Scope aware symbol completion

[skovhus]

Currently, when auto-completing, the LSP shows a lot of irrelevant symbols related to the current scope (especially local variables from other function).

Task: figure out if we can use the tree-sitter AST to improve the symbol completion.

Also see #190 (comment)

[skovhus]

@mads-hartmann thoughts?

[mads-hartmann]

@skovhus Ideally we'd only show completions for the symbols that are in scope (locally defined in a function, loaded from another file through a source invocation, etc.). Doing that correctly would require some pretty sophisticated analysis of the source code though.

So perhaps a smaller first step would be to make it user-configurable what we use to populate the list of completions (local file, workspace, binaries on your path, etc.) :)

[mads-hartmann]

If you want to solve completion based on scope then I'd start with function scope.

E.g. in the following snippet, i_am_local should not be in the completion list outside of the function.

#!/usr/bin/env bash

hello() {
    i_am_global="hello"
    local i_am_local="hej"

    echo "in function: $i_am_global"
    echo "in function: $i_am_local"
}

hello
echo "outside function $i_am_global"
echo "outside function $i_am_local"

One way you might do this would be:

1. Don't add local variables to the symbols list when we process files
2. When asking for completions, traverse the tree upwards and collect any local definitions in scope

Happy to chat more about this approach offline if you're interested :)

[skovhus]

Update on file-aware symbol completion.

The grammar currently doesn't have support for sourcing as a type (neither source ./somefile.sh or . ./somefile.sh ) similar to how variable_assignment is exposed by the grammar. A first step would be to add this to https://github.com/tree-sitter/tree-sitter-bash including an easy way to retrieve the file name.

Then we could use that for building up a tree of files that source each other, which we could use to make the symbol completion file aware.