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hishamhmhishamhm
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Accept __lt and __le for > and >= operators.
As in Lua, "A comparison a > b is translated to b < a and a >= b is translated to b <= a."
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‎spec/metamethods/le_spec.lua

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local util = require("spec.util")
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describe("binary metamethod __le using <=", function()
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it("can be set on a record", util.check([[
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local type Rec = record
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x: number
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metamethod __call: function(Rec, string, number): string
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metamethod __le: function(Rec, Rec): boolean
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end
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local rec_mt: metatable<Rec>
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rec_mt = {
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__call = function(self: Rec, s: string, n: number): string
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return tostring(self.x + n) .. s
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end,
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__le = function(a: Rec, b: Rec): boolean
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return a.x <= b.x
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end
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}
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local r = setmetatable({ x = 10 } as Rec, rec_mt)
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local s = setmetatable({ x = 20 } as Rec, rec_mt)
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if r <= s then
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print("yes")
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end
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]]))
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it("can be used on a record prototype", util.check([[
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local record A
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value: number
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metamethod __call: function(A, number): A
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metamethod __le: function(A, A): boolean
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end
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local A_mt: metatable<A>
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A_mt = {
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__call = function(a: A, v: number): A
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return setmetatable({value = v} as A, A_mt)
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end,
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__le = function(a: A, b: A): boolean
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return a.value <= b.value
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end,
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}
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A.value = 10
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if A <= A then
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print("wat!?")
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end
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]]))
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it("can be used via the second argument", util.check([[
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local type Rec = record
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x: number
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metamethod __le: function(number, Rec): Rec
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end
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local rec_mt: metatable<Rec>
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rec_mt = {
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__le = function(a: number, b: Rec): boolean
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return a <= b.x
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end
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}
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local s = setmetatable({ y = 20 } as Rec, rec_mt)
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if 10 <= s then
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print("yes")
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end
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]]))
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it("preserves nominal type checking when resolving metamethods for operators", util.check_type_error([[
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local type Temperature = record
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n: number
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metamethod __le: function(t1: Temperature, t2: Temperature): boolean
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end
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local type Date = record
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n: number
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metamethod __le: function(t1: Date, t2: Date): boolean
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end
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local temp2: Temperature = { n = 45 }
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local birthday2 : Date = { n = 34 }
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setmetatable(temp2, {
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__le = function(t1: Temperature, t2: Temperature): boolean
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return t1.n <= t2.n
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end,
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})
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setmetatable(birthday2, {
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__le = function(t1: Date, t2: Date): boolean
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return t1.n <= t2.n
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end,
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})
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if temp2 <= birthday2 then
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print("wat")
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end
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]], {
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{ y = 26, msg = "Date is not a Temperature" },
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}))
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end)
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describe("binary metamethod __le using >=", function()
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it("can be set on a record", util.check([[
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local type Rec = record
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x: number
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metamethod __call: function(Rec, string, number): string
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metamethod __le: function(Rec, Rec): boolean
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end
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local rec_mt: metatable<Rec>
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rec_mt = {
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__call = function(self: Rec, s: string, n: number): string
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return tostring(self.x + n) .. s
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end,
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__le = function(a: Rec, b: Rec): boolean
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return a.x <= b.x
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end
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}
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local r = setmetatable({ x = 10 } as Rec, rec_mt)
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local s = setmetatable({ x = 20 } as Rec, rec_mt)
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if s >= r then
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print("yes")
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end
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]]))
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it("can be used on a record prototype", util.check([[
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local record A
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value: number
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metamethod __call: function(A, number): A
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metamethod __le: function(A, A): boolean
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end
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local A_mt: metatable<A>
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A_mt = {
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__call = function(a: A, v: number): A
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return setmetatable({value = v} as A, A_mt)
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end,
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__le = function(a: A, b: A): boolean
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return a.value <= b.value
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end,
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}
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A.value = 10
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if A >= A then
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print("wat!?")
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end
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]]))
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it("can be used via the second argument", util.check([[
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local type Rec = record
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x: number
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metamethod __le: function(number, Rec): Rec
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end
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local rec_mt: metatable<Rec>
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rec_mt = {
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__le = function(a: number, b: Rec): boolean
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return a <= b.x
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end
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}
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local s = setmetatable({ y = 20 } as Rec, rec_mt)
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if s >= 10 then
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print("yes")
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end
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]]))
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it("preserves nominal type checking when resolving metamethods for operators", util.check_type_error([[
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local type Temperature = record
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n: number
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metamethod __le: function(t1: Temperature, t2: Temperature): boolean
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end
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local type Date = record
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n: number
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metamethod __le: function(t1: Date, t2: Date): boolean
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end
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local temp2: Temperature = { n = 45 }
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local birthday2 : Date = { n = 34 }
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setmetatable(temp2, {
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__le = function(t1: Temperature, t2: Temperature): boolean
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return t1.n <= t2.n
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end,
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})
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setmetatable(birthday2, {
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__le = function(t1: Date, t2: Date): boolean
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return t1.n <= t2.n
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end,
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})
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if birthday2 >= temp2 then
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print("wat")
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end
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]], {
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{ y = 26, msg = "Date is not a Temperature" },
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}))
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end)

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