patch for `MLStyle.jl`

testset.jl

# test driven development
# TestSet for `@when` + `@otherwise`
using MLStyle
using Test
using Random

#=
    Test help macro/functions
=#

## PPAP
# I have a macro
# I have a @test_throws
# Eh~
# LoadError!

# no more LoadError! Get the real error.
macro test_macro_throws(errortype, m)
    :(
        @test_throws $errortype try 
                @eval $m 
            catch err
                while err isa LoadError
                    err = err.error
                end
                throw(err)
            end
    )
end

function genRandVal(; 
        hasInt::Bool=true, 
        hasBool::Bool=true,
        hasFloat::Bool=true,
        hasNumber::Bool=true,
        hasString::Bool=true, 
        hasSymbol::Bool=true
    )
    if hasNumber;  hasInt = hasFloat = true; end

    rnd = []
    if hasInt;      push!(rnd, rand(Int)); end
    if hasBool;     push!(rnd, bitrand()[1]); end
    if hasFloat;    push!(rnd, rand()); end
    if hasString;   push!(rnd, randstring()); end
    if hasSymbol;   push!(rnd, randstring('a':'z') |> Symbol); end

    shuffle(rnd)[1]
end

macro rand_test_eq(f, times)
    # TODO
end



#=
    TestSet
=#
@testset "@when" begin
@testset "Only @when" begin
    @test 2 == @when let (a, 1) = (2, 1)
        a
    end
    # @match (2, 1) begin
    #     (a, 1)  => a
    #     _       => nothing
    # end
    
    # for more test, see `test\when.jl`
end


@testset "@when in @when" begin
    
    function f1(args)
        x = Tuple(args)
        @when (a, 1) = x begin
            a
        @when (b, 2)
            (2, b)
        end
        # @match x begin
        #     (a, 1)  => a
        #     (b, 2)  => (2, b)
        #     _       => nothing
        # end
    end
    # case: a
    @test f1(111, 1) == 111
    @test f1(222, 1) == 222
    # case: (2, b)
    @test f1(111, 2) == (2, 111)
    @test f1(222, 2) == (2, 222)
    
    function f2(args)
        x = Tuple(args)
        @when (a, 1) = x begin
            a
        @when (b, 2)
            (:b, b)
        @when (c, 3)
            (:c, c)
        end
        # @match x begin
        #     (a, 1)  => a
        #     (b, 2)  => (:b, b)
        #     (c, 3)  => (:c, c)
        #     _       => nothing
        # end
    end
    @test f2(10, 1) == 10       # case: a
    @test f2(20, 2) == (:b, 20) # case: (:b, b)
    @test f2(30, 3) == (:c, 30) # case: (:c, c)
    
end


@testet "@when + @otherwise" begin
    function f1(args)
        x = Tuple(args)
        @when (a, 1) = x begin
            a
        @otherwise
            x
        end
        # @match x begin
        #     (a, 1)  => a
        #     _       => x
        # end
    end
    @test f1(1) == (1, )    # case: x
    @test f1(1, 2) == (1, 2)# case: x
    @test f1(2, 1) == 2     # case: a
    
    function f2(args)
        x = Tuple(args)
        @when (a, 1) = x begin
            a
        @when (b, 2)
            (:b, b)
        @when (c, 3)
            (:c, c)
        @otherwise
            x
        end
        # @match x begin
        #     (a, 1)  => a
        #     (b, 2)  => (:b, b)
        #     (c, 3)  => (:c, c)
        #     _       => x
        # end
    end
    @test f2(1) == (1, )        # case: x
    @test f2(1, 2) == (1, 2)    # case: x
    @test f2(10, 1) == 10       # case: a
    @test f2(20, 2) == (:b, 20) # case: (:b, b)
    @test f2(30, 3) == (:c, 30) # case: (:c, c)
end


@testet "@when + @otherwise with many bidings" begin
    function f1(xy, z)
        @when let (a, 1) = xy,
                  5      = z
            a
        @otherwise
            0   # default value
        end
        # @match xy begin
        #     (a, 1) => begin
        #         @match z begin
        #             5 => a
        #             _ => 0    # Always return the default value
        #         end
        #     end
        #     _      => 0       # Always return the default value
        # end
    end
    @test f1((123, 1), 5) => 123    # case: a
    @test f1((123, 3), 5) => 0      # not match `(a, 1) = xy`
    @test f1((123, 1), 1) => 0      # not match `5 = z`

    #=
        TODO: Need discuss!!!!
        In fact I would like to throw a syntax_err for the following situations.
    =#

    function f11(xy, z)
        @when let (a, 3) = xy,
                  5      = z
            a
        @when (a, 4)    # ambiguous!
            4
        @otherwise
            0
        end
        # @syntax_err "Syntax is ambiguous!"
    end

    function f2(xy, z)
        @when let (a, 3) = xy,
                  5      = z
            a
        @when (a, 4) = xy
            4
        @otherwise
            0
        end
        # @match xy begin
        #     (a, 1) => begin
        #         @match z begin
        #             5 => a
        #             _ => 
        #                 @match xy begin
        #                     (a, 4)  => 4
        #                     _       => 0
        #                 end
        #         end
        #     end
        #     (a, 4) => 4
        #     _      => 0
        # end
    end

    function f3(xy, z)
        @when let (a, 3) = xy,
                  5      = z
            a
        @when 6 = z
            6
        @otherwise
            0
        end
        # @match xy begin
        #     (a, 1) =>
        #         @match z begin
        #             5 => a
        #             6 => 6
        #             _ => 
        #                 @match z begin
        #                     6 => 6
        #                     _ => 0
        #                 end
        #         end
        #     _       => 
        #         @match z begin
        #             6 => 6
        #             _ => 0
        #         end
        # end
    end

    function f23(xy, z)
        @when let (a, 3) = xy,
                  5      = z
            a
        @when (a, 4) = xy
            4
        @when 6 = z
            4
        @otherwise
            0
        end
        # Too complex...
    end

    function f32(xy, z)
        @when let (a, 3) = xy,
                  5      = z
            a
        @when 6 = z
            4
        @when (a, 4) = xy
            4
        @otherwise
            0
        end
        # Too complex...
    end
end

when-else.jl

#=
    Test case
=#

x = (5, 2)
y = (6, 1)

# simple `@when`
syntax01 = :(# @when 
let (a, 2) = x
    a
end)
# syntax02 = :(@when (a, 2) = x begin a; end)

function m0(syntax)
@match syntax begin
    Expr(:let, bd, ret) => 
        @match bd begin
            :($a = $b) =>
                @format [a, b, ret] quote
                    @match b begin
                        a => ret
                        _ => nothing
                    end
                end
            a => :(let $a; $ret end)
        end
    _ => error("[m0] nothing matched")
end
end

res01 = :(
@match x begin
    (a, 2)  => a
    _       => nothing
end)


# `@when` + `let`
syntax11 = :(# @when 
let (a, 2) = x, 
    (b, 1) = y
    a, b
end)

function m1(syntax)
@match syntax begin
    Expr(:let, Expr(:block, bds...), ret) => 
        foldr(bds, init=ret) do each, last
            @match each begin
                :($a = $b) =>
                    @format [a, b, last] quote
                        @match b begin
                            a => last
                            _ => nothing
                        end
                    end
                a => :(let $a; $last end)
            end
        end
    _ => error("[m1] nothing matched")
end
end

res11 = :(
@match x begin
    (a, 2)  => begin
        @match y begin
            (b, 1)  => (a, b)
            _       => nothing
        end
    end
    _       => nothing
end)


# `@when` in `@when`
syntax21 = :(# @when
let (a, 2) = x
    a, a, a
@when (b, 1) = x
    b
end)
syntax22 = :(# @when
let (a, 1) = x
    a
@when (b, 2) = x
    b
@when (c, 3) = x
    c
end)

function m2(syntax)
@match syntax begin  
Expr(:let, 
    bd,
    Expr(:block, 
        ::LineNumberNode,
        ret1 || Expr(:block, ret1), 
        ::LineNumberNode,
        Expr(:macrocall, 
            name, 
            ::LineNumberNode,
            Expr(:(=), case2, val2)
        ), ::LineNumberNode,
        ret2 || Expr(:block, ret2)
    )
) =>
    # @show bd ret1 ret2 " "
    @match bd begin
        :($a = $b) => begin
            @format [a, b, ret1, ret2, case2, val2] quote
                @match b begin
                    a => ret1
                    case2 => val2
                    _ => nothing
                end
            end
        end

        a => :(let $a; $last end)
    end

_ => error("[m3] nothing matched")
end
end

res21 = :(
@match x begin
    (a, 2) => a
    (b, 2) => b
    _ => nothing
end)
res22 = :(
@match x begin
    (a, 2) => a
    (b, 2) => b
    (c, 3) => c
    _ => nothing
end)


# `@otherwise`
syntax31 = :(# @when
let (a, 2) = x
    a
@otherwise
    x
end)

function m3(syntax)
@match syntax begin  
Expr(:let, 
    bd,
    Expr(:block, 
        ::LineNumberNode,
        ret1 || Expr(:block, ret1), 
        ::LineNumberNode,
        Expr(:macrocall, name, ::LineNumberNode), ::LineNumberNode,
        ret2 || Expr(:block, ret2)
    )
) =>
    # @show bd ret1 ret2 " "
    @match bd begin
        :($a = $b) => begin
            @format [a, b, ret1, ret2] quote
                @match b begin
                    a => ret1
                    _ => ret2
                end
            end
        end

        a => :(let $a; $last end)
    end

_ => error("[m3] nothing matched")
end
end

res31 = :(
@match x begin
    (a, 2)  => a
    _       => x
end)


# `@when` + `@otherwise`
syntax41 = :(# @when
let (a, 2) = x
    a
@when (b, 2) = x
    b
@otherwise
    x
end)

# TODO

res41 = :(
@match x begin
    (a, 2)  => a
    (b, 2)  => b
    _       => x
end)




#=
  match macro with specific name???
=#
syntax50 = :(@when x begin end)
@when Expr(:macrocall, name, body...) = syntax50 begin @show name; end
@when Expr(:macrocall, Symbol("@when"), body...) = syntax50 begin @show name; end # error
@when :(@when para body) = syntax50 begin @show para body; end  # ret nothing