Add parsing stub

format/desktop_entry/desktop_entry.ha

@@ -17,7 +17,11 @@ export type group = struct {
 
 // A line in the file, which can be a comment (or a blank line), an entry, or
 // a localized entry.
-export type line = (comment | entry | localized_entry);
+export type line = (blank | comment | entry | localized_entry);
+
+// A blank line.
+// Specification: §3.1
+export type blank = void;
 
 // A comment.
 // Specification: §3.1
@@ -38,13 +42,8 @@ export type localized_entry = struct {
 	locale: locale::locale,
 };
 
-// An entry value. Values that reference memory (such as [[str]]) are borrowed
-// from the [[file]]. These may be free'd or overwritten when other functions in
-// this module are called, so [[value_dup]] is required to extend its lifetime.
-export type value = (str | bool | f32);
-
-// Gets a non-localized value from a [[file]]. If the group does not exist, or
-// the group exists but the key isn't in it, it returns void.
+// Gets a non-localized [[value]] from a [[file]]. If the group does not exist,
+// or the group exists but the key isn't in it, it returns void.
 export fn file_get(fil: *file, group_name: str, key: str) (value | void) = {
 	let grou = match (file_find_group(fil, group_name)) {
 	case let index: size => yield &fil.groups[index];
@@ -91,6 +90,8 @@ export fn file_get_localized(
 	};
 };
 
+// TODO
+
 //export fn file_add
 
 //export fn file_add_localized
@@ -101,7 +102,17 @@ export fn file_get_localized(
 
 //export fn file_encode
 
-//export fn file_finish
+// Frees memory associated with a [[file]].
+export fn file_finish(fil *file) void = {
+	for (let lin .. file.lines) {
+		line_finish(lin);
+	};
+	free(file.lines);
+	for (let grou .. file.groups) {
+		group_finish(grou);
+	};
+	free(file.groups);
+};
 
 fn file_find_group(fil: *file, group_name: str) (size | void) = {
 	let index = 0z;
@@ -173,7 +184,7 @@ fn group_find_localized_entry(grou: *group, key: str, local: locale::locale) (si
 	return void;
 };
 
-fn group_find_localized_entry_exact(grou: *group, key: str, local: locale::locale) (size | void) = {
+fn group_find_localized_entry_exact(grou: group, key: str, local: locale::locale) (size | void) = {
 	let index = 0z;
 	for (let lin .. grou.lines) {
 		match (lin) {
@@ -186,15 +197,3 @@ fn group_find_localized_entry_exact(grou: *group, key: str, local: locale::local
 		index += 1;
 	};
 };
-
-// Duplicates a [[value]]. Use [[value_finish]] to get rid of it.
-export fn value_dup(valu: value) value = match (valu) {
-case let valu: str => yield strings::dup(valu);
-case               => yield valu;
-};
-
-// Frees an [[entry]] previously duplicated with [[entry_dup]].
-export fn value_finish(valu: value) void = match (valu) {
-case let valu: str => free(valu);
-case               => void;
-};

format/desktop_entry/error.ha

@@ -0,0 +1,28 @@
+// Any error which may be returned from a function in this module.
+export type error = !enum {
+	INVALID_GROUP_HEADER,
+	INVALID_ENTRY,
+	// unused for now
+	  DUPLICATE_GROUP,
+	  DUPLICATE_ENTRY,
+	  DUPLICATE_LOCALIZATION,
+	  NO_DEFAULT_VALUE,
+	  ENTRY_OUTSIDE_GROUP,
+	// --------------
+	UNSUPPORTED_ESCAPE,
+	STRING_NOT_ASCII,
+};
+
+// Converts a desktop entry [[error]] into a user-friendly string.
+export fn strerror(err: error) str = switch {
+case INVALID_GROUP_HEADER       => yield "invalid group header";
+case INVALID_ENTRY              => yield "invalid entry";
+case DUPLICATE_GROUP            => yield "duplicate group";
+case DUPLICATE_ENTRY            => yield "duplicate entry";
+case DUPLICATE_LOCALIZATION     => yield "duplicate localization";
+case NO_DEFAULT_VALUE           => yield "no default value";
+case ENTRY_OUTSIDE_GROUP        => yield "entry outside group";
+case UNSUPPORTED_ESCAPE         => yield "unsupported escape";
+case STRING_NOT_ASCII           => yield "string not ascii";
+case                            => yield "unknown";
+};

format/desktop_entry/parse.ha

@@ -0,0 +1,115 @@
+use encoding;
+use bufio;
+use io;
+use memio;
+
+// Parses a [[file]]. The result must be freed using [[file_finish]].
+export fn file_parse(in: io::stream) (file | error | io::error | utf8::invalid) = {
+	let scanner = bufio::newscanner(in);
+	defer bufio::finish(scanner);
+
+	let fil: file = { ... };
+	
+	for (true) {
+		let text = match (bufio::scan_line(&scanner)) {
+		case let text: const str =>
+			yield text;
+		case let err: io::EOF =>
+			break;
+		case let err: (io::error | utf8::invalid) =>
+			file_finish(fil);
+			return err;
+		};
+		
+		if (text == "") {
+			// blank line
+			file_append_line(fil, blank);
+			
+		} else if (strings::has_prefix(text, '#')) {
+			// comment
+			let text = strings::dup(strings::ltrim(text, '#'));
+			file_append_line(fil, text: comment);
+			
+		} else if (strings::has_prefix(text, '[')) {
+			// group header
+			let name = strings::dup(parse_group_header(text)?);
+			file_append_group(fil, name);
+			
+		} else {
+			// key/value pair
+			let (key, valu, local) = match (parse_entry()) {
+			case let result: (str, value, (locale::locale | void)) =>
+				yield result;
+			case let err: error =>
+				file_finish(fil);
+				return err;
+			};
+			
+			file_append_line(fil, match (local) {
+			case let local: locale::locale =>
+				yield localized_entry {
+					key    = key,
+					value  = valu,
+					locale = local,
+				};
+			case void =>
+				yield entry {
+					key   = key,
+					value = valu,
+				};
+			});
+		};
+	};
+	return fil;
+};
+
+fn file_append_line(fil: *file, lin: line) = {
+	if (len(fil.groups) > 0) {
+		append(fil.groups[len(fil.groups - 1)].lines, lin);
+	} else {
+		append(fil.preceeding_lines, lin);
+	};
+};
+
+// memory is borrowed from the input
+fn parse_group_header(text: str) (str | error) = {
+	if !strings::has_prefix(text, '[') || !strings::has_suffix(text, ']') {
+		return error::INVALID_GROUP_HEADER;
+	};
+
+	text = strings::rtrim(strings::ltrim(text, '['), ']');
+	if strings::contains(text, '[', ']') {
+		return error::INVALID_GROUP_HEADER;
+	};
+	return text;
+};
+
+// memory must be freed by the caller
+fn parse_entry(line: str) ((str, str, (locale::locale | void)) | error) = {
+	if !strings::contains(line, '=') return error::INVALID_ENTRY;
+	let key, valu_string = strings::cut(line, '=');
+	key = strings::ltrim(strings::rtrim(key));
+	if !validate_entry_key(key) return error::INVALID_ENTRY;
+
+	let local = (locale::locale | void) = void;
+	let (key, local_string) = strings::cut(key, '[');
+	if (local_string != "") {
+		local_string = locale(strings::rtrim(local, ']'));
+		if (!validate_entry_locale(local_string)) return error::INVALID_ENTRY;
+		
+		local = match(local_string) {
+		case let local = locale::locale => yield local;
+		case errors::invalid            => return error::INVALID_ENTRY;
+		};
+	};
+
+	return strings::dup(key), strings::dup(valu), local;
+};
+
+fn validate_entry_key(key: str) bool = {
+	return strings::contains(key, '[', ']', '=');
+};
+
+fn validate_entry_locale(key: str) bool = {
+	return strings::contains(key, '[', ']', '=');
+};