1 files changed, 286 insertions, 0 deletions
diff --git a/dejson/dejson.ha b/dejson/dejson.ha
new file mode 100644
index 0000000..74e2752
--- /dev/null
+++ b/dejson/dejson.ha
@@ -0,0 +1,286 @@
+use ascii;
+use encoding::json;
+use fmt;
+use io;
+use math;
+use memio;
+use strings;
+use types;
+
+export type deser = struct {
+	val: *json::value,
+	link: ((*deser, (str | size)) | void),
+};
+
+export type error = !str;
+
+export fn newdeser(val: *json::value) deser =
+	deser { val = val, link = void };
+
+export fn fail(de: *deser, fmt: str, args: fmt::field...) error = {
+	let path: [](str | size) = [];
+	defer free(path);
+	for (let de_ = de; true) match (de_.link) {
+	case let link: (*deser, (str | size)) =>
+		append(path, link.1);
+		de_ = link.0;
+	case void => break;
+	};
+
+	let err = memio::dynamic();
+
+	if (len(path) == 0 || !(path[len(path) - 1] is str)) {
+		memio::concat(&err, ".")!;
+	};
+	for (let i = len(path); i > 0) {
+		i -= 1;
+		match (path[i]) {
+		case let s: str =>
+			memio::concat(&err, ".")!;
+			printfield(&err, s)!;
+		case let n: size =>
+			fmt::fprintf(&err, "[{}]", n)!;
+		};
+	};
+
+	memio::concat(&err, ": ")!;
+	fmt::fprintf(&err, fmt, args...)!;
+
+	return memio::string(&err)!;
+};
+
+export fn printfield(out: io::handle, s: str) (void | io::error) = {
+	let valid = true;
+	let first = true;
+	let it = strings::iter(s);
+	for (true) match (strings::next(&it)) {
+	case let ch: rune =>
+		if (!ascii::isalpha(ch) && ch != '_'
+				&& (first || !ascii::isdigit(ch))) {
+			json::dump(out, s)?;
+			return;
+		};
+		first = false;
+	case done => break;
+	};
+	memio::concat(out, s)?;
+	return;
+};
+
+export fn strfield(s: str) str = {
+	let out = memio::dynamic();
+	printfield(&out, s)!;
+	return memio::string(&out)!;
+};
+
+export fn typename(val: *json::value) str = {
+	match (*val) {
+	case f64 =>
+		return "number";
+	case str =>
+		return "string";
+	case bool =>
+		return "boolean";
+	case json::_null =>
+		return "null";
+	case []json::value =>
+		return "array";
+	case json::object =>
+		return "object";
+	};
+};
+
+export fn optfield(de: *deser, name: str) (deser | void | error) = {
+	const obj = object(de)?;
+	match (json::get(obj, name)) {
+	case let val: *json::value =>
+		return deser {
+			val = val,
+			link = (de, name),
+		};
+	case void => void;
+	};
+};
+
+export fn field(de: *deser, name: str) (deser | error) = {
+	match (optfield(de, name)) {
+	case let de_field: deser =>
+		return de_field;
+	case void =>
+		let fieldname = strfield(name);
+		defer free(fieldname);
+		return fail(de, "Field {} is required but missing", fieldname);
+	};
+};
+
+export fn index(de: *deser, i: size) (deser | error) = {
+	const arr = array(de)?;
+	if (i < len(arr)) {
+		return deser {
+			val = &arr[i],
+			link = (de, i),
+		};
+	} else {
+		return fail(de, "Array index {} is required but missing", i);
+	};
+};
+
+export fn length(de: *deser) (size | error) =
+	len(array(de)?);
+
+export fn assert_length(de: *deser, n: size) (void | error) = {
+	if (length(de)? != n)
+		return fail(de, "Array has {} elements, {} expected",
+			length(de)?, n);
+};
+
+export fn count(de: *deser) (size | error) =
+	json::count(object(de)?);
+
+export fn assert_fields(de: *deser, names: str...) (void | error) = {
+	const obj = object(de)?;
+	let err = memio::dynamic();
+	defer io::close(&err)!;
+	let n = 0z;
+	let it = json::iter(obj);
+	for :fields (true) {
+		match (json::next(&it)) {
+		case let entry: (const str, const *json::value) =>
+			for (let i = 0z; i < len(names); i += 1) {
+				if (entry.0 == names[i]) {
+					continue :fields;
+				};
+			};
+			if (n != 0) {
+				memio::concat(&err, ", ")!;
+			};
+			printfield(&err, entry.0)!;
+			n += 1;
+		case void => break;
+		};
+	};
+	switch (n) {
+	case 0 =>
+		return;
+	case 1 =>
+		return fail(de, "Unknown field {}", memio::string(&err)!);
+	case =>
+		return fail(de, "Unknown fields {}", memio::string(&err)!);
+	};
+};
+
+export type iterator = struct {
+	iter: json::iterator,
+	deser: *deser,
+};
+
+export fn iter(de: *deser) (iterator | error) = {
+	const obj = object(de)?;
+	return iterator {
+		iter = json::iter(obj),
+		deser = de,
+	};
+};
+
+export fn next(it: *iterator) ((str, deser) | void) = {
+	match (json::next(&it.iter)) {
+	case let entry: (const str, const *json::value) =>
+		return (entry.0, deser {
+			val = entry.1,
+			link = (it.deser, entry.0),
+		});
+	case void => void;
+	};
+};
+
+export fn object(de: *deser) (*json::object | error) = {
+	if (*de.val is json::object) {
+		return &(de.val: *struct { t: int, val: json::object }).val;
+	} else {
+		return fail(de, "Expected object, found {}", typename(de.val));
+	};
+};
+
+export fn array(de: *deser) ([]json::value | error) = {
+	match (*de.val) {
+	case let val: []json::value =>
+		return val;
+	case =>
+		return fail(de, "Expected array, found {}", typename(de.val));
+	};
+};
+
+export fn string(de: *deser) (str | error) = {
+	match (*de.val) {
+	case let val: str =>
+		return val;
+	case =>
+		return fail(de, "Expected string, found {}", typename(de.val));
+	};
+};
+
+export fn boolean(de: *deser) (bool | error) = {
+	match (*de.val) {
+	case let val: bool =>
+		return val;
+	case =>
+		return fail(de, "Expected boolean, found {}", typename(de.val));
+	};
+};
+
+export fn number(de: *deser) (f64 | error) = {
+	match (*de.val) {
+	case let val: f64 =>
+		return val;
+	case =>
+		return fail(de, "Expected number, found {}", typename(de.val));
+	};
+};
+
+export fn number_frange(de: *deser, a: f64, b: f64) (f64 | error) = {
+	const val = number(de)?;
+	if (val < a || val > b)
+		return fail(de, "Number {} is outside the allowed range [{},{}]",
+			val, a, b);
+	return val;
+};
+
+export fn number_irange(de: *deser, a: i64, b: i64) (i64 | error) = {
+	const val = number(de)?;
+	if (math::absf64(val) > 9007199254740991.0)
+		return fail(de,
+			"Number {} is too large to be safely converted from f64 to an integer",
+			val);
+	const (ival, frac) = math::modfracf64(val);
+	if (frac != 0.0)
+		return fail(de, "Number {} is not an integer", val);
+	const ival = ival: i64;
+	if (ival < a || ival > b)
+		return fail(de, "Number {} is outside the allowed range [{},{}]",
+			val, a, b);
+	return ival;
+};
+
+export fn number_u8(de: *deser) (u8 | error) =
+	number_irange(de, 0, types::U8_MAX: i64)?: u8;
+
+export fn number_u16(de: *deser) (u16 | error) =
+	number_irange(de, 0, types::U16_MAX: i64)?: u16;
+
+export fn number_u32(de: *deser) (u32 | error) =
+	number_irange(de, 0, types::U32_MAX: i64)?: u32;
+
+export fn number_u64(de: *deser) (u64 | error) =
+	number_irange(de, 0, types::I64_MAX)?: u64;
+
+export fn number_i8(de: *deser) (i8 | error) =
+	number_irange(de, types::I8_MIN, types::I8_MAX)?: i8;
+
+export fn number_i16(de: *deser) (i16 | error) =
+	number_irange(de, types::I16_MIN, types::I16_MAX)?: i16;
+
+export fn number_i32(de: *deser) (i32 | error) =
+	number_irange(de, types::I32_MIN, types::I32_MAX)?: i32;
+
+export fn number_i64(de: *deser) (i64 | error) =
+	number_irange(de, types::I64_MIN, types::I64_MAX);