proper path/query support for REST v1

This also includes a small change to force output of mappings even if empty
New zig correctly detects that without any field, we end up trying to use
a constant that does not exist (this is in the generated code)

codegen/src/json.zig

@@ -0,0 +1,124 @@
+const std = @import("std");
+// options is a json.Options, but since we're using our hacked json.zig we don't want to
+// specifically call this out
+pub fn serializeMap(map: anytype, key: []const u8, options: anytype, out_stream: anytype) !bool {
+    if (map.len == 0) return true;
+    // TODO: Map might be [][]struct{key, value} rather than []struct{key, value}
+    var child_options = options;
+    if (child_options.whitespace) |*child_ws|
+        child_ws.indent_level += 1;
+
+    try out_stream.writeByte('"');
+    try out_stream.writeAll(key);
+    _ = try out_stream.write("\":");
+    if (options.whitespace) |ws| {
+        if (ws.separator) {
+            try out_stream.writeByte(' ');
+        }
+    }
+    try out_stream.writeByte('{');
+    if (options.whitespace) |_|
+        try out_stream.writeByte('\n');
+    for (map) |tag, i| {
+        if (tag.key == null or tag.value == null) continue;
+        // TODO: Deal with escaping and general "json.stringify" the values...
+        if (child_options.whitespace) |ws|
+            try ws.outputIndent(out_stream);
+        try out_stream.writeByte('"');
+        try jsonEscape(tag.key.?, child_options, out_stream);
+        _ = try out_stream.write("\":");
+        if (child_options.whitespace) |ws| {
+            if (ws.separator) {
+                try out_stream.writeByte(' ');
+            }
+        }
+        try out_stream.writeByte('"');
+        try jsonEscape(tag.value.?, child_options, out_stream);
+        try out_stream.writeByte('"');
+        if (i < map.len - 1) {
+            try out_stream.writeByte(',');
+        }
+        if (child_options.whitespace) |_|
+            try out_stream.writeByte('\n');
+    }
+    if (options.whitespace) |ws|
+        try ws.outputIndent(out_stream);
+    try out_stream.writeByte('}');
+    return true;
+}
+// code within jsonEscape lifted from json.zig in stdlib
+fn jsonEscape(value: []const u8, options: anytype, out_stream: anytype) !void {
+    var i: usize = 0;
+    while (i < value.len) : (i += 1) {
+        switch (value[i]) {
+            // normal ascii character
+            0x20...0x21, 0x23...0x2E, 0x30...0x5B, 0x5D...0x7F => |c| try out_stream.writeByte(c),
+            // only 2 characters that *must* be escaped
+            '\\' => try out_stream.writeAll("\\\\"),
+            '\"' => try out_stream.writeAll("\\\""),
+            // solidus is optional to escape
+            '/' => {
+                if (options.string.String.escape_solidus) {
+                    try out_stream.writeAll("\\/");
+                } else {
+                    try out_stream.writeByte('/');
+                }
+            },
+            // control characters with short escapes
+            // TODO: option to switch between unicode and 'short' forms?
+            0x8 => try out_stream.writeAll("\\b"),
+            0xC => try out_stream.writeAll("\\f"),
+            '\n' => try out_stream.writeAll("\\n"),
+            '\r' => try out_stream.writeAll("\\r"),
+            '\t' => try out_stream.writeAll("\\t"),
+            else => {
+                const ulen = std.unicode.utf8ByteSequenceLength(value[i]) catch unreachable;
+                // control characters (only things left with 1 byte length) should always be printed as unicode escapes
+                if (ulen == 1 or options.string.String.escape_unicode) {
+                    const codepoint = std.unicode.utf8Decode(value[i .. i + ulen]) catch unreachable;
+                    try outputUnicodeEscape(codepoint, out_stream);
+                } else {
+                    try out_stream.writeAll(value[i .. i + ulen]);
+                }
+                i += ulen - 1;
+            },
+        }
+    }
+}
+// outputUnicodeEscape and assert lifted from json.zig in stdlib
+fn outputUnicodeEscape(
+    codepoint: u21,
+    out_stream: anytype,
+) !void {
+    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 out_stream.writeAll("\\u");
+        try std.fmt.formatIntValue(codepoint, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, out_stream);
+    } else {
+        assert(codepoint <= 0x10FFFF);
+        // 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 out_stream.writeAll("\\u");
+        try std.fmt.formatIntValue(high, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, out_stream);
+        try out_stream.writeAll("\\u");
+        try std.fmt.formatIntValue(low, "x", std.fmt.FormatOptions{ .width = 4, .fill = '0' }, out_stream);
+    }
+}
+
+/// This function invokes undefined behavior when `ok` is `false`.
+/// In Debug and ReleaseSafe modes, calls to this function are always
+/// generated, and the `unreachable` statement triggers a panic.
+/// In ReleaseFast and ReleaseSmall modes, calls to this function are
+/// optimized away, and in fact the optimizer is able to use the assertion
+/// in its heuristics.
+/// Inside a test block, it is best to use the `std.testing` module rather
+/// than this function, because this function may not detect a test failure
+/// in ReleaseFast and ReleaseSmall mode. Outside of a test block, this assert
+/// function is the correct function to use.
+pub fn assert(ok: bool) void {
+    if (!ok) unreachable; // assertion failure
+}

codegen/src/main.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const smithy = @import("smithy");
 const snake = @import("snake.zig");
+const json_zig = @embedFile("json.zig");
 
 pub fn main() anyerror!void {
     var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
@@ -10,6 +11,9 @@ pub fn main() anyerror!void {
     const args = try std.process.argsAlloc(allocator);
     defer std.process.argsFree(allocator, args);
     const stdout = std.io.getStdOut().writer();
+    const json_file = try std.fs.cwd().createFile("json.zig", .{});
+    defer json_file.close();
+    try json_file.writer().writeAll(json_zig);
     const manifest_file = try std.fs.cwd().createFile("service_manifest.zig", .{});
     defer manifest_file.close();
     const manifest = manifest_file.writer();
@@ -42,6 +46,8 @@ fn processFile(arg: []const u8, stdout: anytype, manifest: anytype) !void {
     file = try std.fs.cwd().createFile(filename, .{ .truncate = true });
     errdefer file.close();
     writer = &file.writer();
+    _ = try writer.write("const std = @import(\"std\");\n");
+    _ = try writer.write("const serializeMap = @import(\"json.zig\").serializeMap;\n");
     _ = try writer.write("const smithy = @import(\"smithy\");\n\n");
     std.log.info("Processing file: {s}", .{arg});
     const service_names = generateServicesForFilePath(allocator, ";", arg, writer) catch |err| {
@@ -68,10 +74,9 @@ fn generateServices(allocator: *std.mem.Allocator, comptime _: []const u8, file:
     defer allocator.free(json);
     const model = try smithy.parse(allocator, json);
     defer model.deinit();
-    const ShapeInfo = @TypeOf(model.shapes[0]); // assume we have at least one shape
-    var shapes = std.StringHashMap(ShapeInfo).init(allocator);
+    var shapes = std.StringHashMap(smithy.ShapeInfo).init(allocator);
     defer shapes.deinit();
-    var services = std.ArrayList(ShapeInfo).init(allocator);
+    var services = std.ArrayList(smithy.ShapeInfo).init(allocator);
     defer services.deinit();
     for (model.shapes) |shape| {
         try shapes.put(shape.id, shape);
@@ -118,7 +123,7 @@ fn generateServices(allocator: *std.mem.Allocator, comptime _: []const u8, file:
         try writer.print("pub const name: []const u8 = \"{s}\";\n", .{name});
         // TODO: This really should just be ".whatevs". We're fully qualifying here, which isn't typical
         try writer.print("pub const aws_protocol: smithy.AwsProtocol = smithy.{s};\n\n", .{aws_protocol});
-        _ = try writer.write("pub const service_metadata : struct {\n");
+        _ = try writer.write("pub const service_metadata: struct {\n");
         try writer.print("    version: []const u8 = \"{s}\",\n", .{version});
         try writer.print("    sdk_id: []const u8 = \"{s}\",\n", .{sdk_id});
         try writer.print("    arn_namespace: []const u8 = \"{s}\",\n", .{arn_namespace});
@@ -131,7 +136,7 @@ fn generateServices(allocator: *std.mem.Allocator, comptime _: []const u8, file:
 
         // Operations
         for (service.shape.service.operations) |op|
-            try generateOperation(allocator, shapes.get(op).?, shapes, writer, constant_name);
+            try generateOperation(allocator, shapes.get(op).?, shapes, writer);
     }
     return constant_names.toOwnedSlice();
 }
@@ -155,67 +160,108 @@ fn constantName(allocator: *std.mem.Allocator, id: []const u8) ![]const u8 {
     // Not a special case - just snake it
     return try snake.fromPascalCase(allocator, id);
 }
-fn generateOperation(allocator: *std.mem.Allocator, operation: smithy.ShapeInfo, shapes: anytype, writer: anytype, service: []const u8) !void {
+
+const GenerationState = struct {
+    type_stack: *std.ArrayList(*const smithy.ShapeInfo),
+    // we will need some sort of "type decls needed" for recursive structures
+    allocator: *std.mem.Allocator,
+    indent_level: u64,
+    all_required: bool,
+};
+
+fn outputIndent(state: GenerationState, writer: anytype) !void {
+    const n_chars = 4 * state.indent_level;
+    try writer.writeByteNTimes(' ', n_chars);
+}
+fn generateOperation(allocator: *std.mem.Allocator, operation: smithy.ShapeInfo, shapes: std.StringHashMap(smithy.ShapeInfo), writer: anytype) !void {
     const snake_case_name = try snake.fromPascalCase(allocator, operation.name);
     defer allocator.free(snake_case_name);
 
-    const prefix = "    ";
     var type_stack = std.ArrayList(*const smithy.ShapeInfo).init(allocator);
     defer type_stack.deinit();
+    const state = GenerationState{
+        .type_stack = &type_stack,
+        .allocator = allocator,
+        .indent_level = 1,
+        .all_required = false,
+    };
+    var child_state = state;
+    child_state.indent_level += 1;
     // indent should start at 4 spaces here
     const operation_name = avoidReserved(snake_case_name);
     try writer.print("pub const {s}: struct ", .{operation_name});
     _ = try writer.write("{\n");
     for (operation.shape.operation.traits) |trait| {
         if (trait == .http) {
-            _ = try writer.write("    pub const http_config = .{\n");
-            try writer.print("        .method = \"{s}\",\n", .{trait.http.method});
-            try writer.print("        .uri = \"{s}\",\n", .{trait.http.uri});
-            try writer.print("        .success_code = {d},\n", .{trait.http.code});
-            _ = try writer.write("    };\n\n");
+            try outputIndent(state, writer);
+            _ = try writer.write("pub const http_config = .{\n");
+            try outputIndent(child_state, writer);
+            try writer.print(".method = \"{s}\",\n", .{trait.http.method});
+            try outputIndent(child_state, writer);
+            try writer.print(".uri = \"{s}\",\n", .{trait.http.uri});
+            try outputIndent(child_state, writer);
+            try writer.print(".success_code = {d},\n", .{trait.http.code});
+            try outputIndent(state, writer);
+            _ = try writer.write("};\n\n");
         }
     }
 
-    try writer.print("    action_name: []const u8 = \"{s}\",\n", .{operation.name});
-    _ = try writer.write("    Request: type = ");
+    try outputIndent(state, writer);
+    try writer.print("action_name: []const u8 = \"{s}\",\n", .{operation.name});
+    try outputIndent(state, writer);
+    _ = try writer.write("Request: type = ");
     if (operation.shape.operation.input) |member| {
-        try generateTypeFor(allocator, member, shapes, writer, prefix, false, &type_stack, false);
+        if (try generateTypeFor(member, shapes, writer, state, false)) unreachable; // we expect only structs here
         _ = try writer.write("\n");
-        try generateMetadataFunction(service, operation_name, prefix, writer);
+        try generateMetadataFunction(operation_name, state, writer);
     } else {
         _ = try writer.write("struct {\n");
-        try generateMetadataFunction(service, operation_name, prefix, writer);
+        try generateMetadataFunction(operation_name, state, writer);
     }
     _ = try writer.write(",\n");
-    _ = try writer.write("    Response: type = ");
+    try outputIndent(state, writer);
+    _ = try writer.write("Response: type = ");
     if (operation.shape.operation.output) |member| {
-        try generateTypeFor(allocator, member, shapes, writer, "    ", false, &type_stack, true);
+        if (try generateTypeFor(member, shapes, writer, state, true)) unreachable; // we expect only structs here
     } else _ = try writer.write("struct {}"); // we want to maintain consistency with other ops
     _ = try writer.write(",\n");
 
     if (operation.shape.operation.errors) |errors| {
-        _ = try writer.write("    ServiceError: type = error{\n");
+        try outputIndent(state, writer);
+        _ = try writer.write("ServiceError: type = error{\n");
         for (errors) |err| {
             const err_name = getErrorName(shapes.get(err).?.name); // need to remove "exception"
-            try writer.print("        {s},\n", .{err_name});
+            try outputIndent(child_state, writer);
+            try writer.print("{s},\n", .{err_name});
         }
-        _ = try writer.write("    },\n");
+        try outputIndent(state, writer);
+        _ = try writer.write("},\n");
     }
     _ = try writer.write("} = .{};\n");
 }
 
-fn generateMetadataFunction(_: []const u8, operation_name: []const u8, comptime prefix: []const u8, writer: anytype) !void {
+fn generateMetadataFunction(operation_name: []const u8, state: GenerationState, writer: anytype) !void {
     // TODO: Shove these lines in here, and also the else portion
     // pub fn metaInfo(self: @This()) struct { service: @TypeOf(sts), action: @TypeOf(sts.get_caller_identity) } {
     //     return .{ .service = sts, .action = sts.get_caller_identity };
     // }
     // We want to add a short "get my parents" function into the response
-    try writer.print("{s}    ", .{prefix});
+    var child_state = state;
+    child_state.indent_level += 1;
+    try outputIndent(child_state, writer);
     _ = try writer.write("pub fn metaInfo() struct { ");
     try writer.print("service_metadata: @TypeOf(service_metadata), action: @TypeOf({s})", .{operation_name});
-    _ = try writer.write(" } {\n" ++ prefix ++ "        return .{ .service_metadata = service_metadata, ");
+    _ = try writer.write(" } {\n");
+    child_state.indent_level += 1;
+    try outputIndent(child_state, writer);
+    _ = try writer.write("return .{ .service_metadata = service_metadata, ");
     try writer.print(".action = {s}", .{operation_name});
-    _ = try writer.write(" };\n" ++ prefix ++ "    }\n" ++ prefix ++ "}");
+    _ = try writer.write(" };\n");
+    child_state.indent_level -= 1;
+    try outputIndent(child_state, writer);
+    _ = try writer.write("}\n");
+    try outputIndent(state, writer);
+    try writer.writeByte('}');
 }
 fn getErrorName(err_name: []const u8) []const u8 {
     if (endsWith("Exception", err_name))
@@ -231,7 +277,8 @@ fn endsWith(item: []const u8, str: []const u8) bool {
     return std.mem.eql(u8, item, str[str.len - item.len ..]);
 }
 /// return type is anyerror!void as this is a recursive function, so the compiler cannot properly infer error types
-fn generateTypeFor(allocator: *std.mem.Allocator, shape_id: []const u8, shapes: anytype, writer: anytype, prefix: []const u8, all_required: bool, type_stack: anytype, end_structure: bool) anyerror!void {
+fn generateTypeFor(shape_id: []const u8, shapes: std.StringHashMap(smithy.ShapeInfo), writer: anytype, state: GenerationState, end_structure: bool) anyerror!bool {
+    var rc = false;
     if (shapes.get(shape_id) == null) {
         std.debug.print("Shape ID not found. This is most likely a bug. Shape ID: {s}\n", .{shape_id});
         return error.InvalidType;
@@ -242,7 +289,7 @@ fn generateTypeFor(allocator: *std.mem.Allocator, shape_id: []const u8, shapes:
     const shape = shape_info.shape;
     // Check for ourselves up the stack
     var self_occurences: u8 = 0;
-    for (type_stack.items) |i| {
+    for (state.type_stack.items) |i| {
         // NOTE: shapes.get isn't providing a consistent pointer - is it allocating each time?
         // we will therefore need to compare ids
         if (std.mem.eql(u8, i.*.id, shape_info.id))
@@ -264,61 +311,78 @@ fn generateTypeFor(allocator: *std.mem.Allocator, shape_id: []const u8, shapes:
         // type to properly reference. Realistically, AWS or the service
         // must be blocking deep recursion somewhere or this would be a great
         // DOS attack
-        try generateSimpleTypeFor("nothing", "[]const u8", writer, all_required);
+        try generateSimpleTypeFor("nothing", "[]const u8", writer);
         std.log.warn("Type cycle detected, limiting depth. Type: {s}", .{shape_id});
-        // std.log.info("  Type stack:\n", .{});
-        // for (type_stack.items) |i|
-        //     std.log.info("  {s}", .{i.*.id});
-        return;
+        // if (std.mem.eql(u8, "com.amazonaws.workmail#Timestamp", shape_id)) {
+        //     std.log.info("  Type stack:\n", .{});
+        //     for (state.type_stack.items) |i|
+        //         std.log.info("  {s}", .{i.*.id});
+        // }
+        return false; // not a map
     }
-    try type_stack.append(&shape_info);
+    try state.type_stack.append(&shape_info);
+    defer _ = state.type_stack.pop();
     switch (shape) {
         .structure => {
-            try generateComplexTypeFor(allocator, shape.structure.members, "struct", shapes, writer, prefix, all_required, type_stack);
+            try generateComplexTypeFor(shape_id, shape.structure.members, "struct", shapes, writer, state);
             if (end_structure) {
                 // epilog
-                try writer.print("{s}", .{prefix});
+                try outputIndent(state, writer);
                 _ = try writer.write("}");
             }
         },
         .uniontype => {
-            try generateComplexTypeFor(allocator, shape.uniontype.members, "union", shapes, writer, prefix, all_required, type_stack);
+            try generateComplexTypeFor(shape_id, shape.uniontype.members, "union", shapes, writer, state);
             // epilog
-            try writer.print("{s}", .{prefix});
+            try outputIndent(state, writer);
             _ = try writer.write("}");
         },
-        .string => |s| try generateSimpleTypeFor(s, "[]const u8", writer, all_required),
-        .integer => |s| try generateSimpleTypeFor(s, "i64", writer, all_required),
+        .string => |s| try generateSimpleTypeFor(s, "[]const u8", writer),
+        .integer => |s| try generateSimpleTypeFor(s, "i64", writer),
         .list => {
             _ = try writer.write("[]");
-            try generateTypeFor(allocator, shape.list.member_target, shapes, writer, prefix, all_required, type_stack, true);
+            // The serializer will have to deal with the idea we might be an array
+            return try generateTypeFor(shape.list.member_target, shapes, writer, state, true);
         },
         .set => {
             _ = try writer.write("[]");
-            try generateTypeFor(allocator, shape.set.member_target, shapes, writer, prefix, all_required, type_stack, true);
+            // The serializer will have to deal with the idea we might be an array
+            return try generateTypeFor(shape.set.member_target, shapes, writer, state, true);
         },
-        .timestamp => |s| try generateSimpleTypeFor(s, "i64", writer, all_required),
-        .blob => |s| try generateSimpleTypeFor(s, "[]const u8", writer, all_required),
-        .boolean => |s| try generateSimpleTypeFor(s, "bool", writer, all_required),
-        .double => |s| try generateSimpleTypeFor(s, "f64", writer, all_required),
-        .float => |s| try generateSimpleTypeFor(s, "f32", writer, all_required),
-        .long => |s| try generateSimpleTypeFor(s, "i64", writer, all_required),
+        .timestamp => |s| try generateSimpleTypeFor(s, "i64", writer),
+        .blob => |s| try generateSimpleTypeFor(s, "[]const u8", writer),
+        .boolean => |s| try generateSimpleTypeFor(s, "bool", writer),
+        .double => |s| try generateSimpleTypeFor(s, "f64", writer),
+        .float => |s| try generateSimpleTypeFor(s, "f32", writer),
+        .long => |s| try generateSimpleTypeFor(s, "i64", writer),
         .map => {
             _ = try writer.write("[]struct {\n");
-            const new_prefix = try std.fmt.allocPrint(allocator, "    {s}", .{prefix});
-            defer allocator.free(new_prefix);
-            try writer.print("{s}    key: ", .{prefix});
-            if (!all_required) try writeOptional(shape.map.traits, writer, null);
-            try generateTypeFor(allocator, shape.map.key, shapes, writer, prefix, all_required, type_stack, true);
-            if (!all_required) try writeOptional(shape.map.traits, writer, " = null");
+            var child_state = state;
+            child_state.indent_level += 1;
+            try outputIndent(child_state, writer);
+            _ = try writer.write("key: ");
+            try writeOptional(shape.map.traits, writer, null);
+            var sub_maps = std.ArrayList([]const u8).init(state.allocator);
+            defer sub_maps.deinit();
+            if (try generateTypeFor(shape.map.key, shapes, writer, child_state, true))
+                try sub_maps.append("key");
+            try writeOptional(shape.map.traits, writer, " = null");
             _ = try writer.write(",\n");
-            try writer.print("{s}    value: ", .{prefix});
-            if (!all_required) try writeOptional(shape.map.traits, writer, null);
-            try generateTypeFor(allocator, shape.map.key, shapes, writer, prefix, all_required, type_stack, true);
-            if (!all_required) try writeOptional(shape.map.traits, writer, " = null");
+            try outputIndent(child_state, writer);
+            _ = try writer.write("value: ");
+            try writeOptional(shape.map.traits, writer, null);
+            if (try generateTypeFor(shape.map.value, shapes, writer, child_state, true))
+                try sub_maps.append("value");
+            try writeOptional(shape.map.traits, writer, " = null");
             _ = try writer.write(",\n");
-            _ = try writer.write(prefix);
+            if (sub_maps.items.len > 0) {
+                _ = try writer.write("\n");
+                try writeStringify(state, sub_maps.items, writer);
+            }
+            try outputIndent(state, writer);
             _ = try writer.write("}");
+
+            rc = true;
         },
         else => {
             std.log.err("encountered unimplemented shape type {s} for shape_id {s}. Generated code will not compile", .{ @tagName(shape), shape_id });
@@ -326,25 +390,19 @@ fn generateTypeFor(allocator: *std.mem.Allocator, shape_id: []const u8, shapes:
             // return error{UnimplementedShapeType}.UnimplementedShapeType;
         },
     }
-    _ = type_stack.pop();
+    return rc;
 }
 
-// fn generateSimpleTypeFor(shape: anytype, type_name: []const u8, writer: anytype, _: bool) !void {
-fn generateSimpleTypeFor(_: anytype, type_name: []const u8, writer: anytype, all_required: bool) !void {
-    // current compiler checks unused variables, but can't handle multiple unused
-    // function parameters. We don't want to change the signature in case we need to work with
-    // these in the future, so this stupid code is only here to trick the compiler
-    if (all_required or !all_required)
-        _ = try writer.write(type_name); // This had required stuff but the problem was elsewhere. Better to leave as function just in case
+fn generateSimpleTypeFor(_: anytype, type_name: []const u8, writer: anytype) !void {
+    _ = try writer.write(type_name); // This had required stuff but the problem was elsewhere. Better to leave as function just in case
 }
-
-fn generateComplexTypeFor(allocator: *std.mem.Allocator, members: []smithy.TypeMember, type_type_name: []const u8, shapes: anytype, writer: anytype, prefix: []const u8, all_required: bool, type_stack: anytype) anyerror!void {
+fn generateComplexTypeFor(shape_id: []const u8, members: []smithy.TypeMember, type_type_name: []const u8, shapes: std.StringHashMap(smithy.ShapeInfo), writer: anytype, state: GenerationState) anyerror!void {
+    _ = shape_id;
     const Mapping = struct { snake: []const u8, json: []const u8 };
-    var json_field_name_mappings = try std.ArrayList(Mapping).initCapacity(allocator, members.len);
+    var json_field_name_mappings = try std.ArrayList(Mapping).initCapacity(state.allocator, members.len);
     defer {
-        for (json_field_name_mappings.items) |mapping| {
-            allocator.free(mapping.snake);
-        }
+        for (json_field_name_mappings.items) |mapping|
+            state.allocator.free(mapping.snake);
         json_field_name_mappings.deinit();
     }
     // There is an httpQueryParams trait as well, but nobody is using it. API GW
@@ -353,28 +411,31 @@ fn generateComplexTypeFor(allocator: *std.mem.Allocator, members: []smithy.TypeM
     // Same with httpPayload
     //
     // httpLabel is interesting - right now we just assume anything can be used - do we need to track this?
-    var http_query_mappings = try std.ArrayList(Mapping).initCapacity(allocator, members.len);
+    var http_query_mappings = try std.ArrayList(Mapping).initCapacity(state.allocator, members.len);
     defer {
-        for (http_query_mappings.items) |mapping| {
-            allocator.free(mapping.snake);
-        }
+        for (http_query_mappings.items) |mapping|
+            state.allocator.free(mapping.snake);
         http_query_mappings.deinit();
     }
-    var http_header_mappings = try std.ArrayList(Mapping).initCapacity(allocator, members.len);
+    var http_header_mappings = try std.ArrayList(Mapping).initCapacity(state.allocator, members.len);
     defer {
-        for (http_header_mappings.items) |mapping| {
-            allocator.free(mapping.snake);
-        }
+        for (http_header_mappings.items) |mapping|
+            state.allocator.free(mapping.snake);
         http_header_mappings.deinit();
     }
+    var map_fields = std.ArrayList([]const u8).init(state.allocator);
+    defer {
+        for (map_fields.items) |f| state.allocator.free(f);
+        map_fields.deinit();
+    }
     // prolog. We'll rely on caller to get the spacing correct here
     _ = try writer.write(type_type_name);
     _ = try writer.write(" {\n");
+    var child_state = state;
+    child_state.indent_level += 1;
     for (members) |member| {
-        const new_prefix = try std.fmt.allocPrint(allocator, "    {s}", .{prefix});
-        defer allocator.free(new_prefix);
         // This is our mapping
-        const snake_case_member = try snake.fromPascalCase(allocator, member.name);
+        const snake_case_member = try snake.fromPascalCase(state.allocator, member.name);
         // So it looks like some services have duplicate names?! Check out "httpMethod"
         // in API Gateway. Not sure what we're supposed to do there. Checking the go
         // sdk, they move this particular duplicate to 'http_method' - not sure yet
@@ -384,20 +445,24 @@ fn generateComplexTypeFor(allocator: *std.mem.Allocator, members: []smithy.TypeM
             switch (trait) {
                 .json_name => {
                     found_name_trait = true;
-                    json_field_name_mappings.appendAssumeCapacity(.{ .snake = try allocator.dupe(u8, snake_case_member), .json = trait.json_name });
+                    json_field_name_mappings.appendAssumeCapacity(.{ .snake = try state.allocator.dupe(u8, snake_case_member), .json = trait.json_name });
                 },
-                .http_query => http_query_mappings.appendAssumeCapacity(.{ .snake = try allocator.dupe(u8, snake_case_member), .json = trait.http_query }),
-                .http_header => http_header_mappings.appendAssumeCapacity(.{ .snake = try allocator.dupe(u8, snake_case_member), .json = trait.http_header }),
+                .http_query => http_query_mappings.appendAssumeCapacity(.{ .snake = try state.allocator.dupe(u8, snake_case_member), .json = trait.http_query }),
+                .http_header => http_header_mappings.appendAssumeCapacity(.{ .snake = try state.allocator.dupe(u8, snake_case_member), .json = trait.http_header }),
                 else => {},
             }
         }
         if (!found_name_trait)
-            json_field_name_mappings.appendAssumeCapacity(.{ .snake = try allocator.dupe(u8, snake_case_member), .json = member.name });
-        defer allocator.free(snake_case_member);
-        try writer.print("{s}    {s}: ", .{ prefix, avoidReserved(snake_case_member) });
-        if (!all_required) try writeOptional(member.traits, writer, null);
-        try generateTypeFor(allocator, member.target, shapes, writer, new_prefix, all_required, type_stack, true);
-        if (!all_required and !std.mem.eql(u8, "union", type_type_name))
+            json_field_name_mappings.appendAssumeCapacity(.{ .snake = try state.allocator.dupe(u8, snake_case_member), .json = member.name });
+        defer state.allocator.free(snake_case_member);
+        try outputIndent(child_state, writer);
+        const member_name = avoidReserved(snake_case_member);
+        try writer.print("{s}: ", .{member_name});
+        try writeOptional(member.traits, writer, null);
+        if (try generateTypeFor(member.target, shapes, writer, child_state, true))
+            try map_fields.append(try std.fmt.allocPrint(state.allocator, "{s}", .{member_name}));
+
+        if (!std.mem.eql(u8, "union", type_type_name))
             try writeOptional(member.traits, writer, " = null");
         _ = try writer.write(",\n");
     }
@@ -409,12 +474,10 @@ fn generateComplexTypeFor(allocator: *std.mem.Allocator, members: []smithy.TypeM
     //     .marker = "Marker",
     //     .max_items = "MaxItems",
     // };
-    var constprefix = try std.fmt.allocPrint(allocator, "{s}    ", .{prefix});
-    defer allocator.free(constprefix);
     if (http_query_mappings.items.len > 0) _ = try writer.write("\n");
-    try writeMappings(constprefix, "pub ", "http_query", http_query_mappings, writer);
+    try writeMappings(child_state, "pub ", "http_query", http_query_mappings, false, writer);
     if (http_query_mappings.items.len > 0 and http_header_mappings.items.len > 0) _ = try writer.write("\n");
-    try writeMappings(constprefix, "pub ", "http_header", http_header_mappings, writer);
+    try writeMappings(child_state, "pub ", "http_header", http_header_mappings, false, writer);
 
     // Add in json mappings. The function looks like this:
     //
@@ -426,23 +489,64 @@ fn generateComplexTypeFor(allocator: *std.mem.Allocator, members: []smithy.TypeM
     //     return @field(mappings, field_name);
     // }
     //
-    var fieldnameprefix = try std.fmt.allocPrint(allocator, "{s}        ", .{prefix});
-    defer allocator.free(fieldnameprefix);
-    try writer.print("\n{s}    pub fn jsonFieldNameFor(_: @This(), comptime field_name: []const u8) []const u8 ", .{prefix});
-    _ = try writer.write("{\n");
-    try writeMappings(fieldnameprefix, "", "mappings", json_field_name_mappings, writer);
-    try writer.print("{s}        return @field(mappings, field_name);\n{s}", .{ prefix, prefix });
-    _ = try writer.write("    }\n");
+    try writer.writeByte('\n');
+    try outputIndent(child_state, writer);
+    _ = try writer.write("pub fn jsonFieldNameFor(_: @This(), comptime field_name: []const u8) []const u8 {\n");
+    var grandchild_state = child_state;
+    grandchild_state.indent_level += 1;
+    // We need to force output here becaseu we're referencing the field in the return statement below
+    try writeMappings(grandchild_state, "", "mappings", json_field_name_mappings, true, writer);
+    try outputIndent(grandchild_state, writer);
+    _ = try writer.write("return @field(mappings, field_name);\n");
+    try outputIndent(child_state, writer);
+    _ = try writer.write("}\n");
+    try writeStringify(child_state, map_fields.items, writer);
 }
 
-fn writeMappings(prefix: []const u8, @"pub": []const u8, mapping_name: []const u8, mappings: anytype, writer: anytype) !void {
-    if (mappings.items.len == 0) return;
-    try writer.print("{s}{s}const {s} = .", .{ prefix, @"pub", mapping_name });
-    _ = try writer.write("{\n");
-    for (mappings.items) |mapping| {
-        try writer.print("{s}    .{s} = \"{s}\",\n", .{ prefix, avoidReserved(mapping.snake), mapping.json });
+fn writeStringify(state: GenerationState, fields: [][]const u8, writer: anytype) !void {
+    if (fields.len > 0) {
+        // pub fn jsonStringifyField(self: @This(), comptime field_name: []const u8, options: anytype, out_stream: anytype) !bool {
+        //     if (std.mem.eql(u8, "tags", field_name))
+        //         return try serializeMap(self.tags, self.jsonFieldNameFor("tags"), options, out_stream);
+        //     return false;
+        // }
+        var child_state = state;
+        child_state.indent_level += 1;
+        try writer.writeByte('\n');
+        try outputIndent(state, writer);
+        _ = try writer.write("pub fn jsonStringifyField(self: @This(), comptime field_name: []const u8, options: anytype, out_stream: anytype) !bool {\n");
+        var return_state = child_state;
+        return_state.indent_level += 1;
+        for (fields) |field| {
+            try outputIndent(child_state, writer);
+            try writer.print("if (std.mem.eql(u8, \"{s}\", field_name))\n", .{field});
+            try outputIndent(return_state, writer);
+            try writer.print("return try serializeMap(self.{s}, self.jsonFieldNameFor(\"{s}\"), options, out_stream);\n", .{ field, field });
+        }
+        try outputIndent(child_state, writer);
+        _ = try writer.write("return false;\n");
+        try outputIndent(state, writer);
+        _ = try writer.write("}\n");
     }
-    _ = try writer.write(prefix);
+}
+
+fn writeMappings(state: GenerationState, @"pub": []const u8, mapping_name: []const u8, mappings: anytype, force_output: bool, writer: anytype) !void {
+    if (mappings.items.len == 0 and !force_output) return;
+    try outputIndent(state, writer);
+    if (mappings.items.len == 0) {
+        try writer.print("{s}const {s} = ", .{ @"pub", mapping_name });
+        _ = try writer.write(".{};\n");
+        return;
+    }
+    try writer.print("{s}const {s} = .", .{ @"pub", mapping_name });
+    _ = try writer.write("{\n");
+    var child_state = state;
+    child_state.indent_level += 1;
+    for (mappings.items) |mapping| {
+        try outputIndent(child_state, writer);
+        try writer.print(".{s} = \"{s}\",\n", .{ avoidReserved(mapping.snake), mapping.json });
+    }
+    try outputIndent(state, writer);
     _ = try writer.write("};\n");
 }
 

smithy/src/smithy.zig

@@ -620,6 +620,7 @@ fn getTrait(trait_type: []const u8, value: std.json.Value) SmithyParseError!?Tra
         \\smithy.api#xmlName
         \\smithy.waiters#waitable
     ;
+    // var iterator = std.mem.split(u8, list, "\n"); // Uncomment for 0.8.1
     var iterator = std.mem.split(list, "\n");
     while (iterator.next()) |known_but_unimplemented| {
         if (std.mem.eql(u8, trait_type, known_but_unimplemented))

src/aws.zig

@@ -100,12 +100,14 @@ pub fn Request(comptime action: anytype) type {
                 .path = Action.http_config.uri,
             };
 
-            log.debug("Rest JSON v1 method: {s}", .{aws_request.method});
-            log.debug("Rest JSON v1 success code: {d}", .{Action.http_config.success_code});
-            log.debug("Rest JSON v1 raw uri: {s}", .{Action.http_config.uri});
-
+            log.debug("Rest JSON v1 method: '{s}'", .{aws_request.method});
+            log.debug("Rest JSON v1 success code: '{d}'", .{Action.http_config.success_code});
+            log.debug("Rest JSON v1 raw uri: '{s}'", .{Action.http_config.uri});
+            aws_request.path = try buildPath(options.client.allocator, Action.http_config.uri, ActionRequest, request);
+            defer options.client.allocator.free(aws_request.path);
+            log.debug("Rest JSON v1 processed uri: '{s}'", .{aws_request.path});
             aws_request.query = try buildQuery(options.client.allocator, request);
-            log.debug("Rest JSON v1 query: {s}", .{aws_request.query});
+            log.debug("Rest JSON v1 query: '{s}'", .{aws_request.query});
             defer options.client.allocator.free(aws_request.query);
             // We don't know if we need a body...guessing here, this should cover most
             var buffer = std.ArrayList(u8).init(options.client.allocator);
@@ -115,6 +117,7 @@ pub fn Request(comptime action: anytype) type {
             if (std.mem.eql(u8, "PUT", aws_request.method) or std.mem.eql(u8, "POST", aws_request.method)) {
                 try json.stringify(request, .{ .whitespace = .{} }, buffer.writer());
             }
+            aws_request.body = buffer.items;
 
             return try Self.callAws(aws_request, .{
                 .success_http_code = Action.http_config.success_code,
@@ -244,7 +247,10 @@ pub fn Request(comptime action: anytype) type {
             // TODO: Handle XML
             if (!isJson) return error.XmlUnimplemented;
 
-            var stream = json.TokenStream.init(response.body);
+            const SResponse = if (Self.service_meta.aws_protocol != .query and Self.service_meta.aws_protocol != .ec2_query)
+                action.Response
+            else
+                ServerResponse(action);
 
             const parser_options = json.ParseOptions{
                 .allocator = options.client.allocator,
@@ -253,12 +259,18 @@ pub fn Request(comptime action: anytype) type {
                 .allow_unknown_fields = true, // new option. Cannot yet handle non-struct fields though
                 .allow_missing_fields = false, // new option. Cannot yet handle non-struct fields though
             };
+            if (std.meta.fields(SResponse).len == 0) // We don't care about the body if there are no fields
+                // Do we care if an unexpected body comes in?
+                return FullResponseType{
+                    .response = .{},
+                    .response_metadata = .{
+                        .request_id = try requestIdFromHeaders(aws_request, response, options),
+                    },
+                    .parser_options = parser_options,
+                    .raw_parsed = .{ .raw = .{} },
+                };
 
-            // const SResponse = ServerResponse(request);
-            const SResponse = if (Self.service_meta.aws_protocol != .query and Self.service_meta.aws_protocol != .ec2_query)
-                action.Response
-            else
-                ServerResponse(action);
+            var stream = json.TokenStream.init(response.body);
 
             const parsed_response = json.parse(SResponse, &stream, parser_options) catch |e| {
                 log.err(
@@ -277,23 +289,10 @@ pub fn Request(comptime action: anytype) type {
             };
 
             if (Self.service_meta.aws_protocol != .query and Self.service_meta.aws_protocol != .ec2_query) {
-                var request_id: []u8 = undefined;
-                var found = false;
-                for (response.headers) |h| {
-                    if (std.ascii.eqlIgnoreCase(h.name, "X-Amzn-RequestId")) {
-                        found = true;
-                        request_id = try std.fmt.allocPrint(options.client.allocator, "{s}", .{h.value}); // will be freed in FullR.deinit()
-                    }
-                }
-                if (!found) {
-                    try reportTraffic(options.client.allocator, "Request ID not found", aws_request, response, log.err);
-                    return error.RequestIdNotFound;
-                }
-
                 return FullResponseType{
                     .response = parsed_response,
                     .response_metadata = .{
-                        .request_id = request_id,
+                        .request_id = try requestIdFromHeaders(aws_request, response, options),
                     },
                     .parser_options = parser_options,
                     .raw_parsed = .{ .raw = parsed_response },
@@ -322,6 +321,21 @@ pub fn Request(comptime action: anytype) type {
     };
 }
 
+fn requestIdFromHeaders(request: awshttp.HttpRequest, response: awshttp.HttpResult, options: Options) ![]u8 {
+    var request_id: []u8 = undefined;
+    var found = false;
+    for (response.headers) |h| {
+        if (std.ascii.eqlIgnoreCase(h.name, "X-Amzn-RequestId")) {
+            found = true;
+            request_id = try std.fmt.allocPrint(options.client.allocator, "{s}", .{h.value}); // will be freed in FullR.deinit()
+        }
+    }
+    if (!found) {
+        try reportTraffic(options.client.allocator, "Request ID not found", request, response, log.err);
+        return error.RequestIdNotFound;
+    }
+    return request_id;
+}
 fn ServerResponse(comptime action: anytype) type {
     const T = action.Response;
     // NOTE: The non-standard capitalization here is used as a performance
@@ -398,6 +412,80 @@ fn queryFieldTransformer(field_name: []const u8, encoding_options: url.EncodingO
     return try case.snakeToPascal(encoding_options.allocator.?, field_name);
 }
 
+fn buildPath(allocator: *std.mem.Allocator, raw_uri: []const u8, comptime ActionRequest: type, request: anytype) ![]const u8 {
+    var buffer = try std.ArrayList(u8).initCapacity(allocator, raw_uri.len);
+    // const writer = buffer.writer();
+    defer buffer.deinit();
+    var in_var = false;
+    var start: u64 = 0;
+    for (raw_uri) |c, inx| {
+        switch (c) {
+            '{' => {
+                in_var = true;
+                start = inx + 1;
+            },
+            '}' => {
+                in_var = false;
+                const replacement_var = raw_uri[start..inx];
+                inline for (std.meta.fields(ActionRequest)) |field| {
+                    if (std.mem.eql(u8, request.jsonFieldNameFor(field.name), replacement_var)) {
+                        var replacement_buffer = try std.ArrayList(u8).initCapacity(allocator, raw_uri.len);
+                        defer replacement_buffer.deinit();
+                        var encoded_buffer = try std.ArrayList(u8).initCapacity(allocator, raw_uri.len);
+                        defer encoded_buffer.deinit();
+                        const replacement_writer = replacement_buffer.writer();
+                        // std.mem.replacementSize
+                        try json.stringify(
+                            @field(request, field.name),
+                            .{},
+                            replacement_writer,
+                        );
+                        const trimmed_replacement_val = std.mem.trim(u8, replacement_buffer.items, "\"");
+                        try uriEncode(trimmed_replacement_val, encoded_buffer.writer());
+                        try buffer.appendSlice(encoded_buffer.items);
+                    }
+                }
+            },
+            else => if (!in_var) {
+                try buffer.append(c);
+            } else {},
+        }
+    }
+    return buffer.toOwnedSlice();
+}
+
+fn uriEncode(input: []const u8, writer: anytype) !void {
+    for (input) |c|
+        try uriEncodeByte(c, writer);
+}
+
+fn uriEncodeByte(char: u8, writer: anytype) !void {
+    switch (char) {
+        '!' => _ = try writer.write("%21"),
+        '#' => _ = try writer.write("%23"),
+        '$' => _ = try writer.write("%24"),
+        '&' => _ = try writer.write("%26"),
+        '\'' => _ = try writer.write("%27"),
+        '(' => _ = try writer.write("%28"),
+        ')' => _ = try writer.write("%29"),
+        '*' => _ = try writer.write("%2A"),
+        '+' => _ = try writer.write("%2B"),
+        ',' => _ = try writer.write("%2C"),
+        '/' => _ = try writer.write("%2F"),
+        ':' => _ = try writer.write("%3A"),
+        ';' => _ = try writer.write("%3B"),
+        '=' => _ = try writer.write("%3D"),
+        '?' => _ = try writer.write("%3F"),
+        '@' => _ = try writer.write("%40"),
+        '[' => _ = try writer.write("%5B"),
+        ']' => _ = try writer.write("%5D"),
+        '%' => _ = try writer.write("%25"),
+        else => {
+            _ = try writer.writeByte(char);
+        },
+    }
+}
+
 fn buildQuery(allocator: *std.mem.Allocator, request: anytype) ![]const u8 {
     // query should look something like this:
     // pub const http_query = .{
@@ -408,22 +496,15 @@ fn buildQuery(allocator: *std.mem.Allocator, request: anytype) ![]const u8 {
     var buffer = std.ArrayList(u8).init(allocator);
     const writer = buffer.writer();
     defer buffer.deinit();
-    var has_begun = false;
+    var prefix = "?";
     const Req = @TypeOf(request);
     if (declaration(Req, "http_query") == null)
         return buffer.toOwnedSlice();
     const query_arguments = Req.http_query;
     inline for (@typeInfo(@TypeOf(query_arguments)).Struct.fields) |arg| {
         const val = @field(request, arg.name);
-        if (@typeInfo(@TypeOf(val)) == .Optional) {
-            if (val) |v| {
-                try addQueryArg(@field(query_arguments, arg.name), v, writer, !has_begun);
-                has_begun = true;
-            }
-        } else {
-            try addQueryArg(@field(query_arguments, arg.name), val, writer, !has_begun);
-            has_begun = true;
-        }
+        if (try addQueryArg(arg.field_type, prefix, @field(query_arguments, arg.name), val, writer))
+            prefix = "&";
     }
     return buffer.toOwnedSlice();
 }
@@ -436,15 +517,103 @@ fn declaration(comptime T: type, name: []const u8) ?std.builtin.TypeInfo.Declara
     return null;
 }
 
-fn addQueryArg(key: []const u8, value: anytype, writer: anytype, start: bool) !void {
-    if (start)
-        _ = try writer.write("?")
-    else
-        _ = try writer.write("&");
-    // TODO: url escaping
-    try writer.print("{s}=", .{key});
-    try json.stringify(value, .{}, writer);
+fn addQueryArg(comptime ValueType: type, prefix: []const u8, key: []const u8, value: anytype, writer: anytype) !bool {
+    switch (@typeInfo(@TypeOf(value))) {
+        .Optional => {
+            if (value) |v|
+                return try addQueryArg(ValueType, prefix, key, v, writer);
+            return false;
+        },
+        // if this is a pointer, we want to make sure it is more than just a string
+        .Pointer => |ptr| {
+            if (ptr.child == u8 or ptr.size != .Slice) {
+                // This is just a string
+                return try addBasicQueryArg(prefix, key, value, writer);
+            }
+            var p = prefix;
+            for (value) |li| {
+                if (try addQueryArg(ValueType, p, key, li, writer))
+                    p = "&";
+            }
+            return std.mem.eql(u8, "&", p);
+        },
+        .Array => |arr| {
+            if (arr.child == u8)
+                return try addBasicQueryArg(prefix, key, value, writer);
+            var p = prefix;
+            for (value) |li| {
+                if (try addQueryArg(ValueType, p, key, li, writer))
+                    p = "&";
+            }
+            return std.mem.eql(u8, "&", p);
+        },
+        else => {
+            return try addBasicQueryArg(prefix, key, value, writer);
+        },
+    }
 }
+fn addBasicQueryArg(prefix: []const u8, key: []const u8, value: anytype, writer: anytype) !bool {
+    _ = try writer.write(prefix);
+    // TODO: url escaping
+    try uriEncode(key, writer);
+    _ = try writer.write("=");
+    try json.stringify(value, .{}, ignoringWriter(uriEncodingWriter(writer).writer(), '"').writer());
+    return true;
+}
+pub fn uriEncodingWriter(child_stream: anytype) UriEncodingWriter(@TypeOf(child_stream)) {
+    return .{ .child_stream = child_stream };
+}
+
+/// A Writer that ignores a character
+pub fn UriEncodingWriter(comptime WriterType: type) type {
+    return struct {
+        child_stream: WriterType,
+
+        pub const Error = WriterType.Error;
+        pub const Writer = std.io.Writer(*Self, Error, write);
+
+        const Self = @This();
+
+        pub fn write(self: *Self, bytes: []const u8) Error!usize {
+            try uriEncode(bytes, self.child_stream);
+            return bytes.len; // We say that all bytes are "written", even if they're not, as caller may be retrying
+        }
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+    };
+}
+
+pub fn ignoringWriter(child_stream: anytype, ignore: u8) IgnoringWriter(@TypeOf(child_stream)) {
+    return .{ .child_stream = child_stream, .ignore = ignore };
+}
+
+/// A Writer that ignores a character
+pub fn IgnoringWriter(comptime WriterType: type) type {
+    return struct {
+        child_stream: WriterType,
+        ignore: u8,
+
+        pub const Error = WriterType.Error;
+        pub const Writer = std.io.Writer(*Self, Error, write);
+
+        const Self = @This();
+
+        pub fn write(self: *Self, bytes: []const u8) Error!usize {
+            for (bytes) |b| {
+                if (b != self.ignore)
+                    try self.child_stream.writeByte(b);
+            }
+            return bytes.len; // We say that all bytes are "written", even if they're not, as caller may be retrying
+        }
+
+        pub fn writer(self: *Self) Writer {
+            return .{ .context = self };
+        }
+    };
+}
+
 fn reportTraffic(allocator: *std.mem.Allocator, info: []const u8, request: awshttp.HttpRequest, response: awshttp.HttpResult, comptime reporter: fn (comptime []const u8, anytype) void) !void {
     var msg = std.ArrayList(u8).init(allocator);
     defer msg.deinit();
@@ -472,6 +641,42 @@ fn reportTraffic(allocator: *std.mem.Allocator, info: []const u8, request: awsht
     reporter("{s}\n", .{msg.items});
 }
 
+// TODO: Where does this belong really?
+fn typeForField(comptime T: type, field_name: []const u8) !type {
+    const ti = @typeInfo(T);
+    switch (ti) {
+        .Struct => {
+            inline for (ti.Struct.fields) |field| {
+                if (std.mem.eql(u8, field.name, field_name))
+                    return field.field_type;
+            }
+        },
+        else => return error.TypeIsNotAStruct, // should not hit this
+    }
+    return error.FieldNotFound;
+}
+
+test "custom serialization for map objects" {
+    const allocator = std.testing.allocator;
+    var buffer = std.ArrayList(u8).init(allocator);
+    defer buffer.deinit();
+    var tags = try std.ArrayList(@typeInfo(try typeForField(services.lambda.tag_resource.Request, "tags")).Pointer.child).initCapacity(allocator, 2);
+    defer tags.deinit();
+    tags.appendAssumeCapacity(.{ .key = "Foo", .value = "Bar" });
+    tags.appendAssumeCapacity(.{ .key = "Baz", .value = "Qux" });
+    const req = services.lambda.tag_resource.Request{ .resource = "hello", .tags = tags.items };
+    try json.stringify(req, .{ .whitespace = .{} }, buffer.writer());
+    try std.testing.expectEqualStrings(
+        \\{
+        \\    "Resource": "hello",
+        \\    "Tags": {
+        \\        "Foo": "Bar",
+        \\        "Baz": "Qux"
+        \\    }
+        \\}
+    , buffer.items);
+}
+
 test "REST Json v1 builds proper queries" {
     const allocator = std.testing.allocator;
     const svs = Services(.{.lambda}){};
@@ -482,6 +687,52 @@ test "REST Json v1 builds proper queries" {
     defer allocator.free(query);
     try std.testing.expectEqualStrings("?MaxItems=1", query);
 }
+test "REST Json v1 handles reserved chars in queries" {
+    const allocator = std.testing.allocator;
+    const svs = Services(.{.lambda}){};
+    var keys = [_][]const u8{"Foo?I'm a crazy%dude"}; // Would love to have a way to express this without burning a var here
+    const request = svs.lambda.untag_resource.Request{
+        .tag_keys = keys[0..],
+        .resource = "hello",
+    };
+    const query = try buildQuery(allocator, request);
+    defer allocator.free(query);
+    try std.testing.expectEqualStrings("?tagKeys=Foo%3FI%27m a crazy%25dude", query);
+}
+test "REST Json v1 serializes lists in queries" {
+    const allocator = std.testing.allocator;
+    const svs = Services(.{.lambda}){};
+    var keys = [_][]const u8{ "Foo", "Bar" }; // Would love to have a way to express this without burning a var here
+    const request = svs.lambda.untag_resource.Request{
+        .tag_keys = keys[0..],
+        .resource = "hello",
+    };
+    const query = try buildQuery(allocator, request);
+    defer allocator.free(query);
+    try std.testing.expectEqualStrings("?tagKeys=Foo&tagKeys=Bar", query);
+}
+test "REST Json v1 buildpath substitutes" {
+    const allocator = std.testing.allocator;
+    const svs = Services(.{.lambda}){};
+    const request = svs.lambda.list_functions.Request{
+        .max_items = 1,
+    };
+    const input_path = "https://myhost/{MaxItems}/";
+    const output_path = try buildPath(allocator, input_path, @TypeOf(request), request);
+    defer allocator.free(output_path);
+    try std.testing.expectEqualStrings("https://myhost/1/", output_path);
+}
+test "REST Json v1 buildpath handles restricted characters" {
+    const allocator = std.testing.allocator;
+    const svs = Services(.{.lambda}){};
+    const request = svs.lambda.list_functions.Request{
+        .marker = ":",
+    };
+    const input_path = "https://myhost/{Marker}/";
+    const output_path = try buildPath(allocator, input_path, @TypeOf(request), request);
+    defer allocator.free(output_path);
+    try std.testing.expectEqualStrings("https://myhost/%3A/", output_path);
+}
 test "basic json request serialization" {
     const allocator = std.testing.allocator;
     const svs = Services(.{.dynamo_db}){};
@@ -546,6 +797,7 @@ test "layer object only" {
     const r = try json.parse(TestResponse, &stream, parser_options);
     json.parseFree(TestResponse, r, parser_options);
 }
+
 // Use for debugging json responses of specific requests
 // test "dummy request" {
 //     const allocator = std.testing.allocator;

src/awshttp.zig

@@ -580,9 +580,11 @@ pub const AwsHttp = struct {
             .service = c.aws_byte_cursor_from_c_str(@ptrCast([*c]const u8, signing_service)),
             .should_sign_header = null,
             .should_sign_header_ud = null,
+            // TODO: S3 does not double uri encode. Also not sure why normalizing
+            //       the path here is a flag - seems like it should always do this?
             .flags = c.bitfield_workaround_aws_signing_config_aws_flags{
-                .use_double_uri_encode = 0,
-                .should_normalize_uri_path = 0,
+                .use_double_uri_encode = 1,
+                .should_normalize_uri_path = 1,
                 .omit_session_token = 1,
             },
             .signed_body_value = c.aws_byte_cursor_from_c_str(""),

src/json.zig

@@ -1324,6 +1324,14 @@ pub const Value = union(enum) {
     }
 };
 
+pub fn dump(value: anytype) void {
+    var held = std.debug.getStderrMutex().acquire();
+    defer held.release();
+
+    const stderr = std.io.getStdErr().writer();
+    std.json.stringify(value, std.json.StringifyOptions{ .whitespace = null }, stderr) catch return;
+}
+
 test "Value.jsonStringify" {
     {
         var buffer: [10]u8 = undefined;
@@ -1402,7 +1410,7 @@ fn parsedEqual(a: anytype, b: @TypeOf(a)) bool {
             if (a == null or b == null) return false;
             return parsedEqual(a.?, b.?);
         },
-        .Union => {
+        .Union => |info| {
             if (info.tag_type) |UnionTag| {
                 const tag_a = std.meta.activeTag(a);
                 const tag_b = std.meta.activeTag(b);
@@ -2858,20 +2866,26 @@ pub fn stringify(
                     try out_stream.writeByte('\n');
                     try child_whitespace.outputIndent(out_stream);
                 }
-                if (comptime std.meta.trait.hasFn("jsonFieldNameFor")(T)) {
-                    const name = value.jsonFieldNameFor(Field.name);
-                    try stringify(name, options, out_stream);
-                } else {
-                    try stringify(Field.name, options, out_stream);
-                }
+                var field_written = false;
+                if (comptime std.meta.trait.hasFn("jsonStringifyField")(T))
+                    field_written = try value.jsonStringifyField(Field.name, child_options, out_stream);
 
-                try out_stream.writeByte(':');
-                if (child_options.whitespace) |child_whitespace| {
-                    if (child_whitespace.separator) {
-                        try out_stream.writeByte(' ');
+                if (!field_written) {
+                    if (comptime std.meta.trait.hasFn("jsonFieldNameFor")(T)) {
+                        const name = value.jsonFieldNameFor(Field.name);
+                        try stringify(name, options, out_stream);
+                    } else {
+                        try stringify(Field.name, options, out_stream);
                     }
+
+                    try out_stream.writeByte(':');
+                    if (child_options.whitespace) |child_whitespace| {
+                        if (child_whitespace.separator) {
+                            try out_stream.writeByte(' ');
+                        }
+                    }
+                    try stringify(@field(value, Field.name), child_options, out_stream);
                 }
-                try stringify(@field(value, Field.name), child_options, out_stream);
             }
             if (field_output) {
                 if (options.whitespace) |whitespace| {