Ace: New Feature: Provide support for max length option

[christianbs]

Sometimes is important set a limit of the script.

[nightwing]

You can use the following code to disable inserting if editor value is longer than some limit

var doc = editor.session.doc
doc.applyAnyDelta = doc.applyAnyDelta || doc.applyDelta
doc.applyDelta = function(delta) {
   if (delta.action == "insert" && this.$maxLength 
       && this.getValue().length > this.$maxLength) {
       return false;
   }
   return this.applyAnyDelta(delta);
}
doc.$maxLength = 20

Could you please tell in which cases do you need this, to help us understand whether this needs to be a part of default set of options or an extension.

[christianbs]

Of course!! So, in our application, the script is persisted at database and there's a limit to this column. I think this should be very common because the editor actually is very used in web applications. On the other hand, the script above should solve my problem... thanks

[zanzlanz]

To ensure the resulting length is the one that gets limited, and to allow large pastes by trimming the end, try this edit:

var doc = editor.session.doc
doc.applyAnyDelta = doc.applyAnyDelta || doc.applyDelta
doc.applyDelta = function(delta) {
    let joinedLines = delta.lines.join("\n")

    if (delta.action == "insert" && this.$maxLength
        && this.getValue().length + joinedLines.length > this.$maxLength) {

        let newPasteLength = this.$maxLength - this.getValue().length
        if(newPasteLength > 0) {
            delta.lines = joinedLines.substr(0, newPasteLength).split("\n")
            if(delta.lines.length == 1 && delta.start.row == delta.end.row) {
                delta.end = {
                    row: delta.start.row,
                    column: delta.start.column+newPasteLength
                }
            } else {
                delta.end = {
                    row: delta.start.row+delta.lines.length,
                    column: delta.lines[delta.lines.length-1].length
                }
            }
        } else return false;
    }
    return this.applyAnyDelta(delta);
}
doc.$maxLength = 20

Might be beneficial to optimize it more for production, but I hope this helps someone anyway!

Also, I ran into the same use case as @christianbs :)