lsp: export convert_signature_help_to_markdown_lines (#11950)

This function is also useful for users to create their own `textDocument/signatureHelp` callback function.

runtime/lua/vim/lsp/callbacks.lua

@@ -125,72 +125,13 @@ M['textDocument/definition'] = location_callback
 M['textDocument/typeDefinition'] = location_callback
 M['textDocument/implementation'] = location_callback
 
---- Convert SignatureHelp response to preview contents.
--- https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_signatureHelp
-local function signature_help_to_preview_contents(input)
-  if not input.signatures then
-    return
-  end
-  --The active signature. If omitted or the value lies outside the range of
-  --`signatures` the value defaults to zero or is ignored if `signatures.length
-  --=== 0`. Whenever possible implementors should make an active decision about
-  --the active signature and shouldn't rely on a default value.
-  local contents = {}
-  local active_signature = input.activeSignature or 0
-  -- If the activeSignature is not inside the valid range, then clip it.
-  if active_signature >= #input.signatures then
-    active_signature = 0
-  end
-  local signature = input.signatures[active_signature + 1]
-  if not signature then
-    return
-  end
-  vim.list_extend(contents, vim.split(signature.label, '\n', true))
-  if signature.documentation then
-    util.convert_input_to_markdown_lines(signature.documentation, contents)
-  end
-  if input.parameters then
-    local active_parameter = input.activeParameter or 0
-    -- If the activeParameter is not inside the valid range, then clip it.
-    if active_parameter >= #input.parameters then
-      active_parameter = 0
-    end
-    local parameter = signature.parameters and signature.parameters[active_parameter]
-    if parameter then
-      --[=[
-      --Represents a parameter of a callable-signature. A parameter can
-      --have a label and a doc-comment.
-      interface ParameterInformation {
-        --The label of this parameter information.
-        --
-        --Either a string or an inclusive start and exclusive end offsets within its containing
-        --signature label. (see SignatureInformation.label). The offsets are based on a UTF-16
-        --string representation as `Position` and `Range` does.
-        --
-        --*Note*: a label of type string should be a substring of its containing signature label.
-        --Its intended use case is to highlight the parameter label part in the `SignatureInformation.label`.
-        label: string | [number, number];
-        --The human-readable doc-comment of this parameter. Will be shown
-        --in the UI but can be omitted.
-        documentation?: string | MarkupContent;
-      }
-      --]=]
-      -- TODO highlight parameter
-      if parameter.documentation then
-        util.convert_input_to_markdown_lines(parameter.documentation, contents)
-      end
-    end
-  end
-  return contents
-end
-
 M['textDocument/signatureHelp'] = function(_, method, result)
   util.focusable_preview(method, function()
     if not (result and result.signatures and result.signatures[1]) then
       return { 'No signature available' }
     end
     -- TODO show popup when signatures is empty?
-    local lines = signature_help_to_preview_contents(result)
+    local lines = util.convert_signature_help_to_markdown_lines(result)
     lines = util.trim_empty_lines(lines)
     if vim.tbl_isempty(lines) then
       return { 'No signature available' }

runtime/lua/vim/lsp/util.lua

@@ -275,6 +275,65 @@ function M.convert_input_to_markdown_lines(input, contents)
   return contents
 end
 
+--- Convert SignatureHelp response to markdown lines.
+-- https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_signatureHelp
+function M.convert_signature_help_to_markdown_lines(signature_help)
+  if not signature_help.signatures then
+    return
+  end
+  --The active signature. If omitted or the value lies outside the range of
+  --`signatures` the value defaults to zero or is ignored if `signatures.length
+  --=== 0`. Whenever possible implementors should make an active decision about
+  --the active signature and shouldn't rely on a default value.
+  local contents = {}
+  local active_signature = signature_help.activeSignature or 0
+  -- If the activeSignature is not inside the valid range, then clip it.
+  if active_signature >= #signature_help.signatures then
+    active_signature = 0
+  end
+  local signature = signature_help.signatures[active_signature + 1]
+  if not signature then
+    return
+  end
+  vim.list_extend(contents, vim.split(signature.label, '\n', true))
+  if signature.documentation then
+    M.convert_input_to_markdown_lines(signature.documentation, contents)
+  end
+  if signature_help.parameters then
+    local active_parameter = signature_help.activeParameter or 0
+    -- If the activeParameter is not inside the valid range, then clip it.
+    if active_parameter >= #signature_help.parameters then
+      active_parameter = 0
+    end
+    local parameter = signature.parameters and signature.parameters[active_parameter]
+    if parameter then
+      --[=[
+      --Represents a parameter of a callable-signature. A parameter can
+      --have a label and a doc-comment.
+      interface ParameterInformation {
+        --The label of this parameter information.
+        --
+        --Either a string or an inclusive start and exclusive end offsets within its containing
+        --signature label. (see SignatureInformation.label). The offsets are based on a UTF-16
+        --string representation as `Position` and `Range` does.
+        --
+        --*Note*: a label of type string should be a substring of its containing signature label.
+        --Its intended use case is to highlight the parameter label part in the `SignatureInformation.label`.
+        label: string | [number, number];
+        --The human-readable doc-comment of this parameter. Will be shown
+        --in the UI but can be omitted.
+        documentation?: string | MarkupContent;
+      }
+      --]=]
+      -- TODO highlight parameter
+      if parameter.documentation then
+        M.convert_input_help_to_markdown_lines(parameter.documentation, contents)
+      end
+    end
+  end
+  return contents
+end
+
 function M.make_floating_popup_options(width, height, opts)
   validate {
     opts = { opts, 't', true };