Merge pull request #238 from JuliaSymbolics/myb/extend

Add `function_to_expr` to make `toexpr` of calls extendible

Author: shashi

Project.toml

@@ -1,7 +1,7 @@
 name = "SymbolicUtils"
 uuid = "d1185830-fcd6-423d-90d6-eec64667417b"
 authors = ["Shashi Gowda"]
-version = "0.9.1"
+version = "0.9.2"
 
 [deps]
 AbstractAlgebra = "c3fe647b-3220-5bb0-a1ea-a7954cac585d"

src/code.jl

@@ -96,23 +96,38 @@ Base.convert(::Type{Assignment}, p::Pair) = Assignment(pair[1], pair[2])
 
 toexpr(a::Assignment, st) = :($(toexpr(a.lhs, st)) = $(toexpr(a.rhs, st)))
 
-function toexpr(O, st)
-    !istree(O) && return O
-    op = operation(O)
+function_to_expr(op, args, st) = nothing
+
+function function_to_expr(::typeof(^), O, st)
     args = arguments(O)
-    if op === (^) && length(args) == 2 && args[2] isa Number && args[2] < 0
+    if length(args) == 2 && args[2] isa Number && args[2] < 0
         ex = args[1]
         if args[2] == -1
             return toexpr(Term{Any}(inv, [ex]), st)
         else
             return toexpr(Term{Any}(^, [Term{Any}(inv, [ex]), -args[2]]), st)
         end
-    elseif op === (SymbolicUtils.ifelse)
-        return :($(toexpr(args[1], st)) ? $(toexpr(args[2], st)) : $(toexpr(args[3], st)))
-    elseif op isa Sym && haskey(st.symbolify, O)
-        return st.symbolify[O]
     end
-    return Expr(:call, toexpr(op, st), map(x->toexpr(x, st), args)...)
+    return nothing
+end
+
+function function_to_expr(::typeof(SymbolicUtils.ifelse), O, st)
+    args = arguments(O)
+    :($(toexpr(args[1], st)) ? $(toexpr(args[2], st)) : $(toexpr(args[3], st)))
+end
+
+function_to_expr(::Sym, O, st) = get(st.symbolify, O, nothing)
+
+function toexpr(O, st)
+    !istree(O) && return O
+    op = operation(O)
+    expr′ = function_to_expr(op, O, st)
+    if expr′ !== nothing
+        return expr′
+    else
+        args = arguments(O)
+        return Expr(:call, toexpr(op, st), map(x->toexpr(x, st), args)...)
+    end
 end
 
 # Call elements of vector arguments by their name.