/// <summary>
/// Compares two sets of SemanticTokens and returns the edits between them.
/// </summary>
private static LSP.SemanticTokensEdit[] ComputeSemanticTokensEdits(
int[] oldSemanticTokens,
int[] newSemanticTokens)
{
if (oldSemanticTokens.SequenceEqual(newSemanticTokens))
{
return(Array.Empty <SemanticTokensEdit>());
}
// We use Roslyn's version of the Myers' Diff Algorithm to compute the minimal edits
// between the old and new tokens.
// Edits are computed by token (i.e. in sets of five integers), so if one value in the token
// is changed, the entire token is replaced. We do this instead of directly comparing each
// value in the token individually so that we can potentially save on computation costs, since
// we can return early if we find that one value in the token doesn't match. However, there
// are trade-offs since our insertions/deletions are usually larger.
// Turning arrays into tuples of five ints, each representing one token
var oldGroupedSemanticTokens = ConvertToGroupedSemanticTokens(oldSemanticTokens);
var newGroupedSemanticTokens = ConvertToGroupedSemanticTokens(newSemanticTokens);
var edits = LongestCommonSemanticTokensSubsequence.GetEdits(oldGroupedSemanticTokens, newGroupedSemanticTokens);
return(ConvertToSemanticTokenEdits(newGroupedSemanticTokens, edits));
}
/// <summary>
/// Compares two sets of SemanticTokens and returns the edits between them.
/// </summary>
private static LSP.SemanticTokensEdit[] ComputeSemanticTokensEdits(
int[] oldSemanticTokens,
int[] newSemanticTokens)
{
if (oldSemanticTokens.SequenceEqual(newSemanticTokens))
{
return(Array.Empty <SemanticTokensEdit>());
}
// We use Roslyn's version of the Myers' Diff Algorithm to compute the minimal edits between
// the old and new tokens. Edits are computed on an int level, with five ints representing
// one token. We compute on int level rather than token level to minimize the amount of
// edits we send back to the client.
var edits = LongestCommonSemanticTokensSubsequence.GetEdits(oldSemanticTokens, newSemanticTokens);
var processedEdits = ProcessEdits(newSemanticTokens, edits.ToArray());
return(processedEdits);
}
