> + ets:insert(State#state.ets, {Name, Value}), + case is_permanent(State, Name) of + true -> + dets:insert(State#state.dets, {Name, Value}); + false -> + ok + end, + {reply, ok, State}; + +handle_call({permanent, Name, Flag}, From, State) -> + case Flag of + false -> + dets:delete(State#state.dets, Name); + true -> + dets:insert(State#state.dets, {Name, do_lookup(State, Name)}) + end, + {reply, ok, State}. + +%%---------------------------------------------------------------------- +%% Func: handle_cast/2 +%% Returns: {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, State} (terminate/2 is called) +%%---------------------------------------------------------------------- +handle_cast(Msg, State) -> + {noreply, State}. + +%%---------------------------------------------------------------------- +%% Func: handle_info/2 +%% Returns: {noreply, State} | +%% {noreply, State, Timeout} | +%% {stop, Reason, State} (terminate/2 is called) +%%---------------------------------------------------------------------- +handle_info(Info, State) -> + {noreply, State}. + +%%---------------------------------------------------------------------- +%% Func: terminate/2 +%% Purpose: Shutdown the server +%% Returns: any (ignored by gen_server) +%%---------------------------------------------------------------------- +terminate(Reason, State) -> + ok. + +%%---------------------------------------------------------------------- +%% Func: code_change/3 +%% Purpose: Convert process state when code is changed +%% Returns: {ok, NewState} +%%---------------------------------------------------------------------- +code_change(OldVsn, State, Extra) -> + {ok, State}. + +%%%---------------------------------------------------------------------- +%%% Internal functions +%%%---------------------------------------------------------------------- + +load_file(Dets, Ets) -> + F = fun(X) -> ets:insert(Ets, X) end, + dets:traverse(Dets, F). + +do_lookup(State, Name) -> + do_lookup(State, Name, undefined). + +do_lookup(State, Name, Default) -> + case ets:lookup(State#state.ets, Name) of + [{_, Value}] -> + Value; + [] -> + Default + end. + +is_permanent(State, Name) -> + case dets:lookup(State#state.dets, Name) of + [] -> + false; + _ -> + true + end. |