Add untested value parsing

format/desktop_entry/value.ha

@@ -0,0 +1,178 @@
+use ascii;
+use strconv;
+use strings;
+
+// Parses a string value. It may contain all ASCII characters except for control
+// characters. The memory must be freed by the caller.
+// Specification: §4
+export fn parse_string(in: str) (str | error) = {
+	for (let char .. strings::toutf8(in)) {
+		if (!ascii::valid(char: rune)) return invalid_ascii;
+	};
+	return parse_localestring(in);
+};
+
+// Parses a localestring value. It is user displayable, and is encoded in UTF-8.
+// The memory must be freed by the caller.
+// Specification: §4
+export fn parse_localestring(in: str) (str | error) = {
+	let escaper = escape_string(in);
+	let string = match(string_escaper_next(&escaper)?) {
+	case let string: str => yield string;
+	case done            => return "";
+	};
+	if (len(escaper) > 0) {
+		free(string);
+		return expected_single;
+	};
+	return string;
+};
+
+// Parses an iconstring value. It is the name of an icon; it may be an absolute
+// path, or a symbolic name for an icon located using the algorithm described in
+// the Icon Theme Specification. Such values are not user-displayable, and are
+// encoded in UTF-8. The memory must be freed by the caller.
+// Specification: §4
+export fn parse_iconstring(in: str) (str | error) = parse_localestring(in);
+
+// Parses a boolean value. It must either be the string "true" or "false".
+// Specification: §4
+export fn parse_boolean(in: str) (bool | error) = {
+	if (in == "true" ) return true;
+	if (in == "false") return false;
+	return invalid_boolean;
+};
+
+// Parses a numeric value. It must be a valid floating point number as
+// recognized by the %f specifier for scanf in the C locale.
+// Specification: §4
+export fn parse_numeric(in: str) (f64 | error) = match (strconv::stof64(in)) {
+case let float: f64 => yield float;
+case                => yield invalid_numeric;
+};
+
+// Parses multiple string values. See [[parse_string]] for more information. The
+// memory must be freed by the caller.
+// Specification: §4
+export fn parse_strings(in: str) ([]str | error) = {
+	for (let char .. strings::toutf8(in)) {
+		if (!ascii::valid(char: rune)) return invalid_ascii;
+	};
+	return parse_localestrings(in);
+};
+
+// Parses multiple localestring values. See [[parse_localestring]] for more
+// information. The memory must be freed by the caller.
+// Specification: §4
+export fn parse_localestrings(in: str) ([]str | error) = {
+	let escaper = escape_string(in);
+	let result: []str = alloc([], 0);
+	for (let in => string_escaper_next(&escaper)) {
+		match (in) {
+		case let string: str =>
+			append(result, string);
+		case let err: error =>
+			strings::freeall(result);
+			return err;
+		};
+	};
+	return result;
+};
+
+// Parses multiple iconstring values. See [[parse_iconstring]] for more
+// information. The memory must be freed by the caller.
+// Specification: §4
+export fn parse_iconstrings(in: str) ([]str | error) = parse_localestrings(in);
+
+// Parses multiple boolean values. See [[parse_boolean]] for more information.
+// The memory must be freed by the caller.
+// Specification: §4
+export fn parse_booleans(in: str) ([]bool | error) = {
+	let splitte = split(in);
+	let result: []bool = alloc([], 0);
+	for (let in => splitter_next(&splitte)) {
+		match (parse_boolean(in)) {
+		case let boolean: bool =>
+			append(result, boolean);
+		case let err: error =>
+			free(result);
+			return err;
+		};
+	};
+	return result;
+};
+
+// Parses multiple numeric values. See [[parse_numeric]] for more information.
+// The memory must be freed by the caller.
+// Specification: §4
+export fn parse_numerics(in: str) ([]f64 | error) = {
+	let splitte = split(in);
+	let result: []f64 = alloc([], 0);
+	for (let in => splitter_next(&splitte)) {
+		match (parse_numeric(in)) {
+		case let number: f64 =>
+			append(result, number);
+		case let err: error =>
+			free(result);
+			return err;
+		};
+	};
+	return result;
+};
+
+type string_escaper = []u8;
+
+fn escape_string(in: str) string_escaper = strings::toutf8(in): string_escaper;
+
+fn string_escaper_next(this: *string_escaper) (str | done | error) = {
+	if (len(*this) < 1) return done;
+	let result: []u8 = alloc([], 0);
+	let end = 0z;
+	let saw_escape = false;
+	for (let byte .. *this) {
+		end += 1;
+		if (saw_escape) {
+			switch (byte) {
+			case ';'  => append(result, ';');
+			case 's'  => append(result, ' ');
+			case 'n'  => append(result, '\n');
+			case 't'  => append(result, '\t');
+			case 'r'  => append(result, '\r');
+			case '\\' => append(result, '\\');
+			case =>
+				free(result);
+				return invalid_escape;
+			};
+			saw_escape = false;
+		} else {
+			switch (byte) {
+			case ';'  => break;
+			case '\\' => saw_escape = true;
+			case      => append(result, byte);
+			};
+		};
+	};
+	*this = (*this)[end..];
+	return strings::fromutf8_unsafe(result);
+};
+
+type splitter = []u8;
+
+fn split(in: str) splitter = strings::toutf8(in): splitter;
+
+fn splitter_next(this: *splitter) (str | done) = {
+	if (len(*this) < 1) return done;
+	let end   = 0z;
+	let knife = 0z;
+	for (let byte .. *this) {
+		knife += 1;
+		if (byte == ';') {
+			break;
+		} else {
+			end += 1;
+		};
+	};
+	let result = this[..end];
+	*this = (*this)[knife..];
+	return strings::fromutf8_unsafe(result);
+};