Methods for get (#744)

Author: mcabbott

Project.toml

@@ -1,6 +1,6 @@
 name = "Compat"
 uuid = "34da2185-b29b-5c13-b0c7-acf172513d20"
-version = "3.30.0"
+version = "3.31.0"
 
 [deps]
 Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"

README.md

@@ -54,6 +54,8 @@ changes in `julia`.
 
 ## Supported features
 
+* `get` accepts tuples and numbers ([#41007], [#41032]) (since Compat 3.31)
+
 * `muladd(A,B,z)` now accepts arrays ([#37065]) (since Compat 3.30)
 
 * `@something` and `@coalesce` as short-circuiting versions of `something` and `coalesce` ([#40729]) (since Compat 3.29)
@@ -248,3 +250,5 @@ Note that you should specify the correct minimum version for `Compat` in the
 [#37454]: https://github.com/JuliaLang/julia/pull/37454
 [#40729]: https://github.com/JuliaLang/julia/pull/40729
 [#37065]: https://github.com/JuliaLang/julia/pull/37065
+[#41007]: https://github.com/JuliaLang/julia/pull/41007
+[#41032]: https://github.com/JuliaLang/julia/pull/41032

src/Compat.jl

@@ -1012,6 +1012,26 @@ if VERSION < v"1.7.0-DEV.1088"
     export @something, @coalesce
 end
 
+import Base: get, Dims, Callable
+
+# https://github.com/JuliaLang/julia/pull/41007
+if VERSION < v"1.7.0-DEV.1220"
+    get(f::Callable, A::AbstractArray, i::Integer) = checkbounds(Bool, A, i) ? A[i] : f()
+    get(f::Callable, A::AbstractArray, I::Tuple{}) = checkbounds(Bool, A) ? A[] : f()
+    get(f::Callable, A::AbstractArray, I::Dims) = checkbounds(Bool, A, I...) ? A[I...] : f()
+
+    get(t::Tuple, i::Integer, default) = i in 1:length(t) ? getindex(t, i) : default
+    get(f::Callable, t::Tuple, i::Integer) = i in 1:length(t) ? getindex(t, i) : f()
+end
+
+# https://github.com/JuliaLang/julia/pull/41032
+if VERSION < v"1.7.0-DEV.1230"
+    get(x::Number, i::Integer, default) = isone(i) ? x : default
+    get(x::Number, ind::Tuple, default) = all(isone, ind) ? x : default
+    get(f::Callable, x::Number, i::Integer) = isone(i) ? x : f()
+    get(f::Callable, x::Number, ind::Tuple) = all(isone, ind) ? x : f()
+end
+
 include("iterators.jl")
 include("deprecated.jl")
 

test/runtests.jl

@@ -1016,3 +1016,54 @@ end
     @test @coalesce(1, error("failed")) === 1
     @test_throws ErrorException @coalesce(missing, error("failed"))
 end
+
+@testset "get" begin
+     A = reshape([1:24...], 4, 3, 2)
+     B = reshape([1:24...], 4, 3, 2)
+
+     global c = 0
+     f() = (global c = c+1; 0)
+     @test get(f, A, ()) == 0
+     @test c == 1
+     @test get(f, B, ()) == 0
+     @test c == 2
+     @test get(f, A, (1,)) == get(f, A, 1) == A[1] == 1
+     @test c == 2
+     @test get(f, B, (1,)) == get(f, B, 1) == B[1] == 1
+     @test c == 2
+     @test get(f, A, (25,)) == get(f, A, 25) == 0
+     @test c == 4
+     @test get(f, B, (25,)) == get(f, B, 25) == 0
+     @test c == 6
+     @test get(f, A, (1,1,1)) == A[1,1,1] == 1
+     @test get(f, B, (1,1,1)) == B[1,1,1] == 1
+     @test get(f, A, (1,1,3)) == 0
+     @test c == 7
+     @test get(f, B, (1,1,3)) == 0
+     @test c == 8
+     @test get(f, TSlow([]), ()) == 0
+     @test c == 9
+
+     @test get((5, 6, 7), 1, 0) == 5
+     @test get((), 5, 0) == 0
+     @test get((1,), 3, 0) == 0
+     @test get(()->0, (5, 6, 7), 1) == 5
+     @test get(()->0, (), 4) == 0
+     @test get(()->0, (1,), 3) == 0
+
+    for x in [1.23, 7, ℯ, 4//5] #[FP, Int, Irrational, Rat]
+         @test get(x, 1, 99) == x
+         @test get(x, (), 99) == x
+         @test get(x, (1,), 99) == x
+         @test get(x, 2, 99) == 99
+         @test get(x, 0, pi) == pi
+         @test get(x, (1,2), pi) == pi
+         c = Ref(0)
+         @test get(() -> c[]+=1, x, 1) == x
+         @test get(() -> c[]+=1, x, ()) == x
+         @test get(() -> c[]+=1, x, (1,1,1)) == x
+         @test get(() -> c[]+=1, x, 2) == 1
+         @test get(() -> c[]+=1, x, -1) == 2
+         @test get(() -> c[]+=1, x, (3,2,1)) == 3
+    end
+end