Merge pull request #111 from JuliaSymbolics/myb/sub

Move the substitute code from MTK

Project.toml

@@ -1,7 +1,7 @@
 name = "Symbolics"
 uuid = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 authors = ["Shashi Gowda <[email protected]>"]
-version = "0.1.6"
+version = "0.1.7"
 
 [deps]
 AbstractAlgebra = "c3fe647b-3220-5bb0-a1ea-a7954cac585d"

src/num.jl

@@ -60,13 +60,33 @@ function Base.show(io::IO, z::Complex{<:Num})
 end
 
 SymbolicUtils.simplify(n::Num; kw...) = Num(SymbolicUtils.simplify(value(n); kw...))
-function substitute(x::Num, rule::Dict; kw...)
-    rule′ = if any(v -> v isa Num, values(rule))
-        Dict((k => v isa Num ? value(v) : v for (k, v) in rule))
-    else
-        rule
-    end
-    Num(substitute(value(x), rule′; kw...))
+"""
+    substitute(expr, s::Dict)
+
+Performs the substitution on `expr` according to rule(s) `s`.
+# Examples
+```julia
+julia> @parameters t
+(t,)
+julia> @variables x y z(t)
+(x, y, z(t))
+julia> ex = x + y + sin(z)
+(x + y) + sin(z(t))
+julia> substitute(ex, Dict([x => z, sin(z) => z^2]))
+(z(t) + y) + (z(t) ^ 2)
+```
+"""
+substitute(expr::Num, s::Pair; kw...) = Num(substituter(s)(value(expr); kw...)) # backward compat
+substitute(expr::Num, s::Vector; kw...) = Num(substituter(s)(value(expr); kw...))
+substitute(expr::Num, s::Dict; kw...) = Num(substituter(s)(value(expr); kw...))
+# TODO: move this to SymbolicUtils
+substitute(expr, s::Pair; kw...) = substituter([s[1] => s[2]])(expr; kw...)
+substitute(expr, s::Vector; kw...) = substituter(s)(expr; kw...)
+
+substituter(pair::Pair) = substituter((pair,))
+function substituter(pairs)
+    dict = Dict(value(k) => value(v)  for (k, v) in pairs)
+    (expr; kw...) -> SymbolicUtils.substitute(expr, dict; kw...)
 end
 
 SymbolicUtils.symtype(n::Num) = symtype(n.val)