"string_to_term/1"？

Question

a_function_id_like_to_have("{1,2,{3,4}}") % => {1,2,{3,4}}

(就像哈斯克尔中的read )

Answer 1

请看this presentation的幻灯片25。

它利用了erl_eval、erl_parse和erl_scan。

1> {ok, Tokens, _} = erl_scan:string("{1,2,{3,4}}.").
{ok,[{'{',1},
     {integer,1,1},
     {',',1},
     {integer,1,2},
     {',',1},
     {'{',1},
     {integer,1,3},
     {',',1},
     {integer,1,4},
     {'}',1},
     {'}',1},
     {dot,1}],
    1}
2> {ok, Abstract} = erl_parse:parse_exprs(Tokens).
{ok,[{tuple,1,
            [{integer,1,1},
             {integer,1,2},
             {tuple,1,[{integer,1,3},{integer,1,4}]}]}]}
3> Bindings = erl_eval:new_bindings().
[]
4> {value, Value, _} = erl_eval:exprs(Abstract, Bindings).
{value,{1,2,{3,4}},[]}
5> erlang:display(Value).
{1,2,{3,4}}
true

Answer 2

您可以简单地使用erl_scan:string/1和erl_parse:parse_term/1。

string_to_term(Str) ->
    {ok, Tokens, _} = erl_scan:string(Str),
    {ok, Term} = erl_parse:parse_term(Tokens),
    Term.

确保Str是以点结尾的。