feat(recipes): add recipe for automatically triggering lsp signature …

…help

lua/astrocommunity/recipes/astrolsp-auto-signature-help/README.md

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+# AstroLSP - Automatically show signature help
+
+**Website:** <https://docs.astronvim.com/recipes/advanced_lsp/#automatic-signature-help>
+
+This plugin specification configures AstroLSP to automatically trigger the LSP signature help when necessary and relevant.

lua/astrocommunity/recipes/astrolsp-auto-signature-help/init.lua

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+return {
+  "AstroNvim/astrolsp",
+  specs = {
+    {
+      "AstroNvim/astrocore",
+      ---@type AstroCoreOpts
+      opts = {
+        autocmds = {
+          signature_help_triggers = {
+            {
+              event = "LspAttach",
+              desc = "Add signature help triggers as language servers attach",
+              callback = function(args)
+                local client = vim.lsp.get_client_by_id(args.data.client_id)
+                if client and client.supports_method "textDocument/signatureHelp" then
+                  vim.b[args.buf].signature_help_trigger = require("astrocore").list_insert_unique(
+                    vim.b[args.buf].signature_help_trigger,
+                    client.server_capabilities.signatureHelpProvider.triggerCharacters or {}
+                  )
+                end
+              end,
+            },
+            {
+              event = "LspDetach",
+              desc = "Safely remove LSP signature help triggers when language servers detach",
+              callback = vim.schedule_wrap(function(args)
+                if not vim.api.nvim_buf_is_valid(args.buf) then return end
+                local signature_help_trigger = {}
+                for _, client in pairs((vim.lsp.get_clients or vim.lsp.get_active_clients) { bufnr = args.buf }) do
+                  if client.id ~= args.data.client_id and client.supports_method "textDocument/signatureHelp" then
+                    require("astrocore").list_insert_unique(
+                      signature_help_trigger,
+                      client.server_capabilities.signatureHelpProvider.triggerCharacters or {}
+                    )
+                  end
+                end
+                vim.b[args.buf].signature_help_trigger = signature_help_trigger
+              end),
+            },
+          },
+        },
+      },
+    },
+  },
+  ---@type AstroLSPOpts
+  opts = {
+    autocmds = {
+      auto_signature_help = {
+        cond = "textDocument/signatureHelp",
+        {
+          event = "TextChangedI",
+          desc = "Automatically trigger signature help when a trigger character is typed",
+          callback = function(args)
+            local signature_help_trigger = vim.b[args.buf].signature_help_trigger
+            if signature_help_trigger then
+              local cur_line = vim.api.nvim_get_current_line():gsub("%s+$", "") -- rm trailing spaces
+              local pos = vim.api.nvim_win_get_cursor(0)[2]
+              local cur_char = cur_line:sub(pos, pos)
+
+              for _, char in ipairs(signature_help_trigger) do
+                if cur_char == char then
+                  vim.lsp.buf.signature_help()
+                  return
+                end
+              end
+            end
+          end,
+        },
+      },
+    },
+  },
+}