switch serialiser to ArrayList for now

possibly later switch to a Writer or precount the number of
bytes that will be written

src/root.zig

@@ -34,8 +34,8 @@ pub const Object = union(enum) {
     float64: f64,
     string: []const u8,
     binary: []const u8,
-    array: []Object,
+    array: []const Object,
-    map: []MapEntry,
+    map: []const MapEntry,
     extension: struct { type: u8, bytes: []u8 },
 
     pub fn deinit(self: Object, alloc: std.mem.Allocator) void {

src/serialise.zig

@@ -13,165 +13,82 @@ fn intInRange(comptime T: type, i: i64) bool {
     return std.math.minInt(T) <= i and i <= std.math.maxInt(T);
 }
 
-fn serialise_int(alloc: std.mem.Allocator, i: i64) SerialiseError![]u8 {
+fn serialise_int(alloc: std.mem.Allocator, buf: *std.ArrayListUnmanaged(u8), i: i64) SerialiseError!void {
-    if (i < 0 and i >= std.math.minInt(i6)) {
+    if (i < 0 and i >= std.math.minInt(i6)) { // neg fixint
-        // neg fixint
+        std.mem.writeInt(i8, try buf.addManyAsArray(alloc, 1), @intCast(i), .big);
-        const bytes = try alloc.alloc(u8, 1);
 
-        std.mem.writeInt(i8, bytes[0..1], @intCast(i), .big);
+        return;
-
-        return bytes;
     }
 
-    if (intInRange(i8, i)) { // int8
+    inline for (0.., &[_]type{ i8, i16, i32, i64 }) |n, T| {
-        const bytes = try alloc.alloc(u8, 1 + 1);
+        if (intInRange(T, i)) {
+            try buf.ensureUnusedCapacity(alloc, 1 + @sizeOf(T));
 
-        bytes[0] = 0xd0;
+            try buf.append(alloc, 0xd0 + n);
 
-        std.mem.writeInt(i8, bytes[1..2], @intCast(i), .big);
+            std.mem.writeInt(T, try buf.addManyAsArray(alloc, @sizeOf(T)), @intCast(i), .big);
 
-        return bytes;
+            return;
+        }
     }
 
-    if (intInRange(i16, i)) { // int16
+    unreachable;
-        const bytes = try alloc.alloc(u8, 1 + 2);
-
-        bytes[0] = 0xd1;
-
-        std.mem.writeInt(i16, bytes[1..3], @intCast(i), .big);
-
-        return bytes;
-    }
-
-    if (intInRange(i32, i)) { // int32
-        const bytes = try alloc.alloc(u8, 1 + 4);
-
-        bytes[0] = 0xd2;
-
-        std.mem.writeInt(i32, bytes[1..5], @intCast(i), .big);
-
-        return bytes;
-    }
-
-    // int64
-    const bytes = try alloc.alloc(u8, 1 + 8);
-
-    bytes[0] = 0xd3;
-
-    std.mem.writeInt(i64, bytes[1..9], i, .big);
-
-    return bytes;
 }
 
 fn uintInRange(comptime T: type, u: u64) bool {
     return u <= std.math.maxInt(T);
 }
 
-fn serialise_uint(alloc: std.mem.Allocator, u: u64) SerialiseError![]u8 {
+fn serialise_uint(alloc: std.mem.Allocator, buf: *std.ArrayListUnmanaged(u8), u: u64) SerialiseError!void {
     if (uintInRange(u7, u)) { // pos fixint
-        const bytes = try alloc.alloc(u8, 1);
+        std.mem.writeInt(u8, try buf.addManyAsArray(alloc, 1), @intCast(u), .big);
 
-        std.mem.writeInt(u8, bytes[0..1], @intCast(u), .big);
+        return;
-
-        return bytes;
     }
 
-    if (uintInRange(u8, u)) { // uint8
+    inline for (0.., &[_]type{ u8, u16, u32, u64 }) |n, T| {
-        const bytes = try alloc.alloc(u8, 1 + 1);
+        if (uintInRange(T, u)) {
+            try buf.ensureUnusedCapacity(alloc, 1 + @sizeOf(T));
 
-        bytes[0] = 0xcc;
+            try buf.append(alloc, 0xcc + n);
 
-        std.mem.writeInt(u8, bytes[1..2], @intCast(u), .big);
+            std.mem.writeInt(T, try buf.addManyAsArray(alloc, @sizeOf(T)), @intCast(u), .big);
 
-        return bytes;
+            return;
+        }
     }
 
-    if (uintInRange(u16, u)) { // uint16
+    unreachable;
-        const bytes = try alloc.alloc(u8, 1 + 2);
-
-        bytes[0] = 0xcd;
-
-        std.mem.writeInt(u16, bytes[1..3], @intCast(u), .big);
-
-        return bytes;
-    }
-
-    if (uintInRange(u32, u)) { // uint32
-        const bytes = try alloc.alloc(u8, 1 + 4);
-
-        bytes[0] = 0xce;
-
-        std.mem.writeInt(u32, bytes[1..5], @intCast(u), .big);
-
-        return bytes;
-    }
-
-    // uint64
-    const bytes = try alloc.alloc(u8, 1 + 8);
-
-    bytes[0] = 0xcf;
-
-    std.mem.writeInt(u64, bytes[1..9], u, .big);
-
-    return bytes;
 }
 
-fn serialise_raw(alloc: std.mem.Allocator, s: []const u8, comptime kind: enum { string, binary }) SerialiseError![]u8 {
+fn serialise_raw(alloc: std.mem.Allocator, buf: *std.ArrayListUnmanaged(u8), s: []const u8, comptime kind: enum { string, binary }) SerialiseError!void {
-    // TODO: should we validate that s in UTF-8 here?
+    // TODO: should we validate that `s` is UTF-8 here?
 
     if (kind == .string and s.len <= 31) { // fixstr
-        const bytes = try alloc.alloc(u8, 1 + s.len);
+        try buf.ensureUnusedCapacity(alloc, 1 + s.len);
 
-        bytes[0] = 0b101_00000 | @as(u8, @intCast(s.len));
+        try buf.append(alloc, 0b101_00000 | @as(u8, @intCast(s.len)));
 
-        @memcpy(bytes[1..], s);
+        try buf.appendSlice(alloc, s);
 
-        return bytes;
+        return;
     }
 
-    if (s.len <= std.math.maxInt(u8)) { // str8 / bin8
+    inline for (0.., &[_]type{ u8, u16, u32 }) |i, T| {
-        const bytes = try alloc.alloc(u8, 1 + 1 + s.len);
+        if (s.len <= std.math.maxInt(T)) {
+            try buf.ensureUnusedCapacity(alloc, 1 + @sizeOf(T) + s.len);
 
-        bytes[0] = switch (kind) {
+            switch (kind) {
-            .string => 0xd9,
+                .string => try buf.append(alloc, 0xd9 + i),
-            .binary => 0xc4,
+                .binary => try buf.append(alloc, 0xc4 + i),
-        };
-
-        bytes[1] = @as(u8, @intCast(s.len));
-
-        @memcpy(bytes[2..], s);
-
-        return bytes;
             }
 
-    if (s.len <= std.math.maxInt(u16)) { // str16 / bin16
+            std.mem.writeInt(T, try buf.addManyAsArray(alloc, @sizeOf(T)), @intCast(s.len), .big);
-        const bytes = try alloc.alloc(u8, 1 + 2 + s.len);
 
-        bytes[0] = switch (kind) {
+            try buf.appendSlice(alloc, s);
-            .string => 0xda,
-            .binary => 0xc5,
-        };
 
-        std.mem.writeInt(u16, bytes[1..3], @intCast(s.len), .big);
+            return;
-
-        @memcpy(bytes[3..], s);
-
-        return bytes;
         }
-
-    if (s.len <= std.math.maxInt(u32)) { // str16 / bin16
-        const bytes = try alloc.alloc(u8, 1 + 4 + s.len);
-
-        bytes[0] = switch (kind) {
-            .string => 0xdb,
-            .binary => 0xc6,
-        };
-
-        std.mem.writeInt(u32, bytes[1..5], @intCast(s.len), .big);
-
-        @memcpy(bytes[5..], s);
-
-        return bytes;
     }
 
     return switch (kind) {
@@ -180,40 +97,44 @@ fn serialise_raw(alloc: std.mem.Allocator, s: []const u8, comptime kind: enum {
     };
 }
 
+fn serialise_array(alloc: std.mem.Allocator, buf: *std.ArrayListUnmanaged(u8), array: []const Object) SerialiseError!void {
+    _ = alloc;
+    _ = buf;
+    _ = array;
+}
+
 pub fn serialise(alloc: std.mem.Allocator, obj: Object) SerialiseError![]u8 {
+    var buf = std.ArrayListUnmanaged(u8){};
+    defer buf.deinit(alloc);
+
     switch (obj) {
-        .nil => return try alloc.dupe(u8, &[_]u8{0xc0}),
+        .nil => try buf.append(alloc, 0xc0),
         .bool => |b| if (b) {
-            return try alloc.dupe(u8, &[_]u8{0xc3});
+            try buf.append(alloc, 0xc3);
         } else {
-            return try alloc.dupe(u8, &[_]u8{0xc2});
+            try buf.append(alloc, 0xc2);
         },
-        .integer => |i| return try serialise_int(alloc, i),
+        .integer => |i| try serialise_int(alloc, &buf, i),
-        .uinteger => |u| return try serialise_uint(alloc, u),
+        .uinteger => |u| try serialise_uint(alloc, &buf, u),
         .float32 => |f| {
-            const bytes = try alloc.alloc(u8, 1 + 4);
+            try buf.ensureUnusedCapacity(alloc, 1 + 4);
 
-            bytes[0] = 0xca;
+            try buf.append(alloc, 0xca);
 
-            std.mem.writeInt(u32, bytes[1..5], @bitCast(f), .big);
+            std.mem.writeInt(u32, try buf.addManyAsArray(alloc, 4), @bitCast(f), .big);
-
-            return bytes;
         },
         .float64 => |f| {
-            const bytes = try alloc.alloc(u8, 1 + 8);
+            try buf.ensureUnusedCapacity(alloc, 1 + 8);
 
-            bytes[0] = 0xcb;
+            try buf.append(alloc, 0xcb);
 
-            std.mem.writeInt(u64, bytes[1..9], @bitCast(f), .big);
+            std.mem.writeInt(u64, try buf.addManyAsArray(alloc, 8), @bitCast(f), .big);
-
-            return bytes;
         },
-        .string => |s| return try serialise_raw(alloc, s, .string),
+        .string => |s| try serialise_raw(alloc, &buf, s, .string),
-        .binary => |b| return try serialise_raw(alloc, b, .binary),
+        .binary => |b| try serialise_raw(alloc, &buf, b, .binary),
+        .array => |array| try serialise_array(alloc, &buf, array),
         else => unreachable,
     }
 
-    // const bytes = try alloc.alloc(u8, 0);
+    return try buf.toOwnedSlice(alloc);
-
-    // return bytes;
 }