commit cfe1fbad0f6a47fa0f5798df1423702b84bf34aa (tree)
parent 597648231b49500bbb8d15daa7f59cd52c1c3279
Author: Andrew Kelley <andrew@ziglang.org>
Date: Sun, 23 Feb 2020 11:25:15 -0500
Merge pull request #4304 from daurnimator/auto-json
Add "automatic" JSON facilities
Diffstat:
| M | lib/std/json.zig | | | 821 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 821 insertions(+), 0 deletions(-)
diff --git a/lib/std/json.zig b/lib/std/json.zig
@@ -19,6 +19,74 @@ const StringEscapes = union(enum) {
},
};
+/// Checks to see if a string matches what it would be as a json-encoded string
+/// Assumes that `encoded` is a well-formed json string
+fn encodesTo(decoded: []const u8, encoded: []const u8) bool {
+ var i: usize = 0;
+ var j: usize = 0;
+ while (i < decoded.len) {
+ if (j >= encoded.len) return false;
+ if (encoded[j] != '\\') {
+ if (decoded[i] != encoded[j]) return false;
+ j += 1;
+ i += 1;
+ } else {
+ const escape_type = encoded[j + 1];
+ if (escape_type != 'u') {
+ const t: u8 = switch (escape_type) {
+ '\\' => '\\',
+ '/' => '/',
+ 'n' => '\n',
+ 'r' => '\r',
+ 't' => '\t',
+ 'f' => 12,
+ 'b' => 8,
+ '"' => '"',
+ else => unreachable,
+ };
+ if (decoded[i] != t) return false;
+ j += 2;
+ i += 1;
+ } else {
+ var codepoint = std.fmt.parseInt(u21, encoded[j + 2 .. j + 6], 16) catch unreachable;
+ j += 6;
+ if (codepoint >= 0xD800 and codepoint < 0xDC00) {
+ // surrogate pair
+ assert(encoded[j] == '\\');
+ assert(encoded[j + 1] == 'u');
+ const low_surrogate = std.fmt.parseInt(u21, encoded[j + 2 .. j + 6], 16) catch unreachable;
+ codepoint = 0x10000 + (((codepoint & 0x03ff) << 10) | (low_surrogate & 0x03ff));
+ j += 6;
+ }
+ var buf: [4]u8 = undefined;
+ const len = std.unicode.utf8Encode(codepoint, &buf) catch unreachable;
+ if (i + len > decoded.len) return false;
+ if (!mem.eql(u8, decoded[i .. i + len], buf[0..len])) return false;
+ i += len;
+ }
+ }
+ }
+ assert(i == decoded.len);
+ assert(j == encoded.len);
+ return true;
+}
+
+test "encodesTo" {
+ // same
+ testing.expectEqual(true, encodesTo("false", "false"));
+ // totally different
+ testing.expectEqual(false, encodesTo("false", "true"));
+ // differnt lengths
+ testing.expectEqual(false, encodesTo("false", "other"));
+ // with escape
+ testing.expectEqual(true, encodesTo("\\", "\\\\"));
+ testing.expectEqual(true, encodesTo("with\nescape", "with\\nescape"));
+ // with unicode
+ testing.expectEqual(true, encodesTo("Ä…", "\\u0105"));
+ testing.expectEqual(true, encodesTo("😂", "\\ud83d\\ude02"));
+ testing.expectEqual(true, encodesTo("withąunicode😂", "with\\u0105unicode\\ud83d\\ude02"));
+}
+
/// A single token slice into the parent string.
///
/// Use `token.slice()` on the input at the current position to get the current slice.
@@ -1201,6 +1269,493 @@ pub const Value = union(enum) {
}
};
+pub const ParseOptions = struct {
+ allocator: ?*Allocator = null,
+
+ /// Behaviour when a duplicate field is encountered.
+ duplicate_field_behavior: enum {
+ UseFirst,
+ Error,
+ UseLast,
+ } = .Error,
+};
+
+fn parseInternal(comptime T: type, token: Token, tokens: *TokenStream, options: ParseOptions) !T {
+ switch (@typeInfo(T)) {
+ .Bool => {
+ return switch (token) {
+ .True => true,
+ .False => false,
+ else => error.UnexpectedToken,
+ };
+ },
+ .Float, .ComptimeFloat => {
+ const numberToken = switch (token) {
+ .Number => |n| n,
+ else => return error.UnexpectedToken,
+ };
+ return try std.fmt.parseFloat(T, numberToken.slice(tokens.slice, tokens.i - 1));
+ },
+ .Int, .ComptimeInt => {
+ const numberToken = switch (token) {
+ .Number => |n| n,
+ else => return error.UnexpectedToken,
+ };
+ if (!numberToken.is_integer) return error.UnexpectedToken;
+ return try std.fmt.parseInt(T, numberToken.slice(tokens.slice, tokens.i - 1), 10);
+ },
+ .Optional => |optionalInfo| {
+ if (token == .Null) {
+ return null;
+ } else {
+ return try parseInternal(optionalInfo.child, token, tokens, options);
+ }
+ },
+ .Enum => |enumInfo| {
+ switch (token) {
+ .Number => |numberToken| {
+ if (!numberToken.is_integer) return error.UnexpectedToken;
+ const n = try std.fmt.parseInt(enumInfo.tag_type, numberToken.slice(tokens.slice, tokens.i - 1), 10);
+ return try std.meta.intToEnum(T, n);
+ },
+ .String => |stringToken| {
+ const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
+ switch (stringToken.escapes) {
+ .None => return std.meta.stringToEnum(T, source_slice) orelse return error.InvalidEnumTag,
+ .Some => {
+ inline for (enumInfo.fields) |field| {
+ if (field.name.len == stringToken.decodedLength() and encodesTo(field.name, source_slice)) {
+ return @field(T, field.name);
+ }
+ }
+ return error.InvalidEnumTag;
+ },
+ }
+ },
+ else => return error.UnexpectedToken,
+ }
+ },
+ .Union => |unionInfo| {
+ if (unionInfo.tag_type) |_| {
+ // try each of the union fields until we find one that matches
+ inline for (unionInfo.fields) |u_field| {
+ if (parseInternal(u_field.field_type, token, tokens, options)) |value| {
+ return @unionInit(T, u_field.name, value);
+ } else |err| {
+ // Bubble up error.OutOfMemory
+ // Parsing some types won't have OutOfMemory in their
+ // error-sets, for the condition to be valid, merge it in.
+ if (@as(@TypeOf(err) || error{OutOfMemory}, err) == error.OutOfMemory) return err;
+ // otherwise continue through the `inline for`
+ }
+ }
+ return error.NoUnionMembersMatched;
+ } else {
+ @compileError("Unable to parse into untagged union '" ++ @typeName(T) ++ "'");
+ }
+ },
+ .Struct => |structInfo| {
+ switch (token) {
+ .ObjectBegin => {},
+ else => return error.UnexpectedToken,
+ }
+ var r: T = undefined;
+ var fields_seen = [_]bool{false} ** structInfo.fields.len;
+ errdefer {
+ inline for (structInfo.fields) |field, i| {
+ if (fields_seen[i]) {
+ parseFree(field.field_type, @field(r, field.name), options);
+ }
+ }
+ }
+
+ while (true) {
+ switch ((try tokens.next()) orelse return error.UnexpectedEndOfJson) {
+ .ObjectEnd => break,
+ .String => |stringToken| {
+ const key_source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
+ var found = false;
+ inline for (structInfo.fields) |field, i| {
+ // TODO: using switches here segfault the compiler (#2727?)
+ if ((stringToken.escapes == .None and mem.eql(u8, field.name, key_source_slice)) or (stringToken.escapes == .Some and (field.name.len == stringToken.decodedLength() and encodesTo(field.name, key_source_slice)))) {
+ // if (switch (stringToken.escapes) {
+ // .None => mem.eql(u8, field.name, key_source_slice),
+ // .Some => (field.name.len == stringToken.decodedLength() and encodesTo(field.name, key_source_slice)),
+ // }) {
+ if (fields_seen[i]) {
+ // switch (options.duplicate_field_behavior) {
+ // .UseFirst => {},
+ // .Error => {},
+ // .UseLast => {},
+ // }
+ if (options.duplicate_field_behavior == .UseFirst) {
+ break;
+ } else if (options.duplicate_field_behavior == .Error) {
+ return error.DuplicateJSONField;
+ } else if (options.duplicate_field_behavior == .UseLast) {
+ parseFree(field.field_type, @field(r, field.name), options);
+ }
+ }
+ @field(r, field.name) = try parse(field.field_type, tokens, options);
+ fields_seen[i] = true;
+ found = true;
+ break;
+ }
+ }
+ if (!found) return error.UnknownField;
+ },
+ else => return error.UnexpectedToken,
+ }
+ }
+ inline for (structInfo.fields) |field, i| {
+ if (!fields_seen[i]) {
+ if (field.default_value) |default| {
+ @field(r, field.name) = default;
+ } else {
+ return error.MissingField;
+ }
+ }
+ }
+ return r;
+ },
+ .Array => |arrayInfo| {
+ switch (token) {
+ .ArrayBegin => {
+ var r: T = undefined;
+ var i: usize = 0;
+ errdefer {
+ while (true) : (i -= 1) {
+ parseFree(arrayInfo.child, r[i], options);
+ if (i == 0) break;
+ }
+ }
+ while (i < r.len) : (i += 1) {
+ r[i] = try parse(arrayInfo.child, tokens, options);
+ }
+ const tok = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
+ switch (tok) {
+ .ArrayEnd => {},
+ else => return error.UnexpectedToken,
+ }
+ return r;
+ },
+ .String => |stringToken| {
+ if (arrayInfo.child != u8) return error.UnexpectedToken;
+ var r: T = undefined;
+ const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
+ switch (stringToken.escapes) {
+ .None => mem.copy(u8, &r, source_slice),
+ .Some => try unescapeString(&r, source_slice),
+ }
+ return r;
+ },
+ else => return error.UnexpectedToken,
+ }
+ },
+ .Pointer => |ptrInfo| {
+ const allocator = options.allocator orelse return error.AllocatorRequired;
+ switch (ptrInfo.size) {
+ .One => {
+ const r: T = allocator.create(ptrInfo.child);
+ r.* = try parseInternal(ptrInfo.child, token, tokens, options);
+ return r;
+ },
+ .Slice => {
+ switch (token) {
+ .ArrayBegin => {
+ var arraylist = std.ArrayList(ptrInfo.child).init(allocator);
+ errdefer {
+ while (arraylist.popOrNull()) |v| {
+ parseFree(ptrInfo.child, v, options);
+ }
+ arraylist.deinit();
+ }
+
+ while (true) {
+ const tok = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
+ switch (tok) {
+ .ArrayEnd => break,
+ else => {},
+ }
+
+ try arraylist.ensureCapacity(arraylist.len + 1);
+ const v = try parseInternal(ptrInfo.child, tok, tokens, options);
+ arraylist.appendAssumeCapacity(v);
+ }
+ return arraylist.toOwnedSlice();
+ },
+ .String => |stringToken| {
+ if (ptrInfo.child != u8) return error.UnexpectedToken;
+ const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
+ switch (stringToken.escapes) {
+ .None => return mem.dupe(allocator, u8, source_slice),
+ .Some => |some_escapes| {
+ const output = try allocator.alloc(u8, stringToken.decodedLength());
+ errdefer allocator.free(output);
+ try unescapeString(output, source_slice);
+ return output;
+ },
+ }
+ },
+ else => return error.UnexpectedToken,
+ }
+ },
+ else => @compileError("Unable to parse into type '" ++ @typeName(T) ++ "'"),
+ }
+ },
+ else => @compileError("Unable to parse into type '" ++ @typeName(T) ++ "'"),
+ }
+ unreachable;
+}
+
+pub fn parse(comptime T: type, tokens: *TokenStream, options: ParseOptions) !T {
+ const token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
+ return parseInternal(T, token, tokens, options);
+}
+
+/// Releases resources created by `parse`.
+/// Should be called with the same type and `ParseOptions` that were passed to `parse`
+pub fn parseFree(comptime T: type, value: T, options: ParseOptions) void {
+ switch (@typeInfo(T)) {
+ .Bool, .Float, .ComptimeFloat, .Int, .ComptimeInt, .Enum => {},
+ .Optional => {
+ if (value) |v| {
+ return parseFree(@TypeOf(v), v, options);
+ }
+ },
+ .Union => |unionInfo| {
+ if (unionInfo.tag_type) |UnionTagType| {
+ inline for (unionInfo.fields) |u_field| {
+ if (@enumToInt(@as(UnionTagType, value)) == u_field.enum_field.?.value) {
+ parseFree(u_field.field_type, @field(value, u_field.name), options);
+ break;
+ }
+ }
+ } else {
+ unreachable;
+ }
+ },
+ .Struct => |structInfo| {
+ inline for (structInfo.fields) |field| {
+ parseFree(field.field_type, @field(value, field.name), options);
+ }
+ },
+ .Array => |arrayInfo| {
+ for (value) |v| {
+ parseFree(arrayInfo.child, v, options);
+ }
+ },
+ .Pointer => |ptrInfo| {
+ const allocator = options.allocator orelse unreachable;
+ switch (ptrInfo.size) {
+ .One => {
+ parseFree(ptrInfo.child, value.*, options);
+ allocator.destroy(v);
+ },
+ .Slice => {
+ for (value) |v| {
+ parseFree(ptrInfo.child, v, options);
+ }
+ allocator.free(value);
+ },
+ else => unreachable,
+ }
+ },
+ else => unreachable,
+ }
+}
+
+test "parse" {
+ testing.expectEqual(false, try parse(bool, &TokenStream.init("false"), ParseOptions{}));
+ testing.expectEqual(true, try parse(bool, &TokenStream.init("true"), ParseOptions{}));
+ testing.expectEqual(@as(u1, 1), try parse(u1, &TokenStream.init("1"), ParseOptions{}));
+ testing.expectError(error.Overflow, parse(u1, &TokenStream.init("50"), ParseOptions{}));
+ testing.expectEqual(@as(u64, 42), try parse(u64, &TokenStream.init("42"), ParseOptions{}));
+ testing.expectEqual(@as(f64, 42), try parse(f64, &TokenStream.init("42.0"), ParseOptions{}));
+ testing.expectEqual(@as(?bool, null), try parse(?bool, &TokenStream.init("null"), ParseOptions{}));
+ testing.expectEqual(@as(?bool, true), try parse(?bool, &TokenStream.init("true"), ParseOptions{}));
+
+ testing.expectEqual(@as([3]u8, "foo".*), try parse([3]u8, &TokenStream.init("\"foo\""), ParseOptions{}));
+ testing.expectEqual(@as([3]u8, "foo".*), try parse([3]u8, &TokenStream.init("[102, 111, 111]"), ParseOptions{}));
+}
+
+test "parse into enum" {
+ const T = extern enum {
+ Foo = 42,
+ Bar,
+ @"with\\escape",
+ };
+ testing.expectEqual(@as(T, .Foo), try parse(T, &TokenStream.init("\"Foo\""), ParseOptions{}));
+ testing.expectEqual(@as(T, .Foo), try parse(T, &TokenStream.init("42"), ParseOptions{}));
+ testing.expectEqual(@as(T, .@"with\\escape"), try parse(T, &TokenStream.init("\"with\\\\escape\""), ParseOptions{}));
+ testing.expectError(error.InvalidEnumTag, parse(T, &TokenStream.init("5"), ParseOptions{}));
+ testing.expectError(error.InvalidEnumTag, parse(T, &TokenStream.init("\"Qux\""), ParseOptions{}));
+}
+
+test "parse into that allocates a slice" {
+ testing.expectError(error.AllocatorRequired, parse([]u8, &TokenStream.init("\"foo\""), ParseOptions{}));
+
+ const options = ParseOptions{ .allocator = testing.allocator };
+ {
+ const r = try parse([]u8, &TokenStream.init("\"foo\""), options);
+ defer parseFree([]u8, r, options);
+ testing.expectEqualSlices(u8, "foo", r);
+ }
+ {
+ const r = try parse([]u8, &TokenStream.init("[102, 111, 111]"), options);
+ defer parseFree([]u8, r, options);
+ testing.expectEqualSlices(u8, "foo", r);
+ }
+ {
+ const r = try parse([]u8, &TokenStream.init("\"with\\\\escape\""), options);
+ defer parseFree([]u8, r, options);
+ testing.expectEqualSlices(u8, "with\\escape", r);
+ }
+}
+
+test "parse into tagged union" {
+ {
+ const T = union(enum) {
+ int: i32,
+ float: f64,
+ string: []const u8,
+ };
+ testing.expectEqual(T{ .float = 1.5 }, try parse(T, &TokenStream.init("1.5"), ParseOptions{}));
+ }
+
+ { // if union matches string member, fails with NoUnionMembersMatched rather than AllocatorRequired
+ // Note that this behaviour wasn't necessarily by design, but was
+ // what fell out of the implementation and may result in interesting
+ // API breakage if changed
+ const T = union(enum) {
+ int: i32,
+ float: f64,
+ string: []const u8,
+ };
+ testing.expectError(error.NoUnionMembersMatched, parse(T, &TokenStream.init("\"foo\""), ParseOptions{}));
+ }
+
+ { // failing allocations should be bubbled up instantly without trying next member
+ var fail_alloc = testing.FailingAllocator.init(testing.allocator, 0);
+ const options = ParseOptions{ .allocator = &fail_alloc.allocator };
+ const T = union(enum) {
+ // both fields here match the input
+ string: []const u8,
+ array: [3]u8,
+ };
+ testing.expectError(error.OutOfMemory, parse(T, &TokenStream.init("[1,2,3]"), options));
+ }
+
+ {
+ // if multiple matches possible, takes first option
+ const T = union(enum) {
+ x: u8,
+ y: u8,
+ };
+ testing.expectEqual(T{ .x = 42 }, try parse(T, &TokenStream.init("42"), ParseOptions{}));
+ }
+}
+
+test "parseFree descends into tagged union" {
+ // tagged unions are broken on arm64: https://github.com/ziglang/zig/issues/4492
+ if (std.builtin.arch == .aarch64) return error.SkipZigTest;
+
+ var fail_alloc = testing.FailingAllocator.init(testing.allocator, 1);
+ const options = ParseOptions{ .allocator = &fail_alloc.allocator };
+ const T = union(enum) {
+ int: i32,
+ float: f64,
+ string: []const u8,
+ };
+ // use a string with unicode escape so we know result can't be a reference to global constant
+ const r = try parse(T, &TokenStream.init("\"with\\u0105unicode\""), options);
+ testing.expectEqual(@TagType(T).string, @as(@TagType(T), r));
+ testing.expectEqualSlices(u8, "withÄ…unicode", r.string);
+ testing.expectEqual(@as(usize, 0), fail_alloc.deallocations);
+ parseFree(T, r, options);
+ testing.expectEqual(@as(usize, 1), fail_alloc.deallocations);
+}
+
+test "parse into struct with no fields" {
+ const T = struct {};
+ testing.expectEqual(T{}, try parse(T, &TokenStream.init("{}"), ParseOptions{}));
+}
+
+test "parse into struct with misc fields" {
+ @setEvalBranchQuota(10000);
+ const options = ParseOptions{ .allocator = testing.allocator };
+ const T = struct {
+ int: i64,
+ float: f64,
+ @"with\\escape": bool,
+ @"withąunicode😂": bool,
+ language: []const u8,
+ optional: ?bool,
+ default_field: i32 = 42,
+ static_array: [3]f64,
+ dynamic_array: []f64,
+
+ const Bar = struct {
+ nested: []const u8,
+ };
+ complex: Bar,
+
+ const Baz = struct {
+ foo: []const u8,
+ };
+ veryComplex: []Baz,
+
+ const Union = union(enum) {
+ x: u8,
+ float: f64,
+ string: []const u8,
+ };
+ a_union: Union,
+ };
+ const r = try parse(T, &TokenStream.init(
+ \\{
+ \\ "int": 420,
+ \\ "float": 3.14,
+ \\ "with\\escape": true,
+ \\ "with\u0105unicode\ud83d\ude02": false,
+ \\ "language": "zig",
+ \\ "optional": null,
+ \\ "static_array": [66.6, 420.420, 69.69],
+ \\ "dynamic_array": [66.6, 420.420, 69.69],
+ \\ "complex": {
+ \\ "nested": "zig"
+ \\ },
+ \\ "veryComplex": [
+ \\ {
+ \\ "foo": "zig"
+ \\ }, {
+ \\ "foo": "rocks"
+ \\ }
+ \\ ],
+ \\ "a_union": 100000
+ \\}
+ ), options);
+ defer parseFree(T, r, options);
+ testing.expectEqual(@as(i64, 420), r.int);
+ testing.expectEqual(@as(f64, 3.14), r.float);
+ testing.expectEqual(true, r.@"with\\escape");
+ testing.expectEqual(false, r.@"withąunicode😂");
+ testing.expectEqualSlices(u8, "zig", r.language);
+ testing.expectEqual(@as(?bool, null), r.optional);
+ testing.expectEqual(@as(i32, 42), r.default_field);
+ testing.expectEqual(@as(f64, 66.6), r.static_array[0]);
+ testing.expectEqual(@as(f64, 420.420), r.static_array[1]);
+ testing.expectEqual(@as(f64, 69.69), r.static_array[2]);
+ testing.expectEqual(@as(usize, 3), r.dynamic_array.len);
+ testing.expectEqual(@as(f64, 66.6), r.dynamic_array[0]);
+ testing.expectEqual(@as(f64, 420.420), r.dynamic_array[1]);
+ testing.expectEqual(@as(f64, 69.69), r.dynamic_array[2]);
+ testing.expectEqualSlices(u8, r.complex.nested, "zig");
+ testing.expectEqualSlices(u8, "zig", r.veryComplex[0].foo);
+ testing.expectEqualSlices(u8, "rocks", r.veryComplex[1].foo);
+ testing.expectEqual(T.Union{ .float = 100000 }, r.a_union);
+}
+
/// A non-stream JSON parser which constructs a tree of Value's.
pub const Parser = struct {
allocator: *Allocator,
@@ -1686,3 +2241,269 @@ test "string copy option" {
}
testing.expect(found_nocopy);
}
+
+pub const StringifyOptions = struct {
+ // TODO: indentation options?
+ // TODO: make escaping '/' in strings optional?
+ // TODO: allow picking if []u8 is string or array?
+};
+
+pub fn stringify(
+ value: var,
+ options: StringifyOptions,
+ context: var,
+ comptime Errors: type,
+ comptime output: fn (@TypeOf(context), []const u8) Errors!void,
+) Errors!void {
+ const T = @TypeOf(value);
+ switch (@typeInfo(T)) {
+ .Float, .ComptimeFloat => {
+ return std.fmt.formatFloatScientific(value, std.fmt.FormatOptions{}, context, Errors, output);
+ },
+ .Int, .ComptimeInt => {
+ return std.fmt.formatIntValue(value, "", std.fmt.FormatOptions{}, context, Errors, output);
+ },
+ .Bool => {
+ return output(context, if (value) "true" else "false");
+ },
+ .Optional => {
+ if (value) |payload| {
+ return try stringify(payload, options, context, Errors, output);
+ } else {
+ return output(context, "null");
+ }
+ },
+ .Enum => {
+ if (comptime std.meta.trait.hasFn("jsonStringify")(T)) {
+ return value.jsonStringify(options, context, Errors, output);
+ }
+
+ @compileError("Unable to stringify enum '" ++ @typeName(T) ++ "'");
+ },
+ .Union => {
+ if (comptime std.meta.trait.hasFn("jsonStringify")(T)) {
+ return value.jsonStringify(options, context, Errors, output);
+ }
+
+ const info = @typeInfo(T).Union;
+ if (info.tag_type) |UnionTagType| {
+ inline for (info.fields) |u_field| {
+ if (@enumToInt(@as(UnionTagType, value)) == u_field.enum_field.?.value) {
+ return try stringify(@field(value, u_field.name), options, context, Errors, output);
+ }
+ }
+ } else {
+ @compileError("Unable to stringify untagged union '" ++ @typeName(T) ++ "'");
+ }
+ },
+ .Struct => |S| {
+ if (comptime std.meta.trait.hasFn("jsonStringify")(T)) {
+ return value.jsonStringify(options, context, Errors, output);
+ }
+
+ try output(context, "{");
+ comptime var field_output = false;
+ inline for (S.fields) |Field, field_i| {
+ // don't include void fields
+ if (Field.field_type == void) continue;
+
+ if (!field_output) {
+ field_output = true;
+ } else {
+ try output(context, ",");
+ }
+
+ try stringify(Field.name, options, context, Errors, output);
+ try output(context, ":");
+ try stringify(@field(value, Field.name), options, context, Errors, output);
+ }
+ try output(context, "}");
+ return;
+ },
+ .Pointer => |ptr_info| switch (ptr_info.size) {
+ .One => {
+ // TODO: avoid loops?
+ return try stringify(value.*, options, context, Errors, output);
+ },
+ // TODO: .Many when there is a sentinel (waiting for https://github.com/ziglang/zig/pull/3972)
+ .Slice => {
+ if (ptr_info.child == u8 and std.unicode.utf8ValidateSlice(value)) {
+ try output(context, "\"");
+ var i: usize = 0;
+ while (i < value.len) : (i += 1) {
+ switch (value[i]) {
+ // normal ascii characters
+ 0x20...0x21, 0x23...0x2E, 0x30...0x5B, 0x5D...0x7F => try output(context, value[i .. i + 1]),
+ // control characters with short escapes
+ '\\' => try output(context, "\\\\"),
+ '\"' => try output(context, "\\\""),
+ '/' => try output(context, "\\/"),
+ 0x8 => try output(context, "\\b"),
+ 0xC => try output(context, "\\f"),
+ '\n' => try output(context, "\\n"),
+ '\r' => try output(context, "\\r"),
+ '\t' => try output(context, "\\t"),
+ else => {
+ const ulen = std.unicode.utf8ByteSequenceLength(value[i]) catch unreachable;
+ const codepoint = std.unicode.utf8Decode(value[i .. i + ulen]) catch unreachable;
+ if (codepoint <= 0xFFFF) {
+ // If the character is in the Basic Multilingual Plane (U+0000 through U+FFFF),
+ // then it may be represented as a six-character sequence: a reverse solidus, followed
+ // by the lowercase letter u, followed by four hexadecimal digits that encode the character's code point.
+ try output(context, "\\u");
+ try std.fmt.formatIntValue(codepoint, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, context, Errors, output);
+ } else {
+ // To escape an extended character that is not in the Basic Multilingual Plane,
+ // the character is represented as a 12-character sequence, encoding the UTF-16 surrogate pair.
+ const high = @intCast(u16, (codepoint - 0x10000) >> 10) + 0xD800;
+ const low = @intCast(u16, codepoint & 0x3FF) + 0xDC00;
+ try output(context, "\\u");
+ try std.fmt.formatIntValue(high, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, context, Errors, output);
+ try output(context, "\\u");
+ try std.fmt.formatIntValue(low, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, context, Errors, output);
+ }
+ i += ulen - 1;
+ },
+ }
+ }
+ try output(context, "\"");
+ return;
+ }
+
+ try output(context, "[");
+ for (value) |x, i| {
+ if (i != 0) {
+ try output(context, ",");
+ }
+ try stringify(x, options, context, Errors, output);
+ }
+ try output(context, "]");
+ return;
+ },
+ else => @compileError("Unable to stringify type '" ++ @typeName(T) ++ "'"),
+ },
+ .Array => |info| {
+ return try stringify(value[0..], options, context, Errors, output);
+ },
+ else => @compileError("Unable to stringify type '" ++ @typeName(T) ++ "'"),
+ }
+ unreachable;
+}
+
+fn teststringify(expected: []const u8, value: var) !void {
+ const TestStringifyContext = struct {
+ expected_remaining: []const u8,
+ fn testStringifyWrite(context: *@This(), bytes: []const u8) !void {
+ if (context.expected_remaining.len < bytes.len) {
+ std.debug.warn(
+ \\====== expected this output: =========
+ \\{}
+ \\======== instead found this: =========
+ \\{}
+ \\======================================
+ , .{
+ context.expected_remaining,
+ bytes,
+ });
+ return error.TooMuchData;
+ }
+ if (!mem.eql(u8, context.expected_remaining[0..bytes.len], bytes)) {
+ std.debug.warn(
+ \\====== expected this output: =========
+ \\{}
+ \\======== instead found this: =========
+ \\{}
+ \\======================================
+ , .{
+ context.expected_remaining[0..bytes.len],
+ bytes,
+ });
+ return error.DifferentData;
+ }
+ context.expected_remaining = context.expected_remaining[bytes.len..];
+ }
+ };
+ var buf: [100]u8 = undefined;
+ var context = TestStringifyContext{ .expected_remaining = expected };
+ try stringify(value, StringifyOptions{}, &context, error{
+ TooMuchData,
+ DifferentData,
+ }, TestStringifyContext.testStringifyWrite);
+ if (context.expected_remaining.len > 0) return error.NotEnoughData;
+}
+
+test "stringify basic types" {
+ try teststringify("false", false);
+ try teststringify("true", true);
+ try teststringify("null", @as(?u8, null));
+ try teststringify("null", @as(?*u32, null));
+ try teststringify("42", 42);
+ try teststringify("4.2e+01", 42.0);
+ try teststringify("42", @as(u8, 42));
+ try teststringify("42", @as(u128, 42));
+ try teststringify("4.2e+01", @as(f32, 42));
+ try teststringify("4.2e+01", @as(f64, 42));
+}
+
+test "stringify string" {
+ try teststringify("\"hello\"", "hello");
+ try teststringify("\"with\\nescapes\\r\"", "with\nescapes\r");
+ try teststringify("\"with unicode\\u0001\"", "with unicode\u{1}");
+ try teststringify("\"with unicode\\u0080\"", "with unicode\u{80}");
+ try teststringify("\"with unicode\\u00ff\"", "with unicode\u{FF}");
+ try teststringify("\"with unicode\\u0100\"", "with unicode\u{100}");
+ try teststringify("\"with unicode\\u0800\"", "with unicode\u{800}");
+ try teststringify("\"with unicode\\u8000\"", "with unicode\u{8000}");
+ try teststringify("\"with unicode\\ud799\"", "with unicode\u{D799}");
+ try teststringify("\"with unicode\\ud800\\udc00\"", "with unicode\u{10000}");
+ try teststringify("\"with unicode\\udbff\\udfff\"", "with unicode\u{10FFFF}");
+}
+
+test "stringify tagged unions" {
+ try teststringify("42", union(enum) {
+ Foo: u32,
+ Bar: bool,
+ }{ .Foo = 42 });
+}
+
+test "stringify struct" {
+ try teststringify("{\"foo\":42}", struct {
+ foo: u32,
+ }{ .foo = 42 });
+}
+
+test "stringify struct with void field" {
+ try teststringify("{\"foo\":42}", struct {
+ foo: u32,
+ bar: void = {},
+ }{ .foo = 42 });
+}
+
+test "stringify array of structs" {
+ const MyStruct = struct {
+ foo: u32,
+ };
+ try teststringify("[{\"foo\":42},{\"foo\":100},{\"foo\":1000}]", [_]MyStruct{
+ MyStruct{ .foo = 42 },
+ MyStruct{ .foo = 100 },
+ MyStruct{ .foo = 1000 },
+ });
+}
+
+test "stringify struct with custom stringifier" {
+ try teststringify("[\"something special\",42]", struct {
+ foo: u32,
+ const Self = @This();
+ pub fn jsonStringify(
+ value: Self,
+ options: StringifyOptions,
+ context: var,
+ comptime Errors: type,
+ comptime output: fn (@TypeOf(context), []const u8) Errors!void,
+ ) !void {
+ try output(context, "[\"something special\",");
+ try stringify(42, options, context, Errors, output);
+ try output(context, "]");
+ }
+ }{ .foo = 42 });
+}
