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70 lines
2.3 KiB
Haxe
70 lines
2.3 KiB
Haxe
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package funkin.util.tools;
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import funkin.data.song.SongData.SongNoteData;
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/**
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* A static extension which provides utility functions for `Array<SongNoteData>`s.
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*/
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class SongNoteDataArrayTools
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{
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/**
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* Queries whether the provided `SongNoteData` is contained in the provided array.
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* The input array must be already sorted by `time`.
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* Vastly more efficient than `array.indexOf`.
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* This is not crazy or premature optimization, I'm writing this because `ChartEditorState.handleNoteDisplay` is using like 71% of its CPU time on this.
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* @param arr The array to search.
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* @param note The note to search for.
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* @param predicate
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* @return The index of the note in the array, or `-1` if it is not present.
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*/
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public static function fastIndexOf(input:Array<SongNoteData>, note:SongNoteData):Int
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{
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// I would have made this use a generic/predicate, but that would have made it slower!
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// Prefix with some simple checks to save time.
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if (input.length == 0) return -1;
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if (note.time < input[0].time || note.time > input[input.length - 1].time) return -1;
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// Thank you Github Copilot for suggesting a binary search!
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var lowIndex:Int = 0;
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var highIndex:Int = input.length - 1;
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// When lowIndex overtakes highIndex
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while (lowIndex <= highIndex)
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{
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// Get the middle index of the range.
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var midIndex = Std.int((lowIndex + highIndex) / 2);
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// Compare the middle note of the range to the note we're looking for.
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// If it matches, return the index, else halve the range and try again.
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var midNote = input[midIndex];
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if (midNote.time < note.time)
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{
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// Search the upper half of the range.
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lowIndex = midIndex + 1;
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}
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else if (midNote.time > note.time)
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{
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// Search the lower half of the range.
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highIndex = midIndex - 1;
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}
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// Found it? Do a more thorough check.
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else if (midNote == note)
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{
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return midIndex;
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}
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else
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{
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// We may be close, so constrain the range (but only a little) and try again.
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highIndex -= 1;
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}
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}
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return -1;
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}
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public static inline function fastContains(input:Array<SongNoteData>, note:SongNoteData):Bool
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{
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return fastIndexOf(input, note) != -1;
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}
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}
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