Bad performance in deep nested dynamic nodes

[Entoryvekum]

The code below implemented a snippet to help input matrix. It insert 2 spaces when & is detected and insert a new row when \\ is detected.

local function Matrix1()
    --SimpleMatrix
    local generateElm
    generateElm=function()
        return sn(
            nil,{
                t{"  "},
                i(1),
                d(2,
                    function (arg,snip,oldState)
                        local str=arg[1][1]
                        local len=string.len(str)
                        if string.sub(str,len,len)=="&" then
                            return sn(nil,{d(1,generateElm,{})})
                        elseif string.sub(str,len-1,len)=="\\\\" then
                            return sn(nil,{t{"",""},d(1,generateElm,{})})
                        else
                            return sn(nil,{})
                        end
                    end,
                    {1}
                )
            }
        )
    end
    snip(
        s({trig="mat",hidden=true},{
            t{"\\begin{matrix}",""},
            d(1,
                function (arg,snip,oldState)
                    return sn(nil,{d(1,generateElm,{})})
                end
            ),
            t{"","\\end{matrix}"}
        },{condition=mathZone})
    )
end
Matrix1()

The snip function will insert the snippet to the table that will be returned to the loader.

However, as the matrix getting larger the performance decreases dramaticly.

The gif show tht after I typed in the entire row, vim sponse very slow.

[L3MON4D3]

Phuh, yeah I haven't given much thought to performance yet, there are probably many points that could be optimized.
But also, try not to nest the snippet as deep 😬😬
Maybe hook & in insertNode up to update the external_update_dynamicnode, and generate all those insertNodes as children of one dynamicNode

[L3MON4D3]

Did some testing, enter_node and set_mark_rgrav are the culprits:

Its purpose is to set the gravities of extmarks, such that text entered into the region of the node, actually shifts the extmarks into the correct direction.
Currently, this is handled by essentially touching all of the nodes in some snippetNode whenever one of its children is entered. We may be able to improve this by also adjusting gravities whenever a node is left, but I'll have to take a closer look to be certain

[L3MON4D3]

Did some work in #852, it's faster now :)