From 3d542d32bc5d9fddce2feef7ce577db626e0195c Mon Sep 17 00:00:00 2001
From: Wynand Badenhorst <wynandbadenhorst@hotmail.com>
Date: Tue, 6 Sep 2022 16:25:11 +0100
Subject: [PATCH] Add singleton support (#191)

* Add singleton support

* add back commented test

* bump JSON3 and StructTypes version

* bump structtypes version
---
 Project.toml     | 4 ++--
 src/structs.jl   | 2 +-
 src/write.jl     | 3 +++
 test/runtests.jl | 7 +++++--
 4 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/Project.toml b/Project.toml
index 491ea19..548ab40 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "JSON3"
 uuid = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
 authors = ["Jacob Quinn <quinn.jacobd@gmail.com>"]
-version = "1.9.6"
+version = "1.10.0"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
@@ -12,7 +12,7 @@ UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 Parsers = "0.3, 1, 2"
-StructTypes = "1.5"
+StructTypes = "1.10"
 julia = "1.6"
 
 [extras]
diff --git a/src/structs.jl b/src/structs.jl
index 0f65267..9feac0b 100644
--- a/src/structs.jl
+++ b/src/structs.jl
@@ -1,4 +1,4 @@
-import StructTypes: StructType, CustomStruct, DictType, ArrayType, StringType, NumberType, BoolType, NullType, NoStructType, Struct, OrderedStruct, Mutable, construct, AbstractType, subtypes, subtypekey
+import StructTypes: StructType, CustomStruct, DictType, ArrayType, StringType, NumberType, BoolType, NullType, NoStructType, SingletonType, Struct, OrderedStruct, Mutable, construct, AbstractType, subtypes, subtypekey
 
 struct RawType <: StructType end
 
diff --git a/src/write.jl b/src/write.jl
index d69f77a..1387329 100644
--- a/src/write.jl
+++ b/src/write.jl
@@ -86,6 +86,7 @@ write(::NumberType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringTyp
 write(::NullType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringType(), buf, pos, len, Base.string(T))
 write(::BoolType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringType(), buf, pos, len, Base.string(T))
 write(::AbstractType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringType(), buf, pos, len, Base.string(T))
+write(::SingletonType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringType(), buf, pos, len, Base.string(T))
 write(::NoStructType, buf, pos, len, ::Type{T}; kw...) where {T} = write(StringType(), buf, pos, len, Base.string(T))
 
 write(::NoStructType, buf, pos, len, ::T; kw...) where {T} = throw(ArgumentError("$T doesn't have a defined `StructTypes.StructType`"))
@@ -191,6 +192,8 @@ function write(::BoolType, buf, pos, len, x::Bool; kw...)
     return buf, pos, len
 end
 
+write(::SingletonType, buf, pos, len, x; kw...) = write(StringType(), buf, pos, len, x; kw...)
+
 # adapted from base/intfuncs.jl
 function write(::NumberType, buf, pos, len, y::Integer; kw...)
     x, neg = Base.split_sign(y)
diff --git a/test/runtests.jl b/test/runtests.jl
index 563dfdf..70fdf60 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -38,6 +38,8 @@ struct D
     c::String
 end
 
+struct ParametricSingleton{T} end
+
 abstract type Vehicle end
 
 struct Car <: Vehicle
@@ -436,9 +438,10 @@ obj2 = JSON3.read("""
 @test_throws ArgumentError JSON3.read!("{\"a\": 1, a", A(1, 2, 3, 4))
 @test_throws ArgumentError JSON3.read!("}", A(1, 2, 3, 4))
 
-@test_throws ArgumentError JSON3.read("{}", C)
-@test_throws ArgumentError JSON3.write(C())
+@test JSON3.write(C()) == "\"C()\""
+@test JSON3.write(ParametricSingleton{Int64}()) == "\"ParametricSingleton{Int64}()\""
 
+@test_throws MethodError JSON3.read("{}", C)
 StructTypes.StructType(::Type{C}) = StructTypes.Struct()
 
 @test JSON3.read("{}", C) == C()