On Mon, 2018-07-30 at 13:23 +0200, Georg Chini wrote: > On 30.07.2018 11:18, Tanu Kaskinen wrote: > > On Sun, 2018-07-29 at 22:36 +0200, Georg Chini wrote: > > > On 29.07.2018 21:47, Tanu Kaskinen wrote: > > > > On Fri, 2018-07-27 at 10:51 +0200, Georg Chini wrote: > > > > > On 27.07.2018 10:08, Tanu Kaskinen wrote: > > > > > > On Thu, 2018-07-26 at 18:02 +0200, Georg Chini wrote: > > > > > > > On 26.07.2018 12:37, Tanu Kaskinen wrote: > > > > > > > > On Sun, 2018-07-22 at 21:11 +0200, Georg Chini wrote: > > > > > > > > > On 22.07.2018 17:48, Tanu Kaskinen wrote: > > > > > > > > > > On Sun, 2018-07-22 at 16:02 +0200, Georg Chini wrote: > > > > > > > > > > > On 21.07.2018 20:17, Tanu Kaskinen wrote: > > > > > > > > > > > > On Mon, 2018-04-09 at 19:35 +0200, Georg Chini wrote: > > > > > > > > > > > > > + > > > > > > > > > > > > > +/* Read functions */ > > > > > > > > > > > > > + > > > > > > > > > > > > > /* Split the specified string into elements. An element is defined as > > > > > > > > > > > > > * a sub-string between curly braces. The function is needed to parse > > > > > > > > > > > > > * the parameters of messages. Each time it is called returns the position > > > > > > > > > > > > > * of the current element in result and the state pointer is advanced to > > > > > > > > > > > > > - * the next list element. > > > > > > > > > > > > > + * the next list element. On return, the parameter *is_unpacked indicates > > > > > > > > > > > > > + * if the string is plain text or contains a sub-list. is_unpacked may > > > > > > > > > > > > > + * be NULL. > > > > > > > > > > > > > > > > > > > > > > > > is_unpacked looks like unnecessary complexity. > > > > > > > > > > > > pa_message_params_read_string() should always unescape the value. > > > > > > > > > > This is not about parameter type, it is just to distinguish between > > > > > a list and a simple value. One example comes to my mind immediately: > > > > > Consider a parameter list that consists of strings and a couple of > > > > > arrays. Now you can read this list as an array of strings (patch 8 > > > > > provides a function for that) and then examine those strings that > > > > > contain arrays separately. Having the flag (and using it in read_string()) > > > > > provides a more flexible and convenient way to parse a parameter list. > > > > > > > > > > The flag may not be strictly necessary at the moment, but I would still > > > > > like to keep it. > > > > > > > > To continue a familiar theme of my review: if there's a > > > > read_string_array() function, I want that to be used only for string > > > > arrays, not a mishmash of random types. There could be a separate > > > > function split_list_into_array() that does something similar to > > > > what you wanted to do with read_string_array(). > > > > split_list_into_array() wouldn't do special string handling, > > > > though, so unescaping would be left to the application. I find that > > > > only logical, since other basic types don't get special handling > > > > either (i.e. floats aren't converted to C floats). > > > > > > > > Your use case could be served with a vararg function that instead of > > > > producing a string array would read into separate variables, like this: > > > > > > > > pa_message_params_read(c, state, > > > > PA_TYPE_STRING, ¶m1, > > > > PA_TYPE_FLOAT, ¶m2, > > > > PA_TYPE_RAW, ¶m3, > > > > 0); > > > > > > > > PA_TYPE_RAW would be useful for reading a list (or anything else) into > > > > a C string without unescaping or other processing. There could be also > > > > PA_TYPE_IGNORE for uninteresting variables, and PA_TYPE_*_ARRAY for > > > > arrays of basic types. > > > > > > > > (Now it occurred to me that the 'c' argument name that is used in the > > > > parsing functions is a bit weird and unhelpful. Maybe "param_list" > > > > would be good?) > > > > > > > > > > I still don't see your point. Again, the use of is_unpacked is > > > transparent for the > > > user of read_string(), so the user just reads a string without having to > > > care about > > > unescaping. The flag does not complicate the API, it simplifies it > > > because the > > > unescaping is done automatically. > > > > The flag complicates the split_list() function parameters, but also the > > read_string() semantics: you need to explain to the user that unlike > > all the other read_foo() functions, read_string() can read any value > > and unescaping becomes conditional because of this. > > read_string() is not supposed to read any value, it is only supposed > to read strings. Actually, the user does not need to know anything > about escaping, because read_string() and write_string() do the > necessary escaping/unescaping completely transparent for the user. > > The is_unpacked flag is at least useful to check if something returned > by split_list() is really a simple type and not a structure or array. I am > currently not using it in the read_foo() functions, but I think I should. I guess you'd use is_unpacked for catching errors in the read_foo() functions? That seems reasonable, but I'd like that to be done in an internal function. You said that maybe split_list() could be made an internal function, and that seems like a good idea. An alternative would be to have an internal function for which split_list() would be a simplified wrapper. > > > > > Your approach seems unnecessary > > > complicated to me. A string is a string, even if it contains > > > sub-structures. Your > > > split_list_into_array() function would basically return an array of > > > strings, so what > > > would be the advantage? It would only make parsing more cumbersome, because > > > the task of unescaping is given to the user instead of doing it > > > automatically where > > > necessary. > > > > That's why I came up with the vararg function. I agree that > > split_list_into_array() is unlikely to be very useful. > > > > > Also there is no "mishmash of random types", they are all strings It is > > > only the > > > difference between a "simple" string which needs no further processing and a > > > "complex" string which needs further parsing. > > > > The API defines types for the parameters. There are no separate > > "simple" and "complex" strings in the type system. The string type is > > different than the list type. What you call complex strings are in my > > mind just the raw unprocessed serialized data, which is a different > > abstraction level than the values that the various read_foo() functions > > return. It feels just very wrong to have a function that returns values > > in both domains: unparsed raw data and parsed values. Especially when > > the function is a family of read_foo() functions where all other > > functions only operate on their designated types. > > Yes, that is some additional functionality that the read_string() > function provides on top of reading what I called "simple strings" > above. But that does not hinder the function to work exactly > like expected when reading a plain string. Maybe a better name > for the function would be read_string_element(), indicating that > it can read either a plain string or an element of the parameter > list as a string. > I could split this into two functions, read_string() which always > does unescaping and read_element() which would be a wrapper > around split_list() and would never do unescaping. In both functions, > the is_unpacked flag can be useful to check if the input matches > the type "plain string" or "serialized data". A separate function for reading the raw data sounds good to me. Are you attached to the read_element() name, or could it be read_raw() (or perhaps read_raw_value() or read_raw_element())? Somehow read_raw() seems better to me, but I can't make strong arguments for why it should be called that. -- Tanu https://www.patreon.com/tanuk https://liberapay.com/tanuk
