Re: How to test for the existence of a 'goto' target label?

[Coda Highland <chighland@...>]

On Sun, Sep 9, 2012 at 8:59 AM, marbux <marbux@gmail.com> wrote:
> On Sat, Sep 8, 2012 at 11:18 PM, Rena <hyperhacker@gmail.com> wrote:
>
>> The problem with simple string searching is it fails easily:
>>
>> if label_exists('foo') then
>>   error("oops, the string '::foo::' occurs in this file")
>> end
>>
>> --::bar:: doThingsWeDontNeedRightNow()
>> if label_exists('bar') then
>>   error("oh no!")
>> end
>
> It's not so problematic in the particular use case I'm looking at if
> the colons are included in the pattern to search for. E.g., "::foo::",
>  "::bar::". This works because I'm searching the script's plain text
> fetched as a variable.
>
> The outliner that embeds Lua, NoteCase Pro, allows multiple plain text
> tags (node metadata) per node. Tags are rather exuberantly useful
> because the app has a mode in which arbitrary groups of nodes can be
> displayed in a flat (non-hierarchical) list view, All tags used in the
> current document are displayed in the Tags Pane, regardless of mode.
>
> I am toying with the concept of using tags as script branchers, by
> adding a Ctrl+Enter event trigger that fires if the focus is in the
> Tags Pane and a tag is selected when the keyboard action is executed.
> The second related enhancement would be a new API that returns the
> text of the currently selected tag, Nc_Note_Tag_GetCurrent().
>
> My prototype script that would be assigned to the new event trigger
> follows.[1] It seems to work just fine so far. Note that the call to
> the hypothesized API is in a long comment, since I don't have that API
> to play with. The two lines following that comment are string
> assignments that simulate the API's possible returns, one for a tag
> that has a corresponding label and one for a tag that does not.
>
> The script presented an unusual problem in that a given tag may or may
> not have a corresponding label in the script. So testing whether the
> corresponding label exists before branching is necessary.
>
> Also, I wanted to work with the goto statement to make it easier for
> novices to drop in and remove scripted actions but the label name in
> the goto statement had to be a variable rather than a literal string.
> The following two lines work around the goto statement's distaste for
> string variables:
>
> strToLoad = "goto strLabelText"
>   load(strToLoad)
>
> Best regards,
>
> Paul
> ______________
>
> [1] Hopefully, the API names' somewhat Hungarian notation will aid in
> understanding what they do. :-)
>
> function Test_If_Label_Exists(nScriptDocID, strScriptNoteID, strLabel)
>
>   -- get this script's plain text
>   local strContent = Nc_Note_Content_Get(nScriptDocID, strScriptNoteID, 0)
>
>   -- look for label & evaluate
>   local nFrom, nTo = string.find(strContent, strLabel)
>   if nFrom ~= nil and nTo ~= nil then
>     nFoundLabel = 1
>   else
>     nFoundLabel = 0
>   end -- if nFrom
>
>  return nFoundLabel
> end -- function
>
> nFoundLabel = nil
>
> -- get script's doc and note IDs
> nScriptDocID = Nc_Script_DocID_Get()
> strScriptNoteID = Nc_Script_NoteID_Get()
>
> --[[
>  local strLabelText = Nc_Note_Tag_GetCurrent()
> --]]
>
> strLabelText = 'clone node'
> -- strLabelText = 'no corresponding label'
>
> strLabelText = string.gsub(strLabelText, '%s', '')
> strLabel = '::' .. strLabelText .. '::'
>
> -- goto label if it exists, else abort
> nLabelExists = Test_If_Label_Exists(nScriptDocID, strScriptNoteID, strLabel)
> if nLabelExists == 1 then
>   strToLoad = 'goto strLabelText'
>   load(strToLoad)
> else
>   goto exit
> end
>
> -- begin tag-specific actions
>
> ::insertdate::
> Nc_GUI_InfoBox('Scripted action for \'insert date\' tag inserts the
> date in current note at cursor position.', 1, 'Action')
> goto exit
>
> ::clonenode::
> Nc_GUI_InfoBox('Scripted action for \'clone node\' tag clones the
> current note to the HTML clipboard for insertion elsewhere in the same
> doc.', 1, 'Action')
> goto exit
>
> ::eventdate::
> Nc_GUI_InfoBox('Scripted action for \'event date\' tag launches pop-up
> for adding or deleting the current node's EventDate custom property
> and value.', 1, 'Action')
> goto exit
>
> -- etc.
>
> ::exit::
>

Is there a reason those things can't be... y'know... functions?

/s/ Adam