Add support for literals (#10)

Author: vchuravy

Diff for: Project.toml

@@ -1,6 +1,6 @@
 name = "GPUToolbox"
 uuid = "096a3bc2-3ced-46d0-87f4-dd12716f4bfc"
-version = "0.1.0"
+version = "0.2.0"
 
 [compat]
 julia = "1.10"

Diff for: README.md

@@ -23,5 +23,6 @@ This package currently exports the following:
 - `@checked`: Add to a function definition to generate an unchecked and a checked version.
 - `@debug_ccall`: like `ccall` but prints the ccall, its arguments, and its return value
 - `@gcsafe_ccall`: like `@ccall` but marking it safe for the GC to run.
+-  Suffix literals like `1i8` (`i8`, `i16`, `i32`, `u8`, `u16`, `u32`) for constructing literals of a certain type.
 
 For more details on a specific symbol, check out its docstring in the Julia REPL.

Diff for: src/GPUToolbox.jl

@@ -2,5 +2,6 @@ module GPUToolbox
 
 include("simpleversion.jl") # exports SimpleVersion, @sv_str
 include("ccalls.jl") # exports @checked, @debug_ccall, @gcsafe_ccall
+include("literals.jl")
 
 end # module GPUToolbox

Diff for: src/literals.jl

@@ -0,0 +1,27 @@
+export i8, i16, i32, u8, u16, u32
+# helper type for writing smaller than Int64 literals
+
+"""
+    Literal{T}
+
+Construct an object that can be used to convert literals to other types.
+One can use the object in suffix form `1*i8` or `1i8` to perform the conversion.
+
+## Exported constants
+- `i8`: Convert to `Int8`
+- `i16`: Convert to `Int16`
+- `i32`: Convert to `Int32`
+- `u8`: Convert to `UInt8`
+- `u16`: Convert to `UInt16`
+- `u32`: Convert to `UInt32`
+```
+"""
+struct Literal{T} end
+Base.:(*)(x::Number, ::Type{Literal{T}}) where {T} = T(x)
+
+const i8 = Literal{Int8}
+const i16 = Literal{Int16}
+const i32 = Literal{Int32}
+const u8 = Literal{UInt8}
+const u16 = Literal{UInt16}
+const u32 = Literal{UInt32}

Diff for: test/runtests.jl

@@ -43,6 +43,18 @@ using InteractiveUtils
         @test !(sv2 > sv2) # Default
     end
 
+    @testset "Literals" begin
+        @test 1i8 === Int8(1)
+        @test 1i16 === Int16(1)
+        @test 1i32 === Int32(1)
+        @test_throws InexactError 128i8
+
+        @test 1u8 === UInt8(1)
+        @test 1u16 === UInt16(1)
+        @test 1u32 === UInt32(1)
+        @test_throws InexactError 256u8
+    end
+
     @testset "gcsafe_ccall" begin
         function gc_safe_ccall()
             # jl_rand is marked as JL_NOTSAFEPOINT