From fec1e508330d7956dfee6d998dc247a711dfd91b Mon Sep 17 00:00:00 2001
From: Jason Phan <jason@ket.so>
Date: Fri, 25 Nov 2022 20:34:16 -0600
Subject: [PATCH] de: Add ignore_unknown_fields attribute

---
 src/attributes.zig                 |  6 +++---
 src/de.zig                         |  2 ++
 src/de/impls/ignored.zig           |  8 ++++----
 src/de/impls/visitor/struct.zig    | 22 ++++++++++++++++++++--
 src/de/interfaces/deserializer.zig |  2 +-
 5 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/attributes.zig b/src/attributes.zig
index 9cf9855c..01ce4071 100644
--- a/src/attributes.zig
+++ b/src/attributes.zig
@@ -18,7 +18,7 @@ const ContainerAttributes = struct {
     // Always error during deserialization when encountering unknown fields.
     //
     // This attribute isn't compatible with `flatten`.
-    //deny_unknown_fields: bool = false,
+    ignore_unknown_fields: bool = false,
 
     // Deserialize this type by deserializing into the given type, then
     // converting.
@@ -71,8 +71,8 @@ const FieldAttributes = struct {
     // Flatten the contents of this field into the container it is
     // defined in.
     //
-    // This attribute is not compatible with the
-    // deny_unknown_fields attribute.
+    // This attribute is not compatible with the ignore_unknown_fields
+    // attribute.
     //flatten: bool = false,
 
     // Serialize and deserialize this field with the given name
diff --git a/src/de.zig b/src/de.zig
index 3cf2f039..90ec21c4 100644
--- a/src/de.zig
+++ b/src/de.zig
@@ -74,6 +74,8 @@ pub const de = struct {
     pub const Seed = @import("de/interfaces/seed.zig").Seed;
     pub const DefaultSeed = @import("de/impls/seed/default.zig").DefaultSeed;
 
+    pub const Ignored = @import("de/impls/ignored.zig").Ignored;
+
     /// Frees resources allocated during Getty deserialization.
     ///
     /// Values that cannot be deallocated, such as `bool` values, are ignored.
diff --git a/src/de/impls/ignored.zig b/src/de/impls/ignored.zig
index f7ced968..62bc1a1c 100644
--- a/src/de/impls/ignored.zig
+++ b/src/de/impls/ignored.zig
@@ -1,19 +1,19 @@
 const std = @import("std");
 
-const de = @import("../../../de.zig");
+const de = @import("../../de.zig").de;
 
 /// Default `getty.de.Seed` implementation.
-const Ignored = struct {
+pub const Ignored = struct {
     const Value = void;
 
-    pub usingnamespace de.de.Seed(
+    pub usingnamespace de.Seed(
         Ignored,
         Value,
         .{ .deserialize = deserialize },
     );
 
     fn deserialize(i: Ignored, allocator: ?std.mem.Allocator, deserializer: anytype) @TypeOf(deserializer).Error!Value {
-        return try deserializer.deserializeIgnored(allocator, i);
+        return try deserializer.deserializeIgnored(allocator, i.visitor());
     }
 
     pub usingnamespace de.Visitor(
diff --git a/src/de/impls/visitor/struct.zig b/src/de/impls/visitor/struct.zig
index 44cd424d..16d66e63 100644
--- a/src/de/impls/visitor/struct.zig
+++ b/src/de/impls/visitor/struct.zig
@@ -31,6 +31,20 @@ pub fn Visitor(comptime Struct: type) type {
                 }
             }
 
+            const ignore_unknown_fields = comptime blk: {
+                if (attributes) |attrs| {
+                    if (@hasField(@TypeOf(attrs), "Container")) {
+                        const attr = attrs.Container;
+
+                        if (@hasField(@TypeOf(attr), "ignore_unknown_fields") and attr.ignore_unknown_fields) {
+                            break :blk true;
+                        }
+                    }
+                }
+
+                break :blk false;
+            };
+
             key_loop: while (try map.nextKey(allocator, []const u8)) |key| {
                 var found = false;
 
@@ -75,9 +89,10 @@ pub fn Visitor(comptime Struct: type) type {
                             }
                         }
 
+                        // Deserialize and assign value to field.
                         switch (field.is_comptime) {
-                            true => @compileError("TODO"),
                             false => @field(structure, field.name) = try map.nextValue(allocator, field.field_type),
+                            true => @compileError("TODO"),
                         }
 
                         seen[i] = true;
@@ -88,7 +103,10 @@ pub fn Visitor(comptime Struct: type) type {
                 }
 
                 if (!found) {
-                    return error.UnknownField;
+                    switch (ignore_unknown_fields) {
+                        true => _ = try map.nextValueSeed(allocator, (de.Ignored{}).seed()),
+                        false => return error.UnknownField,
+                    }
                 }
             }
 
diff --git a/src/de/interfaces/deserializer.zig b/src/de/interfaces/deserializer.zig
index 1140bab0..afd309c2 100644
--- a/src/de/interfaces/deserializer.zig
+++ b/src/de/interfaces/deserializer.zig
@@ -164,7 +164,7 @@ pub fn Deserializer(
                 @compileError("deserializeFloat is not implemented by type: " ++ @typeName(Context));
             }
 
-            /// Hint that the value being deserialized into is expecting to
+            /// Hint that the type being deserialized into is expecting to
             /// deserialize a value whose type does not matter because it is
             /// ignored.
             pub fn deserializeIgnored(self: Self, allocator: ?std.mem.Allocator, visitor: anytype) Return(@TypeOf(visitor)) {