use LSPString in requests too for consistency

10 files changed, 228 insertions, 152 deletions

diff --git a/buffer.c b/buffer.c
index 94cebff..1d8effd 100644
--- a/buffer.c
+++ b/buffer.c
@@ -497,15 +497,12 @@ static void buffer_send_lsp_did_close(TextBuffer *buffer, LSP *lsp, const char *
 	buffer->lsp_opened_in = 0;
 }
 
-// buffer_contents must either be NULL or allocated with malloc or similar
-//   - don't free it after calling this function.
-// if buffer_contents = NULL, fetches the current buffer contents.
-static void buffer_send_lsp_did_open(TextBuffer *buffer, LSP *lsp, char *buffer_contents) {
-	if (!buffer_contents)
-		buffer_contents = buffer_contents_utf8_alloc(buffer);
+static void buffer_send_lsp_did_open(TextBuffer *buffer, LSP *lsp) {
+	size_t buffer_contents_len = buffer_contents_utf8(buffer, NULL);
 	LSPRequest request = {.type = LSP_REQUEST_DID_OPEN};
 	LSPRequestDidOpen *open = &request.data.open;
-	open->file_contents = buffer_contents;
+	char *contents = lsp_message_alloc_string(&request.base, buffer_contents_len, &open->file_contents);
+	buffer_contents_utf8(buffer, contents);
 	open->document = lsp_document_id(lsp, buffer->path);
 	open->language = buffer_language(buffer);
 	lsp_send_request(lsp, &request);
@@ -529,7 +526,7 @@ LSP *buffer_lsp(TextBuffer *buffer) {
 		if (curr_lsp)
 			buffer_send_lsp_did_close(buffer, curr_lsp, NULL);
 		if (true_lsp)
-			buffer_send_lsp_did_open(buffer, true_lsp, NULL);
+			buffer_send_lsp_did_open(buffer, true_lsp);
 	}
 	buffer->last_lsp_check = buffer->ted->frame_time;
 	return true_lsp;
@@ -1798,13 +1795,11 @@ static void buffer_send_lsp_did_change(LSP *lsp, TextBuffer *buffer, BufferPos p
 	u32 nchars_deleted, String32 new_text) {
 	if (!buffer_is_named_file(buffer))
 		return; // this isn't a named buffer so we can't send a didChange request.
-	LSPDocumentChangeEvent event = {0};
-	if (new_text.len > 0)
-		event.text = str32_to_utf8_cstr(new_text);
-	event.range.start = buffer_pos_to_lsp_position(buffer, pos);
+	LSPRange range = {0};
+	range.start = buffer_pos_to_lsp_position(buffer, pos);
 	BufferPos pos_end = buffer_pos_advance(buffer, pos, nchars_deleted);
-	event.range.end = buffer_pos_to_lsp_position(buffer, pos_end);
-	lsp_document_changed(lsp, buffer->path, event);
+	range.end = buffer_pos_to_lsp_position(buffer, pos_end);
+	lsp_document_changed(lsp, buffer->path, range, new_text);
 }
 
 BufferPos buffer_insert_text_at_pos(TextBuffer *buffer, BufferPos pos, String32 str) {
diff --git a/ide-definitions.c b/ide-definitions.c
index aab145a..79677e8 100644
--- a/ide-definitions.c
+++ b/ide-definitions.c
@@ -240,9 +240,8 @@ void definitions_send_request_if_needed(Ted *ted) {
 	}
 	LSPRequest request = {.type = LSP_REQUEST_WORKSPACE_SYMBOLS};
 	LSPRequestWorkspaceSymbols *syms = &request.data.workspace_symbols;
-	syms->query = str_dup(query);
-	// cancel old request
-	definition_cancel_lookup(ted);
+	syms->query = lsp_request_add_string(&request, query);
+	definition_cancel_lookup(ted); // cancel old request
 	defs->last_request = lsp_send_request(lsp, &request);
 	defs->last_request_time = ted->frame_time;
 	free(defs->last_request_query);
diff --git a/ide-rename-symbol.c b/ide-rename-symbol.c
index ed7483c..b5208cc 100644
--- a/ide-rename-symbol.c
+++ b/ide-rename-symbol.c
@@ -26,7 +26,7 @@ void rename_symbol_at_cursor(Ted *ted, TextBuffer *buffer, const char *new_name)
 		LSPRequest request = {.type = LSP_REQUEST_RENAME};
 		LSPRequestRename *data = &request.data.rename;
 		data->position = buffer_cursor_pos_as_lsp_document_position(buffer);
-		data->new_name = str_dup(new_name);
+		data->new_name = lsp_request_add_string(&request, new_name);
 		rs->request_id = lsp_send_request(lsp, &request);
 	}
 	
@@ -119,12 +119,6 @@ void rename_symbol_process_lsp_response(Ted *ted, const LSPResponse *response) {
 		return;
 	}
 	
-	if (response->error) {
-		ted_error(ted, "%s", response->error);
-		goto cleanup;
-		
-	}
-	
 	const LSPResponseRename *data = &response->data.rename;
 	LSP *lsp = ted_get_lsp_by_id(ted, rs->request_id.lsp);
 	if (!lsp) {
diff --git a/lsp-parse.c b/lsp-parse.c
index c07679a..ace4881 100644
--- a/lsp-parse.c
+++ b/lsp-parse.c
@@ -32,19 +32,6 @@ static WarnUnusedResult bool lsp_expect_number(LSP *lsp, JSONValue value, const
 	return lsp_expect_type(lsp, value, JSON_NUMBER, what);
 }
 
-
-static LSPString lsp_response_add_json_string(LSPResponse *response, const JSON *json, JSONString string) {
-	if (string.len == 0) {
-		return (LSPString){0};
-	}
-	u32 offset = arr_len(response->string_data);
-	arr_set_len(response->string_data, offset + string.len + 1);
-	json_string_get(json, string, response->string_data + offset, string.len + 1);
-	return (LSPString){
-		.offset = offset
-	};
-}
-
 static int completion_qsort_cmp(void *context, const void *av, const void *bv) {
 	const LSPResponse *response = context;
 	const LSPCompletionItem *a = av, *b = bv;
@@ -692,7 +679,7 @@ static WarnUnusedResult bool parse_id(const JSON *json, LSPRequest *request) {
 		}
 		} break;
 	case JSON_STRING:
-		request->id_string = json_string_get_alloc(json, id_value.val.string);
+		request->id_string = lsp_request_add_json_string(request, json, id_value.val.string);
 		return true;
 	default: break;
 	}
@@ -700,7 +687,8 @@ static WarnUnusedResult bool parse_id(const JSON *json, LSPRequest *request) {
 }
 
 // handles window/showMessage, window/logMessage, and window/showMessageRequest parameters
-static bool parse_window_message(LSP *lsp, const JSON *json, LSPRequestMessage *m) {
+static bool parse_window_message(LSP *lsp, const JSON *json, LSPRequest *request) {
+	LSPRequestMessage *m = &request->data.message;
 	JSONObject params = json_force_object(json_get(json, "params"));
 	JSONValue type = json_object_get(json, params, "type");
 	JSONValue message = json_object_get(json, params, "message");
@@ -716,7 +704,7 @@ static bool parse_window_message(LSP *lsp, const JSON *json, LSPRequestMessage *
 	}
 	
 	m->type = (LSPWindowMessageType)mtype;
-	m->message = json_string_get_alloc(json, message.val.string);
+	m->message = lsp_request_add_json_string(request, json, message.val.string);
 	return true;
 }
 
@@ -731,7 +719,7 @@ static bool parse_server2client_request(LSP *lsp, JSON *json, LSPRequest *reques
 	
 	if (streq(method, "window/showMessage")) {
 		request->type = LSP_REQUEST_SHOW_MESSAGE;
-		return parse_window_message(lsp, json, &request->data.message);
+		return parse_window_message(lsp, json, request);
 	} else if (streq(method, "window/showMessageRequest")) {
 		// we'll deal with the repsonse right here
 		LSPResponse response = {0};
@@ -744,10 +732,10 @@ static bool parse_server2client_request(LSP *lsp, JSON *json, LSPRequest *reques
 		lsp_send_response(lsp, &response);
 		
 		request->type = LSP_REQUEST_SHOW_MESSAGE;
-		return parse_window_message(lsp, json, &request->data.message);
+		return parse_window_message(lsp, json, request);
 	} else if (streq(method, "window/logMessage")) {
 		request->type = LSP_REQUEST_LOG_MESSAGE;
-		return parse_window_message(lsp, json, &request->data.message);
+		return parse_window_message(lsp, json, request);
 	} else if (streq(method, "workspace/workspaceFolders")) {
 		// we can deal with this request right here
 		LSPResponse response = {0};
@@ -988,14 +976,11 @@ void process_message(LSP *lsp, JSON *json) {
 			// now response_to is response's responsibility
 			memset(&response_to, 0, sizeof response_to);
 	
-			// make sure (LSPString){0} gets treated as an empty string
-			arr_add(response.string_data, '\0');
-			
 			if (error.type == JSON_STRING) {
-				response.error = json_string_get_alloc(json, error.val.string);
+				response.error = lsp_response_add_json_string(&response, json, error.val.string);
 			}
 			
-			if (response.error) {
+			if (!lsp_string_is_empty(response.error)) {
 				if (error_code != LSP_ERROR_REQUEST_CANCELLED)
 					add_to_messages = true;
 			} else switch (response.request.type) {
@@ -1049,7 +1034,11 @@ void process_message(LSP *lsp, JSON *json) {
 						LSPRequest configuration = {
 							.type = LSP_REQUEST_CONFIGURATION
 						};
-						configuration.data.configuration.settings = lsp->configuration_to_send;
+						configuration.data.configuration.settings = lsp_request_add_string(
+							&configuration,
+							lsp->configuration_to_send
+						);
+						free(lsp->configuration_to_send);
 						lsp->configuration_to_send = NULL;
 						lsp_send_request(lsp, &configuration);
 					}
@@ -1063,8 +1052,8 @@ void process_message(LSP *lsp, JSON *json) {
 			if (add_to_messages) {
 				SDL_LockMutex(lsp->messages_mutex);
 				LSPMessage *message = arr_addp(lsp->messages_server2client);
-				message->type = LSP_RESPONSE;
-				message->u.response = response;
+				response.base.type = LSP_RESPONSE;
+				message->response = response;
 				SDL_UnlockMutex(lsp->messages_mutex);
 			} else {
 				lsp_response_free(&response);
@@ -1076,8 +1065,8 @@ void process_message(LSP *lsp, JSON *json) {
 		if (parse_server2client_request(lsp, json, &request)) {
 			SDL_LockMutex(lsp->messages_mutex);
 			LSPMessage *message = arr_addp(lsp->messages_server2client);
-			message->type = LSP_REQUEST;
-			message->u.request = request;
+			request.base.type = LSP_REQUEST;
+			message->request = request;
 			SDL_UnlockMutex(lsp->messages_mutex);
 		} else {
 			lsp_request_free(&request);
diff --git a/lsp-write.c b/lsp-write.c
index 85c5781..99a4e82 100644
--- a/lsp-write.c
+++ b/lsp-write.c
@@ -495,7 +495,7 @@ void write_request(LSP *lsp, LSPRequest *request) {
 				write_key_file_uri(o, "uri", open->document);
 				write_key_string(o, "languageId", lsp_language_id(open->language));
 				write_key_number(o, "version", 0);
-				write_key_string(o, "text", open->file_contents);
+				write_key_string(o, "text", lsp_request_string(request, open->file_contents));
 			write_obj_end(o);
 		write_obj_end(o);
 	} break;
@@ -525,7 +525,7 @@ void write_request(LSP *lsp, LSPRequest *request) {
 					write_arr_elem(o);
 					write_obj_start(o);
 						write_key_range(o, "range", event->range);
-						write_key_string(o, "text", event->text ? event->text : "");
+						write_key_string(o, "text", lsp_request_string(request, event->text));
 					write_obj_end(o);
 				}
 			write_arr_end(o);
@@ -598,13 +598,13 @@ void write_request(LSP *lsp, LSPRequest *request) {
 		const LSPRequestRename *rename = &request->data.rename;
 		write_key_obj_start(o, "params");
 			write_document_position(o, rename->position);
-			write_key_string(o, "newName", rename->new_name);
+			write_key_string(o, "newName", lsp_request_string(request, rename->new_name));
 		write_obj_end(o);
 	} break;
 	case LSP_REQUEST_WORKSPACE_SYMBOLS: {
 		const LSPRequestWorkspaceSymbols *syms = &request->data.workspace_symbols;
 		write_key_obj_start(o, "params");
-			write_key_string(o, "query", syms->query);
+			write_key_string(o, "query", lsp_request_string(request, syms->query));
 		write_obj_end(o);
 	} break;
 	case LSP_REQUEST_DID_CHANGE_WORKSPACE_FOLDERS: {
@@ -630,7 +630,7 @@ void write_request(LSP *lsp, LSPRequest *request) {
 		const LSPRequestConfiguration *config = &request->data.configuration;
 		write_key_obj_start(o, "params");
 			write_key(o, "settings");
-			str_builder_append(&o->builder, config->settings);
+			str_builder_append(&o->builder, lsp_request_string(request, config->settings));
 		write_obj_end(o);
 		} break;
 	}
@@ -657,8 +657,9 @@ static void write_response(LSP *lsp, LSPResponse *response) {
 	LSPRequest *request = &response->request;
 	
 	write_obj_start(o);
-		if (request->id_string)
-			write_key_string(o, "id", request->id_string);
+		const char *id_string = lsp_request_string(request, request->id_string);
+		if (*id_string)
+			write_key_string(o, "id", id_string);
 		else
 			write_key_number(o, "id", request->id);
 		write_key_string(o, "jsonrpc", "2.0");
@@ -686,10 +687,10 @@ static void write_response(LSP *lsp, LSPResponse *response) {
 void write_message(LSP *lsp, LSPMessage *message) {
 	switch (message->type) {
 	case LSP_REQUEST:
-		write_request(lsp, &message->u.request);
+		write_request(lsp, &message->request);
 		break;
 	case LSP_RESPONSE:
-		write_response(lsp, &message->u.response);
+		write_response(lsp, &message->response);
 		break;
 	}
 }
diff --git a/lsp.c b/lsp.c
index 77e1454..5944c29 100644
--- a/lsp.c
+++ b/lsp.c
@@ -29,13 +29,75 @@ bool lsp_get_error(LSP *lsp, char *error, size_t error_size, bool clear) {
 	return has_err;
 }
 
+bool lsp_string_is_empty(LSPString string) {
+	return string.offset == 0;
+}
+
+char *lsp_message_alloc_string(LSPMessageBase *message, size_t len, LSPString *string) {
+	u32 offset = arr_len(message->string_data);
+	if (len == 0) {
+		offset = 0;
+	} else if (offset == 0) {
+		// reserve offset 0 for empty string
+		arr_add(message->string_data, 0);
+		offset = 1;
+	}
+	arr_set_len(message->string_data, offset + len + 1);
+	string->offset = offset;
+	return message->string_data + offset;
+}
+
+static LSPString lsp_message_add_string(LSPMessageBase *message, const char *string) {
+	LSPString ret = {0};
+	size_t len = strlen(string);
+	if (len == 0) {
+		return ret;
+	}
+	char *dest = lsp_message_alloc_string(message, len, &ret);
+	memcpy(dest, string, len);
+	return ret;
+}
+static LSPString lsp_message_add_json_string(LSPMessageBase *message, const JSON *json, JSONString string) {
+	LSPString ret = {0};
+	size_t len = string.len;
+	if (len == 0) {
+		return ret;
+	}
+	char *dest = lsp_message_alloc_string(message, len, &ret);
+	json_string_get(json, string, dest, len + 1);
+	return ret;
+}
+static LSPString lsp_message_add_string32(LSPMessageBase *message, String32 string) {
+	LSPString ret = {0};
+	size_t len32 = string.len;
+	if (len32 == 0) {
+		return ret;
+	}
+	char *dest = lsp_message_alloc_string(message, len32 * 4 + 1, &ret);
+	str32_to_utf8_cstr_in_place(string, dest);
+	return ret;
+}
+
+LSPString lsp_request_add_string(LSPRequest *request, const char *string) {
+	return lsp_message_add_string(&request->base, string);
+}
+LSPString lsp_response_add_string(LSPResponse *response, const char *string) {
+	return lsp_message_add_string(&response->base, string);
+}
+LSPString lsp_response_add_json_string(LSPResponse *response, const JSON *json, JSONString string) {
+	return lsp_message_add_json_string(&response->base, json, string);
+}
+LSPString lsp_request_add_json_string(LSPRequest *request, const JSON *json, JSONString string) {
+	return lsp_message_add_json_string(&request->base, json, string);
+}
+
 
-static void lsp_document_change_event_free(LSPDocumentChangeEvent *event) {
-	free(event->text);
+static void lsp_message_base_free(LSPMessageBase *base) {
+	arr_free(base->string_data);
 }
 
 void lsp_request_free(LSPRequest *r) {
-	free(r->id_string);
+	lsp_message_base_free(&r->base);
 	switch (r->type) {
 	case LSP_REQUEST_NONE:
 	case LSP_REQUEST_INITIALIZE:
@@ -55,23 +117,15 @@ void lsp_request_free(LSPRequest *r) {
 	case LSP_REQUEST_DID_CLOSE:
 	case LSP_REQUEST_WORKSPACE_FOLDERS:
 	case LSP_REQUEST_DOCUMENT_LINK:
-		break;
-	case LSP_REQUEST_CONFIGURATION: {
-		LSPRequestConfiguration *config = &r->data.configuration;
-		free(config->settings);
-		} break;
-	case LSP_REQUEST_DID_OPEN: {
-		LSPRequestDidOpen *open = &r->data.open;
-		free(open->file_contents);
-		} break;
+	case LSP_REQUEST_CONFIGURATION:
+	case LSP_REQUEST_DID_OPEN:
 	case LSP_REQUEST_SHOW_MESSAGE:
 	case LSP_REQUEST_LOG_MESSAGE:
-		free(r->data.message.message);
+	case LSP_REQUEST_RENAME:
+	case LSP_REQUEST_WORKSPACE_SYMBOLS:
 		break;
 	case LSP_REQUEST_DID_CHANGE: {
 		LSPRequestDidChange *c = &r->data.change;
-		arr_foreach_ptr(c->changes, LSPDocumentChangeEvent, event)
-			lsp_document_change_event_free(event);
 		arr_free(c->changes);
 		} break;
 	case LSP_REQUEST_DID_CHANGE_WORKSPACE_FOLDERS: {
@@ -79,18 +133,12 @@ void lsp_request_free(LSPRequest *r) {
 		arr_free(w->added);
 		arr_free(w->removed);
 		} break;
-	case LSP_REQUEST_RENAME:
-		free(r->data.rename.new_name);
-		break;
-	case LSP_REQUEST_WORKSPACE_SYMBOLS:
-		free(r->data.workspace_symbols.query);
-		break;
 	}
 	memset(r, 0, sizeof *r);
 }
 
 void lsp_response_free(LSPResponse *r) {
-	arr_free(r->string_data);
+	lsp_message_base_free(&r->base);
 	switch (r->request.type) {
 	case LSP_REQUEST_COMPLETION:
 		arr_free(r->data.completion.items);
@@ -120,17 +168,16 @@ void lsp_response_free(LSPResponse *r) {
 		break;
 	}
 	lsp_request_free(&r->request);
-	free(r->error);
 	memset(r, 0, sizeof *r);
 }
 
 void lsp_message_free(LSPMessage *message) {
 	switch (message->type) {
 	case LSP_REQUEST:
-		lsp_request_free(&message->u.request);
+		lsp_request_free(&message->request);
 		break;
 	case LSP_RESPONSE:
-		lsp_response_free(&message->u.response);
+		lsp_response_free(&message->response);
 		break;
 	}
 	memset(message, 0, sizeof *message);
@@ -254,8 +301,9 @@ LSPServerRequestID lsp_send_request(LSP *lsp, LSPRequest *request) {
 	bool is_notification = request_type_is_notification(request->type);
 	if (!is_notification)
 		request->id = get_request_id();
-	LSPMessage message = {.type = LSP_REQUEST};
-	message.u.request = *request;
+	LSPMessage message = {0};
+	request->base.type = LSP_REQUEST;
+	message.request = *request;
 	lsp_send_message(lsp, &message);
 	return (LSPServerRequestID) {
 		.lsp = lsp->id,
@@ -264,14 +312,28 @@ LSPServerRequestID lsp_send_request(LSP *lsp, LSPRequest *request) {
 }
 
 void lsp_send_response(LSP *lsp, LSPResponse *response) {
-	LSPMessage message = {.type = LSP_RESPONSE};
-	message.u.response = *response;
+	LSPMessage message = {0};
+	response->base.type = LSP_RESPONSE;
+	message.response = *response;
 	lsp_send_message(lsp, &message);
 }
 
+static const char *lsp_message_string(const LSPMessageBase *message, LSPString string) {
+	// important that we have this check here, since
+	// it's possible that message->string_data is NULL (i.e. if no strings were ever added)
+	if (string.offset == 0) {
+		return "";
+	}
+	assert(string.offset < arr_len(message->string_data));
+	return &message->string_data[string.offset];
+}
+
 const char *lsp_response_string(const LSPResponse *response, LSPString string) {
-	assert(string.offset < arr_len(response->string_data));
-	return &response->string_data[string.offset];
+	return lsp_message_string(&response->base, string);
+}
+
+const char *lsp_request_string(const LSPRequest *request, LSPString string) {
+	return lsp_message_string(&request->base, string);
 }
 
 // receive responses/requests/notifications from LSP, up to max_size bytes.
@@ -652,9 +714,13 @@ void lsp_free(LSP *lsp) {
 	free(lsp);
 }
 
-void lsp_document_changed(LSP *lsp, const char *document, LSPDocumentChangeEvent change) {
+void lsp_document_changed(LSP *lsp, const char *document, LSPRange range, String32 new_text) {
 	// @TODO(optimization, eventually): batch changes (using the contentChanges array)
 	LSPRequest request = {.type = LSP_REQUEST_DID_CHANGE};
+	LSPDocumentChangeEvent change = {
+		.range = range,
+		.text = lsp_message_add_string32(&request.base, new_text),
+	};
 	LSPRequestDidChange *c = &request.data.change;
 	c->document = lsp_document_id(lsp, document);
 	arr_add(c->changes, change);
@@ -734,7 +800,7 @@ void lsp_cancel_request(LSP *lsp, LSPRequestID id) {
 		
 		for (u32 i = 0; i < arr_len(lsp->messages_client2server); ++i) {
 			LSPMessage *message = &lsp->messages_client2server[i];
-			if (message->type == LSP_REQUEST && message->u.request.id == id) {
+			if (message->type == LSP_REQUEST && message->request.id == id) {
 				// we haven't sent this request yet
 				arr_remove(lsp->messages_client2server, i);
 				break;
diff --git a/lsp.h b/lsp.h
index ab095f5..a03256d 100644
--- a/lsp.h
+++ b/lsp.h
@@ -9,6 +9,7 @@
 #include "base.h"
 #include "ds.h"
 #include "os.h"
+#include "util.h"
 
 /// an ID specific to a path. a document's ID is never 0 (thanks to lsp_create).
 typedef u32 LSPDocumentID;
@@ -116,8 +117,7 @@ typedef struct {
 typedef struct {
 	u64 language;
 	LSPDocumentID document;
-	// freed by \ref lsp_request_free
-	char *file_contents;
+	LSPString file_contents;
 } LSPRequestDidOpen;
 
 typedef struct {
@@ -127,8 +127,8 @@ typedef struct {
 // see TextDocumentContentChangeEvent in the LSP spec
 typedef struct {
 	LSPRange range;
-	/// new text. will be freed. you can use NULL for the empty string.
-	char *text;
+	/// new text.
+	LSPString text;
 } LSPDocumentChangeEvent;
 
 typedef struct {
@@ -145,8 +145,7 @@ typedef enum {
 
 typedef struct {
 	LSPWindowMessageType type;
-	// freed by \ref lsp_request_free
-	char *message;
+	LSPString message;
 } LSPRequestMessage;
 
 
@@ -197,12 +196,12 @@ typedef struct {
 
 typedef struct {
 	// string to filter the symbols by
-	char *query;
+	LSPString query;
 } LSPRequestWorkspaceSymbols;
 
 typedef struct {
 	LSPDocumentPosition position;
-	char *new_name;
+	LSPString new_name;
 } LSPRequestRename;
 
 typedef struct {
@@ -211,14 +210,23 @@ typedef struct {
 } LSPRequestDidChangeWorkspaceFolders;
 
 typedef struct {
-	// this string should be valid JSON. will be freed.
-	char *settings;
+	// this string should be valid JSON.
+	LSPString settings;
 } LSPRequestConfiguration;
 
 typedef struct {
+	LSPMessageType type;
+	/// LSP requests/responses tend to have a lot of strings.
+	/// to avoid doing a ton of allocations+frees,
+	/// they're all stored here.
+	char *string_data;
+} LSPMessageBase;
+
+typedef struct {
+	LSPMessageBase base;
 	LSPRequestID id;
 	LSPRequestType type;
-	char *id_string; // if not NULL, this is the ID (only for server-to-client messages; we always use integer IDs)
+	LSPString id_string; // if non-empty, this is the ID (only for server-to-client messages; we always use integer IDs)
 	// one member of this union is set depending on `type`.
 	union {	
 		LSPRequestCancel cancel;
@@ -491,14 +499,11 @@ typedef struct {
 } LSPResponseDocumentLink;
 
 typedef struct {
+	LSPMessageBase base;
 	/// the request which this is a response to
 	LSPRequest request;
 	/// if not NULL, the data field will just be zeroed
-	char *error;
-	/// LSP responses tend to have a lot of strings.
-	/// to avoid doing a ton of allocations+frees,
-	/// they're all stored here.
-	char *string_data;
+	LSPString error;
 	/// one of these is filled based on request.type
 	union {
 		LSPResponseCompletion completion;
@@ -514,12 +519,13 @@ typedef struct {
 	} data;
 } LSPResponse;
 
-typedef struct {
+// *technically* using unions this way is UB,
+// but Xlib/SDL/others do it so compilers've gotta deal with it.
+typedef union {
 	LSPMessageType type;
-	union {
-		LSPRequest request;
-		LSPResponse response;
-	} u;
+	LSPMessageBase base;
+	LSPRequest request;
+	LSPResponse response;
 } LSPMessage;
 
 typedef struct {
@@ -629,8 +635,18 @@ void lsp_cancel_request(LSP *lsp, LSPRequestID id);
 // don't free the contents of this response! let me handle it!
 void lsp_send_response(LSP *lsp, LSPResponse *response);
 const char *lsp_response_string(const LSPResponse *response, LSPString string);
-// Start up an LSP server.
-// configuration and log can be NULL.
+const char *lsp_request_string(const LSPRequest *request, LSPString string);
+/// low-level API for allocating message strings.
+///
+/// sets `*string` to the LSPString, and returns a pointer which you can write the string to.
+/// the returned pointer will be zeroed up to and including [len].
+char *lsp_message_alloc_string(LSPMessageBase *message, size_t len, LSPString *string);
+LSPString lsp_request_add_string(LSPRequest *request, const char *string);
+LSPString lsp_response_add_string(LSPResponse *response, const char *string);
+bool lsp_string_is_empty(LSPString string);
+/// Start up an LSP server.
+///
+/// configuration and log can be NULL.
 LSP *lsp_create(const char *root_dir, const char *command, const char *configuration, FILE *log);
 // try to add a new "workspace folder" to the lsp.
 // IMPORTANT: only call this if lsp->initialized is true
@@ -640,7 +656,7 @@ LSP *lsp_create(const char *root_dir, const char *command, const char *configura
 // with root directory `new_root_dir`.
 bool lsp_try_add_root_dir(LSP *lsp, const char *new_root_dir);
 // report that this document has changed
-void lsp_document_changed(LSP *lsp, const char *document, LSPDocumentChangeEvent change);
+void lsp_document_changed(LSP *lsp, const char *document, LSPRange range, String32 new_text);
 // is this path in the LSP's workspace folders?
 bool lsp_covers_path(LSP *lsp, const char *path);
 // get next message from server
@@ -775,6 +791,8 @@ char *json_string_get_alloc(const JSON *json, JSONString string);
 void json_debug_print(const JSON *json);
 size_t json_escape_to(char *out, size_t out_sz, const char *in);
 char *json_escape(const char *str);
+LSPString lsp_response_add_json_string(LSPResponse *response, const JSON *json, JSONString string);
+LSPString lsp_request_add_json_string(LSPRequest *request, const JSON *json, JSONString string);
 /// free resources used by lsp-write.c
 void lsp_write_quit(void);
 
diff --git a/main.c b/main.c
index e6bd506..1bb1163 100644
--- a/main.c
+++ b/main.c
@@ -874,37 +874,36 @@ int main(int argc, char **argv) {
 			while (lsp_next_message(lsp, &message)) {
 				switch (message.type) {
 				case LSP_REQUEST: {
-					LSPRequest *r = &message.u.request;
+					LSPRequest *r = &message.request;
 					switch (r->type) {
 					case LSP_REQUEST_SHOW_MESSAGE: {
 						LSPRequestMessage *m = &r->data.message;
 						MessageType type = ted_message_type_from_lsp(m->type);
-						ted_set_message(ted, type, "%s", m->message);
+						ted_set_message(ted, type, "%s", lsp_request_string(r, m->message));
 						} break;
 					case LSP_REQUEST_LOG_MESSAGE: {
 						LSPRequestMessage *m = &r->data.message;
-						ted_log(ted, "%s\n", m->message);
+						ted_log(ted, "%s\n", lsp_request_string(r, m->message));
 						} break;
 					default: break;
 					}
 					} break;
 				case LSP_RESPONSE: {
-					LSPResponse *r = &message.u.response;
-					if (r->error) {
-						// not displaying this right now
-						// idk it might be spammy
-						//ted_error(ted, "%s", r->error);
+					LSPResponse *r = &message.response;
+					if (!lsp_string_is_empty(r->error)) {
+						ted_error(ted, "LSP error: %s", lsp_response_string(r, r->error));
+					} else {
+						// it's important that we send error responses here too.
+						// we don't want to be waiting around for a response that's never coming.
+						autocomplete_process_lsp_response(ted, r);
+						signature_help_process_lsp_response(ted, r);
+						hover_process_lsp_response(ted, r);
+						definitions_process_lsp_response(ted, lsp, r);
+						highlights_process_lsp_response(ted, r);
+						usages_process_lsp_response(ted, r);
+						document_link_process_lsp_response(ted, r);
+						rename_symbol_process_lsp_response(ted, r);
 					}
-					// it's important that we send error responses here too.
-					// we don't want to be waiting around for a response that's never coming.
-					autocomplete_process_lsp_response(ted, r);
-					signature_help_process_lsp_response(ted, r);
-					hover_process_lsp_response(ted, r);
-					definitions_process_lsp_response(ted, lsp, r);
-					highlights_process_lsp_response(ted, r);
-					usages_process_lsp_response(ted, r);
-					document_link_process_lsp_response(ted, r);
-					rename_symbol_process_lsp_response(ted, r);
 					} break;
 				}
 				lsp_message_free(&message);
diff --git a/util.c b/util.c
index b146c82..1b9b9f3 100644
--- a/util.c
+++ b/util.c
@@ -1018,24 +1018,27 @@ String32 str32_from_utf8(const char *utf8) {
 	return string;
 }
 
-// returns a null-terminated UTF-8 string
-// the string returned should be free'd
-// this will return NULL on failure
+
+bool str32_to_utf8_cstr_in_place(String32 s, char *out) {
+	char *p = out;
+	for (size_t i = 0; i < s.len; ++i) {
+		size_t bytes = unicode_utf32_to_utf8(p, s.str[i]);
+		if (bytes == (size_t)-1) {
+			// invalid UTF-32 code point
+			*p = '\0';
+			return false;
+		} else {
+			p += bytes;
+		}
+	}
+	*p = '\0';
+	return true;
+}
+
 char *str32_to_utf8_cstr(String32 s) {
 	char *utf8 = calloc(4 * s.len + 1, 1); // each codepoint takes up at most 4 bytes in UTF-8, + we need a terminating null byte
 	if (utf8) {
-		char *p = utf8;
-		for (size_t i = 0; i < s.len; ++i) {
-			size_t bytes = unicode_utf32_to_utf8(p, s.str[i]);
-			if (bytes == (size_t)-1) {
-				// invalid UTF-32 code point
-				free(utf8);
-				return NULL;
-			} else {
-				p += bytes;
-			}
-		}
-		*p = '\0';
+		str32_to_utf8_cstr_in_place(s, utf8);
 	}
 	return utf8;
 }
diff --git a/util.h b/util.h
index b3d4fba..25ff72b 100644
--- a/util.h
+++ b/util.h
@@ -259,6 +259,18 @@ String32 str32(char32_t *str, size_t len);
 String32 str32_substr(String32 s, size_t from, size_t len);
 void str32_free(String32 *s);
 String32 str32_from_utf8(const char *utf8);
+/// convert UTF-32 to UTF-8.
+///
+/// returns false on invalid UTF-32 (and `out` will be truncated to just
+/// the prefix of `s` that is valid UTF-32)
+///
+/// out buffer must be long enough to fit the UTF-8 representation of `s`!
+/// (`s.len * 4 + 1` is a safe buffer size)
+bool str32_to_utf8_cstr_in_place(String32 s, char *out);
+/// returns a null-terminated UTF-8 string
+///
+/// the string returned should be free'd
+/// this will return NULL on failure
 char *str32_to_utf8_cstr(String32 s);
 int str32_cmp_ascii(String32 s, const char *ascii);
 bool str32_has_ascii_prefix(String32 s, const char *ascii);