From a984dc501804613e2c5f726c6daaaf4cf040c1ec Mon Sep 17 00:00:00 2001
From: Penelope Yong <penelopeysm@gmail.com>
Date: Thu, 12 Sep 2024 17:56:41 +0100
Subject: [PATCH] Conversion of VarName to/from string

---
 src/AbstractPPL.jl |  1 +
 src/varname.jl     |  2 ++
 test/varname.jl    | 30 ++++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/src/AbstractPPL.jl b/src/AbstractPPL.jl
index 775576a..012364f 100644
--- a/src/AbstractPPL.jl
+++ b/src/AbstractPPL.jl
@@ -8,6 +8,7 @@ export VarName,
     subsumes,
     subsumedby,
     varname,
+    varname_from_str,
     vsym,
     @varname,
     @vsym
diff --git a/src/varname.jl b/src/varname.jl
index b4960ef..dc12c76 100644
--- a/src/varname.jl
+++ b/src/varname.jl
@@ -663,6 +663,8 @@ function drop_escape(expr::Expr)
     return Expr(expr.head, map(x -> drop_escape(x), expr.args)...)
 end
 
+varname_from_str(str::AbstractString) = eval(drop_escape(varname(Meta.parse(str))))
+
 function _parse_obj_optic(ex)
     obj, optics = _parse_obj_optics(ex)
     optic = Expr(:call, Accessors.opticcompose, optics...)
diff --git a/test/varname.jl b/test/varname.jl
index d0e3de7..4ca7912 100644
--- a/test/varname.jl
+++ b/test/varname.jl
@@ -137,4 +137,34 @@ end
         @inferred get(c, @varname(b.a[1]))
         @inferred Accessors.set(c, @varname(b.a[1]), 10)
     end
+
+    @testset "roundtrip conversion to/from string" begin
+        # Static optics
+        vns = [
+            @varname(x),
+            @varname(x.a),
+            @varname(x[1]),
+            @varname(x[1:10]),
+            @varname(x[1, 2]),
+            @varname(x[1, 2:5]),
+            @varname(x[:]),
+            @varname(x.a[1]),
+            @varname(x.a[1:10]),
+            @varname(x[1].a),
+        ]
+        for vn in vns
+            @test varname_from_str(repr(vn)) == vn
+        end
+
+        # Post-concretisation
+        x = ones(10)
+        vn = @varname(x[begin:end])
+        @test varname_from_str(repr(vn)) == vn
+
+        # When forcing concretisation
+        vn = @varname(x[:], true)
+        @test_broken varname_from_str(repr(vn)) == vn
+        dump(varname_from_str(repr(vn)))
+        dump(vn)
+    end
 end